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SSWMM96 User`s Manual

1. SSWMM96 DOCUMENTATION EXAMPLE DATA RUNOFF BLOCK SUBCATCHMENT OVERLAND FLOW HYDROGRAPHS CONTINUITY CHECK FOR SUBCATCHMEMT SIMULATION SSWMM96 RUNOFF BLOCK WATERSHED AREA ACRES 171 000 TOTAL RAINFALL CINCHES 1 663 TOTAL INFILTRATION 5 630 TOTAL WATERSHED OUTFLOW INCHES 995 TOTAL SURFACE 5 END STORM 5 036 ERROR IN CONTINUITY PERCENTAGE OF RAINFALL 142 2 21 RUNOEFF Block TABLE 2 7 continued SSWMM96 DOCUMENTATION EXAMPLE DATA RUNOFF BLOCK SUBCATCHMENT OVERLAND FLOW HYDROGRAPHS PEAK FLOWS FROM SUBCATCHMENTS SUBCATCHMENT PEAK TIME ELEMENT CFS HR MIN 1031 7 48 12 50 1051 8 27 12 45 1061 13 25 12 50 1062 15 26 12 50 1071 20 09 12 50 1072 7 93 12 50 1081 24 47 12 50 1082 8 06 12 50 1083 10 07 12 50 2 22 RUNOFF CONVEYANCE ROUTING OUTPUT FILE RUNOFF BLOCK OF SSWMM96 DEVELOPED BY RUNOFF Block TABLE 2 8 METCALF EDDY INC UNIVERSITY OF FLORIDA WATER RESOURCES ENGINEEERS INC SEPTEMBER 1970 UPDATED BY UNIVERSITY OF FLORIDA JUNE 1973 HYDROLOGIC ENGINEERING CENTER CORPS OF ENGINEERS MISSOURI RIVER DIVISION CORPS OF ENGINEERS SEPTEMBER 1974 BOYLE ENGINEERING CORPORATION JULY 1985 MONTGOMERY WATSON AMERICAS INC JAN 1996 SSWMM96 DOCUMENTATION EXAMPLE DATA RUNOFF BLOCK CONVEYANCE ROUTING HYDROGRAPH ROUTING ONLY 1
2. n eene 3 11 3 4 2 4 Junction Elements Data Section ss esses 3 13 3 4 2 5 Storage Junction Data Section n annassa 3 14 342 6O0rnficeDataSectlon eee 3 15 3427 Weir Data Section za oboe netos A IR e 3 16 3 42 8 Pump Data Section t E ERREUR IRR EROS bnm 3 16 3 4 2 9 Free Outfall Data Sections cse eite cei e bee tidie 3 18 3 4 2 10 Outfall with Flap Gate Section sse 3 19 3 4 2 11 Tide or Stage Boundary Data Section a 3 19 3 4 2 12 Initial Flows Velocities and Heads Data Section 3 20 3 4 2 13 User Defined Inflow Hydrograph 3 21 3 5 Outp t DESCHpL N eerte rp e e RR rero e us 3 22 3 5 1 Definition of Output Variables 018 00000000 00000500 3 22 3 6 Debugging and Stabilization Hints sess eere ener enne 3 30 3 6 1 Important Limitations svc se ecce eee RU 3 30 3 6 2 Calibration to oat rt Ee be ite lam les tare 3 31 3 6 3 Fatal Error Messages ce WIESO Dated s aep D E rae ECRIRE RET TR 3 32 3 6 3 Termination of Execution Error Message 3 37 3 6 4 Warning M sSa86S ms laaan lll eek ll 3 38 3 1 EXTRAN G ADS kod ion isa GONNA ON E
3. an m anl SANA LL Tate er 3 3 3 5 Onificesiand Wits sasana a Sal le en Ba oan 3 4 3 6 Pump Operation Curves sede lil selen iie anla adas li 3 5 3 7 We Input Definiti nsu ml alada deo dme 3 16 a Full page figures are on page following number shown in this list Hi SECTION 1 BACKGROUND This section of the SSWMM96 User s Manual gives a brief history of the evolution of the EPA SWMM model into the RUNOFF and EXTRAN blocks that make up SSWMM96 Figure 1 1 is a schematic illustrating the way that the RUNOFF and EXTRAN blocks are related As indicated in the figure the RUNOFF block watershed simulation is first used to develop runoff hydrographs for each subcatchment in the watershed Then the RUNOFF block conveyance simulation may optionally be used to perform hydrologic routing through various conveyance elements Finally the EXTRAN block is used to dynamically route the hydrographs through the remainder of the conveyance system usually the major interceptors and trunk lines Figure 1 2 is a conceptual view of the relationship between RUNOFF and EXTRAN As shown in the figure RUNOFF is used to simulate the hydrologic parameters for areas Aj and Ao along with the gutter or pipe hydrologic routing through Ap These hydrologic parameters in combination with a precipitation hyetograph are used by RUNOFF to develop runoff hydrographs Oj and Q for areas Aj and A5 The hydrograph from A is routed
4. ERROR 2 THE HYDROGRAPH OF SUBCATCHMENT XX WAS NOT STORED The user specified subcatchment XX in the Subcatchment Conveyance Element Relationships section A hydrograph for this subcatchment is not found in the input hydrograph data for this run Check 2 28 RUNOFF Block input data and modify Subcatchment Conveyance Element Relationships section as needed 3 ERROR 3 STOPPED BY UNMATCHING CONVEYANCE ELEMENT NO XX Conveyance element XX was specified in the Conveyance Element Data Section for which there is no corresponding input hydrograph or vice versa Check input data and either remove conveyance element XX or change input hydrograph number 4 ERROR 4 STOPPED BY MORE THAN 10 CONVEYANCE ELEMENTS CONNECTING TO CONVEYANCE ELEMENT NO XX Up to 10 conveyance elements may connect be tributary to another conveyance element Conveyance element XX has more than 10 tributary conveyance elements Check input data and modify connecting conveyance elements 5 WARNING 2 ORDER OF TREE STRUCTURE NGUT VALUE DECREASES THROUGH DIVERSION FROM CONVEYANCE ELEMENT TO CONVEYANCE ELEMENT YY COMPUTATION THROUGH DIVERSION WILL LAG ONE TIME STEP UNLESS CONVEYANCE ELEMENT DATA ARE MODIFIED TO REVERSE DIVERSION Diversion specified from conveyance element XX to conveyance element YY in the Conveyance Element Data Section may be in the wrong direction Check input data and modify as necessary 6 WAR
5. N z ki s Fa ee m V gt gt gt SAN VERS STORAGE 3 INFLOW HYDROGRAPH gt AN 9 A LL x z gt ji HOURS FIGURE 2 4 SPECIAL FLOW ROUTING CONVEYANCE ELEMENTS n 020 overflow 20 e 16 feet E j5 n 015 gutter 47A 5 feet 4 feet FULL STREET TWO GUTTER W O STORM SEWER FOR ONE GUTTER USE ONE HALF OF SECTION 020 overflow 4A feet FULL STREET WITH STORM SEWER FIGURE 2 5 TRAPEZOIDAL APPROXIMATIONS FOR STREETS RUNOFF Block 2 5 INPUT DATA PREPARATION The input data format for the RUNOFF block has been designed to be flexible and to allow the user to insert notes and comments as part of the input RUNOEFF ignores any input line beginning with an asterisk in the first column The user may place comment lines at any point in the input except where the program is expecting a certain number of input values such as during the specification of a pump curve All input variables are entered in free format meaning that the precise column in which a particular variable is entered is not important What is important is the order in which the data is entered the grouping in which it is entered and presence of a space or comma between each data value For each type of data 1 subcatchment data or rainfall data RUNOFF expects each line to contain a specified number of data values If more than that number of values are entered they will be ign
6. HYDROGRAPHIC amp HYDRAULIC OUTPUT FIGURE 1 1 MW SWMM HYDROGRAPH SIMULATION SCHEMATIC Options to Estimate Flow Q from Areas and 1 Estimate Q from a combined area A plus A using the watershed element in the RUNOFF Block 2 Estimate Q and Q separately then route Q and combine it with Q Routing Options i Conveyance Element in RUNOFF Block ii EXTRAN Block 3 Major Trunk Routing in EXTRAN Block FIGURE 1 2 CONCEPTUAL RELATIONSHIP OF RUNOFF AND EXTRAN Background presentation Input is now free format with input variable descriptions in the input itself Output formats were clarified and expanded to meet the needs of the City 1 1 2 EXTRAN Block EXTRAN block used in SSWMM96 was originally developed by Water Resources Engineers WREJ for the City of San Francisco in 1973 In 1974 EPA acguired this model and incorporated it into the SWMM package calling it the Extended Transport Model EXTRAN to distinguish it from the TRANSPORT Module developed by the University of Florida as part of the original SWMM package Extensive modifications were made to the EXTRAN block by BEC during their work on the City of Sacramento s combined sewer system These modifications included overflow simulation components to simulate street flooding simulation of various pumping plant configurations and a modified numerical solution technique for quicker more accurate results Montgome
7. lt 0 Inflow restricted to specified peak flow Excess is sent to storage and then lost from system A blank line or 99999 indicates the end of the Junction Data none 3 4 2 5 Storage Junction Data Section Regular storage junctions in EXTRAN are defined as uniform tanks that can be described by a crown elevation and a storage capacity in cubic feet per foot of junction height Irregular storage junctions can have any shape and are represented by a table of area depth data pairs Input data for both types of storage junction are illustrated in the Storage Junction Data Section in Table 3 1 3 14 Name JSTORE ZCROWN ASTORE NUMV VCURVE 99999 EXTRAN Block Description Identification number of Junction containing storage facility Must already have been listed in the Junction Elements Data Section Junction crown elevation in feet This elevation must be higher than the crown of any pipe that enters the storage Junction Storage volume parameter gt 0 Storage volume per foot of Junction height in cubic feet for a regular storage Junction 1 Irregular storage junction Area stage data pairs follow Number of area stage data pairs for irregular storage junction 0 Required for regular storage junctions gt Number of area stage data pairs on next lines For irregular storage junction area stage data pairs Area in square feet and stage in feet above junction invert A blank line or 99999
8. NUMBER OF TIME STEPS NSTEP 179 ROUTING TIME INTERVAL IN MINUTES DELT SSWMM96 DOCUMENTATION EXAMPLE DATA RUNOFF BLOCK CONVEYANCE ROUTING HYDROGRAPHS FROM SSWMMM95 RUNOFF ARE LISTED FOR THE FOLLOWING 5 00 HORIZ TO VERT L 0 5 0 0 0 0 1083 SIDE MANNING 9 SUBCATCHMENTS AVERAGE VALUES WITHIN TIME INTERVALS SLOPES DEPTH FT 5 00 4 00 4 00 6 00 TIMECHR MIN 1031 1051 1061 1062 1071 1072 1081 1082 8 55 0 00 0 00 0 00 0 00 0 00 0 00 0 00 0 00 9 00 0 00 0 00 0 00 0 00 0 00 0 00 0 00 0 00 9 05 0 00 0 00 0 00 0 00 0 00 0 00 0 00 0 00 9 10 0 00 0 00 0 00 0 00 0 00 0 00 0 00 0 00 Output has been abridged 23 35 0 00 0 00 0 01 0 01 0 03 0 01 0 03 0 00 23 40 0 00 0 00 0 01 0 01 0 03 0 01 0 03 0 00 23 45 0 00 0 00 0 01 0 01 0 03 0 01 0 03 0 00 Page 3 SSWMM96 DOCUMENTATION EXAMPLE DATA RUNOFF BLOCK CONVEYANCE ROUTING WIDTH OVERBANK SURCHARGE ELEMENT ELEMENT NDP NP OR DIAM LENGTH SLOPE JK NUMBER CONNECTION FT FT FT FT 103 105 0 1 CHANNEL 10 0 450 0 0100 0 105 0 5 2 4 0 600 0 0100 345 DIVERSION CONVEYANCE ELEMENT NUMBER 345 TOTAL Q VS DIVERTED Q IN CFS 0 0 0 0 10 0 5 0 20 0 10 0 30 0 15 0 106 0 5 2 4 0 800 0 0100 0 RESERVOIR STORAGE ACRE FEET VS SPILLWAY OUTFLOW 0 0 0 0 2 0 5 0 4 0 10 0 6 0 15 0 107 0 5 1 CH
9. City of Sacramento User s Manual for Sacramento Stormwater Management Model SSWMM96 January 1996 City of Sacramento Stormwater Management Model SSWMM96 User s Manual January 1996 By Montgomery Watson 777 Campus Commons Road Suite 250 Sacramento CA 95825 TABLE OF CONTENTS PAGE SECTION T BACKGROUND u Z aa lele eet a ih mn ra il sas 1 1 1 1 History of SSWMMI 6 RR Su A OO a usus s 1 1 1 RUNOFE Block uq z EO AO s nen COO K AC 1 1 I E2 EXTRAN BIOCK ui e RZE a 1 2 SECTION RUNOFE BLOCK 3 lme ad Wid e Ba naz me le 2 1 2 1 Introduction a z oe d GAR ep wa 2 1 2 2 SubcatchmentParametersi 4 ve A ee e i e e e Ier Den e e Te Rede 2 2 2 2 Drainage Area oret REO ERO hiya RR RES 2 2 2 2 2 Subcatchment Width RAR EE E UE EA aate aus 2 2 2 23 Slope osse eie e RR RR RERO eB RO E RIEN 2 3 2 2 A Tr pervioUsness cine e EO UR E ec de i t zan dad ni ss 2 3 2 2 5 Roughness Coefficient Manning s n 2 4 2 2 6 Depression Storage uu sus asa ER RO RR EVI ee eo Hemen s ittis 2 5 2 27 Infiltration is se RI Ade e e Hie ed 2 6 2 3 Conveyance cedet re rer eo GS rs 2 7 2 3 T Conveyance Elemerits Ne RR PER 2 7 2 3 2 Special Flow Routing Elements ea ae aaa aa
10. SD QD SD Flow in conveyance element N in cfs QD Flow diverted to conveyance element JK in cfs 2 17 RUNOFF Block Detention Basin Option Input Line s JK 0 and NDP gt 0 NDP data pairs describing detention basin storage versus outflow discharge SD QD SD Storage in detention basin in acre feet QD Outflow from detention basin in cfs Inflow Hydrograph Option Input Line s JK 1 and NDP gt 0 NDP data pairs of time versus inflow SD QD SD Time in hours QD Inflow to the conveyance element in cfs 99999 A blank line or 99999 indicates the end of the Conveyance none Element Data Section Conveyance Element Save and Print Control contains the parameters to control the disposition and printing of the conveyance element hydrographs created by RUNOFF This section is required for all runs using conveyance elements Name Description Default N21 If N21 gt I hydrographs from each conveyance element are none to be saved for subsequent routing in EXTRAN NPRNT Number of conveyance elements for which hydrographs are none to be printed INTERV Number of timesteps between printing 1 IPRNT x If NPRNT gt 0 conveyance element numbers for which none values are to be printed End of Input Line CNAME ENDPROGRAM indicates the end of input data none 2 6 OUTPUT DESCRIPTION Every effort has been made to make the output from the RUNOFF block easy to understand with headings for each of the output se
11. TABLE 2 5 SUBCATCHMENT SIMULATION INPUT TEMPLATE This is a subcatchment overland flow simulation input file for the RUNOFF block of SSWMM96 5 SSWMM96 DOCUMENTATION EXAMPLE DATA RUNOFF BLOCK SUBCATCHMENT OVERLAND FLOW HYDROGRAPHS SYSTEM PARAMETERS SECTION free input format 0 IOPT 0 for overland flow 179 NSTEP Number of timesteps to be calculated 8 55 NHR NMN Hour and minutes of start of storm 5 0 DELT Integration period min NRGAG Number of rain gage hyetographs PCTZER Percent of impervious area with zero detention IPFlag 1 1 for rainfall parameters printout IPFlag 2 1 for subarea data printout IPFlag 3 1 for output hydrographs printout IPKCHK 1 for printed summary of peak flows 75 PRPRPROR RAINFALL PARAMETERS SECTION This section required for subcatchment overland flow simulation 0 NHISTO No of data points for each hyetograph 10 0 THISTO Time interval between values Rainfall data ten year storm Intensity in inches hour for each timestep 0 0 0 0 0 13 0 13 0 13 0 13 0 13 0 13 0 16 0 16 0 16 0 16 0 16 0 16 0 28 0 30 0 36 0 52 1 98 0 48 0 36 0 36 0 36 0 36 0 36 0 36 0 20 0 20 0 20 0 20 0 20 0 20 0 16 0 16 0 16 0 16 0 16 0 16 0 0 0 0 0 0 0 0 SUBCATCHMENT DATA SECTION One line for each subcatchment IK N NGOTO WWIDTH WAREA PCIMP WSLOPE 5 6 7 8 WLMAX WLMIN DECAY Hyeto Sub Convev Sub Sub 96 Sub Manni
12. To indicate end of Weir Data Section enter 99999 99999 PUMP DATA SECTION Data for Pump Stations with on and off switch operation Down Wet No Junc strm Pump well of On Off Capacity a b depth No Junc Type Vol Pumps Stage Stage a b 1 pump and off stages represent wet well volume 20 0 1 100 1 160 120 230 0 0 0 Type 2 pump on and off stages represent depth above invert of junction 20 0 2 0 3 4 1 2 0 114 0 0 0 5 2 2 0 114 0 0 0 6 3 3 0 114 0 0 0 Data for Pump Stations with variable speed pumps Down Wet Junc strm Pump well Enter No 2 Type Vol Zero Stage Cap 1 pump stages represent wet well volume 20 0 1 120 0 120 0 130 0 0 150 93 200 0 294 300 0 720 Type 2 pump stages represent depth above invert of junction 20 0 2 0 0 0 0 3 86 0 5 86 93 6 83 294 7 86 720 10 86 928 3 pump pumpback from storage id Beginning Maximum d Down Storage Storage Maximum Junc strm Pump Volume Enter Volume Pumpback Pumpback No Junc cu ft Zero cu ft Conduit Rate 89002 9071 3 0 0 0 1000000 51 10 To indicate end of Pump Data Section enter 99999 99999 3 8 Revised January 1996 EXTRAN Block TABLE 3 1 continued FREE OUTFALL DATA SECTION Junction Sequence Number Number 20 L To indicate end of Free Outfall Data Section ent
13. be determined for each development If rooftops are treated as draining to pervious areas then those pervious areas will be subject to more incoming water than they would get from rainfall alone This will probably produce more runoff from the pervious area quicker than if rainfall alone was considered If this effect is considered to be important it can be modeled by altering the infiltration parameters lowering infiltration rates for the pervious areas receiving roof runoff For example if all downspouts in a residential area with type C soils are designed to discharge to the lawns around the homes then the pervious area infiltration coefficient could be changed from 0 11 to 0 10 or 0 09 2 2 5 Roughness Coefficient Manning s n Values of roughness coefficient n are not as easily determined for subcatchment overland flow as they are for conveyance elements because of the variability in ground cover and small depths that occurs in overland flow situations It is recommended that suggested values in Table 2 2 be used to estimate the roughness of the subcatchment because they have been found to work reasonably well in urban situations Resistance factors for the pervious and impervious areas of the subcatchment are specified separately with default values of 0 25 and 0 013 for pervious and impervious overland flow respectively RUNOEFF Block TABLE 2 2 SUBCATCHMENT OVERLAND FLOW ROUGHNESS COEFFICIENTS Suggested Ground Cover Manni
14. conduit types 1 through 5 Overflow section data continues on same line see Figure 3 4 for description of elements ODEEP Depth of the main trapezoidal section in feet none OWIDE Bottom width of the main trapezoidal section in feet This none represents total gutter width both sides of the street ORNI Manning s n coefficient for the main trapezoidal section none ORN2 Manning s n coefficient for the overflow trapezoidal section none OTHEI Average slope of both sides of the main trapezoidal section none horizontal vertical in feet foot This slope corresponds to the street cross slope and is used with ODEEP to determine street width ODEEP OTHEI 2 OTHE2 Average slope of both sides of the overflow trapezoidal none section horizontal vertical in feet foot This slope corresponds to the slope of the ground outside the street 99999 A blank line or 99999 indicates the end of the Conveyance none Element Data Section 3 12 EXTRAN Block 3 4 2 4 Junction Elements Data Section A line with Junction element data is required for each of the following Junction element types in the network regular Junctions storage and diversion junctions pump junctions and outfall junctions It is very important to remember that the junction invert elevation must equal the lowest invert elevation of the conduits connecting to the junction ZP 0 Program execution will terminate with an error message if this condition is not met
15. through the gutter and combined with the hydrograph from A to yield the resultant hydrograph Q12 The combination hydrograph represented by Q12 is used as input to the EXTRAN block and is then dynamically routed through the major trunk line to the storm drain outfall 1 1 HISTORY OF SSWMM96 1 1 1 RUNOFF Block The RUNOFF block was first developed as one part of the EPA Stormwater Management Model SWMM It simulated both the quality and quantity of runoff from urban drainage basins along with hydrologic routing of the flows through conveyance systems Hydrologic Engineering Center and the Missouri River Division MRD of the U S Army Corps of Engineers modified a quantity only version of the original RUNOFF block to correct deficiencies that had been encountered in the model This version of the RUNOFF block simulated only the quantity of stormwater and not the quality Boyle Engineering Corporation BEC made a further revision to the MRD version allowing it to be run on personal computers Montgomery Watson Americas Inc MW has further modified the RUNOFF block for SSWMM96 These modifications mostly affected the input data formatting and output data 1 1 1 SIMULATION AND RUNOFF BLOCK SIMULATION POSTPROCESSOR gt v _ RUNOFF RUNOFF HYDROGRAPH HYDROGRAPH gt lt Y RUNOFF BLOCK ONVEYANCE SIMULATION v ES GUTTER HYDROGRAP E v EXTRAN BLOCK ONVEYANCE SIMULATION
16. 2 Sample Extr n Output anma da tee eet dede A 3 23 3 3 Hydrograph Plotting Example nn n enne 3 39 4 1 HEC I Postprocessor Example aaa aaa aaa ee 4 2 sump 43 RUNORBE Inpu t eiie tei tdeo do O een ented dees RAE A 2 A T Sump 43 RUNOFF sell sie eel vie tes uae ed eve Lance veal rtv d 4 Sump 43 EXTRAN Input Data see elle elli S ses elale Ve B 2 B 2Sump43EXTRANOutputData eee B 6 LIST OF FIGURES FIGURE NO TITLE 1 1 SWMM91 Hydrograph Simulation Schematic nn 1 1 1 2 Conceptual Relationship of RUNOFF and 1 1 2 1 Idealized Subcatchment Gutter Arrangement Showing Subcatchment Width 2 2 2 2 Calculating Basin Width for Irregular Shaped Subcatchments 2 3 2 3 ConveyanceFlementConfiguratlons eee 2 7 2 4 Special Flow Routing Conveyance Elements 2 8 2 5 Trapezoidal Approximations for 5 2 8 3 1 Operation of EX TRAN ss i Nie e Seah RTA oh ett he as e est RAL azes 3 1 3 2 Definition of Terms for Pipe ener 3 3 3 3 TypesofConduitsinEXTRAN eee 3 3 3 4 Sti et Overtlow Section
17. 3 Termination of Execution Error Message EXECUTION TERMINATED BECAUSE OF XX DATA ERROR S A total of XX errors have been found in the input data for this 3 37 EXTRAN Block simulation Program execution was terminated Check input data error descriptions in output file Correct errors and rerun EXTRAN 3 6 4 Warning Messages The following warning messages will not cause EXTRAN to terminate but may cause the program to produce erroneous results The user should carefully check the input data for the conduits and junctions specified in the warning message s and should make the appropriate changes The output at the specified locations should also be checked carefully for instabilities and other possible problems 1 WARNING 1 C DELT LEN IN CONDUIT IS YY Y AT FULL DEPTH The length of conduit XX is probably too short for the given timestep DELT Either shorten the timestep or lengthen the pipe as required Otherwise check the output around conduit XX for instability WARNING 2 JUNCTION XX IS NOT ASSOCIATED WITH ANY PIPE A junction was specified in the Junction Elements Data Section but was not connected to a conduit in the Conveyance Elements Data Section WARNING 3 JUNCTION XX IS NOT ASSOCIATED WITH ANY OVERFLOW CONVEYANCES No overflow sections have been specified for the conduits connected to this junction Overflow routing will not occur at this junction unless overflow secti
18. In this way the losses in the pipe can be adjusted to represent the junction losses that would otherwise occur Flow and Depth Measurements Accurate calibration of EXTRAN requires both flow and depth measurements Depth measurements are relatively easy to obtain by installing automatic stage recorders at various locations Flows on the other hand require measurement of both velocity and depth which can be very difficult especially in pipes flowing full Velocities may vary widely across the pipe section and velocity instruments are prone to failure and inaccuracy For this reason calibration is normally achieved by comparing depth only In many areas this may provide satisfactory results 3 6 3 Fatal Error Messages The following error messages are fatal and will cause EXTRAN to terminate prematurely 1A 1B ERROR 1A CONDUIT XX HAS FLOW AREA EQUAL TO ZERO There is an error in the input data for conduit XX The diameter has been set to zero Check input data and set conduit diameter or depth to a number greater than zero ERROR 1B CONDUIT XX HAS LENGTH EQUAL TO ZERO There is an error in the input data for conduit XX The length has been set to zero Check input data and set conduit length to a number greater than Zero ERROR 2 JUNCTION XX IS ASSOCIATED WITH MORE THAN 8 PIPES Each junction may have up to eight pipes connected to it Junction XX has passed that limit Check the input data
19. OF RUN WATERSHED MAX HYDROGRAPH SYSTEM SYSTEM INFLOW FROM SURCHARGE JUNCTION INFLOW STORAGE EXCESS INFLOW OUTFLOW FLOODING TO STREET 20 2520 0 0 2520 947340 0 0 101 0 0 0 0 0 0 0 102 0 0 0 0 0 0 0 103 66274 0 0 66274 0 0 0 104 0 0 0 0 0 0 0 105 63197 0 0 63197 0 0 0 106 265067 0 0 265067 0 0 0 107 272718 0 0 272718 0 0 0 108 352002 51786 404 351598 0 404 0 109 0 0 0 0 0 0 0 110 4320 0 0 4320 0 0 0 TOTAL 1026099 51786 404 1025695 947340 404 0 VOLUME LEFT IN PIPE 49390 CU FT VOLUME LEFT IN STREET 0 CU FT VOLUME LEFT IN STORAGE 0 CU FT ERROR IN CONTINUITY PERCENT 3 03 CINFLOW OUTFLOW VOLUME LEFT INFLOW SACRAMENTO STORMWATER MANAGEMENT MODEL SWMM EXTENDED TRANSPORT PROGRAM BLOCK SSWMM96 DOCUMENTATION EXAMPLE DATA EXTRAN BLOCK CUMULATIVE INFLOW AND OUTFLOW IN CU FT TIME WATERSHED NODE HYDROGRAPH SYSTEM SYSTEM INFLOW FROM SURCHARGE VOLUME PUMPBACK HR MIN INFLOW STORAGE EXCESS INFLOW OUTFLOW FLOODING TO STREET ST VOLUME 0 20 1260 0 0 1260 0 0 0 0 0 0 40 2520 0 0 2520 0 0 0 0 0 1 00 3803 0 0 3803 0 0 0 0 0 1 20 7962 0 0 7962 0 0 0 0 0 1 40 18766 0 0 18766 0 0 0 0 0 2 00 36073 0 0 36073 0 0 0 0 0 2 20 59726 0 0 59726 0 0 0 0 0 2 40 87630 0 0 87630 20520 0 0 0 0 3 00 117804 0 0 117804 44460 0 0 0 0 3
20. The explanation of ground and invert elevations is shown in Figure 3 1 The ground elevation is the elevation at which the assumption of pressure flow is no longer valid Normally this will be the street or ground elevation of the top of the manhole because when the depth in the manhole exceeds that elevation overflow onto the ground begins If the manholes are bolted down the ground elevation should be set high enough that the simulated water surface elevation does not exceed it Alternatively the junction may be defined such that overflows are not allowed as described below and shown in the Junction Elements Data Section in Table 3 1 The inflow capacity control option allows the user to select the maximum flow rate that will be allowed into the system from the RUNOFF hydrograph file at the inflow junction All flows in excess of this rate will be stored at the junction and can be allowed to enter the system when capacity is available or can be assumed to be lost from the system The inflow capacity control simulates the operation of storage facilities before the flows enter the pipe conveyance system Name Description Default JUN Unique junction identification number none GRELEV Ground elevation at the top of the junction in feet msl none Z Junction elevation in feet msl none QINST Net constant flow into the junction may be negative in cfs none In a combined sewer system this could be the sanitary sewage contribution Could also be
21. and the entire EXTRAN block must be recompiled and relinked before running the simulation ERROR 29 NGATEO IN COMMON INC SHOULD BE GREATER THAN XX The number of flap tide gates specified in the input data exceeds the allowable dimension NGATEO If the number of flap gates specified in the input is required for this simulation the parameter NGATEO in COMMON INC must be increased and the entire EXTRAN block must be recompiled and relinked before running the simulation ERROR 30 NWEIRO IN COMMON INC SHOULD BE GREATER THAN XX The number of weirs specified in the input data exceeds the allowable dimension NWEIRO If the number of weirs specified in the input is required for this simulation the parameter NWEIRO m COMMON INC must be increased and the entire EXTRAN block must be recompiled and relinked before running the simulation ERROR 31 TOTAL NUMBER OF JUNCTIONS INCLUDING WEIRS EXCEED PROGRAM DIMENSIONS NJ XX Total number of junctions including weirs orifices pumps and outfalls specified in the input data exceeds the allowable dimension If the number of junctions specified in the input is required for this simulation the parameter NJO in COMMON INC must be increased and the entire EXTRAN block must be recompiled and relinked before running the simulation ERROR 32 TOTAL NUMBER OF CONDUITS EXCEEDS PROGRAM DIMENSIONS NTLO XX Total number of conduits specified in the input data exceed
22. cfs fps cfs fps Must also enter initial depths for each junction real and internal in the order specified in the Junction Element Data Section Depth Depth Depth Depth Depth Depth Depth Depth Depth Depth ft ft ft ft ft ft ft ft ft ft To indicate end of Initial Flow Data Section enter 99999 99999 INPUT HYDROGRAPHS SECTION Required only if NJSW gt 0 System Parameters Section Enter junctions for which hydrographs are being input Junc 1 Junc 2 Junc 3 Junc 4 Junc 5 Junc 6 Junc 7 Enter time and flows for each junction and each time in hydrograph Time QG 000 08 Q 4 065 906 00 hrs cfs cfs cfs cfs cfs cfs cfs END PROGRAM 3 9 Revised January 1996 Name DELT TZERO TEND NHPRT NWPRT NQPRT PSTART DINTER HINTER NJSW MAXIT EXTRAN Block Description Default Length of integration timestep in seconds This variable is none critical to the stability of the EXTRAN block and must be selected carefully First compute ty the time for a surface wave to travel from one end of the shortest conveyance element in the system to the other L ep where t time for a surface wave to travel from one end of a conduit to the other in seconds L length of shortest conduit in feet g 32 2 feet second and D channel depth or pipe diameter in feet The timestep may exceed t by a factor of 1 5 to 2 0 but only for a few
23. data respectively The fourth page of the EXTRAN output contains the internal connectivity information This information is extremely important because it indicates how the program thinks the system is set up based on the users input data The internal connectivity information is a good way to check for input errors by verifying that the system connectivity matches the system the user is trying to simulate Page 5 The fifth page of the EXTRAN output contains the summary printout for the junctions and conduits at the print cycle specified in the System Parameters Section of the input data The cycle description includes simulation time flow differential in the surcharged area and the iterations required to solve the flow equations for that timestep 3 22 EXTRAN Block TABLE 3 2 SAMPLE EXTRAN OUTPUT ENTRY MADE TO EXTENDED TRANSPORT MODEL UPDATED BY MONTGOMERY WATSON JANUARY 1996 SACRAMENTO STORMWATER MANAGEMENT MODEL SSWMM96 EXTENDED TRANSPORT PROGRAM EXTRAN BLOCK DATE OF THIS RUN 02 25 94 SSWMM96 DOCUMENTATION EXAMPLE DATA EXTRAN BLOCK INTEGRATION CYCLES 1200 LENGTH OF INTEGRATION STEP IS 30 SECONDS PRINTING FOR ALL CONDUITS AND NODES STARTS IN CYCLE 40 AND PRINTS AT INTERVALS OF 60 CYCLES INITIAL TIME 9 00 HOURS SURCHARGE VARIABLES ITMAX 99999 SURTOL 050 PRINTED OUTPUT AT THE FOLLOWING 11 JUNCTIONS 20 101 102 103 104 105 106 107 108 109 110 WATER BALANCE AT THE FOLLOWING 4 JUNCTIO
24. end of the run The continuity balance lists for each junction the total watershed inflow maximum storage hydrograph excess system inflow system outflow inflow from flooding and the surcharging to the street The definitions of the items in the continuity balance are Watershed Inflow total of all inflows from RUNOFF module or from user created gut file Maximum Storage maximum total storage at all Junction resulting from inflows greater than user defined inflow capacities Hydrograph Excess total of inflows that didn t enter the pipe conveyance system from RUNOFF due to limited downstream pipe capacity System Inflow difference between the watershed inflow and the hydrograph excess System Outflow total flow out of the system Inflow from Flooding total flow entering the pipe conveyance system through street inlets from flooding in the streets Surcharge to Street total flow entering the streets due to pipe surcharging The continuity balance also takes into account the volume of stormwater left in the pipes in the street and in storage at the end of the simulation If the error in continuity is more than 10 percent this is an indication that problems are occurring in the system and a careful study of the output is necessary to determine the location of the problems and possible solutions Page 7 Page seven is the cumulative inflow and outflow summary For each print cycle the cumulative wate
25. for that variable Identification number of the conveyance element downstream of conveyance element N This may be the manhole number in EXTRAN into which the hydrograph from this conveyance element will be put for dynamic routing Normally zero unless one of the special routing element options explained for JK is to be used In that case NDP is a positive number equal to the number of sets of tabular values to be input under the JK option Type of conveyance element 1 channel 2 pipe 3 direct flow no routing 4 channel with overflow channel 5 pipe with overflow channel Bottom width of channel or pipe diameter in feet Length of conveyance element in feet Invert slope in feet foot Left hand looking downstream side slope in feet foot Right hand looking downstream side slope in feet foot Manning s n resistance factor for the channel or pipe Depth of channel when full or the pipe diameter in feet When an overflow section has been specified the depth at which overflow begins If an overflow channel has been specified NP 4 or 5 variables GWIDTH GLEN GSLOPE GS1 GS2 GS and DFULL must be specified for the overflow channel on the next line none none none none 0 001 none 0 001 0 001 0 001 0 020 10 Diversion Option Input Line s JK gt 0 and NDP gt 0 NDP data pairs describing flow in the element versus diverted flow JK is conveyance element number receiving the diverted flow
26. indicates the end of the Storage Junction Data Default none none none none none 3 4 2 6 Orifice Data Section Orifices in EXTRAN are described as equivalent pipes Each orifice is defined between two junctions Two types of orifice side and bottom discharge may be used in EXTRAN Orifice data is entered on one line per orifice Comment lines are allowable between orifice data lines Use of both types of orifice is illustrated in the Orifice Data Section in Table 3 1 Name NJUNC 1 NJUNC 2 NKLASS AORIF CORIF ZP 99999 Description Junction containing the orifice Must already have been listed in the Junction Elements Data Section Junction to which the orifice discharges Must already have been listed in the Junction Elements Data Section Type of orifice as shown in Figure 3 5 1 side outlet orifice 2 bottom outlet orifice Orifice area in square feet Orifice discharge coefficient Typical value for discharge coefficient is around 0 6 Distance of orifice invert above junction invert Set to zero for bottom orifice A blank line or 99999 indicates the end of the Orifice Data Section 3 15 Default none none none none none none none EXTRAN Block 3 4 2 7 Weir Data Section Weirs in EXTRAN may be of two types side flow or transverse Data is entered on one line per weir with comment lines allowable between weir data lines Weir parameters are given in the Weir Data Section of Tabl
27. or if required add a junction and pipe upstream of the free outfall junction ERROR 21 CONDUIT XX REQUESTED FOR PRINTOUT IS NOT CONTAINED IN CONDUIT DATA All conduits requested for 3 34 22 23 24 25 26 27 28 Block printout must be described in Elements Data Section Check input data and correct the conduit number in the conduit printout section ERROR 22 NI IN THE TIDAL DATA SHOULD BE LESS THAN 50 Reduce the number of tidal information points to less than 50 ERROR 23 PROGRAM CANNOT MATCH HYDROGRAPH NODE XX TO JUNCTION DATA An inflow hydrograph has been specified at node junction XX This junction number does not exist in the Junction Elements Data Section Check input and either add the junction to the Junction Elements Data Section or change the output node number in the RUNOFF block input data and rerun RUNOFF to create the correct inflow hydrographs ERROR 24 NJO IN COMMON INC SHOULD BE GREATER THAN XX The number of junctions that have been specified as input to this simulation is greater than the dimensioned number of junctions NJO The parameter NJO in the file COMMON INC must be increased and the EXTRAN block must be recompiled and relinked if it is necessary to run a simulation with the current number of junctions ERROR 25 NSTORO IN COMMON INC SHOULD BE GREATER THAN XX The number of storage
28. outfall junction number or add the free outfall junction to the Junction Elements Data Section ERROR 16 FLAP TIDE GATE JUNCTION XX IS NOT CONTAINED IN JUNCTION DATA flap tide gate junctions must be described in the Junction Elements Data Section Check input data and either correct the flap gate junction number or add the flap gate junction to the Junction Elements Data Section ERROR 17 FLAP TIDE GATE JUNCTION XX IS ASSOCIATED WITH MORE THAN 1 PIPE A flap tide gate junction may be connected to only one pipe Check input data and remove the extra pipe s or if required add a junction and pipe upstream of the flap gate junction ERROR 18 JUNCTION XX REQUESTED FOR PRINTOUT IS CONTAINED IN JUNCTION DATA All junctions requested for printout must be described in the Junction Elements Data Section Check input data and correct the junction number in the junction printout section ERROR 19 MORE THAN ONE PIPE IS INFLUENT TO PUMP JUNCTION XX The pump type for junction XX was specified as an off line pump Off line pumps are allowed to have only one influent pipe Check input data and either change the pump type to on line or remove influent pipes until there is only one influent pipe to the junction ERROR 20 FREE OUTFALL JUNCTION IS ASSOCIATED WITH MORE THAN 1 PIPE A free outfall junction may be connected to only one pipe Check input data and remove the extra pipe s
29. through the conveyance elements of the study watershed Pipes and initial channel sections are permitted to surcharge when full or if desired overflow sections may be provided to convey RUNOEFF Block the flow exceeding the pipe or the initial channel capacity The routing is based on a kinematic wave approach that utilizes Manning s equation both for subcatchment and conveyance elements 2 2 SUBCATCHMENT PARAMETERS Subcatchments can be thought of as idealized areas with a uniform slope and uniform ground cover This ground cover may represent one actual type of ground cover such as impervious asphalt paving or pervious turf or it may represent a mix of impervious and pervious ground cover types Important information required to characterize a subcatchment includes area width ground slope percent imperviousness roughness coefficients surface retention depth depression losses and soil infiltration coefficients Since the subcatchments encountered in the real world are not rectangular areas with uniform characteristics some approximations must be made in order to represent the subcatchments in the model The important subcatchment parameters that are required in order to describe subcatchments for use by the RUNOFF block are described in the following paragraphs 2 2 1 Drainage Area This is the total area of the subcatchment and it is typically measured from a topographic map of the area being modeled with the subcatchment boundar
30. 0 100 250 3 00 50 00180 11083 08 1600 10 3 80 0 0010 016 050 100 250 3 00 50 00180 TOTAL NUMBER OF SUBCATCHMENTS 9 TOTAL TRIBUTARY AREA ACRES 171 00 2 20 RUNOFF Block TABLE 2 7 continued SSWMM96 DOCUMENTATION EXAMPLE DATA RUNOFF BLOCK SUBCATCHMENT OVERLAND FLOW HYDROGRAPHS HYDROGRAPHS ARE LISTED FOR THE FOLLOWING 9 SUBCATCHMENTS AVERAGE VALUES WITHIN TIME INTERVALS TIME HR MIN 1031 1051 1061 1062 1071 1072 1081 1082 1083 9 00 00 00 00 00 00 00 00 00 00 9 15 00 00 00 00 00 00 00 00 00 9 30 00 00 00 00 00 00 00 00 00 Output has been abridged 11 30 87 89 1 55 1 79 2 35 93 2 88 94 1 17 11 45 94 92 1 66 1 97 2 69 1 05 3 22 1 00 1 25 12 00 1 05 1 04 1 87 2 23 3 09 1 20 3 66 1 12 1 40 12 15 1 48 1 50 2 62 3 09 4 24 1 65 5 04 1 58 1 98 12 30 2 05 2 10 3 63 4 26 5 84 2 27 6 95 2 20 2 75 Page 4 SUBCATCHMENT HYDROGRAPHS CONTINUED TIMECHR MIN 1031 1051 1061 1062 1071 1072 1081 1082 1083 12 45 7 28 8 27 12 92 14 28 17 97 7 20 22 42 7 99 9 95 13 00 4 58 3 90 8 11 10 30 15 41 5 82 17 50 4 75 5 97 13 15 2 98 2 48 5 26 6 94 11 23 4 11 12 18 3 05 3 84 13 30 2 52 2 21 4 45 5 80 9 43 3 43 10 15 2 60 3 27 Output has been abridged 23 15 00 00 01 01 04 01 03 00 00 23 30 00 00 01 01 03 01 03 00 00 23 45 00 00 01 01 03 01 02 00 00 Page 5
31. 0 0 50 0 12 10 3 10 99999 0 210 3 23 EXTRAN Block TABLE 3 2 continued PUMP DATA JUNCTIONS TYPE INITIAL VOLUME CONST RATE CFS VARIABLE DEPTH DEPTH FROM TO RATE DEPTH ON OFF 1 20 0 2 0 114 0 4 2 114 0 5 2 114 0 6 3 Page 4 SACRAMENTO STORMWATER MANAGEMENT MODEL SSWMM96 EXTENDED TRANSPORT PROGRAM EXTRAN BLOCK DOCUMENTATION EXAMPLE DATA EXTRAN BLOCK INTERNAL CONNECTIVITY INFORMATION CONDUIT JUNCTION JUNCTION 201 101 20 202 102 101 Output Abridged in this Section 210 110 109 90011 20 0 Page 5 SSWMM96 DOCUMENTATION EXAMPLE DATA EXTRAN BLOCK SUMMARY OF INITIAL HEADS FLOWS AND VELOCITIES INITIAL HEADS FLOWS AND VELOCITIES ARE ZERO SACRAMENTO STORMWATER MANAGEMENT MODEL SSWMM96 EXTENDED TRANSPORT PROGRAM EXTRAN BLOCK SSWMM96 DOCUMENTATION EXAMPLE DATA EXTRAN BLOCK SUMMARY PRINTOUT FOR ALL JUNCTIONS AND CONDUITS CYCLE 60 TIME 9 HRS 30 00 MIN FLOW DIFFERENTIAL IN SURCHARGED AREA 0 00 ITERATIONS REQUIRED 1 JUNCTIONS MANHOLE DEPTH FLOODING DEPTH 20 0 14 0 00 101 0 00 0 00 102 0 01 0 00 103 0 10 0 00 104 0 03 0 00 105 0 24 0 00 106 0 27 0 00 107 0 14 0 00 108 0 16 0 00 109 0 05 0 00 110 0 21 0 00 CONDUITS CONDUIT FLOW OVERFLOW 2
32. 01 0 00 0 00 202 0 00 0 00 203 0 02 0 00 204 0 01 0 00 205 0 12 0 00 206 0 42 0 00 207 0 07 0 00 208 0 07 0 00 209 0 01 0 00 210 0 07 0 00 CYCLE 120 TIME 10 HRS 0 00 MIN FLOW DIFFERENTIAL IN SURCHARGED AREA 0 00CFS ITERATIONS REQUIRED 1 7 JUNCTIONS MANHOLE DEPTH FLOODING DEPTH 20 0 26 0 00 101 0 02 0 00 102 0 08 0 00 103 0 29 0 00 104 0 25 0 00 105 0 43 0 00 106 0 29 0 00 107 0 24 0 00 108 0 23 0 00 109 0 16 0 00 110 0 24 0 00 CONDUITS CONDUIT FLOW OVERFLOW 201 0 03 0 00 202 0 02 0 00 203 0 19 0 00 204 0 46 0 00 205 0 64 0 00 206 0 56 0 00 207 0 19 0 00 208 0 15 0 00 209 0 07 0 00 210 0 13 0 00 90011 0 00 0 00 Output Abridged in This Section 3 24 EXTRAN Block TABLE 3 2 continued CYCLE 1200 TIME 19 5 0 00 MIN FLOW DIFFERENTIAL IN SURCHARGED AREA 0 00 5 ITERATIONS REQUIRED 1 JUNCTIONS MANHOLE DEPTH FLOODING DEPTH 20 3 85 0 00 101 3 65 0 00 102 3 04 0 00 103 2 58 0 00 104 1 05 0 00 105 0 65 0 00 106 0 49 0 00 107 0 57 0 00 108 0 42 0 00 109 0 21 0 00 110 0 22 0 00 CONDUITS CONDUIT FLOW OVERFLOW 201 0 48 0 00 202 1 26 0 00 203 0 95 0 00 204 1 27 0 00 205 1 89 0 00 206 1 68 0 00 207 1 07 0 00 208 0 57 0 00 209 0 13 0 00 210 0 12 0 00 90011 0 00 0 00 SACRAMENTO STORMWATER MANAGEMENT MODEL SWMM EXTENDED TRANSPORT PROGRAM EXTRAN BLOCK SSWMM96 DOCUMENTATION EXAMPLE DATA EXTRAN BLOCK CONTINUITY BALANCE IN CU FT AT END
33. 20 159295 0 0 159295 75240 0 0 0 0 3 40 228325 1585 0 226740 116280 0 0 0 0 4 00 424381 42607 404 381371 205200 193 0 211 0 4 20 539914 51652 404 487858 287280 404 0 0 0 4 40 626418 50427 404 575588 383040 404 0 0 0 5 00 704580 46641 404 657535 478800 404 0 0 0 5 20 764910 36719 404 727788 557460 404 0 0 0 5 40 813294 22790 404 790099 632700 404 0 0 0 6 00 857311 7566 404 849341 701100 404 0 0 0 6 20 896276 0 404 895872 762660 404 0 0 0 6 40 931730 0 404 931326 813960 404 0 0 0 3 25 EXTRAN Block TABLE 3 2 continued 7 00 965304 0 404 964900 855000 404 0 0 0 7 20 986728 0 404 986324 892620 404 0 0 0 7 40 998500 0 404 998096 909720 404 0 0 0 8 00 1006049 0 404 1005645 919980 404 0 0 0 8 20 1011386 0 404 1010982 926820 404 0 0 0 8 40 1015454 0 404 1015050 933660 404 0 0 0 9 00 1018734 0 404 1018330 940500 404 0 0 0 9 20 1021503 0 404 1021099 940500 404 0 0 0 9 40 1023925 0 404 1023521 947340 404 0 0 0 10 00 1026099 0 404 1025695 947340 404 0 0 0 Page 8 SACRAMENTO STORMWATER MANAGEMENT MODEL SWMM EXTENDED TRANSPORT PROGRAM EXTRAN BLOCK SSWMM96 DOCUMENTATION EXAMPLE DATA EXTRAN BLOCK NODE 108 INFLOW AND OUTFLOW IN CU FT TIME W
34. 7 2 88 5 76 24 52 1 73 0 0 0 1 4 D 0 0 S 20 0 1 0 0 0 Output has been abridged SSWMM96 DOCUMENTATION EXAMPLE DATA RUNOFF BLOCK CONVEYANCE ROUTING PEAK FLOWS STAGES AND STORAGE OF CONVEYANCE ELEMENTS AND DETENTION DAMS CONVEYANCE STAGE STORAGE TIME ELEMENT CFS AC FT CHR MIN 1 14 0 4 12 45 5 14 0 4 12 50 4 57 1 0 12 45 3 53 2 0 12 45 2 29 1 4 12 45 2 25 RUNOFF Block element 1 depth of flow above the invert 2 storage in acre feet for a detention dam 3 conveyance element inflow in cfs from a specified inflow hydrograph 4 discharge diverted from the conveyance element and 5 storage in acre feet for a surcharged conveyance element The data are listed for each timestep Page 5 of the output contains a summary of the peak flows stages and storage of the conveyance elements and detention dams This summary includes the time at which the peak flow occurred 2 7 DEBUGGING AND STABILIZATION HINTS The preceding subsections of this section have described in detail the data input procedure to be used when running the RUNOFF Block of SSWMM96 This subsection will describe important limitations inherent to the RUNOFF Block along with a description of calibration and a listing of RUNOFF warning and error messages and their probable causes and solutions The following list describes the output data items that need to be checked first when debugging a RUNOFF model input data se
35. ANNEL 10 0 350 0 0100 1 TIME IN HRS VS INFLOW IN CFS 2 23 108 0 0 TOTAL NUMBER OF CONVEYANCE ELEMENTS 5 RUNOFF Block 1 0 5 0 2 0 10 0 CHANNEL 10 0 450 OVERFLOW 5 0 450 2 24 RUNOFF Block TABLE 2 8 continued SSWMM96 DOCUMENTATION EXAMPLE DATA RUNOFF BLOCK CONVEYANCE ROUTING ARRANGEMENT OF SUBCATCHMENTS AND CONVEYANCE ELEMENTS CONVEYANCE ELEMENT TRIBUTARY CONVEYANCE ELEMENT TRIBUTARY SUBAREA D A AC 103 0 0 0 0 0 0 0 0 0 0 1031 0 0 0 0 0 0 0 0 0 13 9 105 103 0 0 0 0 0 0 0 0 0 1051 0 0 0 0 0 0 0 0 0 26 9 106 0 0 0 0 0 0 0 0 0 0 1061 1062 0 0 0 0 0 0 0 0 59 1 107 0 0 0 0 0 0 0 0 0 0 1071 0 0 0 0 0 0 0 0 0 30 1 108 0 0 0 0 0 0 0 0 0 0 1072 0 0 0 0 0 0 0 0 0 11 2 RUNOFF BLOCK ROUTING HYDROGRAPHS ARE LISTED FOR THE FOLLOWING 5 CONVEYANCE ELEMENTS THE UPPER NUMBER IS DISCHARGE IN CFS THE LOWER NUMBER IS ONE OF THE FOLLOWING CASES DENOTES DEPTH ABOVE INVERT IN FEET S DENOTES STORAGE IN AC FT FOR DETENTION DAM DISCHARGE INCLUDES SPILLWAY OUTFLOW DENOTES CONVEYANCE ELEMENT INFLOW IN CFS FROM SPECIFIED INFLOW HYDROGRAPH D DENOTES DISCHARGE IN CFS DIVERTED FROM THIS CONVEYANCE ELEMENT 0 DENOTES STORAGE AC FT FOR SURCHARGED CONVEYANCE ELEMENT TIME CHR MIN 103 105 106 107 108 9 0 00 0 00 0 00 0 00 25 29 0 00 0 0 0 0 0 D 0 0 S 20 0 1 0 0 0 Output has been abridged 11 30 00 1 42 2 79 5 51 24 15 1 60 0 0 0 1 4 D 0 0 S 20 0 1 0 0 0 11 45 00 1 4
36. ATERSHED NODE HYDROGRAPH SYSTEM SYSTEM INFLOW FROM SURCHARGE VOLUME PUMPBACK HR MIN INFLOW STORAGE EXCESS INFLOW OUTFLOW FLOODING TO STREET IN ST VOLUME 0 20 156 0 0 156 0 0 0 0 0 40 312 0 0 312 0 0 0 0 1 00 477 0 0 477 0 0 0 0 1 20 1716 0 0 1716 0 0 0 0 1 40 5456 0 0 5456 0 0 0 0 2 00 11625 0 0 11625 0 0 0 0 2 20 20138 0 0 20138 0 0 0 0 2 40 30199 0 0 30199 0 0 0 0 3 00 41063 0 0 41063 0 0 0 0 3 20 56117 0 0 56117 0 0 03 0 3 40 81406 1585 0 79820 0 0 0 0 4 00 152427 42607 404 109417 0 193 0 211 4 20 191472 51652 404 139417 0 404 0 0 4 40 220247 50427 404 169417 0 404 0 0 5 00 246462 46641 404 199417 0 404 0 0 5 20 266539 36719 404 229417 0 404 0 0 5 40 282611 22790 404 259417 0 404 0 0 6 00 297387 7566 404 289417 0 404 0 0 6 20 310518 0 404 310114 0 404 0 0 6 40 322518 0 404 322114 0 404 0 0 7 00 333956 0 404 333552 0 404 0 0 7 20 341031 0 404 340627 0 404 0 0 7 40 344687 0 404 344283 0 404 0 0 8 00 346907 0 404 346503 0 404 0 0 8 20 348399 0 404 347994 0 404 0 0 8 40 349484 0 404 349080 0 404 0 0 9 00 350314 0 404 349910 0 404 0 0 9 20 350979 0 404 350574 0 404 0 0 9 40 351531 0 404 351127 0 404 0 0 10 00 352002 0 404 351598 0 404 0 0 SACRAMENTO STORMWATER MANAGEMENT MODEL SWMM EXTENDED TRANSPORT PROGRAM EXTRAN BL
37. CCURENCE FLOODING NUMBER FT FT FT HR MIN ELEVATION ELEVATION MIN AF FT HR MIN MIN 20 21 70 0 14 5 05 13 15 0 19 21 51 1 0 00 0 00 0 0 0 Output Abridged in this Section 110 14 39 5 50 13 59 12 56 14 09 0 30 21 0 00 0 00 0 0 0 Page 11 SACRAMENTO STORMWATER MANAGEMENT MODEL SSWMM96 EXTENDED TRANSPORT PROGRAM BLOCK SSWMM96 DOCUMENTATION EXAMPLE DATA EXTRAN BLOCK keke RR ko k Wok amp w TIME HISTORY OF FLOW AND VELOCITY ko k k ox o W QCCFS VELCFPS CONDUIT 201 CONDUIT 202 CONDUIT 203 CONDUIT 204 CONDUIT 205 CONDUIT 206 TIME CONDUIT FLOODING CONDUIT FLOODING CONDUIT FLOODING CONDUIT FLOODING CONDUIT FLOODING CONDUIT FLOODING HR MIN FLOW VEL FLOWS FLOW VEL FLOWS FLOW VEL FLOWS FLOW VEL FLOWS FLOW VEL FLOWS FLOW VEL FLOWS 0 20 0 00 0 00 0 00 0 00 0 19 0 00 0 01 0 26 0 00 0 00 0 04 0 00 0 03 0 37 0 00 0 20 0 86 0 00 0 40 0 00 0 00 0 00 0 00 0 19 0 00 0 04 0 39 0 00 0 07 0 46 0 00 0 29 0 85 0 00 0 48 0 91 0 00 Output Abridged This Section 10 00 0 48 0 03 0 00 1 26 0 10 0 00 0 95 0 05 0 00 1 27 0 20 0 00 1 89 0 86 0 00 1 68 1 33 0 00 SSWMM96 DOCUMENTATION EXAMPLE DATA EXTRAN BLOCK ow ok ok w w w w Se w SUMMARY STATISTICS FOR CONDUITS wow ok ok ow MX CONDUIT MAXIMUM TIME MAXIMUM TIME RATIO OF MAXIMUM ELEV MAXIMUM TIME DESIGN DESIGN
38. ENSITY q RATE OF OVERLAND FLOW UNIT WIDTH W 2 TOTAL WIDTH OF OVERLAND FLOW FIGURE 2 1 IDEALIZED SUBCATCHMENT GUTTER ARRANGEMENT SHOWING SUBCATCHMENT WIDTH MAIN DRAINAGE CHANNEL DIRECTION OF OVERLAND FLOW FIGURE 2 2 CALCULATING BASIN WIDTH FOR IRREGULAR SHAPED SUBCATCHMENTS RUNOEFF Block A A y 2 5 1 where y skew factor 0 lt y x 1 0 area to one side of channel A area to other side of channel A total area Then the width W 16 W 2 p where W subcatchment width length of main drainage 2 2 3 Slope The subcatchment slope should reflect the average along the pathway of overland flow to inlet locations For simple geometry e g rectangular subcatchments as illustrated in Figure 2 1 the calculation is simply the elevation difference divided by the straight line length of flow For the more complex situations encountered in the real world several overland flow paths may be determined their slopes calculated and a weighted slope computed using a path length weighted average 2 2 4 Imperviousness The percent imperviousness of a subcatchment is obtained by using aerial photos or land use maps to determine the extent of each particular land use that exists in a subcatchment Although this extent can be measured accurately with a planimeter or some other method it Is more common to use visual estimates of the percentage of a subcatchment that is oc
39. LL BE CALCULATED 0 NUMBER OF TIME STEPS NSTEP 179 THE STORM BEGINS AT 8 55 NHR NMN INTEGRATION TIME INTERVAL IN MINUTES DELT 5 00 75 0 PERCENT OF IMPERVIOUS AREA HAS ZERO DETENTION DEPTH PCTZER FOR 50 RAINFALL STEPS NHISTO THE TIME INTERVAL IS 10 00 MINUTES THISTO FOR RAINGAGE NUMBER 1 RAINFALL HISTORY IN INCHES PER HOUR 00 00 00 00 00 00 13 13 13 13 513 413 16 16 16 16 16 16 28 30 36 52 1 98 48 36 36 36 36 36 36 20 20 20 20 20 20 16 16 16 16 16 16 00 00 00 00 00 00 00 00 Page 2 SSWMM96 DOCUMENTATION EXAMPLE DATA RUNOFF BLOCK SUBCATCHMENT OVERLAND FLOW HYDROGRAPHS SUBAREA CONVEY WIDTH AREA PERCENT SLOPE RESISTANCE FACTOR SURFACE STORAGECIN INFILTRATION RATECIN HR GAGE NUMBER ELEMENT AC IMPERV CFT FT IMPERV PERV IMPERV PERV MAXIMUM MINIMUM DECAY RATE tabs 03 1100 13 9 45 0 0010 016 050 100 250 3 00 50 00180 951 05 1800 13 0 45 0 0010 016 050 100 250 3 00 50 00180 4061 06 1960 24 6 45 0 0010 016 050 100 250 3 00 50 00180 4062 06 1800 34 5 40 0 0010 016 050 100 250 3 00 50 00180 E 07 1750 30 1 70 0 0010 016 050 100 250 3 00 50 00180 22 07 770 11 2 70 0 0010 016 050 100 250 3 00 50 00180 7081 08 2520 26 1 90 0 0010 016 050 100 250 3 00 50 00180 4082 08 1300 753 90 0 0010 016 05
40. MM96 Carefully following the instructions given in preceding sections will help to ensure that the input data file is as error free and correct as possible 3 6 1 Important Limitations It is important to remember that EXTRAN has limitations which must be taken into account when using the model to solve a real world problem Overstepping the bounds set by these limitations can result in the model blowing up or becoming unstable and terminating execution Even more serious the model may run to completion but the output data may be erroneous Some of the significant limitations are 1 Headloss at manholes expansions contractions bends etc are not explicitly accounted for in EXTRAN These losses must be simulated by adjusting the value of Manning s friction factor n in the conduits upstream and or downstream of the junction at which the losses occur 2 Changes in hydraulic grade line due to rapid expansions or contractions are neglected At expansions the headloss will tend to equalize the heads but at contractions the headloss could aggravate the problem 3 EXTRAN is not capable of simulating water quality transport 3 30 EXTRAN Block 3 6 2 Calibration EXTRAN was developed using the full dynamic flow equations which have been proved to give reasonably accurate results in simulating surcharged and unsurcharged flow in conveyance systems Unlike RUNOFF EXTRAN has few estimated parameters and assumptions The simulati
41. N 3 39 SECTION 4 HYDROGRAPHS eee 4 1 4 1 Inttod ction eed bilyan ha ee se ene sala ba a bend 4 1 4 2 Input Data Preparations ceca eee a e EU e E REN a PG E He da 4 2 43 Example oerte nae ee Pm 4 2 APPENDIX A RUNOFF EXAMPLE PROBLEM ener nnne enne nns 1 APPENDIX B EXTRAN EXAMPLE PROBLEM eene enne enne enne nennen A 2 LIST OF TABLES TABLE NO TITLE PAGE 2 1 Land sesandPercentlmperviousness 2 4 2 2 Subcatchment Overland Flow Roughness 1 2 5 2 3 Typical Depression Storage for Various Land Covers 2 5 2 4 RecommendedlinfiltrationCoefficients nanna enne 2 7 2 5 RUNOFF Subcatchment Simulation Input Template 2 41020 00400000040000000000000000000000 4 2 10 2 6 RUNOFF Conveyance Routing Input Template 2 15 2 7 RUNOFF Subcatchment SimulationOutputFike 2 20 2 8 RUNOFFConveyanceRoutingOutputfFile 2 23 2 9 HydrographPlottingExamplk ener nnne nennen 2 30 3 1 3 7 3
42. NING 3 CHECK RESULTS NOT CONVERGED IN CONVEYANCE ELEMENT ROUTING Errors have occurred in the kinematic routing equations in subroutine GUTTER and they did not converge on a suitable result Check results for location of error 2 8 RUNOFF GRAPHS In the Subcatchment or Conveyance Element Save and Print control sections of the input data the user specifies subcatchments or conveyance elements to be printed out NPRNT IPRNT i RUNOFF also saves these same hydrographs to a special hydrograph plotting file that is saved with the extension of PLH The graphics program supplied with SSWMM96 SWMGRAPH can plot the hydrographs saved in the PLH file Table 2 9 contains the commands that were used to plot an example hydrograph Required user input is underlined in the table The graphics program will display each of the available hydrograph plots one at a time 2 29 RUNOFF Block TABLE 2 9 HYDROGRAPH PLOTTING EXAMPLE Windows C SWMM GRAPHICS gt SWMGRAPH Initialize Program for Screen Viewing 1 Monochrome screen 2 Color screen Enter Number gt 2 Enter Name of Input Data File For Plotting gt RUNOFF PLH READY TO DISPLAY DRAWING Press lt return gt when ready to continue SWMM MODEL OUTPUT DATA RUNOFF HYDROGRAPH SUBBASIN 1031 Example RUNOFF Graph 8 00 10 00 6 00 1 1 RUNOFF CFS 0 00 2 00 4 00 1 a Y N N Would You Like Plots from Different Data Y N gt N Stop Prog
43. NS 105 106 107 108 AND FOR THE FOLLOWING 10 CONDUITS 201 202 203 204 205 206 207 208 209 210 SACRAMENTO STORMWATER MANAGEMENT MODEL SSWMM96 EXTENDED TRANSPORT PROGRAM BLOCK SSWMM96 DOCUMENTATION EXAMPLE DATA EXTRAN BLOCK CONDUIT INPUT DATA CONDUIT LENGTH SLOPE CLASS AREA MANNING MAX WIDTH DEPTH JUNCTIONS INVERT HEIGHT NUMBER FT FT FT SQ COEF FT FT AT ENDS ABOVE JUNCTIONS 1 201 900 0 00022 CIRCULAR 19 63 0 014 5 00 5 00 101 20 0 00 0 00 OVERFLOW 0 016 0 020 0 50 0 50 Output Abridged in This Section 9 209 900 0 00027 CIRCULAR 19 63 0 014 5 00 5 00 109 108 0 00 0 11 OVERFLOW 0 016 0 020 0 50 0 58 10 210 800 0 00020 CIRCULAR 19 63 0 014 5 00 5 00 110 109 0 00 0 01 OVERFLOW 0 016 0 020 0 50 0 58 Page 3 TRAPEZOID SIDE SLOPE 37 50 38 50 38 50 SACRAMENTO STORMWATER MANAGEMENT MODEL SSWMM96 EXTENDED TRANSPORT PROGRAM BLOCK SSWMM96 DOCUMENTATION EXAMPLE DATA EXTRAN BLOCK JUNCTION INPUT DATA JUNCTION GROUND CROWN INVERT QINST INLET INLET INFLOW CAP CONNECTING CONDUITS NUMBER ELEV ELEV ELEV CFS LENGTH COEF CFS 1 20 21 70 0 14 4 86 0 07 TI 3 10 99999 0 201 Output Abridged in This Section 9 108 12 65 5 09 0 02 0 13 22 3 10 25 0 208 209 10 109 14 46 5 34 0 33 0 00 20 3 10 99999 0 209 210 11 110 14 39 5 5
44. OCK DATE OF THIS RUN 02 25 94 SSWMM96 DOCUMENTATION EXAMPLE DATA EXTRAN BLOCK ok w k k w k w M TIME HISTORY OF H G L CVALUES IN FEET JUNCTION 20 JUNCTION 101 JUNCTION 102 JUNCTION 103 GRND 21 70 GRND 20 16 GRND 17 99 GRND 17 49 TIME HGL HGL FLOOD HGL HGL FLOOD HGL HGL FLOOD HGL HGL FLOOD HR MIN ELEV DEPTH DEPTH ELEV DEPTH DEPTH ELEV DEPTH DEPTH 0 20 4 76 0 10 0 00 4 66 0 00 0 00 4 04 0 00 0 40 4 67 0 19 0 00 4 66 0 00 0 00 4 02 0 02 Output Abridged in this Section 10 00 1 01 3 85 0 00 1 01 3 65 0 00 1 00 3 04 0 00 3 54 0 07 0 00 3 48 0 13 0 00 1 03 2 58 3 26 ELEV DEPTH DEPTH 0 00 0 00 0 00 JUNCTION 104 GRND 16 09 HGL HGL ELEV DEPTH 2 08 0 01 2 01 0 08 1 04 1 05 FLOOD DEPTH 0 00 JUNCTION kk RR RR RR RR KR k 105 GRND 13 90 HGL HGL FLOOD ELEV DEPTH DEPTH 1 48 0 12 1 24 0 36 0 95 0 65 EXTRAN Block TABLE 3 2 continued SACRAMENTO STORMWATER MANAGEMENT MODEL SSWMM96 EXTENDED TRANSPORT PROGRAM EXTRAN BLOCK SSWMM96 DOCUMENTATION EXAMPLE DATA EXTRAN BLOCK SUMMARY STATISTICS FOR JUNCTIONS JE JE S 3 NE oe UPPERMOST MAXIMUM TIME MAXIMUM FEET MAX LENGTH MAXIMUM TIME LENGTH GROUND PIPE CROWN COMPUTED OF WATER DEPTH IS OF FLOODED FLOODING OF OF JUNCTION ELEVATION ELEVATION DEPTH OCCURENCE SURFACE BELOW GROUND SURCHARGE VOLUME DEPTH O
45. One line of data VMax PBCond PBMax 99999 Maximum storage volume in cubic feet none Conduit number where available capacity will be used to none determine pumpback rate Maximum pumpback rate in cubic feet per second A blank line or 99999 indicates the end of the Pump Data none Section 3 4 2 9 Free Outfall Data Section Free outfalls are outfalls without flap gates The water surface elevation at the terminal junction determines the outflow from the outfall junction The information for each free outfall is listed on a separate line Comments are allowable between free outfall data lines Only one conduit may be connected to a free outfall Sample input is illustrated in the Free Outfall Data Section in Table 3 1 Name JFREE NBCF 99999 Description Default Junction from which the outfall occurs Must already have none been listed in the Junction Elements Data Section Only one conduit may be connected to the free outfall junction Location of tide or stage information in Tide or Stage none Boundary Information Section A blank line or 99999 indicates the end of the Free Outfall none Data Section 3 18 Revised January 1996 EXTRAN Block 3 4 2 10 Outfall with Flap Gate Data Section Outfalls with flap gates are a special case of the free outfall Flow will not leave the system at an outfall with a flap gate if the water surface elevation at the flap gate is higher than the water surface at the outfa
46. PFLAG 2 Subarea data printout IPFLAG 3 Output hydrographs printout printout IPKCHK Peak flow and depth of flow summary table flag none 0 No summary table 1 Print peak flow and depth of flow summary table at end of run 2 5 2 3 Rainfall Parameters Section The Rainfall Parameters Section contains the parameters controlling the size and time intervals for the precipitation hyetographs as well as the hyetographs themselves 2 11 RUNOEFF Block Name Description Default NHISTO Number of data points for each rainfall hyetograph none maximum of 399 THISTO Time interval in minutes for each value of the hyetograph none Does not have to be the same as the computation timestep DELT RAIN x Rainfall intensity values for each timestep in the hyetograph none May have as many values as wanted on a line only requirement is that values be separated by either a blank or a comma For ease in error checking use the same format on each line as shown in Table 2 5 2 5 2 4 Subcatchment Data Section The Subcatchment Data Section contains the data describing each of the subcatchments being simulated the data values for subcatchment are placed on one line Comment lines are allowed between subcatchment data lines so long as the data lines contain all the data values for a subcatchment Global changes in default values for any subcatchment variable for which default a value is defined may be made through the use of N 2 in the
47. PUT DATA PREPARATION Detailed instructions for preparing HEC 1 input data are given in the HEC 1 Flood Hydrograph Package User s Manual HEC 1990 This section of the SSWMM96 User s Manual will describe the procedure used to modify HEC 1 hydrograph output for use in SSWMM96 In order for the hydrographs from HEC 1 to be used in either RUNOFF or EXTRAN each subbasin for which a SSWMM 96 hydrograph is wanted must have a card with a 1 in the first field indicating that all output should be printed for that subbasin Care must be taken to insure that the names on the KK card for each subbasin used to describe the hydrograph locations correspond to the proper location in the SSWMM96 programs For routing in RUNOFF the name should be the same as the subcatchment number A program POSTHEC1 has been developed to modify HEC 1 output and put it into a form usable by RUNOFF or EXTRAN as needed This program reads in the HEC 1 output and then depending on the instructions from the user processes it into a form that RUNOFF or EXTRAN can use as inflow hydrographs 4 3 EXAMPLE Table 4 1 illustrates the sequence of commands to run POSTHECI for creation of a RUNOFF or EXTRAN inflow hydrograph file User inputs are underlined for clarity TABLE 4 1 HEC 1 POSTPROCESSOR EXAMPLE C gt POSTHEC1 HEC 1 SSWMM96 Post Processor Montgomery Watson Americas Inc January 1996 Enter the HEC 1 Output File Name gt HEC1 OUT HEC1 gut Already exists O
48. Subcatchment Data Section as described below It is also possible to substitute N 1 which will alter all subsequent subcatchment values by specified modification ratios as described below Name Description Default JK Hyetograph number for use with this subcatchment A none number is given to each hyetograph based on the order in which they are read N The unique subcatchment identification number Also used none to control subcatchment default values and modification ratios gt 0 Subcatchment identification number 2 Modify default values for each variable based on values entered on this line Any non zero value entered on a line with N 2 will replace the current default value for that variable 1 Alter subsequent values for a variable by the modification ratio entered on this line for that variable NGOTO The identification number of the conveyance element in the none conveyance module of RUNOFF or the junction element in EXTRAN to which the subcatchment connects 2 12 WWIDTH WAREA PCIMP WSLOPE W5 W W7 WS WLMAX WLMIN DECAY 99999 RUNOFF Block The subcatchment width in feet This represents the width of the downstream side of the idealized sloping rectangular subcatchment area When the subcatchment conveyance element approximately bisects the subcatchment Figure 2 1 use twice the length of the conveyance element for WWIDTH Area of the subcatchment in acres Percent of
49. T 1 1 subcatchment hydrographs are input from another source This option is used when subcatchment hydrographs from a previous RUNOFF simulation or from are to be input for routing through RUNOFF conveyance elements NSTEP Number of timesteps to be calculated Should be sufficient none to insure that most of the runoff occurs Depends on the size of the watershed the length of the precipitation and the size of the timestep NHR NMN Hour and minutes of start of the storm May be 0 0 none DELT Size of the computation timestep in minutes For all but very none small subcatchments DELT 5 minutes is adequate IPFLAG Input data print echo switches none 0 off l on IPFLAG 1 Rainfall parameters printout IPFLAG 2 Subarea data printout IPFLAG 3 Output hydrographs printout printout 2 14 RUNOFF CONVEYANCE ROUTING INPUT TEMPLATE RUNOFF Block TABLE 2 6 This is a conveyance routing input file for the RUNOFF block of SSWMM96 TITLE SECTION SSWMM96 DOCUMENTATION EXAMPLE DATA RUNOFF BLOCK CONVEYANCE ROUTING SYSTEM PARAMETERS SECTION free input format 1 1 for routing only 179 NSTEP Number of timesteps to be calculated 8 55 NHR NMN Hour and minutes of start of storm 5 0 DELT Integration period min 1 IPFlag 1 1 for rainfall parameters printout 1 IPFlag 2 1 for subarea data printout 1 IPFlag 3 1 for output hydrographs printout 1 IPKCHK 1 for printed summary o
50. TIDE 4 Tide coefficient calculation control line Name Description Default KO KO 1 four information points for tide coefficient none development KO gt 1 NI information points for tide coefficient development NI Number of information points for developing tide none coefficients NI 4ifKO 1 NI lt 50ifKO gt 1 NCHTID NCHTID 1 will print out information on tide coefficient none development NCHTID 0 no print out TTG Time of information point in hours none YY i Tidal stage in feet none For NTIDE 5 Stage history boundary condition NI Number of stage history point pairs none NCHTID NCHTID 1 will print out information on stage history none boundary condition NCHTID 0 no print out Stage history point pairs time and stage NI point pairs total No comments allowed in stage history data TTG Time of stage data point in hours none YYG Stage in feet none 99999 A blank line or 99999 indicates the end of the Tide or Stage none Boundary Information Data 3 4 2 12 Initial Flows Velocities and Heads Data Section In some situations it is desirable to begin a simulation with initial flows and velocities in the conduits and stages in the junctions These initial flows velocities and stages represent the antecedent flow conditions just prior to the storm being simulated The initial flow data section allows the user to input initial flow data but if this o
51. VERTICAL COMPUTED OF COMPUTED OF MAX TO UP DOWN FLOODING OF CONDUIT UP DOWN FLOW VELOCITY SIZE FLOW OCCURENCE VELOCITY OCCURENCE DESIGN NODE NODE FLOW OCCURENCE NUMBER NODE NODE CFS FPS IN CFS HR MIN FPS HR MIN FLOW FT FT CFS HR MIN 201 101 20 36 0 1 8 60 0 123 9 13 16 14 2 13 3 3 4 7 30 0 19 0 0 0 202 102 101 65 3 3 3 60 0 115 9 12 58 5 9 12 58 1 8 9 21 7 30 0 0 0 Output Abridged This Section 210 110 109 34 2 1 7 60 0 21 2 12 56 1 1 12 56 0 6 14 09 13 37 0 0 0 koxox EXTENDED TRANSPORT MODEL SIMULATION ENDED 3 27 EXTRAN Block The data for each junction is junction number depth of flow in the manhole junction and the street flooding depth at that junction An asterisk next to a manhole depth number indicates that the manhole is surcharged the hydraulic grade line in the manhole is above the highest pipe crown in the manhole A plus sign next to a manhole depth number indicates that an overflow into the street is occurring at this manhole The data for each conduit is conduit number flow in the conduit and overflow in the street above the conduit An asterisk next to the conduit flow number indicates that the differences in water surface elevation between the upstream and downstream junctions could not be solved explicitly The upstream end is solved using normal depth Page 6 Page six of the output is the continuity balance in cubic feet at each junction in the system at the
52. a aaa aaa aaa aaa aaa aaa cana 2 8 22222 s M a ie RR RR la ala yayaya 2 8 2 4 ae a eere e EU e e RAN uer d Oe ded 2 8 2 5 Input Data Preparations E A 2 9 2 5 T Default Values De od Ed pd ed LL US 2 9 2 5 2 Overland Flow Input Data Template essere 2 9 DS Dol Title secilen iine t Rte Re re 2 11 2 5 2 2 System Parameters 2 11 2 5 23RainfallParametersSectlon nn 2 11 2 5 2 4 Subcatchment Data 2 12 2 5 3 Routing Input Data Template sss ener 2 14 2 5 3 2 System Parameters 2 14 2 5 3 3 Subcatchment Conveyance Element Relationships Section 2 14 2 5 3 3 Conveyance Element Data Section sss 2 16 2 6 Output Description Ee A ves 2 18 2 6 1 RUNOFF Subcatchment Simulation Output sss 2 18 2 6 2 RUNOFF Conveyance Routing Output eere eee 2 19 2 7 Debugging And Stabilization Hints nennen nennen 2 26 2 72 Important Limitations eR TE gal li 2 26 21 2 Calibration i a 2 27 2 7 3 Warnings and Error 5 2
53. and either correct the storage junction number or add the storage junction to the junction data ERROR 11 ORIFICE JUNCTION XX IS NOT CONTAINED IN JUNCTION DATA An orifice junction was specified that was not described as part of the Junction Data Section Check the input data and either correct the orifice junction number or add the orifice junction to the Junction Data Section ERROR 12 ORIFICE TOP LIES ABOVE GROUND ELEVATION AT JUNCTION XX The specified orifice diameter plus the specified distance above the junction invert when added to the junction invert elevation is higher than the specified ground elevation for Junction XX Check input data 20 21 EXTRAN Block ERROR 13 WEIR JUNCTION IS NOT CONTAINED IN JUNCTION DATA weir junctions must be described in the Junction Elements Data Section Check input data and either correct the weir junction number or add the weir junction to the Junction Elements Data Section ERROR 14 PUMP JUNCTION IS NOT CONTAINED IN JUNCTION DATA All pump junctions must be described in the Junction Elements Data Section Check input data and either correct the pump junction number or add the pump junction to the Junction Elements Data Section ERROR 15 FREE OUTFALL JUNCTION XX IS NOT CONTAINED IN JUNCTION DATA free outfall junctions must be described in the Junction Elements Data Section Check input data and either correct the free
54. and renumber junctions and required ERROR 3 JUNCTION XX IS ASSOCIATED WITH MORE THAN 8 PIPES INCLUDING ORIFICES See 2 above 3 32 EXTRAN Block ERROR 4 JUNCTION IS ASSOCIATED WITH MORE THAN 8 PIPES INCLUDING WEIRS See 2 above ERROR 5 JUNCTION IS ASSOCIATED WITH MORE THAN 8 PIPES INCLUDING PUMPS See 2 above ERROR 6 JUNCTION IS ASSOCIATED WITH MORE THAN 8 PIPES INCLUDING FREE OUTFALLS See 2 above ERROR 7 JUNCTION XX ON CONDUIT YY IS CONTAINED IN JUNCTION DATA The input data indicates that conduit YY is connected to Junction XX Junction XX is not in the Junction Elements Data Section Check input data ERROR 8 CONDUIT XX HAS CAUSED ZCROWN OF JUNCTION YY TO LIE ABOVE THE SPECIFIED GROUND ELEV The elevation of the junction YY invert plus the ZP for conduit XX plus the diameter or depth of conduit XX results in a top of conduit elevation higher than the ground elevation specified for junction YY Check input data ERROR 9 ALL CONDUITS CONNECTING XX TO JUNCTION YY LIE ABOVE THE JUNCTION INVERT EXTRAN requires that at least one of the conduits connecting to a junction have the same invert elevation as the junction ZP 0 Check input data ERROR 10 STORAGE JUNCTION XX IS NOT CONTAINED IN JUNCTION DATA A storage junction was specified that was not described as part of the Junction Data Section Check the input data
55. aulic head exceeded the ground elevation at a junction the program assumed that the excess water that overflowed onto the ground became lost from the system To overcome this deficiency the SSWMM96 EXTRAN block was modified to allow for the simulation of overflows in streets and reentrance of the overflow water back into the system through inlets and manholes As developed by WRE EXTRAN solved the continuity and Saint Venant flow equations using the modified Euler explicit numerical scheme An implicit numerical solution scheme was developed and incorporated into the modified version of EXTRAN to cut the execution time required for a simulation in half without impairing the accuracy of results At the same time provision for up to ten different pumping rates at a pump station was added to the model 3 1 Geometric Data Outflow Hydrographs o System Geometry From RUNOFF Block or Pipe Sizes shapes amp slopes Q HEC 1 o Location of inlets diversions A A amp overflows lt 74 Operation Rules e N y o Pumps N Offline storage ud gt T S 3 ee o Regulated flow ge diverters EXTRAN BLOCK Q Hydrographs at A Selected Points in DA System l Printed ZU ku Suput L A Time History of gt T Heads and Flows in the System FIGURE 3 1 OPERATION OF THE EXTRAN BLOCK EXTRAN Block Recent modifications to EXTRAN for SSWMM96 have included Specification of simulation duration rather than a
56. ber of pumps for which on off operation is defined One line of pump operation data is required for each pump 0 Variable speed pump Up to ten paired values of stage or volume for Type 1 pump and pump capacity required on next lines 0 Pumpback from storage Maximum storage volume pumpback conduit and maximum pumpback rate required on next line On Off Pump Operation Data MPUMP lines of data one for each pump PSON PSOFF PRATE Stage or volume for pump to come on in feet or cubic feet Stage or volume for pump to go off in feet or cubic feet Base pump capacity in cubic feet per second 3 17 Default none none none none none none Name VRATE EXTRAN Block Description Default Variable pump capacity cubic feet per second per foot Total pump capacity is based on equation 0 0 0 5 where Total pump capacity at a given stage in cubic feet per second Q Base pump capacity PRATE in cubic feet per sec Q Variable pump capacity VRATE in cubic feet per second per foot or cubic feet per second per cubic foot S Stage volume in pump junction feet or cubic feet Variable Speed Pump Operation Data Up to 10 lines with paired values of stage volume and pumping capacity VRATE Stage or volume for Type 1 pump in feet or cubic feet none PRATE Pump capacity corresponding to VRATE in cubic feet per none second Pumpback from Storage Pump Operation Data
57. cond 3 21 EXTRAN Block 99999 A blank line or 99999 indicates the end of the Initial Flow none Data Section 3 5 DESCRIPTION Every effort has been made to make the output from the block easy to understand with headings for each of the output sections that are complete and concise Table 3 2 is sample output file from the EXTRAN block The output shown in Tables 3 2 has been abridged but still shows all the major headings and output data The following paragraphs describe each of the output headings and follow the sample output in Table 3 2 3 5 1 Definition of Output Variables The word page in the following output description is used to describe a section of output that contains specific output data The data on a page may cover more than one physical page in the output file Page 1 The first page of EXTRAN output begins with a title block describing the evolution of the program This title block is followed by a second title block describing the particular EXTRAN input being run It is made up of the two line title block from the EXTRAN input data file Also on the first page is a reiteration of the major control parameters such as the number of integration cycles length of integration timestep starting time and the conduit and junction numbers for detailed printout Pages 2 through 4 The second and third pages begin with the two line title block and then summarize the conduit and junction input
58. ctions that are complete and concise Table 2 7 is a sample output file for subcatchment simulation in the RUNOFF block Table 2 8 is a sample output file for conveyance routing in the RUNOFF block The output shown in Tables 2 7 and 2 8 has been abridged but still shows all the major headings and output data The following paragraphs describe each of the output headings and follow the sample output in Tables 2 7 and 2 8 2 6 1 RUNOFF Subcatchment Simulation Output The first page of RUNOFF subcatchment simulation output begins with a title block describing the evolution of the program This title block is followed by a second title block describing the particular RUNOFF input being run It is made up of the two line title block from the RUNOFF input data Also on the first page is a reiteration of the major control parameters as well as the rainfall hyetographs for the subcatchment simulation 2 18 RUNOFF Block The second page begins with the two line title block and then summarizes the input data This input data consists of the subcatchment subarea descriptions for subcatchment simulations or conveyance element descriptions for conveyance routing The third and succeeding pages of the subcatchment simulation output shown in Table 2 7 contain the printed hydrographs requested in the Subcatchment Print and Control Section in the input data The last page of the output gives the results of a continuity check on the subcatchment overland f
59. cupied by each land use Table 2 1 presents a list of City of Sacramento land uses and their suggested percentage of imperviousness for use in the RUNOFF block Remember that these percentages are just suggestions and actual percentages especially for schools and parks could vary widely depending on the specific site Care must be taken to insure that impervious areas are hydraulically connected to the drainage system For instance if rooftops drain onto adjacent pervious areas they should not be treated as impervious On the other hand if a driveway drains to a street and then to a storm drain inlet the driveway would be considered to be hydraulically connected Rooftops with downspouts connected directly to the storm drain or discharging onto adjacent impervious areas are hydraulically connected RUNOFF Block TABLE 2 1 LAND USES AND PERCENT IMPERVIOUSNESS Suggested Percent Impervious Commercial Highways Parking Apartments Offices Trailers Condominiums Schools Industry Residential 8 10 units acre Residential 6 8 units acre Residential 4 6 units acre Residential 3 4 units acre Residential 2 3 units acre Residential 1 2 units acre Residential 5 1 units acre Residential 2 5 units acre Residential lt 2 units acre Open Space Grassland Cropland Open Space Woodland Table 2 5 Sacramento City County Drainage Manual 1991 Note These percentages may be used as default values but actual percentages should
60. difficult and hard to conceptualize Methods have been provided in this manual to make the job easier but it can still be difficult to resolve a real world subcatchment into a subcatchment that can be used in the model 2 kinematic wave simulation works well when a large area is modeled using a number of small subcatchments In that case any timing and magnitude errors tend to cancel out when the small area hydrographs are summed to represent the larger area When a large area is represented as only one subcatchment the timing errors will not be canceled out and may be significant Maximum size for subcatchments in RUNOFF modeling should be on the order of 200 to 400 acres Subcatchments larger than 100 to 150 acres should probably include a RUNOFF Conveyance Routing step before using the output in EXTRAN 3 As with all hydrologic models the most sensitive input parameter in RUNOFF is the percent impervious This parameter can be very difficult to estimate accurately and changes in percent impervious can yield significant differences in the volume of runoff from a subcatchment 4 Another hydrologic parameter that is difficult to estimate is the subcatchment slope In RUNOFF the subcatchment slope is assumed to be the slope of the subcatchment plane In the real world the subcatchment is comprised of numerous small planes with widely varying slopes 2 7 2 Calibration Calibration or verification of a model is an important step tha
61. duit discharge data saved in the PLC file It can also plot the inflow hydrographs found in the GUT files created by RUNOFF Table 3 3 contains the commands that were used to plot an example junction water surface elevation graph Required user input is underlined in the table The graphics program will display each of the available data plots one at a time TABLE 3 3 HYDROGRAPH PLOTTING EXAMPLE Windows C SWMM GRAPHICS gt SWMGRAPH Initialize Program for Screen Viewing 1 Monochrome screen 2 Color screen Enter Number 2 Enter Name of Input Data File For Plotting gt EXTRAN PLJ Plot Elevation or Depth E D D READY TO DISPLAY DRAWINC Press return when ready to continue SWMM MODEL OUTPUT DATA DEPTH AT JUNCTION NO 102 Example EXTRAN Graph Hardcopy Y N gt N Would You Like Other Plots from the Same Data Y N gt N Would You Like Plots from Different Data Y N gt N Stop Program terminated 3 39 SECTION 4 HEC 1 HYDROGRAPHS 4 1 INTRODUCTION The HEC 1 model developed by the U S Army Corps of Engineers Hydrologic Engineering Center HEC is designed to simulate the surface runoff response of a watershed to precipitation This is accomplished by representing the watershed as an interconnected system of hydrologic and hydraulic components Each model component represents a specific aspect of the rainfall runoff processes occurring in a portion of the watershed A component may represe
62. e 2 Pipe A circular pipe of any diameter 3 Direct flow This element provides only instantaneous direct translation of the flows from the upstream to the downstream conveyance element and does not modify the hydrograph 4 Channel with overflow channel Same as the channel element above except that a larger trapezoidal channel is also specified to accept the flows exceeding the capacity of the initial channel cross section 1 TRAPEZOIDAL CHANNEL 2 CIRCULAR PIPE 3 DIRECT FLOW NOT SHOWN 4 CHANNEL WITH OVERFLOW OVERFLOW CHANNEL 5 PIPE WITH OVERFLOW CHANNEL STREET FIGURE 2 3 GENERAL CONVEYANCE ELEMENT CONFIGURATIONS RUNOFF Block 5 Pipe with overflow channel Same as the pipe element above except that a trapezoidal channel is also specified to accept the flows exceeding the capacity of the pipe 2 3 2 Special Flow Routing Elements The three special flow routing conveyance elements shown in Figure 2 4 are as follows 1 Diversion A table of flows in a conveyance element versus the flow diverted to another conveyance element may be specified using this option 2 Storage reservoir detention basin A table of reservoir storage in acre feet versus outflow in cubic feet per second cfs may be specified using this option This operation may be used in conjunction with the pipe routing element The pipe capacity has to be exceeded before the storage outflow function is utilized 3 I
63. e 3 1 and are illustrated in Figure 3 7 Name Description Default NJUNC 1 Junction at which the weir is located Must already have none been listed in the Junction Elements Data Section NJUNC 2 Junction to which the weir discharges Must already have none been listed in the Junction Elements Data Section KWEIR Type of weir none 1 transverse 2 transverse with flap gate 3 side flow 4 side flow with flap gate YCREST Height of weir crest above invert of junction in feet none YTOP Height of top of weir opening above invert of junction in none feet This is the level at which the weir surcharges and begins to operate as an orifice WLEN Weir length in feet none COEF Coefficient of discharge for the weir A typical value for the none discharge coefficient would be around 2 8 99999 A blank line or 99999 indicates the end of the Weir Data none Section 3 4 2 8 Pump Data Section Pumps in EXTRAN may be of three types an off line pump station with a wet well storage junction an on line lift station or a pump for use in pumpback from storage Pump operation for the Type 1 and Type 2 pumps may be either on off operation or variable speed Type 3 pump operation is dependent on the flow in the specified pumpback conduit Input data for the three types of pumps is illustrated in the Pump Data Section of Table 3 1 Name Description Default NJUNC 1 Junction in which the pump is located Note that for a Type none 1 pump we
64. e element the width or diameter length invert slope side slopes and Manning s n of the conveyance element the depth at which overflow begins and JK the special routing element description The total number of conveyance elements in the simulation is listed at the bottom of page 3 The fourth page begins with the title block as do all pages of the output After the title block each conveyance element is listed along with conveyance elements and subareas that are tributary to it The total drainage area upstream of the conveyance element is also listed Following the connectivity table the hydrograph data for each conveyance element selected for printing in the Conveyance Element Save and Print Control Section of the input data file are listed These data include the discharge through the conveyance as the upper number and then of the following depending on the type of conveyance 2 19 RUNOFF Block TABLE 2 7 RUNOFF SUBCATCHMENT SIMULATION OUTPUT FILE RUNOFF BLOCK OF SSWMM96 DEVELOPED BY METCALF EDDY INC UNIVERSITY OF FLORIDA WATER RESOURCES ENGINEEERS INC SEPTEMBER 1970 UPDATED BY UNIVERSITY OF FLORIDA JUNE 1973 HYDROLOGIC ENGINEERING CENTER CORPS OF ENGINEERS MISSOURI RIVER DIVISION CORPS OF ENGINEERS SEPTEMBER 1974 BOYLE ENGINEERING CORPORATION JULY 1985 MONTGOMERY WATSON AMERICAS INC JAN 1996 SSWMM96 DOCUMENTATION EXAMPLE DATA RUNOFF BLOCK SUBCATCHMENT OVERLAND FLOW HYDROGRAPHS OVERLAND FLOW WI
65. e system 1 free outfalls Inflow from Flooding flows entering the system through street inlets from flooding in the streets Surcharge to Street flows entering the streets due to pipe surcharging Volume in the Street total volume in the street at the junction Pumpback from storage allows the user to define storage locations that pumpback to the pipe conveyance system based on the available capacity in a designated pipe Pumpback should be used in those locations where storage will be required to prevent overflows and where the storage will likely require a pump to return it to the system If a location can be fed and discharged by gravity then a storage junction should be used rather than the pumpback option EXTRAN Block 3 2 CONVEYANCE ELEMENTS The basic conveyance element input data required in EXTRAN are specifications for shape size length hydraulic roughness connecting junctions and invert distances referenced from the junction invert as shown in Figure 3 2 3 2 1 Conduits The various types of conduits are circular rectangular horseshoe elliptical arch and trapezoidal channels These types of conduits are illustrated in Figure 3 3 The elevation of each end of a conduit is described in relation to the invert of the junction to which the end of the conduit is connected as shown in Figure 3 2 The junction invert elevation is specified in the Junction Elements Data Section of the input file The distance ZP i
66. e used For the special conveyance element option additional lines are required to describe the diversion detention or input hydrograph For the overflow option an additional line is required to describe the overflow channel Name Description Default JK If the variable NDP 0 JK is ignored If NDP gt 0 then none values of JK are as follows gt 0 a diversion from this conveyance element to the conveyance element indicated by JK Must be followed by line s with a table of Total Q cfs versus Diverted Q cfs NDP is the number of sets of tabular values 0 adetention basin at this location Must be followed by line s with a table of Detention Storage ac ft versus Basin Outflow Capacity cfs 1 an inflow hydrograph will be specified for this location Must be followed by line s with a table of Time hrs versus Inflow cfs NDP is the number of sets of tabular values 2 16 NGOTO NDP NP GWIDTH GLEN GSLOPE GSI GS2 GS DFULL RUNOFF Block Unique identification number of the conveyance element Also used to control conveyance element default values and modification ratios gt 0 Conveyance element identification number 2 Modify default values for each variable based on values entered on this line Any non zero value entered on a line with N 2 will replace the current default value for that variable 1 Alter subsequent values for a variable by the modification ratio entered on this line
67. eginning of surcharge SEPARATION INVERT _ NOT ALLOWED PIPE N 1 PIPE N 1 PIPEN 1 ZP N 1 1 ZP N 1 2 v INVERT INVERT JUNCTION J PIPE N FIGURE 3 2 DEFINITIONS OF TERMS FOR PIPE JUNCTIONS 3 lt p gt D A P V lt W gt CIRCULAR RECTANGULAR HORSESHOE 4 we A ET D M A s gt CU C NI J D Ay KW Y A V Z p 2 gt ELLIPTICAL ARCH TRAPEZOIDAL A AREA OF CONDUIT D VERTICAL DEPTH OF CONDUIT W MAXIMUM WIDTH OF CONDUIT bottom width for trapezoidal Z SIDE SLOPE OF TRAPEZOIDAL horizontal vertical FIGURE 3 3 TYPES OF CONDUITS IN EXTRAN TYPICAL STREET SECTION TRANSFORMING TYPICAL STREET SECTION TO TRAPEZOIDAL APPROXIMATION lt OVERFLOW OVERFLOW gt SECTION T MAIN SECTION SECTION A ODEEP 1 2 v OTHE1 lt OWIDE gt DEFINITIONS FIGURE 3 4 STREET OVERFLOW SECTION EXTRAN Block 3 3 1 Storage Junctions Conceptually storage Junctions may be either tanks of constant surface area over their depth or Irregular shaped detention basins Storage may be placed at any junction in the system either in line or off line The elevation of the top of the storage is specified in the storage junction data and must be at least as high as the highest pipe crown at the junction If this condition is violated the system will go into simulated surcharge before the highest pipe is flowing full Irregula
68. er 99999 or blank line 99999 OUTFALLS WITH FLAP GATES TIDE GATES DATA SECTION one outfall junction number per line Junction Sequence Number Number i 35 4 To indicate end of for Outfalls W Flap Gates Data Section enter 99999 or blank line 99999 TIDE OR STAGE BOUNDARY DATA SECTION If no water surface elevation at outfall Ntide 1 Ntide 1 If constant water surface elevation at outfall Ntide 2 Ntide Al 2 47 If tide coefficients provided by user Ntide 3 Tidal NTide 1 2 5 6 A7 Period a 1 4 5 2 2 25 If tide coefficients to be computed by program Ntide 4 Tidal Ntide Period 4 25 KO Number Print Points Flaq 1 4 1 o Time Tide Time Tide Time Tide Time Tide 1 34 8 37 14 33 21 31 If staqe history boundary condition Ntide 5 Ntide lt 5 Number Print Points Flag 10 0 o Time Stage Time Stage Time Stage Time Stage Time Stage 0 34 1 34 5 3 35 5 4 36 0 5 37 0 6 38 0 7 37 5 8 36 5 9 36 0 10 35 5 To indicate end of Tide or Stage Boundary Data Section enter 99999 blank line 99999 INITIAL FLOW DATA SECTION If entering initial flow data must enter initial flows for each conduit real and internal in the order specified n the Conveyance Element Data Section Q V Q V Q V Q cfs fps cfs fps cfs fps
69. f peak flows and stages Subcatchment Conveyance Element Relationships One line for each subcatchment hydrograph being read in jndicating conveyance element associated with each subcatchment N IDGUT Sub Convey catch Element No No 1031 103 1051 105 1061 106 1062 106 1071 107 indicate end of subcatchment data enter 99999 or blank 99999 CONVEYANCE ELEMENT DATA SECTION One line for each conveyance element IK N NGOTO NDP NP GWIDTH GLEN GSLOPE 51 GS2 GS DFULL Special Convey Next No Type Bottom Length Invert Left Right Mannings Depth Routing Element Elem Added Convey Width Convey Slope Side Side n or Element No No Value Element or Dia Element Slope Slope Dia 5 ft ft ft ft ft ft ft ft ft 0 103 0 0 1 10 450 01 15 15 02 5 345 105 0 5 2 4 600 01 0 0 018 4 If NDP gt 0 and JK gt 0 Element Divert Element Divert Element Divert Element Divert Element Divert ki cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs 0 0 10 5 20 10 30 15 40 20 0 106 0 5 2 4 800 01 0 0 018 4 If NDP gt 0 and JK 0 Storage Outflow Storage Outflow Storage Outflow Storage Outflow Storage Outflow ac ft Ccfs Cac ft Ccfs ac ft cfs ac ft cfs ac ft cfs 0 0 2 5 4 10 6 15 10 20 1 107 0 5 1 10 350 01 5 ES 025 6 If gt 0 and JK 1 Inflow Time Inflow Time Inflow Time Inflow Time Inflow hrs cfs hrs cfs hrs cfs hr
70. he Junction Elements Data Section 99999 A blank line or 99999 indicates the end of the Initial Flow none Data Section 3 4 2 13 User Defined Inflow Hydrograph Section EXTRAN provides for the input of user defined inflow hydrographs where it is desirable to run EXTRAN alone without prior use of the RUNOFF program or when the user wants to add additional input hydrographs either at the same or different junctions to those computed by RUNOFF The individual junctions receiving user defined hydrographs are specified on the first line s of this section of the input After the junctions receiving hydrographs have been specified the times and discharges for all points on the hydrographs are input next The time of each discharge point is given in decimal hours i e 10 45 am is 10 75 Hydrograph time input points can be specified at any convenient time as long as a discharge is included for each junction specified The hydrographs used by EXTRAN are constructed by interpolating between consecutive time input points for each time step These input lines required only if NJSW gt 0 Program Parameters Section Name Description Default JSW 1 Junctions for NJSW input hydrographs All the junctions none must already have been listed in the Junction Elements Data Section TEO Time in decimal hours for hydrograph point none Name Description Default QCARDY 1 Flow rate at each of NJSW nodes in the order specified for JSW in cubic feet per se
71. ies overlaid on top It is important to understand the topography of the subcatchment as well as any conveyance elements that carry runoff into or out of the subcatchment prior to delineating the subcatchments on the map The topography will determine the subcatchment boundaries except where conveyance structures may divert water into or out of the subcatchment Subcatchments should be chosen to coincide with different land uses and with drainage divides as described above if possible 2 2 2 Subcatchment Width If overland flow in a subcatchment is visualized as occurring in an idealized rectangular subcatchment such as the one shown in Figure 2 1 then the width of the subcatchment is the physical width of the overland flow Since the overland flow per unit width qq occurs along a length the total flow is equal to qq multiplied by the width In the idealized example shown in Figure 2 1 the two sides of the subcatchment are symmetrical giving total width that is twice the length of the gutter flow 2 If the subcatchment in question was just one side of the subcatchment shown in Figure 2 1 the width would simply be Subcatchments in the real world are rarely consistent with the idealized situation shown in Figure 2 1 Most of them will be irregular in shape and will have a drainage channel that is not centered in the basin as shown in Figure 2 2 A simple way to handle this case is to compute a skew factor 2 2 UNIFORM RAINFALL INT
72. ill result in conduit velocities that are not feasible It is always a good idea to check the conduit design velocity in the Summary Statistics for Conduits in the output data against the maximum computed velocity If the maximum computed velocity is significantly higher than the design velocity it is likely that the model has become numerically unstable at that location Total Inflow If there are big differences between the observed and computed hydrographs many times they are due to problems that are carried over from RUNOFF Be sure to check the RUNOFF output carefully before attempting to calibrate or verify EXTRAN Other items that are important to consider when calibrating an EXTRAN model are 3 31 EXTRAN Block Steady Flows The first simulation to try with a newly created EXTRAN input data set is steady flow simulation First run the simulation with steady flows and free outfalls This may highlight many problems in the input data Second add any pumps to the simulation and run again with steady flows Finally when both of these simulations work add the inflow hydrographs from RUNOFF Remember if it doesn t work with steady flow it certainly won t work with unsteady inflow hydrographs Junction Losses The EXTRAN block ignores junction losses as mentioned above as a limitation To correct for junction losses where needed the user should increase the Manning s n roughness coefficient for the pipe downstream of the junction
73. infiltration and inflow coming into the system CLEN Sum of the length of curb inlets per thousand feet both sides none of the street into the system in the area of influence of the junction The area of influence is defined as 4 the distance along each conduit connected to the junction Example if the two conduits connecting to the junction have an average of one 3 foot inlet on each side of the street every 500 feet then 3 CLEN E3 TZ 1000 12 500 3 13 EXTRAN Block Name Description Default OWEIRC Average curb inlet weir coefficient for the inlets the none conduits connecting to the junction A typical number for this coefficient is 3 1 A combination of CLEN and OWEIRC is also used to provide better control of overflow from and inlet inflow to each junction as follows Flow out Flow into to Street Junction 1 CLEN 0 No No OWEIRC 0 2 CLEN gt 0 Yes No OWEIRC 0 3 CLEN gt 0 Yes Yes OWEIRC gt 0 Head may become greater than ground elevation CLEN and OWEIRC act only as switches for cases A and B shown above and may be any positive value or zero For case C the values used for CLEN and OWEIRC must represent the actual inlet situation as described above QCAP This parameter controls the inflow capacity from RUNOFF of the junction 0 No restrictions on inflow from RUNOFF gt 0 Inflow restricted to specified peak flow Excess sent to storage and then added to system as capacity allows
74. ions ERROR 37 CONDUIT XX SPECIFIED FOR PUMPBACK IS NOT CONTAINED IN CONDUIT DATA The conduit specified in the pumpback option to be used for determining the pumpback rate from storage is not contained in the conduit data Check your data and either enter the correct conduit information to the conveyance element data section or change the pumpback conduit number in the pumpback data ERROR 38 JUNCTION XX SPECIFIED FOR PUMPBACK STORAGE CANNOT BE IN DETAILED HEAD PRINTOUT Detailed head printout is not applicable to the junctions at which pumpback to the system is implemented Remove the reference to junction XX from the list of junctions where heads are to be printed ERROR 39 ERROR READING THE HOT START FILE The file specified as the hot start file was not found or was not a legal hot start file Check the file name and type then rerun EXTRAN ERROR 40 ERROR WRITING THE HOT START FILE An error occurred while writing the hot start data to a file The probable cause for this error is insufficient room on the disk Check your disk and rerun EXTRAN ERROR 41 JUNCTION XX TIDE OR STAGE BOUNDARY CONDITION YY NOT INPUT CORRECTLY A tide or stage boundary condition was specified but not supplied in the tide or stage data ERROR 42 FOUR TIDE POINTS DO NOT FALL IN THE TIDAL PERIOD The tide data given for calculating the tidal coefficients is outside of the specified tidal period 3 6
75. junctions specified in the input data is greater than the allowable dimension NSTORO If the number of storage junctions specified in the input data is required for this simulation the parameter NSTORO in COMMON INC must be increased and the entire EXTRAN block must be recompiled and relinked before running the simulation ERROR 26 NORIFO IN COMMON INC SHOULD BE GREATER THAN XX The number of orifices specified in the input data exceeds the allowable dimension NORIFO If the number of orifices specified in the input is required for this simulation the parameter NORIFO in COMMON INC must be increased and the entire EXTRAN block must be recompiled and relinked before running the simulation ERROR 27 NPUMPO IN COMMON INC SHOULD BE GREATER THAN XX The number of pumps specified in the input data exceeds the allowable dimension NPUMPO If the number of pumps specified in the input is required for this simulation the parameter NPUMPO in COMMON INC must be increased and the entire EXTRAN block must be recompiled and relinked before running the simulation ERROR 28 NFREEO IN COMMON INC SHOULD BE GREATER THAN XX The number of free outfalls specified in the input data 3 35 29 30 31 32 33 34 EXTRAN Block exceeds the allowable dimension NFREEO If the number of free outfalls specified in the input is required for this simulation the parameter NFREEO in COMMON INC must be increased
76. lated using the Horton infiltration equation pe where f f c infiltration rate inches hour initial maximum infiltration rate inches hour final infiltration rate inches hour natural logarithm base decay coefficient time in seconds The U S Soil Conservation Service SCS has classified most soils into Hydrologic Soil Groups A B C and D describing their infiltration capacities They are as follows Group A Low runoff potential Group A is made up of soils having high infiltration rates even when thoroughly wetted and consisting chiefly of deep well to excessively drained sands or gravels Group B Moderately low runoff potential Group B contains soils having moderate infiltration rates when thoroughly wetted and consisting chiefly of moderately deep to deep moderately well to well drained soils with fine to moderately coarse textures These soils have a moderate rate of water transmission Group C Moderately high runoff potential Group C is comprised of soils having slow infiltration rates when thoroughly wetted and consisting chiefly of soils with a layer that impedes downward movement of water or soils with moderately fine to fine texture These soils have a slow rate of water transmission Group D High runoff potential Group D includes soils having very slow infiltration rates when thoroughly wetted and consisting chiefly of clay soils with a high swelling pote
77. ll Name JGATE NBCG 99999 Description Default Junction from which the outfall with a flap gate occurs none Must already have been listed in the Junction Elements Data Section One outfall Junction number per line Location of tide or stage information in Tide or Stage none Boundary Information Section A blank line or 99999 indicates the end of the Outfall with none Flap Gate Data 4 2 11 Tide or Stage Boundary Data Section This section may contain up to 20 tide or stage boundary descriptions All tide or stage data on one line except if NTIDE 4 or 5 Name NTIDE Al to A7 Description Default Tide index none 1 no water surface elevation at outfalls 2 outfall control water surface at constant elevation Al 3 tide control coefficients provided by user 4 program will compute tide coefficients 5 stage history of water surface elevation boundary condition for NTIDE 1 4 or 5 Al to A7 not required none for NTIDE 2 Al outfall control water surface elevation A2 to A7 not required for NTIDE 3 Al to A7 tidal coefficients for computing the current tide elevation using the following A A sin OT sin2 T 4 sin 30T cos OT 4 cos2 0T A cos30T r NTIDE 3 or 4 tidal period in hours Typical tidal none periods are 12 5 and 25 hours but any value may be used 3 19 Revised January 1996 EXTRAN Block For N
78. low simulation The continuity indicates the difference between the total rainfall on the watershed and the abstractions from the watershed infiltration watershed outflow and depression storage This difference shown as percent of rainfall that is not accounted for indicates how well the program has simulated the rainfall runoff characteristics of the entire watershed Values of the continuity error should not exceed 1 to 2 percent A simulation that results in higher values than these should be checked carefully for problems 2 6 2 RUNOFF Conveyance Routing Output The first page of the RUNOFF conveyance routing output shown in Table 2 8 begins with a title block describing the evolution of the program This title block is followed by a second title block describing the particular RUNOFF input being run It is made up of the two line title block from the RUNOFF input data Also on the first page is the number of time steps in the simulation and the routing time interval in minutes The second page of the RUNOFF conveyance routing output contains a listing of the hydrographs from RUNOFF subcatchment simulation or from HEC 1 that are being used as input to the simulation The hydrographs are listed for each subcatchment for all timesteps The third page reiterates the conveyance element input data including element number downstream connection if any NDP the number of special data sets associated with the JK option the type of conveyanc
79. n the Conveyance Element Section in Table 3 1 Name Description Default NCOND Unique conduit identification number none NJUNC 1 Junction number at upstream end of conduit none NJUNC 2 Junction number at downstream end of conduit none 3 11 EXTRAN Block Name Description Default NKLASS Type of conduit shape none circular rectangular horseshoe elliptical arch trapezoidal channel AFULL Cross sectional area of the conduit in square feet This value none is required only for conduit types 3 4 and 5 AFULL may be set to zero for conduit types 1 2 and 6 DEEP Vertical depth of conduit in feet none WIDE Maximum width of conduit in feet For the trapezoidal none channel type 6 it is the bottom width in feet LEN Length of the conduit between the junctions in feet none ZP 1 Distance of the conduit invert above the junction invert at the none upstream junction NJUNC 1 ZP 2 Distance of the conduit invert above the junction invert at the none downstream junction NJUNC 2 ROUGH Manning s n roughness coefficient or resistance factor for 0 014 the conduit The n should include adjustments for entrance and exit losses at the manholes STHETA Slope of one side of trapezoidal channel horizontal vertical none 0 vertical in feet feet Set to zero for conduit types 1 through 5 SPHI Slope on the other side of trapezoidal channel none horizontal vertical 0 vertical in feet foot Set to zero for
80. nflow hydrograph This option may be used to specify an input hydrograph table of time in hours versus the flow in cfs for any routing element 2 3 3 Manning s n For hydrologic routing through the conveyance elements described above the resistance Manning s n coefficients should not be the same as those that would be used for the same type of conveyance element where hydraulic calculations are being performed Studies have shown that increasing the typical values of Manning s n by approximately 25 percent provides more realistic results when using RUNOFF For example when doing hydraulic calculations a concrete gutter would normally have n 0 013 That same gutter when being used for hydrologic routing in RUNOFF would have n 0 016 Hydrologic routing in streets Is approximated using the trapezoidal sections illustrated in Figure 2 5 2 4 PRECIPITATION Precipitation for use with RUNOFF may come from two different sources Historical Storm Data Design Storm Data The precipitation data may be input for any time interval desired but it is best to keep the time intervals between 5 to 30 minutes for the best storm definition without having excessive precipitation values Each value in a precipitation hyetograph is the average intensity in inches per hour that took place during the timestep 2 8 1 DIVERSION DIVERSION GUTTER DIVERSION N GUTTER INFLOW 2 STORAGE RESERVOIR DETENTION BASIN
81. ng s Manning s Storage Storage Infiltration graph catch Elem catch catch Imper catch n n on on Decay No No No Width Area vious Slope Imperv Perv Imperv Perv Max Min Rate Cft ac ft ft in Cin in hr 1 1031 103 1100 13 9 45 001 016 0 05 100 250 3 00 0 50 0 0018 1 1051 105 1800 13 0 45 001 016 0 05 100 250 3 00 0 50 0 0018 1 1061 106 1960 24 6 45 001 016 0 05 100 250 3 00 0 50 0 0018 1 1062 106 1800 34 5 40 001 016 0 05 100 250 3 00 0 50 0 0018 Comments are allowed in the subcatchment data section 1 1071 107 1750 30 1 70 001 016 0 05 100 250 3 00 0 50 0 0018 1 1072 107 770 11 2 70 001 016 0 05 100 250 3 00 0 50 0 0018 1 1081 108 2520 26 1 90 001 016 0 05 100 250 3 00 0 50 0 0018 1 1082 108 1300 2 3 90 001 016 0 05 100 250 3 00 0 50 0 0018 1 1083 108 1600 10 3 80 001 016 0 05 100 250 3 00 0 50 0 0018 indicate end of subcatchment data enter 99999 or blank 99999 Subcatchment Save Print Control 1 N7 If gt 0 hydrographs saved for routing in RUNOFF Block 0 N21 If gt 0 hydrographs saved for routing in EXTRAN Block 9 NPRNT No of subcatchments for which hydrographs are printed 3 INTERV No of timesteps between printings Enter subbasin numbers if NPRNT gt 0 1031 1051 1061 1062 1071 1072 1081 1082 1083 ENDPROGRAM 2 10 RUNOFF Block 2 5 2 1 Title Section The title section is two lines containing up to 80 characte
82. ng s n for Overland Flow Impervious Smooth Asphalt Asphalt or concrete paving Pervious Native grass Urban lawns Dense shrubbery and forest litter 2 2 6 Depression Storage Rainfall that is collected and held in small depressions and does not become part of the general surface runoff is call depression storage or retention Most of this water eventually infiltrates on pervious areas or evaporates Depression storage also includes water intercepted by trees and bushes and water that is detained on the surface and does not run off Depression storage will depend on specific subcatchment conditions but Table 2 3 gives suggested values for typical depression storage for various types of land cover TABLE 2 3 TYPICAL DEPRESSION STORAGE FOR VARIOUS LAND COVERS Typical Depression Recommended and Detention Storage Storage Values Land Cover Values inches inches Impervious Areas Large Paved Areas 0 05 0 15 Roofs Flat 0 10 0 30 Roofs Sloped 0 05 0 10 Pervious Areas Lawn Grass Wooded Areas and Open Fields In RUNOFF depression storage may be used as a calibration parameter particularly to adjust runoff volumes If runoff volumes from a subcatchment or basin being calibrated appear to 2 5 RUNOFF Block be too high or too low the depression storage values being used in RUNOFF may be adjusted within the ranges given in Table 2 3 2 2 7 Infiltration Coefficients Infiltration from pervious areas is calcu
83. nnns 2 28 2 7 3 1 Subcatchment Warnings and Error Messages 2 28 2 7 3 2 Conveyance Element Routing Warnings and Error Messages 2 28 2 5 Runoff de RR RET 2 29 SECTION 3 EXTRANBLOCK teen aaa aaa aaa etn 3 1 3 I Introduction ero ero Eee beige tee 3 1 3 2 Conveyance Elements mala lava a de RE OG Oda qn 3 3 3 2 T Condults ete oat a er eme gatur qs 3 3 32 27 Overflow Sectlolls nie cet s ove AKL 3 3 3 3 Junction Elements do Ri O d et RARE EH id ie a P AERE SA R 3 3 3 3 1 Storage J nctions sz di e ce e eee ee e E RHEIN GS 3 4 3 3 2 OTM COS e o tee RR M y M A AL A MAL 3 4 LRQ di MEN 3 4 Table of Contents PAGE FIA PUMPS e M see 3 4 32359 Free Outfalls esis eles A i erede oi a 3 5 3 3 6 Flap Tide Gates rcu ete A e es 3 5 t eid 3 6 T D tault Values s RAR SANA ID hens 3 6 3 42 Input Data Template e ana ame O aa 3 6 3 42 T Title SeCtlon cer re een e E rop e rre eee 3 6 3 4 2 2 System Parameters Section enne 3 6 3 4 2 3 Conveyance Elements Section
84. nt the runoff occurring in a subbasin the routing of flows down a stream channel or the routing of flows through a reservoir Description of the components of a model requires estimation of a set of parameters that describes the hydrologic and hydraulic characteristics of the components Parameters describing the various components of the model are based on land use soils vegetation and topography For example the land use in a subbasin will determine the percent of that subbasin that is impervious and the average condition of the drainage channels The end result of the modeling process is the computation of streamflow hydrographs including peak flows at specified locations throughout the watershed HEC 1 provides a wide variety of rainfall runoff simulation methods including Synthetic Unit Hydrographs _ Clark Unit Hydrograph Snyder Unit Hydrograph SCS Dimensionless Unit Hydrograph User defined Unit Hydrograph Kinematic Wave Overland Flow Routing Land surface interception depression storage and infiltration are referred to in the HEC 1 model as precipitation losses The losses may be represented in a variety of ways Initial and Uniform Loss Rate Exponential Loss Rate SCS Curve Number Holtan Loss Rate Green and Ampt Infiltration Function The output file from HEC 1 is run through a post processor POSTHECI that prepares hydrograph input files for use with either RUNOFF or EXTRAN HEC 1 Hydrographs 4 22 IN
85. ntial soils with a permanent high water table soils with a claypan or clay layer at or near the surface and shallow soils over nearly impervious material These soils have a very slow rate of water transmission Urban High runoff potential Urban soils have been disturbed and recompacted usually having slow infiltration rates when thoroughly wetted These soils have a slow rate of water transmission and should be handled the same as Group D soils 2 6 RUNOFF Block Soil types for a particular area in the City of Sacramento can be determined from the SCS Soil Survey maps that are available from the local SCS office Recommended values for fj fo and listed in Table 2 4 TABLE 2 4 RECOMMENDED INFILTRATION COEFFICIENTS Infiltration Initial Infiltration Final Infiltration Decay Coefficient SCS Soil Type i i a Note The infiltration decay coefficient used in the combined system model is 0 000362 2 3 CONVEYANCE PARAMETERS There are five standard types of conveyance elements and three special flow routing conveyance elements that are used in RUNOFF 2 3 1 Conveyance Elements The RUNOFF Block has eight conveyance elements available for routing flows Figure 2 3 illustrates general conveyance element configurations The five standard conveyance elements are 1 Channel A trapezoidal channel used to represent or approximate an open channel gutter condition The channel is defined by its bottom width and side slop
86. on is based on a description of the physical system being modeled During the model testing and calibration the following elements should be checked 1 Connectivity Errors in EXTRAN are very often a result of input data errors Some important parameters to check are pipe invert elevations pipe sizes ZPs and pump specifications The internal connectivity summary in the output data must be carefully checked to insure that conduit and junction connections are correct Many problems encountered during calibration can be traced back to input data problems Input Data Verification During model verification all system description parameters must be checked carefully to insure that they match the actual system being modeled Continuity One of the best indicators of proper model operation is the percent error in continuity listed at the bottom of page six of the output from EXTRAN This error should always be less than ten percent If it is greater than five percent it is suggested that the input data be checked carefully for input data errors see 1 above or instabilities see 3 below Oscillations Large and rapid oscillations in junction water surface elevations or in flow and velocity in conduits are also good indicators of numerical instabilities in the EXTRAN simulation Check for conduits that are too short and or rerun the simulation with a lower AT Excessively High Velocity At times the numerical solution to the flow equations w
87. on the volume level of water in the wet well If the inflow rate to the wet well exceeds the maximum pump capacity and the volume level in the wet well approaches the maximum volume the inflow to the wet well will be reduced to the maximum pump rate This inflow reduction will cause the hydraulic grade line upstream of the wet well to rise No flooding will occur at the wet well junction A Type pump may have only one influent pipe entering the pump junction TO STORAGE TO STORAGE RESERVOIR RESERVOIR _ OVERFLOW WEIR _ DRY WEATHER DRY WEATHER C FLOW TO 2 gt FLOW TO lt TREATMENT TREATMENT PLANT PLANT COMBINED SEWER COMBINED SEWER PLAN VIEW _ SIDE BOTTOM ORIFICE ORIFICE O0 SECTION VIEW BOTTOM ORIFICE SIDE ORIFICE WITH WITH HIGH OUTLET OVERFLOW WEIR FIGURE 3 5 WEIRS AND ORIFICES EXTRAN Block 2 On line lift station The lift station pumps according to the level of the water surface at the junction being pumped When the inflow rate to the pump junction exceeds the maximum pump capacity and the level of the water surface at the junction is higher than the ground surface overflow will occur at the pump junction A Type 2 pump may have multiple influent pipes entering the pump junction 3 Pumpback from storage pump station At this station the rate of pumping from storage back into the system depends on the excess capacity of a specified conveyance element When flo
88. ons are added to the conduits WARNING 4 AT STORAGE JUNCTION XX AREA DECREASES BETWEEN STAGES YY AND ZZ Area must increase with increasing stage in the irregular storage junction WARNING 5 SIMULATION STARTS BEFORE TIME HISTORY OF STAGE BEGINS FOR STAGE BOUNDARY CONDITION XX PROGRAM DEFAULTS TO THE FIRST STAGE VALUE The simulation start time is earlier than the start time specified in the stage boundary condition input data The program will use the first given stage data point for all simulation times prior to the first point WARNING 6 SIMULATION CONTINUES AFTER THE TIME HISTORY OF STAGE ENDS FOR STAGE BOUNDARY CONDITION XX PROGRAM DEFAULTS TO THE LAST STAGE VALUE The simulation end time is past the end of the data in the stage boundary condition input data The program will use the last given stage data point for all simulation times after the last point 3 38 Revised January 1996 EXTRAN Block 3 7 EXTRAN GRAPHS In the System Parameters Section of the EXTRAN input data the user specifies junctions or conveyance elements to be printed out NHPRT JPRT i NQPRT CPRT i also saves these same hydrographs to special junction and conduit plotting files that are saved with the extensions of PLJ and PLC respectively The graphics program supplied with SSWMM96 SWMGRAPH can plot the junction water surface elevation data saved in the PLJ file as well as the con
89. ored If less than the expected number of values are entered RUNOFF will read the remaining input values from the next line of input 2 5 1 Default Values Many variables used by the RUNOFF block have default values that will be used in the computations if the variable in question is not specified 1 a zero Where default values are supplied in the model they will be noted in this manual as part of the input parameters description The standard defaults incorporated in the RUNOFF block may not be applicable in all situations Methods are available in RUNOFF to change any of the default values to match individual situations Multiplication ratios may also be added for any of the subcatchment parameters enabling the user to change all subsequent subcatchments by a given amount For example as part of a calibration procedure the maximum infiltration rate for a series of subcatchments could be multiplied by a factor of 1 1 to decrease the volume of runoff produced by a given amount of rainfall 2 5 2 Overland Flow Input Data Template Table 2 5 is a sample input file illustrating the input format and layout of a typical overland flow RUNOFF input data file for use in creating hydrographs The input is divided into sections as follows Title Section System Parameters Section Rainfall Parameters Section Subcatchment Data Section Each of these sections and its associated input variables will be discussed in detail 2 9 RUNOFF Block
90. print switches none 0 off l on IPFLAG 1 Conduit parameters printout IPFLAG 2 Junction parameters printout IPFLAG 3 Miscellaneous input data printout IPFLAG 4 Junctions and conduits summary printout IPFLAG 5 Hydraulic grade line summary printout IPFLAG 6 Summary statistics for junctions printout IPFLAG 7 Flow and velocity summary printout IPFLAG 8 Summary statistics for conduits printout Junction and Conveyance Elements for Detailed Printout JPRT 1 Junction element numbers for detailed hydraulic grade line none printout KPRT i Junction element numbers for detailed water balance none printout CPRT i Conveyance element numbers for detailed flow and velocity none printout 3 4 2 3 Conveyance Elements Section Conveyance elements include conduits various shapes of pipes and trapezoidal channels as illustrated in Figure 3 3 and their associated overflow sections This section of the input data gives a complete description of each conduit including size upstream and downstream junction elements Manning s n resistance factor slope from upstream and downstream invert elevations and overflow channel section description All the data values for a conveyance element are placed on one line Comment lines are allowed between conveyance element data lines so long as the each data lines contains all the data values for a conveyance element A sample input line for each type of conveyance element is given i
91. ption is used data must be input for every conduit and every junction in the system The initial discharge and velocity must be specified for all real conduits plus all internal links There is one internal link for each orifice weir pump and outfall in the system Ina complex network the total number of real plus internal conduits is best determined from the conduit connectivity summary in a trial run with EXTRAN As an example in a system of 25 real conduits 28 junctions 2 orifices 3 weirs and 1 free outfall we have a total of 31 links The specification of initial discharges requires that flow and velocity pairs be input for each of the 31 links 3 20 Revised January 1996 EXTRAN Block Similarly the initial depths not elevations must be specified for all real and internal junctions Internal junctions are specified automatically by EXTRAN for each weir in the system Thus in the example above we would input depth values for a total of 31 junctions Name Description Default VG Initial discharge and velocity pair for each conduit real and none internal in the system in cubic feet per second and feet per second respectively Must be entered in the order that the conduits were specified in the Conveyance Elements Data Section 1 Initial depth of flow each Junction real Internal none system in feet above junction invert Must be entered in the order that the Junctions were specified in t
92. r detailed printing of head output 4 NWPRT No of junctions for detailed water balance 14 NQPRT No of conduits for detailed printing of discharge 1 PSTART First time step to begin print cycle 30 DINTER Interval between print cycles for all junctions and conduits 20 HINTER Interval between print cycles for detailed printouts 0 NJSW No of input junctions 100 MAXIT Maximum number of iterations per timestep 0 JREDO Hot Start Control O No l Yes 2 New 3 Yes amp New 1 IPFlag 1 1 for conduit parameters printout 1 IPFlag 2 1 for junction parameters printout 1 IPFlag 3 1 for miscellaneous input data printout 0 IPFlag 4 1 for junctions and conduits summary printout IPFlag 5 1 for hydraulic grade line summary printout 1 IPFlag 6 1 for summary statistics for junctions printout 1 IPFlag 7 1 for flow and velocity summary printout 1 IPFlag 8 1 for summary statistics for conduits printout Node junction numbers where heads to be printed NHPRT junctions 20 101 102 103 104 105 106 107 108 109 110 150 151 152 153 Node junction numbers for detailed water balance NWPRT junctions 105 106 107 108 Conduit numbers where flows are to be printed NQPRT conduits 201 202 203 204 205 206 207 208 209 210 251 252 253 254 CONVEYANCE ELEMENTS DATA SECTION Con Up Down Con Conduit Up Down 15 2nd Overflow duit strm strm d
93. r shaped detention basins are described in EXTRAN by defining data pairs containing surface area and depth information These data pairs can define storage of any shape and size and are not limited to the regular constant surface area of a storage tank junction 3 3 2 Orifices EXTRAN simulates orifices as equivalent pipes created automatically by the program The term equivalent pipes means that for a given head at a junction the flow in the equivalent pipe created by the system will be the same as the flow that would pass through the orifice for the same head at the junction Data entry is straightforward For sump bottom orifices the program automatically sets the invert of the orifices one diameter below the junction invert so that the orifice is flowing full before there is any discharge overflow to conduits downstream of the junction containing the orifice Figure 3 5 illustrates the use of orifices 3 3 3 Weirs Weirs may be specified as either transverse or side flow SSWMM96 Flow at the weir may be below the weir crest over the weir from either side or surcharged from either side Weirs are often put into systems to provide wet weather relief when levels in a junction go above the level of the weir crest as shown in Figure 3 5 3 3 4 Pumps Pumps may be of three types off line on line and pumpback The characteristics of these pumps are as follows 1 Off line pump station with a wet well the rate of pumping depends up
94. ram terminated SECTION 3 EXTRAN BLOCK 3 1 INTRODUCTION EXTRAN is a dynamic flow routing model that routes inflow hydrographs through an open channel and or closed conduit system based on a solution of the full dynamic equation for gradually varied flow The EXTRAN Block receives hydrograph input at specified model locations by file transfer from the RUNOFF Block or from HEC 1 and or by direct input in the EXTRAN input file Figure 3 1 illustrates the operation of the EXTRAN Block EXTRAN performs dynamic routing of stormwater flows through the major storm drainage system to the points of outfall to the receiving water system The program simulates branched or looped networks backwater due to tidal or non tidal conditions free surface flow pressure flow or surcharge flow reversals flow transfers by weirs orifices and pumping facilities and storage at on or off line facilities Types of channels that can be simulated include circular rectangular horseshoe elliptical and arch pipes plus trapezoidal channels Simulation output takes the form of water surface elevations and discharge at selected system locations For junctions invert and ground elevations are required The various types of flow structures such as storage diversion weirs pumps and outfalls are specified at junctions The original version of EXTRAN lacked the capability of handling overflow conditions resulting from inadequate conveyance capacities When the hydr
95. re to be saved for subsequent routing in EXTRAN Number of subcatchments for which hydrographs are to be printed and sent to file for use with plot program Number of timesteps between printing If NPRNT gt 0 Subcatchment numbers for which values are to be printed and sent to file for use with plot program 2 13 Default none none none 1 none RUNOFF Block 2 5 3 Routing Input Data Template Table 2 6 is a sample input file illustrating the input format and layout of a typical RUNOFF routing input data file for use in routing previously created hydrographs The input is divided into sections as described below Title Section System Parameters Section Conveyance Element Data Section Each of these sections and its associated input variables will be discussed in detail below 2 5 3 1 Title Section The title section is two lines containing up to 80 characters in each line The title should be descriptive but may be anything the user wants 2 5 3 2 System Parameters Section This section of the input contains the overall simulation parameters that control the length of the simulation timestep size etc Descriptions of each of the system parameters are given below No comment lines are allowed inside the System Parameters Section Name Description Default IOPT Indicates whether subcatchment hydrographs will be none simulated in RUNOFF or if they will be input from another source For hydrograph routing IOP
96. rs in each line The title should be descriptive but may be anything the user wants 2 5 2 2 System Parameters Section This section of the input contains the overall simulation parameters that control the length of the simulation timestep size etc Descriptions of each of the system parameters are given below comment lines allowed inside the System Parameters Section Name Description Default IOPT Indicates whether subcatchment hydrographs will be none simulated in RUNOFF or if they will be input from another source For subcatchment overland flow simulation 0 0 subcatchment hydrographs will be simulated in RUNOFF The hydrographs may be routed through RUNOFF conveyance elements before being saved but that is not required NSTEP Number of timesteps to be calculated Should be sufficient none to insure that most of the runoff occurs Depends on the size of the watershed the length of the precipitation and the size of the timestep NHR NMN Hour and minutes of start of the storm May be 0 0 none DELT Size of the computation timestep in minutes For all but very none small subcatchments DELT 5 minutes is adequate NRGAG Number of rain gage hyetographs provided Up to 10 none hyetographs are allowed PCTZER Percentage of the impervious area that has no depression 25 storage depth and runs off immediately IPFLAG Input data print echo switches none 0 off l on IPFLAG 1 Rainfall parameters printout I
97. rshed inflow node storage hydrograph excess system inflow system outflow inflow from flooding surcharge to street volume in street and pumpback volume The definition of the headings in the cumulative inflow and outflow summary are Watershed Inflow cumulative inflow at all junctions from RUNOFF module or from user created gut file Node Storage timestep storage at all junction resulting from inflows greater than user defined inflow capacities 3 28 EXTRAN Block Hydrograph Excess sum of all watershed inflows that didn t enter the pipe conveyance system from RUNOFF due to limited downstream pipe capacity System Inflow cumulative difference between the watershed inflow and the hydrograph excess and node storage System Outflow cumulative flow out of the system Inflow from Flooding cumulative flow entering the pipe conveyance system through street inlets from flooding in the streets Surcharge to Street cumulative flow entering the streets due to pipe surcharging Volume in Street cumulative volume in street Pumpback Volume cumulative volume in pumpback storage Page 8 Page eight is the detailed water balance time history for Junctions nodes selected for detailed water balance printout For each print cycle the watershed inflow node storage hydrograph excess system inflow system outflow inflow from flooding surcharge to street volume in street and pumpback volume are gi
98. ry Watson has further modified the EXTRAN block for SSWMM 96 These modifications included new input and output data formats that make it easier to develop debug and understand the results of EXTRAN simulations Major modifications were made in the way EXTRAN handles weirs and separated pipes Pumpback storage and downstream boundary conditions have also been added Output graphics for plotting flow and stage hydrographs and an HEC 1 post processor to allow HEC 1 to be used to develop runoff hydrographs for use in EXTRAN were also developed as part of these modifications ICamp Dresser amp McKee SECTION 2 RUNOFF BLOCK 2 1 INTRODUCTION The purpose of the RUNOFF block is to transform precipitation into runoff that then enters the storm drainage or combined sewer system being modeled It represents a watershed as a number of smaller subbasins or subcatchments and their associated conveyance systems The subcatchments and conveyances are idealized for ease In describing their characteristics The RUNOFF block uses precipitation in the form of rainfall hyetographs that give the rainfall intensity in inches per hour for each timestep in the model The program uses these rainfall hyetographs to make a step by step accounting of rainfall infiltration losses in previous areas surface retention overland flow and gutter flow leading to the calculation of hydrographs The drainage basin is subdivided into subcatchment areas that produce runoff h
99. s cfs hrs cfs 0 0 1 5 2 10 3 15 4 20 0 108 0 0 4 10 450 01 5 5 02 5 Overflow channel 5 450 05 01 01 025 10 indicate end of element data enter 99999 blank 99999 Conveyance Element Save And Print Control 1 N21 If gt 0 hydrographs saved for routing in EXTRAN Block 5 NPRNT No of conveyance elements for which hydrographs are to be printed 3 INTERV No of timesteps between printings Enter conveyance element numbers if NPRNT gt 0 103 105 106 107 108 ENDPROGRAM 2 15 RUNOFF Block IPKCHK Peak flow and depth of flow summary table flag none 0 No summary table 1 Print peak flow and depth of flow summary table at end of run 2 5 3 3 Subcatchment Conveyance Element Relationships Section This section lists the subcatchment hydrographs and their associated conveyance element The hydrograph read in from the subcatchment will be routed through the conveyance element on the same line Name Description Default N Subcatchment number for which a hydrograph will be read none in IDGUT Conveyance element number through which the none subcatchment hydrograph will be routed 2 5 3 3 Conveyance Element Data Section The Conveyance Element Data Section contains the data describing any of the RUNOFF conveyance elements being simulated All the data values for a specified conveyance element are put on one line unless the special conveyance element or overflow options ar
100. s the allowable dimension If the number of conduits specified in the input is required for this simulation the parameter NCO in COMMON INC must be increased and the entire EXTRAN block must be recompiled and relinked before running the simulation ERROR 33 ORIFICE OUTLET AT JUNCTION XX IS HIGHER THAN INLET The ZP of the junction specified as the outlet to orifice XX is higher than the orifice inlet Either raise the orifice or lower the outlet junction ERROR 34 THE INVERT OF CONDUIT XX LIES ABOVE THE CROWN OF ALL OTHER CONDUITS AT JUNCTION YY A gap between the crown of a conduit and the invert of the next highest conduit is not allowed at a junction One solution to the problem is to bridge the gap with a dummy pipe that has an invert below the crown of the lower pipe and a crown above the invert of the high pipe The dummy pipe leads to a junction 3 36 35 36 37 38 39 40 41 42 EXTRAN Block with no outlet Another solution to the problem is to designate the junction as storage junction Gaps are allowed to occur at storage junctions ERROR 35 CONDUIT XX IS LISTED TWICE INPUT DATA Two lines of conduit data have been given the same number Check your data file and renumber one of the conduits ERROR 36 JUNCTION XX IS LISTED TWICE INPUT DATA Two lines of junction data have been given the same number Check your data file and renumber one of the junct
101. s the height of the invert of the connecting conduit above the invert of the junction The lowest conduit connected to a junction must have a ZP of zero If it didn t the junction would act as a sink in the simulation and all water entering the junction would leave the system Because of this problem the program will generate an error message and terminate if the input data contains junctions where all conduits have ZPs greater than zero 3 2 2 Overflow Sections It is assumed a street configuration for simulation of overflow in the street can be approximated by a trapezoidal section shown in Figure 3 4 The longitudinal slope of the overflow section is based on the junction rim elevations of junctions connected by conduits 3 3 JUNCTION ELEMENTS To perform flow routing with EXTRAN it is required that the sewer system be idealized as a series of conduits which are connected at nodes or junctions Junction points should be identified at each Upstream terminal points in the system Outfall and discharge points Pump stations storage junctions orifice and weir diversions Junctions where inflow hydrographs will be input either by EXTRAN input or hydrographs from RUNOFF Pipe junctions Points where pipe size and or shape changes significantly Points where pipe slope changes significantly and Points where pipe inverts are significantly different GROUND ELEV STREETSURFACE V JUNCTION J CROWN OF JUNCTION J b
102. specified number of timesteps Specification of time cycles for hydrograph output Welr flow modifications to handle surcharged conditions Modifications to overflow simulation User may specify whether or not overflow to streets or reentrance from streets will occur at a given junction Replacing the linear approximation of the flow equation for overflow sections with an iteration scheme that solves the nonlinear flow equation Street flooding depth is limited to ten feet Irregular shaped storage detention junctions Hot start feature allowing model runs to begin where a previous run ended Control of inflow from RUNOFF Detailed water balance at a junction Pumpback from storage Stage hydrograph boundary condition The hot start or restart capability allows a file to be read and or created to establish the initial conditions for a run This capability is often used to avoid re running of lengthy dry weather stabilization time periods prior to the start of a storm event simulation The detailed water balance at a junction keeps track of Watershed Inflow inflows from RUNOFF module or from user created inflow gut file Node Storage storage at the junction resulting from inflows greater than user defined inflow capacity Hydrograph Excess inflows that can t enter the system due to limited downstream pipe capacity System Inflow difference between the watershed inflow and the hydrograph excess System Outflow flows out of th
103. t 1 Total Drainage Area Make sure that the total drainage area listed in the output is the same as the actual size of the drainage area being simulated in the RUNOFF Block This will quickly indicated whether there are input data errors 2 Imperviousness Check the input data for each subcatchment to insure that the correct percent impervious has been entered 3 Rainfall amount and time distribution Make sure that the total rainfall amount listed in the continuity check output data equals the intended total rainfall for the storm Check the rainfall time interval and the history printed in the output data 4 Continuity The last item in the continuity check output data is the percent error in continuity This error should be very small always less than 10 percent A large error probably indicates an input data error 2 7 1 Important Limitations All models have limitations because they use mathematical formulas to represent physical processes RUNOFF is no exception to this rule and it is important to take these limitations into account when using RUNOFF to solve real world problems Some of the important limitations are 2 26 RUNOFF Block 1 RUNOFF is based on a kinematic wave simulation in which the subcatchment is viewed as a plane that is represented in the model as rectangular in shape Schematizing the irregular shape of an actual subcatchment area into a rectangular shape with subcatchment width and length can be quite
104. t connected to the junction Page 11 The detailed flow history for each of the conduits specified for detailed printouts is on page eleven of the output Three values are given at each timestep for the specified conduits flow and velocity in the conduit and overflow flooding flows in the street above 3 29 EXTRAN Block the conduit Negative numbers for the any of the values indicate flows that are going counter to the direction of the conduit indicated the Internal Connectivity Information on page four Page 12 Page twelve of the output contains the Summary Statistics for Conduits The summary statistics are given in one line for each junction in the model The values summarized for each junction in the system are Conduit number and upstream and downstream junctions nodes Design flow cfs and velocity fps for the conduit conduit flowing full no surcharging Vertical size of the conduit ft Maximum computed flow cfs and time of occurrence Maximum computed velocity fps and time of occurrence Ratio of the maximum computed flow to the design flow Maximum water surface elevation at the upstream and downstream junctions nodes and Maximum overflow flooding flows cfs in the street above the conduit and time of occurrence 3 6 DEBUGGING AND STABILIZATION HINTS This section has described in detail the individual data elements that make up the input file for the EXTRAN Block of SSW
105. t leads to more trust in the model results It is also a very difficult step to accomplish in many instances For small urban subcatchments there is usually very little data with which to calibrate the RUNOFF model Adequate amounts of both precipitation and flow data are necessary in order to calibrate the model This may involve large amounts of data because precipitation and runoff patterns can vary widely within even the smallest subcatchment especially during the smaller more frequent storm events Even when data is available it is essential that the data be analyzed carefully to insure that it really represents what happened in the basin during the storm In particular rain gages used for calibration should be inside the subcatchment that is being calibrated Flow data must be checked to determine whether there are any unknown factors that are acting to change the flow i e pumps plugged inlets etc Calibration basically involves two steps 2 27 RUNOFF Block Compare the observed and computed volumes of runoff from the subcatchment Computed volumes can be adjusted by modifying the percent impervious and the infiltration rates for the subcatchment In changing these parameters one must be careful to maintain their values within representative ranges Compare the timing and shape of the observed and computed hydrographs Hydrograph timing and shape are controlled mostly by the basin shape and roughness coefficient and by any ro
106. t well only one influent pipe may be connected to the pump junction Junction must already have been listed in the Junction Elements Data Section NJUNC 2 Junction to which the pump is discharging Must already none have been listed in the Junction Elements Data Section Enter zero if the pump is discharging out of the system 3 16 Weir acts as orifice above this point A YTOP Weir submerged when taiwater is above this point 2 Downstream junction NJUNC N 2 Y Y Upstream junction NJUNC N 1 FIGURE 3 7 WEIR INPUT DEFINITIONS Name IPTYP VWELL MPUMP EXTRAN Block Description Type of pump 1 off line pump with wet well No flooding will occur when inflow exceeds pump capacity On off or variable speed operation will be based on the volume of stormwater in the wet well 2 on line lift pump Flooding may occur at pump junction when inflow exceeds pump capacity On off or variable speed operation will be based on the stage at the junction 3 pumpback from storage Pumping rate is determined by available capacity in the specified pumpback conduit Flows exceeding the specified maximum storage volume will not be allowed to enter the junction For Type 1 pump Initial wet well volume in cubic feet Type 2 pump 0 zero Type 3 pump Initial volume in storage in cubic feet Type of pump operation gt 0 On off operation MPUMP indicates the num
107. the subcatchment that is impervious such as paved roads paved parking lots roofs sidewalks driveways etc The average ground slope of the subcatchment normal to the tributary width in feet foot Manning s n resistance factor for the impervious surfaces in the subcatchment Table 2 2 default is smooth asphalt Manning s n resistance factor for the pervious surfaces in the subcatchment Table 2 2 default is urban lawns Depression storage on impervious surfaces in inches Saved as WSTORE 1 Table 2 3 default is paved area or flat roof Depression storage on pervious surfaces in inches Saved as WSTORE 2 Table 2 3 default is lawn grass Initial maximum infiltration rate in Horton s equation in inches hour Table 2 4 Final minimum infiltration rate f in Horton s equation in inches hour Table 2 4 Decay rate of infiltration per second a in Horton s equation Table 2 4 A blank line or 99999 indicates the end of the Subcatchment Data Section none none 45 0 001 0 016 0 250 0 010 0 35 1 0 0 08 0 0018 none Subcatchment Save and Print Control contains the parameters to control the disposition and printing of the subcatchment hydrographs created by RUNOFF Name 7 N21 NPRNT INTERV IPRNT x Description If N7 gt 1 hydrographs from each subcatchment are to be saved for subsequent conveyance routing in RUNOFF If N21 gt I hydrographs from each subcatchment a
108. to junction 102 17 99 4 04 0 12 0 Overflow to street and return flow to junction 103 17 49 3 61 10 12 3 1 0 Control of inflow from to 15 cfs 104 16 09 2 09 T2 3 1 15 105 13 90 1 60 E 12 3 1 0 106 12 24 58 47 12 3 1 0 Comments allowed in Junction Data Section 107 12 87 30 12 12 3 2 0 108 12 65 02 1 12 3 1 0 109 14 46 33 0 12 3 1 0 3 7 Revised January 1996 EXTRAN Block TABLE 3 1 continued 110 14 39 53 12 12 3 1 0 To indicate end of Junction Data Section enter 99999 99999 STORAGE JUNCTION DATA SECTION Junc Crown Storage Number of No Elev Vol Stages ka cf ft 0 reg storage Regular Storage Junction 34 45 200 0 Irregular Storage Junction 7046 35 0 1 5 Area Stage Area Stage Area Stage Area Stage Area Stage ft2 ft ft2 ft ft2 ft ft2 ft ft2 ft xo 1 3000 5 10000 10 15000 15 20000 20 To indicate end of Storage Junction Data Section enter 99999 99999 ORIFICE DATA SECTION Up Down strm strm Orifice Junc Junc Type Area Coeff ZP Side orifice type 1 316 325 1 7 37 0 6 3 85 Bottom orifice type 2 1317 326 2 1 49 0 6 0 0 To indicate end of Orifice Data Section enter 99999 99999 WEIR DATA SECTION Up Down Weir stream stream Type Ht Ht Length Coeff Junc Junc Bot Top Type of weir l transverse 2 transverse w flap gate 3 side 4 side w flap gate 791 5711 3 2 50 7 50 30 2 8
109. to sections as follows Title Section System Parameters Section Conveyance Elements Data Section Junction Elements Data Section Storage Junction Data Section Orifice Data Section Weir Data Section Pump Data Section Free Outfalls Data Section Outfalls with Flap Gates Tide Gates Data Section Initial Flow Data Section User Defined Inflow Hydrograph Section Each of these sections and its associated input variables will be discussed in detail below 3 4 2 1 Title Section The title section is two lines containing up to 80 characters in each line The title should be descriptive but may be anything the user wants 3 4 2 2 System Parameters Section This section of the input contains the overall simulation parameters which control the length of the simulation timestep size etc Hot start and output control switches are also located in the System Parameters Section of the input data Descriptions of each of the system parameters are given below No comment lines are allowed inside the System Parameters Section EXTRAN Block TABLE 3 1 EXTRAN INPUT TEMPLATE This is an input file for the EXTRAN block of SSWMM96 TITLE SECTION 2 lines SSWMM96 DOCUMENTATION EXAMPLE DATA EXTRAN BLOCK PARAMETERS SECTION free input format 30 0 DELT Length of integration step in seconds 9 00 TZERO Start of simulation decimal hours 19 00 TEND End of simulation decimal hours 15 NHPRT No of junctions fo
110. uit strm strm N Side Side Main Over Main Over No Node Node Type Area Depth Width Length ZP ZP Slope Slope Depth Width N N Slope Slope ft2 ft ft ft ft ft ft ft ft ft ft ft ft ft ft ft Circular conduit 201 101 20 1 0 5 0 0 900 0 0 0 0 0 0 5 0 5 0 016 0 020 37 50 Rectangular conduit 202 102 101 2 0 5 0 6 0 850 0 0 0 0 0 0 5 0 5 0 016 0 020 37 50 Horseshoe conduit 203 103 102 3 13 3 5 0 4 0 850 0 0 0 0 0 0 5 0 5 0 016 0 020 37 50 Elliptical conduit 204 104 103 4 15 7 5 0 4 0 950 0 0 0 0 0 0 5 0 5 0 0 37 50 Arch conduit 205 105 104 5 19 6 3 8 6 1 850 0 0 0 0 0 0 58 0 5 0 016 0 020 38 50 Trapezoidal conduit 206 106 105 6 0 5 0 3 0 900 0 0 015 2 0 2 5 0 58 0 5 0 016 0 020 38 50 207 107 106 1 0 5 0 0 1000 0 0 0 0 0 0 58 0 5 0 016 0 020 38 50 208 108 107 1 0 5 0 0 900 0 0 03 0 0 0 0 58 0 5 0 016 0 020 38 50 209 109 108 1 0 5 0 0 900 0 0 11 0 0 0 0 58 0 5 0 016 0 020 38 50 210 110 109 1 0 5 0 0 800 0 0 01 0 0 0 0 58 0 5 0 016 0 020 38 50 indicate end of Conduit Data Section enter 99999 99999 JUNCTION ELEMENTS DATA SECTION free input format Junc In Const Inlet tion Grnd vert In Inlet weir Inlet No Elev Elev flow Length Coeff Capacity ft ft cfs ft cfs 20 21 70 4 86 07 12 3 2 0 No overflow to street and return flow to junction 101 20 16 4 66 0 0 0 Overflow to street but no return flow
111. uting that occurs in the subcatchment In general the longer the basin width the sharper and faster the hydrograph peak Manning s n roughness factor can also be used to control hydrograph peaks The lower the roughness coefficient the higher and faster the peak The user always needs to remember that the roughness coefficient used in RUNOFF will generally be higher than that used in a hydraulic model such HEC 2 because of the shallow overland flow debris and irregular slopes that occur in a subcatchment The following list describes the important output variable to check during the verification and calibration procedure 2 7 3 Warnings and Error Messages 2 7 3 1 Subcatchment Warnings and Error Messages 1 WARNING 1 CHECK RESULTS NO CONVERGENCE IN SUBCATCHMENT SIMULATION Errors have occurred in the kinematic wave overland flow equations in the WSHED subroutine preventing convergence Check the results printout and look for values in the subcatchment hydrographs that are unstable or seem to be excessively high or low 2 7 3 2 Conveyance Element Routing Warnings and Error Messages 1 ERROR 1 THE GIVEN DELT IS DIFFERENT FROM THAT USED IN THE INPUT HYDROGRAPH the integration time increment DELT specified in the System Parameters Section is not the same as the integration time at which the input hydrographs were saved Change either the integration timestep for the hydrograph input or for the routing
112. ven The definition of the headings in the detailed water balance are the same as for the cumulative inflow and outflow summary but are for one junction only Page 9 The detailed Time History Of The Hydraulic Grade Line for each of the junctions specified for detailed printouts is on page nine of the output Each junction is described with a number and ground elevation Three columns of results are given for each junction water surface elevation depth and overflow flooding depth in the street These results are printed for each print cycle Page 10 Page ten of the output contains the Summary Statistics for Junctions The summary statistics are given in one line for each junction in the model The values summarized for each junction in the system are Junction number Junction ground elevation Crown elevation of the uppermost pipe in the junction Maximum computed depth and its time of occurrence Maximum water surface elevation Number of feet the maximum computed depth is below the ground elevation Length of time the junction is surcharged water surface elevation above the crown elevation of the uppermost pipe in the Junction and Maximum flooded volume and depth in the street above the junction time of occurrence of the maximum flooding depth and the length of flooding flood depth gt 0 The area of influence of the flooding information is defined as half the length of each overflow section condui
113. verwrite Y N gt Y Are Hydrographs to be used in 1 RUNOFF or 2 EXTRAN gt 2 Delt 5 000000 NHR NMN 8 55 Intervals 179 Reading Hydrograph for Subcatchment 1031 Reading Hydrograph for Subcatchment 1051 Reading Hydrograph for Subcatchment 1061 Reading Hydrograph for Subcatchment 1082 Reading Hydrograph for Subcatchment 1083 Stop Program terminated 4 2
114. w in the conveyance element is lower than its capacity and the storage is not empty the pump will begin pumping at a rate equal to the difference between the available capacity and the actual flow rate in the pipe but always less than a specified maximum pumping rate A Type 3 pump may have only one influent pipe entering the pump storage junction Two types of pump operation curves illustrated in Figure 3 6 are available for the Type 1 and Type 2 pumps 1 stage capacity pump operation curve or volume capacity for a Type 1 pump describes the operation of a variable speed pump The capacity of the pump will vary according to the stage or volume at the pump junction The stage capacity curve can vary in a stepwise fashion or in a smooth curve 2 other type of pump operation curve describes a pump or pumps with on and off pump settings As shown in Figure 3 6 the pump can have different on and off settings as well as having variable speed characteristics that increase the capacity with increase in stage As described above pump operation for the Type 3 pump is controlled solely by the capacity of the specified pumpback conduit and the specified maximum pump capacity 3 3 5 Free Outfalls A free outfall is simply an outfall junction which discharges based on given backwater conditions If the elevation of the receiving water is low enough the outfall will be simulated using either critical or normal depth in the conduit
115. whichever is less If backwater exists the receiving water surface elevation is used for the water surface elevation at the free outfall Only one conduit may be connected to a free outfall 3 3 6 Flap Tide Gates Flap gates sometimes called tide gates are simulated in EXTRAN by specifying the outfall junction numbers for pipes with flap gates A flap gate functions in EXTRAN to prevent 3 5 LU O c lt sa a a gt STAGE l STAGE AND CAPACITV RELATIONSHIPS x E x ta YOFF iia STAGE AND OFF SETTINGS FIGURE 3 6 PUMP OPERATION CURVES EXTRAN Block flow from moving from the outfall Junction into the system even though the water surface elevation at the outfall Junction is greater than that the system Outflow from the system will be zero if the elevation downstream of the junction is higher than the incoming water surface elevation 3 4 INPUT DATA PREPARATION 3 4 1 Default Values Most variables used by the EXTRAN block do not have default values This means that the value for each variable must be explicitly defined Where default values are supplied in the model they will be noted in this manual as part of the input parameters description 3 4 2 Input Data Template Table 3 1 is a sample input file illustrating the input format and layout of a typical EXTRAN input data file The input is divided in
116. widely separated conveyance elements For most problems conduit lengths will allow a timestep of 15 to 20 seconds Start of simulation in decimal hours May be set to zero none End of simulation in decimal hours Must be a non zero none number because this sets the number of timesteps used in the simulation Number of junctions selected for detailed printing of head none output Number of junctions selected for printing of detailed water none balance Number of conveyance elements selected for detailed none printing of discharge Time to begin detailed printing in decimal hours none Time between printing cycles for all conveyance and junction none elements in minutes DINTER 0 indicates no printout Time between detailed printing cycles for specified none conveyance and junction elements in minutes HINTER 0 indicates no printout Number of input junctions for user defined inflow none hydrographs If NJSW gt 0 NJSW inflow hydrographs must be defined later in input Maximum number of iterations per timestep EXTRAN 100 assumes a minimum number of 100 iterations 3 10 EXTRAN Block Name Description Default JREDO Hot start option control none 0 hot start operations Use existing hot start file to begin this run 2 Create a new hot start file at the end of this run 3 Use existing hot start file to begin this run and create a new hot start file at the end of the run IPFLAG Input and output data
117. ydrographs These hydrographs may be used directly as input for the EXTRAN block or may be routed in RUNOFF through gutters or pipes to compute hydrographs at the inlet points to the major storm drain conveyance system Overbank floodway sections may be used in conjunction with gutters and pipes Detention basins with a specified storage outflow relationship may be used Also RUNOFF allows the user to specify a flow diversion table for routing elements Pipes gutters diversions and detentions are referred to as conveyance elements in this manual Two types of elements are available to the RUNOFF user 1 Subcatchment elements overland flow 2 Conveyance elements channel flow pipe flow storage etc These two elements are analyzed as separate operations in RUNOFF That is if the user intends to create overland flow hydrographs and then route them through RUNOFF conveyance elements he will need to use RUNOFF twice The first RUNOFF simulation will calculate the runoff hydrographs and second one will use the calculated hydrographs as input for routing through conveyance elements The subcatchment elements receive rainfall account for infiltration loss using Horton s equation permit surface storage such as ponding or retention on grass or shrubbery and route excess rainfall to develop overland flows The results from the subcatchment overland flow analysis are saved to a file for future routing The overland flows may then be routed

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