MOUSE TRAP User Guide
Contents
1. Figure 5 8 The ST Sediment removal in basins data dialog DHI Software 43 amp 5 lt MOUSE TRAP 5 5 9 TRAP IST Weir Removal There are three methods available for removal of sediments in weirs e Constant efficiency factor User specified relation between efficiency and discharge towards the weir Max 6 values can be specified covering the whole range of expected flows towards the weir Efficiency as a function of fall velocity and velocity of the approaching flow A desired method is selected in a combo box Depending on which type of weirs is selected central weir or vortex separator different default values of constants which are used in a reversed normal distribution curve will be given z ST SEDIMENT REMOVAL IN WEIRS 15 x Fast Query Location Flow To pee ID Rw Insert Location 33 El Show gt Flow To 553 Select List gt Method Constant efficiency z Efficiency factor Eff Q Efficiency factor Efficiency factor Efffw Aa Weir Type d Sigma Myl Sigmal L Ne Location FlowTo Method e Factor Constant efficiency Figure 5 9 The ST Sediment removal in weirs data dialog 5 6 Boundary Conditions for the Sediment Transport Model 5 6 1 Types of Boundary Data Boundary conditions for the ST module can be specified via sediment transport results from a surface calculation SMR2. concentration time series with the related discharge Computation With The Mouse Trap Sediment Transport Model A ST simulation is started from the MOUSE Pipe Flow Computation Dialog Both the explicit and the morphological sediment transport model run in parallel with the hydrodynamic model The data files needed to run a sediment transport simulation comprise the same set as for Hydrodynamic simulation with addition of a TRAP data file TRP which includes some ST data The ST module is activated if a TRP file containing some sediment transport data is specified as a part of the simulation input For the morphological model the boundary conditions must be specified together with the hydrodynamic boundary conditions If the explicit sediment transport model is run no additional sediment bed level or sediment fractions boundary conditions have to be specified in the Boundary System File DHI Software 45 amp 5 lt MOUSE TRAP The number of time steps between saving of results refers to the time step in the sediment transport calculations The time step in the sediment transport calculations can as a rule of thumb be taken as 6 10 times the time step in the hydrodynamic calculation The main limitations to the time step in the sediment transport calculation are the boundary conditions Both the hydrodynamic and the morphological boundary conditions should be well resolved Finally the calculated changes in the bed level sh
3. Pollutants with Water Quality Processes DO Temperature SRQ gully pots BOD COD e Dry Weather Flow DO e Boundary Database Temperature BOD COD Dissolve BOD COD Suspend Bacteria Sediments j SRQ surface only EE fractions ST mineral Fine Organic and AD e Dry Weather Flow Fine Mineral e Boundary Database Coarse Mineral Sediment Attached Pollutants with or without WQ processes E g BOD Fine AD SRQ gully pots surface BOD Coarse WQ e Dry Weather Flow E g PO4 Fine ST e Boundary Database DCH Coarse E g Metal Fine Metal Coarse Figure 1 3 Overview of pollutant and sediment types and appropriate modules DHI Software THE MOUSE TRAP OVERVIEW INPUT REQUIREMENT TO THE MODEL WHERE IN MOUSE TRAP Initial Conditions HD Discharge Water depths Concentrations Mass Concentrations Concentrations Sediment Transport Sediment Depths Fraction Values Boundary Conditions HD Discharge Water depths SRQ Rain Intensity Rain Depth AD WQ Concentrations ST Concentrations Sediment Transport Bottom Levels Fraction Values Process Related Data SRQ Module AD Module WQ Module ST Module Figure 1 4 Cold or Hotstart SRQ Data AD Data ST Deta For all modules Boundary Database Dry Weather Flow SRQ Results At least one of the above for each module used except SRQ which only requires Boundary Database SRQ Data AD Data WQ Data ST Deta Input data requirements for MOUSE T
4. and the sediment transport formulae are briefly described below For more detailed technical outlines of the sediment transport models and the sediment transport formula refer to the MOUSE TRAP Technical Reference The Sediment Transport Models in MOUSE TRAP ST The sediment transport models in MOUSE TRAP ST can be divided into two groups e explicit models e morphological models The main difference between the two model types is that in the explicit models the bed levels are fixed during the simulation In the morphological models the bed levels sediment deposits are updated dynamically during the simulation The Explicit Sediment Transport Models In the explicit sediment transport models the bed level is fixed throughout the simulation and the only feed back from the sediment transport computations to the hydrodynamics is established via the Manning number The sediment transport capacity is calculated in time and space as an explicit function of the corresponding hydrodynamic flow parameters i e the model calculates a potential sediment transport and no sediment is moved around in the system The explicit models are in general used to e investigate the hydraulic capacity in pipes with sediment deposits e calculation of the sediment transport at locations where the bed levels changes are insignificant during a simulation L In order to select an explicit sediment transport model leave the checkbox UPDATE THE BED LE
5. dialog in Figure 4 2 30 DHI Software WATER QUALITY WQ 4 2 2 WU BOD COD DO Processes Figure 4 2 WQ BOD COD DO Processes data dialog TRAP WQ I Reaeration The reaeration is a relevant process in cases of non full flow in the pipes An empirical expression based on measurements in sewer pipes is provided to simulate the reaeration process The reaeration rate is modelled as a function of the flow velocity the mean hydraulic water depth and the pipe slope The reaeration rate is also dependent on the temperature expresses by an Arrhenius temperature coefficient The reaeration constant is calculated at 20 C and adjusted to the actual temperature by means of the temperature coefficient The expression used for calculation of the reaeration rate is shown in Figure 4 3 The constants in this expression can be changed by the user totally three constants Besides these constants a temperature coefficient can be specified WQ Reareation Figure 4 3 The WQ Reareation data dialog DHI Software 31 MOUSE TRAP 4 2 3 4 2 4 TRAP I WQ I Bacteria The Group 4 of determinants is the bacteria that can be faecal and total coliform bacteria and streptococci Most pathogenic microorganisms are usually unable to multiply or survive for extensive periods in the aquatic environment Sedimentation starvation pH changes temperature plus competition with and predation by other naturally occ
6. eser ak ei Svat e eb Saka 3 DHI Software i 5 a a MOUSE TRAP 4 2 3 FRAP WO l B tterid ide ett teer e eere ree Ev se cove E REP HOS ER EAE 32 4 2 4 TRAP WQ Sediment Pollutente eene eee enne nnne enne nnne nnns 32 SEDIMENT TRANSPORT ST saccsssssscssesescssssteseosssentessonsesasssonsoesaesconssssesseocsdeonessaasensecsesssensssesesees 35 5 1 GENERAL OVER VIEW Ed eendeiteg EE 35 5 2 THE SEDIMENT TRANSPORT MODELS IN MOUSE TRAP SI 35 5 2 1 The Explicit Sediment Transport Models eese rennen 35 5 2 2 The Morphological Modelle 35 5 3 THE TRANSPORT FORMULAE SHORT DESCRIPTION essere nennen 36 5 3 1 The Ackers White formulae sssrinin nenne nennen eene nennen 36 5 3 2 The Engelund Hansen formula 36 5 3 3 The Engelund Freds e Deigaard formulae eene 36 5 3 4 The van Rijn formulae iii Eo t Ea in etae e er HE ERR ERE A e e A 37 5 4 THE FLOW RESISTANCE IN SEWER SYSTEMS WITH SEDIMENT DEPOSITS eene 37 5 5 SEDIMENT TRANSPORT DATA DIALOGS eese nennen 37 5 5 1 General c ten I ut MM iu ipu ME 37 5 5 2 TRAP VST Grain Diameter Eeselen isa coke ee e E dees eege 37 5 5 3 TRAP ST Model and Formula i este see BOAR 38 5 5 4 TRAR ST e 39 29 5 TRAP 1 97 Graded E 40 5 5 6 TRAP ST Sediment Distribution sarissa a AEAEE E 41 5 5 7 TRAP ST Initial Sediment Depth AA 41 5 5 8 TRAP ST Basin Remo 43 5 5 9 TRA
7. of fractions A mean grain size mm for each fraction and the percentage distribution for both the active and passive layers must be specified The sum of the initial percentage distributions for both the active and passive layers must equal 100 If the fall velocity is specified to zero then it wil be calculated by the program The equations used for the fall velocity calculation are given in the MOUSE TRAP Technical Reference Manual The Transport Mode combo box allows for the choice whether the sediment fraction is transported with ordinary non cohesive sediment transport formulations or the fraction is transported by the Advection Dispersion formulations The transport of fine organic sediment fractions is better described by use of an Advection Dispersion transport formulation instead of the non cohesive sediment transport formulae If it has been selected to transport the fraction with the Advection Dispersion model then the critical shear stress for deposition Tea the critical shear stress for erosion Te and the erodibility coefficient must be specified The morphological changes resulting from the sediments transported by the Advection Dispersion formulations are still included in the calculation of the bed level but the changes in bed levels are now calculated from source sink terms For further information refer to MOUSE TRAP Technical Reference Manual The dry weather flow concentration of sediment fraction can be specifie
8. single component type is the simplest entry It does not include any interaction between sediments and pollutants Where required the system automatically supplies the necessary companion components DO and temperature for BOD and COD As dissolved suspended available only for BOD and COD A distinction is made between dissolved and suspended form of BOD or COD The DO and temperature are automatically supplied e As PPC Pollutant Partitioning Concept components The total content of a certain component is distributed between three forms dissolved attached to fine sediments and attached to coarse sediments For BOD and COD DO and temperature are automatically supplied Bacteria can be specified as coliform or streptococci For coliform bacteria a distinction between the total and faecal content is automatically introduced User specified components are included by the Insert function They can be specified either as single or PPC components For BOD COD temperature DO and bacteria MOUSE provides reasonable values of concentration and the most appropriate units are pre selected However any other selection from the list can be taken independently of the units applied in boundary time series The exceptions are temperature and bacteria where only degree Celsius and count 106 100ml respectively are the only units applicable The specified units will be assumed for initial conditions and decay coefficients for the
9. the extension TRP TRAP I ST Grain Diameter The grain diameter and the DWF concentration may be specified nodes in the network In the links connecting two nodes with different specified grain diameters the grain sizes are linearly interpolated ST SEDIMENT GRAIN DIAMETER Global Bisi xi Grain Diameter 0 500 mm Close DWF Concentration fi 000 mgl Help 37 MOUSE TRAP 5 5 3 Figure 5 1 The ST Sediment grain diameter Global data dialog TRAP ST Model and Formula Selection of the sediment transport formulae and type of model takes place in the Data Dialog TRAP ST Model and Formula In this dialog it is also specified whether the bed shear stress is going to be computed or not during the simulation In a case when it has been chosen to calculate the bed shear stress during the simulation the updated values will be used in the hydraulic computations This implies that the Manning number specified for the bed may vary during the simulation A detailed description of how the shear stress is calculated is given in the MOUSE TRAP Technical Reference Manual If it has been chosen to update the bed level then a morphological model is run during the simulation Hence boundary conditions in terms of time series of sediment transport bed levels and or available fraction percentages must be specified at every point where inflow occurs in the sewer netwotk If it has been chosen not to upd
10. the hydrological models available in MOUSE i e the Surface Runoff Model A the Surface Runoff Model B and the Surface Runoff Model C Hence the sediment is routed according to the hydrological description in the surface runoff models The surface runoff models are described in the MOUSE User Manual and MOUSE Technical Reference Output from the model consists of time series of sediment transport or concentration mass and accumulated mass for each sediment fraction In addition a time series of mass of the fine sediment fraction on the surface is available The Sediment and Pollutants model is an optional model which describes the attachment of pollutants to the sediment Output from the model consists of time series of mass or concentration and accumulated mass of pollutants attached to the two sediment fractions The Gully Pot model is an optional lumped model which serves as a link between the Surface Runoff Quality model and the Pipe model The purpose of the gully pot model is to include a description of the release of polluted water from gully pots which under some circumstances contributes significantly to a First Foul Flush The Build up Wash off model and the Gully Pot model can be run independently of the other models The Sediment and Pollutant model has to be run together with the Build up Wash off model A detailed technical information about all three models is available in the MOUSE TRAP Technical reference DHI Softw
11. the selection of the exponent b If the exponent is set equal to zero then the dispersion coefficient is constant and independent of the flow velocity The unit for the dispersion factor will then be m2 s If the exponent is 1 i e the dispersion coefficient is a linear function of the flow velocity then the unit of the dispersion factor will be meter and the dispersion factor will in this case be equal to what is generally termed the dispersivity It is possible to specify values of the minimum and the maximum dispersion coefficients in order to limit the range of the dispersion coefficient calculated during the simulation Advection Dispersion Global Data Dispersion factor 2 000 Close Exponent poo Help Minimum dispersion coefficient poo m2 s Maximum dispersion coefficient ioo m2 s Figure 3 4 The Advection Dispersion Global Data dialog The description of the dispersion coefficient can be given either globally or locally The global description will be used at all locations except for those pipes where local conditions have been specified in the menu In the example above the global statement indicates that a constant dispersion coefficient of 2 00 m s is applicable and independent of the flow velocity the exponent is zero On the lines following the global statements the example shows the dispersion coefficient in the pipe from node 1 to node 2 from 0 1000 m is dependent on the flow velocity acc
12. E TRAP OVERVIEW Introduction MOUSE TRAP is a suite of modules which are capable of simulating pollution and sediment transport as well as water quality processes in sewer systems and on catchment surfaces MOUSE TRAP is divided into various modules representing different transport or water quality processes The MOUSE TRAP Modules The modules in MOUSE TRAP are e SURFACE RUNOFF QUALITY SRQ e SEDIMENT TRANSPORT ST e ADVECTION DISPERSION AD e WATER QUALITY WQ The modules can be used independently or in conjunction which depends on the level of required sophistication However using the WQ module requires a simultaneous run of the AD module Figure 1 1 shows the individual modules and their connections The SRQ module can be used by itself to study water quality and sediment transport processes on catchments The result can be used as input to a river model MIKE11 or to the MOUSE TRAP modules which deal with processes in the pipe model If only dissolved pollutants are of concern it is sufficient to use the AD module possibly with the WQ module in conjunction If the pollutants attached to sediment are to be modelled it is re commended to use the ST AD and the WQ modules simultaneously Finally if the sediment transport is the only modelling purpose the ST module can be used separately DHI Software 11 amp 5 lt MOUSE TRAP MOUSE TRAP Surface Quality Runoff Module MOUSE MOUSE TRAP Hydrodyn
13. MOUSE MOUSE TRAP User Manual WATER amp ENVIRONMENT CONTENTS PART I INTRODUCTION TO MOUSE TRAP 1 ABOUT MOUSE TRAP MODULE wii ccssscssssccessccccesssscscsssccsesscccssssscccssssscccessscscsssscesessssseesss 3 1 1 KEY FEATURES AND APPLICATION DOMAINE 3 1 1 1 Surface Runoff Quality SRQ Module 3 1 1 2 Pipe Sediment Transport ST Module 3 1 1 3 Pipe Advection Dispersion AD Module esee eene 3 1 1 4 Pipe Water Quality WQ Module esee nennen nennen nenne 4 1 2 SOFTWARE 4 2 ABOUT MOUSE TRAP USER MANUAL eee esee een eee tnos teen sete ense teens esee ense eee 5 3 MOUSE TRAP USER SUPPOR EF vssssccicctscsiscstectacistiesscesescastecsetsusccescesnasssesbuccsesescess usteedsvastoasseessiceses 7 3 1 PRODUCT SUppORT s sess eee a sans iEn nnns 7 3 2 DHI TRAINING Coups 7 3 3 COMMENTS AND SUGGESTIONS ssssssoesseeessesotersssrsrttersrssssretsrsssrerotessssesntrensssssrrressrssseereeesssse 7 1 THE MOUSE TRAP OVERVIEW cssscccsssssccsssscccssssccesssccscssssccsessscccsssssesessssccssssssecessssccessnsers 11 1 1 TINTRODUCTION eL 11 1 1 1 The MOUSE TRAP Modules re Bassai r 11 2 SURFACE RUNOFF QUALITY SRO ssiccssccscsisssssseccssccoscssdecc
14. MOUSE HD and MOUSE Runoff is essential and recommended as a support for work with this module 4 DHI Software Ss ABOUT MOUSE TRAP USER MANUAL This manual provides information related to the modelling principles and data specification techniques for the simulation of the pollution and sediment transport in urban drainage and sewer systems The document contains a comprehensive reference on the MOUSE TRAP s capabilities allowing users to define and execute pollution and or sediment transport simulations This MOUSE TRAP User Manual contains a detailed information for usage of the MOUSE TRAP data dialogs along with the discussion of the fundamental principles behind the applied simulation techniques and solutions However it is assumed throughout this manual that the user is well acquainted with the standard MOUSE system Fundamental knowledge of hydrology and hydraulics also facilitates the successful use of MOUSE TRAP The information concerning the scientific foundations which form the frame of the MOUSE TRAP concept is accessible in the associated MOUSE TRAP Reference Manual Usage of the standard MOUSE and its other add on modules is described in respective user manuals amp tutorials This manual is divided in two units Part I Introduction Some general information about MOUSE TRAP and about this document Part UT MOUSE TRAP User Manual Basic information about MOUSE TRAP simulation principles and techniques and ex
15. P ST Weir Remo 44 5 6 BOUNDARY CONDITIONS FOR THE SEDIMENT TRANSPORT Mopp 44 5 6 1 Iypes of Boundary Data iiss iss iere eerte rece eee rei de rep bee Ud 44 5 6 2 Time Series Database aided vedete tre eve eG 45 5 6 3 Connecting Time Series from the Time Series Database to the Network Model 45 5 7 COMPUTATION WITH THE MOUSE TRAP SEDIMENT TRANSPORT MODEL een 45 DHI Software Copyright This document refers to proprietary computer software which is protected by copyright All rights are reserved Copying or other reproduction of this manual or the related programs is prohibited without prior written consent of DHI Water amp Environment Warranty The warranty given by DHI Water amp Environment is limited as specified in your Software License Agreement The following should be noted Because programs are inherently complex and may not be completely free of errors you are advised to validate your work When using the programs you acknowledge that DHI has taken every care in the design of them DHI shall not be responsible for any damages arising out of the use and application of the programs and you shall satisfy yourself that the programs provide satisfactory solutions by testing out sufficient examples 1pHlisa private non profit research and consulting organization providing a broad spectrum of services and technology in offshore coastal port river water resources utban drainag
16. RAP modules DHI Software 15 MOUSE TRAP 16 Software 2 1 Ss SURFACE RUNOFF QUALITY SRQ Introduction The Surface Runoff Quality module is used to generate input for the sediment transport advection dispersion or water quality computation in the underlying pipe model The Surface Runoff Quality module consists of three models e a model for the description of the accumulation build up and wash off of particles on the catchment surface e a model for the description of the surface transport of pollutants attached to the sediments e a model for the description of the build up and wash out of dissolved pollutants in gully pots The Build up Wash off model consists of two sub models a model for the description of the accumulation of particles on the catchment and a model for the description of the detachment of particles by rainfall and subsequent routing of the wash off by the overland flow The model works with two sediment fractions a fine and a coarse each fraction characterised by its mean diameter The fine fraction typically has a particle size less than 0 1 mm and is limited in supply On the contrary the coarse fraction is typically unlimited in supply Thus for the coarse fraction transport capacity is always satisfied and therefore the build up description is only applicable to the fine sediment fraction to determine the mass available for transport The surface sediment transport model is based on
17. The verification based on 600 data sets showed that 77 of the predicted bed load rates were within 0 5 and 2 times the observed values van Rijn 1984a The verification for the suspended load using 800 data sets showed that 76 of the predicted values were within 0 5 and 2 times the observed values van Rijn 1984b The Flow Resistance in Sewer Systems with Sediment Deposits The hydraulic resistance in the sewer originates from the pipe wall and from the sediment deposits on the bottom of the sewer The resistance from the sediment deposits consists of two contributions one part originates from the grain friction and the other part originates from the expansion loss behind the bed forms The dimensions of the bed forms are determined by the sediment transport and the flow the resistance from the bed forms can be described through sediment transport formulae The average shear stress in a pipe with sediment deposits is calculated from the Einstein side wall elimination procedure The calculation is based on the pipe roughness and the bed shear stress calculated from the sediment deposits Sediment Transport Data Dialogs General The data dialogs under the Menu option TRAP ST contain input parameters to the sediment transport model MOUSE ST The data are e g sediment grain diameter relative density of the sediment critical bed shear stress type of sediment transport model etc All the sediment related data are stored in a file with
18. VEL on the dialog TRAP ST Model and Formula unchecked The Morphological Models The morphological models in MOUSE TRAP ST are e morphological model for uniform sediment e morphological model for non uniform sediment DHI Software 35 MOUSE TRAP 5 3 5 3 1 5 3 2 5 3 3 In the morphological models the sediment transport continuity equation is solved based on the corresponding values of the hydrodynamic parameters i e discharge water levels etc The feedback to the hydrodynamic module is established through dynamically changed flow area and flow resistance number The morphological model for uniform sediment uses one grain diameter at each point in the sewer system to calculate the sediment transport In the morphological model for non uniform sediment it is possible to calculate the sediment transport from a range of grain diameters For the transport of fine organic particles some of the non uniform sediment fractions can be chosen to be transported by use of the Advection Dispersion transport formulation instead of the non cohesive sediment transport formula as the transport of particles transported in suspension is better described by used of the advection dispersion equation The fractions transported by the advection dispersion module are still included in the morphological calculation but the description of erosion deposition is changed Note the morphological models require sediment or bed level bou
19. amic Sediment Transport Module Module MOUSE TRAP Advection Dispersion Module f OUSE TRA Water Quality Module Figure 1 1 The MOUSE TRAP modules and their links Figure 1 2 shows which modules should be used for a list of problem types Figure 1 3 gives an overview of the required modules for different pollutant and sediment types Finally figure 1 4 systematises the initial conditions boundary conditions and process related data necessary for each module and where these can be found 12 DHI Software THE MOUSE TRAP OVERVIEW SS TYPE OF PROBLEM MODULES TO BE USED e Single event pollution spill at weirs amp Pollution Loads to Treatment Plants Dissolved Pollutants AD AD WQ Sediment Attached Pollutants AD ST AD WQ ST Sediments ST e Sedimentation in sewers Uniform sediments Graded Sediments e Pollution of receiving waters from surface catchments amp Pollution input to pipe system Sediments Sediment Attached Pollutants Dissolved Pollutants Figure 1 2 Problem Types and Modules DHI Software 14 MOUSE TRAP renum ee MORNE NRCS mee IN PIPE MODULE FACILITY FOR POELDTANT SEDIMENT renum ee MORNE NRCS mee TO BE USED SOURCE GENERATION Dissolved Pollutants without WQ processes but with 1st order decay possibility Ammonia BOD User Defined Components e g Chloride SRQ gully pots Dry Weather Flow Boundary Database e e Dissolved
20. are 17 a MOUSE TRAP 2 2 Surface Sediment Data Dialogs The data for the surface sediment transport calculation is entered under the TRAP SRQ menu The data for the surface sediment model consists of data for the Build up Wash off model data for the Sediment and Pollutant model and data for the Gully Pot model 2 2 1 TRAP I SRQ I Sediment Build Up Wash Off The sediment parameters used in the build up wash off computations are specified under TRAP SRQ Sediment Build Up Wash Off The parameters for the build up wash off model can be specifiedin the dialog displayed in Fig 2 1 The Build Up Method defines build up method for the fine sediment on the surface A linear build up function or an exponential function can be chosen SRQ Surface SEDIMENT BUILD UP WASH OFF Global Fine Sediment Coarse sediment Close Build Up Method Exponential Size 0 100 1 000 mm DO Help Build Up Rate 50000 ka ha day Density 2650 0 2850 0 kg m3 Maximum Value 500 000 kg ha ADWP 0 000 days Detachment rate fi 0000000 m hr Save as conc n Power 000 Figure 2 1 SRQ Surface Sediment Build up Wash off Global data dialog Most of the parameters are self explanatory ADWP stands for Antecedent Dry Weather Period and is responsible for the determination of initial amount of surface sediments 18 DHI Software ADVECTION DISPERSION AD 2 2 2 I SRQ I Sedime
21. arized in the following expression If the actual sedimentdepth gt the maximumeroded sediment depth 5 3 T Ze Shields ELSE Y sediment EXP To Toot T ZZ Y initial depth where Tot the critical bed shear stress at the bottom of the pipe Trop the critical bed shear stress at top of the initial sediment deposit Ysediment the actual depth of the sediment deposit initial depth the initial depth of the sediment deposit ST INITIAL SEDIMENT DEPTH Global xi Sediment Depth m Critical bed shear stress for cohesive sediments mi Close Manning Number Use Type Computed Manning zj Crit bed shear stress at the bottom of the deposit Help Manning Number Crit bed shear stress at the top of the deposit Variation of critical bed shear stress in the deposit Figure 5 6 The ST Initial Sediment Depth Global data dialog DHI Software SEDIMENT TRANSPORT ST Ss 5 5 8 Figure 5 7 The ST Initial Sediment Depth Local data dialog TRAP ST Basin Removal Sediments can be removed from nodes tanks basins according to the formula E 1 1 W nx 5 4 where E efficiency W setting velocity n removal coefficient Q flow into basin A surface area of the basin The calculated efficiency multiplied with the inflowing sediment transport gives the amount of the sediment retained in the structure There is no updating of the bed level in the structure
22. assesossesccssssaeccssstsscsedscoesentevssscsssess 17 2 1 log TobjS e1b o Em 17 2 2 SURFACE SEDIMENT DATA 18 2 2 1 TRAP SRQ Sediment Build Up Wash Off eese tenent eene 18 2 2 2 TRAP SRQ Sediment Pollutants eese esee nennen enne nennen 19 ADVECTION DISPERSION AD e eene e eee eno eee eroe ette tnos ette ose teen es seen esee sense eese esee eene 21 3 1 INTRODUCTION cranu iced EE eue Cube oou bo Oo Ie vent 21 3 2 ADVECTION DISPERSION DATA DIALOGS ccccccccesssssseeeeeceeseesssneeeeceecessesaseeeceeseesssaseeeeeeeeseesaaea 21 3 2 1 TRAP AD Components eee tester ster itta De uae nds 21 3 2 2 TRAP AD WQ AD Connection 22 3 2 3 TRAP AD Disp rsion cete teer tree nest eL stein ba e tcd vane 23 3 2 4 TRAP AD Initial Concentrations nene eene nenne eene eene eene eene nennen 25 3 2 5 TRAP AD DeCGy MER 26 3 2 6 TRAP AD Open Boundary Conditions 26 4 WATER QUALITY WO wsissssississsssencessssossscvsssoisvusisssevasessescusessncsssssincessessonsssessusssouscsossssacesesteussees 29 4 INTRODUCTION 29 4 2 WATER QUALITY DATA DIALOGS der epit coord rte pietate coc dade 29 4 2 1 TRAP W BOD COD DO ace i eet Recette ce ee EE 30 4 2 2 TRAP Re ratiot eie ter ted bana
23. ate the bed level then an explicit sediment transport model is run during the simulation and boundary conditions for sediment transport are not required The results of an explicit sediment transport calculation represent the potential sediment transport The option STORING OF BED SUSPENDED LOAD is only applicable to the Engelund Fredsoe Deigaard and the van Rijn formulae as these divide the calculation of the total load into bed load and suspended load components Additional parameters to the sediment transport modelling are also specified in this dialog Default values are supplied automatically for all parameters but as these parameters are very important for the calculation of the sediment transport this menu must be edited before a sediment transport calculation can be carried out 38 DHI Software SEDIMENT TRANSPORT ST SF 5 5 4 The various model parameters represent the following e Relative Density of the sediment density of the mineral sediment relative to water e Porosity sediment porosity Theta critical the critical Shields parameter e Relative Density of fine sediment AD density of the fine sediment containing organic material relative to water e Min Max Manning number minimum maximum limits for the friction resistance number in the calculations The default values of computation parameters are typical values but the actual values of viscosity density and porosity should be substituted as appr
24. components The simulation results will be stored and presented in the specified units The AD module can be run with the components specifications only In this case all model specific parameters decay constant dispersion coefficient initial concentration as well as boundary conditions are set to zero TRAP I AD WQ AD Connection The WQ AD Connection gives the possibility of naming each components as the user desires In the dialog displayed in the figure 3 3 below each user specified component is connected to a standard component in the WQ module so that the WQ module knows how to model each component 22 DHI Software ADVECTION DISPERSION AD 3 2 3 WQ AD Connection my DO Temperature Figure 3 3 Predefine Component definition dialog TRAP AD Dispersion The dispersion coefficients or factors can be specified as Specific values applicable for individual conduits or as Global values applicable for the entire model except for those conduits with Specific data definition DHI Software 23 24 a MOUSE TRAP The dispersion coefficient is specified as a function of the flow velocity The function is given as D a 3 1 where D the dispersion coefficient m2 s a the dispersion factor u the flow velocity m s b a dimensionless exponent The unit of the dispersion coefficient is always m2 s hence the unit of the dispersion factor a depends on
25. d This concentration is used together with the DWF specification in MOUSE HD to calculate the sediment load for a given fraction ST DATA FOR GRADED SEDIMENT TRANSPORT Global ST oraded2 01 00 mm Jad hd Close fo 200 a m2 s Help Transport Mode Erodibility Coefficient Fraction ID Fraction Diameter STgradedt STaraded2 40 DHI Software 0 100 0 100 OST OAD 0 000 0 0 000 0 1 000 1 000 0 700 0 700 Fall velocity cm s Critical bed shear stress for Insert Active layer Deposition Cd 0 700 Misc Passive layer Pa oti Erosion Ce 1 000 N m2 DWF Concentration 250 000 SRG Input me zl 0 200 0 200 250 000 fine SEDIMENT TRANSPORT ST 5 5 6 5 5 7 Sc Figure 5 4 Specification of the data for graded sediment transport TRAP ST Sediment Distribution The distribution of sediment among the outflowing conduits at a node is carried out according to the ratio of flow discharges The distribution is calculated applying the coefficients and exponents K and n values in the following relationship n3 n l K3 bd 1 9e 5 1 Au 3 n4 Mu S12 v K 3 Q 3 K 4 Figure 5 7 illustrates the situation at a node K aun K Ja 2 q e e O Figure 5 5 Distribution of Sediment According to Discharge For the default distribution K to K4 and n to n4 equal to 1 For further informa
26. d decay rates Advection Dispersion Data Dialogs TRAP AD Components Each of the components substances to be included in the Advection Dispersion computations should be specified in this Data dialog shown in Figure 3 1 The components defined in this dialog are automatically associated with wastewater equal for all sources and for all catchments For other lateral sources of polluted water specified as boundary time series or as runoff hydrographs concentrations must be specified individually The standard components including BOD COD ammonia phosphate and bacteria are specified by using the Predefine button For other user specified components the component names and other data must be typed individually in the respective fields of the dialog Z AD COMPONENT SELECTION loj Component Name BOD Type Sine zl Close Unit mon ConcentationinDwF Hep f Component Type Uses Unit Dw iet Single Predefine Single Figure 3 1 The AD component selection data dialog DHI Software 21 MOUSE TRAP 3 2 2 AD COMPONENT DEFINITION cd xi BOD COD BOD Close as type E Help Ammonia Not Used hd Define Phosphate Not Used Not Used e Figure 3 2 Component definition dialog The pollution components can be specified in two or three different forms e As single components The
27. dvection Dispersion model can be used for calculation of the transport of dissolved substances and for modelling of water temperature variation within the sewer network The model is based on the one dimensional transport equations for dissolved material The equations reflect two transport mechanisms the advective or convective transport with the mean flow velocity and the dispersive transport due to concentration gradients in the water The transport equations are solved by use of an implicit finite difference scheme which is fully time and space centred in order to minimize the numerical dispersion The main assumptions of the model are 1 The considered substance is completely mixed over the cross sections This implies that a soutce sink term is con sidered to mix instan taneously over the cross section 2 The substance is conservative or subject to a first order reaction linear decay 3 Fick s diffusion law can be applied ie the disp ersive trans port is proportional to the con centra tion gradient Special considerations have been given to the transport at manholes and other structures More information on the technical background of the model is given in the MOUSE TRAP Technical Reference Manual The Advection Dispersion model requires two types of data time series of concentrations at the model boundaries and data for full definition of the components to be modelled e g initial concentrations dispersion coefficients an
28. e This is also described below section 4 2 Water Quality Determinants Water Quality Data Dialogs The determinants included in MOUSE TRAP WQ distributed in 6 groups as shown in the menu Group 1 includes the aspects of the classical BOD DO problem eg the degradation of organic material and subsequent consumption of oxygen The oxygen demand can be specified as BOD or as COD The processes included in the simulation of these parameters are the degradation of organic material and the resulting oxygen consumption and the reaeration of oxygen Group 2 is the nutrients relevant for sewer systems eg the reduced form of nitrogen ammonia ammonium and phosphate The nutrients are modelled as conservative substances Group 3 is the heavy metals The model does not a priori determines which metals to be included This is defined by the user The Heavy metals are modelled similarly to the nutrients eg as conservative substances Group 4 is bacteria arising from human and animal wastes Three groups of bacteria can be modelled faecal coliform total coliform and streptococci The coliform bacteria are assumed to be subject to a decay death that depends on the temperature DHI Software 29 a a MOUSE TRAP 4 2 1 Group 5 and 6 ate facilities for specifying the parameters needed when pollutants are modelled as sediment attached This can be any pollutant BOD heavy metals etc When a group of parameters to be modelled has bee
29. e and environmental engineering DHI Software iii MOUSE TRAP iv DHI Software PART INTRODUCTION TO MOUSE TRAP DHI Software 1 MOUSE TRAP 2 DHI Software 1 1 1 1 1 1 1 2 1 1 3 ABOUT MOUSE TRAP MODULE Key features and application domain Under the common name MOUSE TRAP MOUSE provides several modules for the simulation of sediment transport and water quality for both urban catchments surfaces and sewer systems Since pollutants are carried by sediment sediment transport process and water quality in sewer systems closely interconnected This is important for understanding phenomena like the first flush effect which can only be simulated with a description of the temporal and spatial distribution of sediment deposits on the catchment surface and in the sewer system MOUSE can model these complex mechanisms using its Surface Runoff Quality SRQ Pipe Sediment Transport ST Pipe Advection Dispersion AD and Pipe Water Quality WQ Modules Output from these modules such as pollutant graphs from combined sewer overflows can then be applied directly to receiving waters models MIKE 11 and MIKE 21 Using MIKE 11 or MIKE 21 in conjunction with MOUSE allows assessment of water quality for the water bodies receiving these sewer overflows such as rivers streams lakes and coastal waters The output from the MOUSE TRAP modules can also be used as input to the DHI EFOR model for Waste Water Treatment Plant
30. ewer system 5 Prediction of reduction in hydraulic capacity due to observed and simulated sediment deposits 6 Analysis of the sewer system due to modified regulation strategies Pipe Advection Dispersion AD Module The MOUSE TRAP Pipe Advection Dispersion AD Module simulates the transport of dissolved substances and suspended fine sediments in pipe flow Conservative materials as well as those that DHI Software 3 MOUSE TRAP 1 1 4 1 2 are subject to a linear decay can be simulated The computed pipe flow discharges water levels and cross sectional flow areas are used in the AD Module computation The solution of the advection dispersion equation is obtained using an implicit finite difference scheme which has negligible numerical dispersion Concentration profiles with very steep fronts can be accurately modelled The computed results can be displayed as longitudinal concentration profiles and pollutant graphs which could be used at the inflow to a sewage treatment plant or an overflow structure The AD Module can be linked to the MOUSE T Module to provide long term simulations of pollutant transport Pipe Water Quality WQ Module The MOUE TRAP Pipe Water Quality WQ Module works in conjunction with the Advection Dispersion Module thereby providing many options for describing the reaction processes of multi compound systems including degradation of organic matter bacterial fate exchange of oxygen with the at
31. f pollutants for each component each must be specified During dry weather flow the concentration of dissolved pollutants will build up according to a user specified linear build up function with a maximum threshold value During storms all sediment is routed straight through the gully pots and a simple mixing model is used to mix the incoming water with the gully pot liquor The data for the gully pot model can be specified in the data forms displayed in the Figures 2 3 and 2 4 In Figure 2 3 the data for the gully pots are given SRQ GULLY POT LIQUOR Global 1 Land Use Type Green Area No of Pots per Ha 10 DO in Runoff fi 0 000 mg l PSEZ Vol per Pot 230 000 litre Close Help Figure 2 3 The SRQ Gully Pot Liquor Global I data dialog The data e g Initial Concentration and Build up Rate for the different components in the gully pots are given in the data dialog in Figure 2 4 Figure 2 4 DHI Software ID Component Initial Concentration Build up Rate Max Value SRQ GULLY POT CATCHBASIN Gh fra Close NH4 mg l Insert egal 10000 Ne Component Initial cone Buildup Rate Value _ 0 300 0 100 The SRQ Gully Pot Liquor Global Il data dialog ADVECTION DISPERSION AD E 3 3 1 3 2 3 2 1 ADVECTION DISPERSION AD Introduction The MOUSE TRAP A
32. file and or via the time series database In the time series database four types of boundary conditions can be specified to the morphological model sediment transport concentration variation in the bed level and the volumetric percentage of fractions available in the bed The latter is only applicable for the graded sediment model Boundary conditions must be specified at all inflow points in the sediment transport model Hence if a water level at an outlet results in inflow to the model a boundary condition must be specified at this location for the morphological model An appropriate boundary condition at such a location will often be to specify the sediment transport equal to zero 44 Software SEDIMENT TRANSPORT ST E 5 6 2 5 6 3 5 7 Time Series Database The time series of concentrations sediment transport bed levels and sediment fraction percentages are entered and maintained in the MOUSE Time Series Database which is accessed through the time series editor The Concentration Data are only used if a given ST fraction is to be modelled with the ST module Note the fraction number in the Time Series Editor corresponds to the fraction number specified in the dialog TRAP ST Graded Sediment If the field is left empty then the time series is used for all fractions at the location where the boundary condition is specified The sum of the sediment fractions in the bed must be equal to 100 throughout the simulati
33. gs are presented in figures 3 6 and 3 7 obal dat iolxi ID IC Close Component BOD he Help Concentration ham Insert Figure 3 6 The Initial concentration Global data dialog DHI Software 25 amp 5 lt MOUSE TRAP 3 2 5 3 2 6 Fast Query Close Node Component he Insert ID e Show gt 543 E Select List gt Component BOD e Concentration fi 0 000 mg l No Node Component name Concentration Figure 3 7 The AD Initial concentration Specific data dialog TRAP AD Decay By defining decay constants non conservative components can be specified For such non conservative component the concentration is assumed to decay according to the first order expression Eet 3 3 dt where K the decay coefficient hours C the concentration The decay constant is defined as a uniform decay over the entire model Figure 3 8 The AD Decay constants Global data dialog TRAP AD Open Boundary Conditions The main purpose of specifying an open boundary condition is to enable exchange of mass between the MOUSE network and the surroundings recipient during the computations If only inflow takes 26 DHI Software ADVECTION DISPERSION AD a place at a boundary then it is not necessary to specify a boundary as an open boundary Open boundaries will typically be located at outle
34. ires a good perception of modelling techniques and the capabilities of the software Therefore DHI provides training courses in the use of our products A list of standard courses is offered to our clients ranging from introduction courses to courses for more advanced users The courses are advertised via DHI Software News and via DHI home page on the Internet http www dhi dk DHI can adapt training courses to very specific subjects and personal wishes DHI can also assist you in yout effort to build models applying the MOUSE software If you have any questions regarding DHI training courses do not hesitate to contact us Comments and Suggestions Success in perception of the information presented in this document together with the user s general knowledge of urban sewer systems and experience in numerical modelling is essential for getting a maximum benefit from MOUSE TRAP This implies that the quality of the documentation in terms of presentation style completeness and scientific competence constitutes an important aspect of the software product quality DHI will therefore appreciate any suggestion in that respect hoping that future edition will contribute to the improved overall quality of MOUSE TRAP Please give your contribution via e mail fax or a letter DHI Software 7 MOUSE TRAP 8 DHI Software PART Il MOUSE TRAP USER MANUAL DHI Software 9 MOUSE TRAP 10 DHI Software 1 1 1 1 1 1 THE MOUS
35. mix is given in the MOUSE TRAP Technical Reference Manual DHI Software 27 MOUSE TRAP 28 DHI Software 4 4 1 4 2 WATER QUALITY WQ Introduction This part of MOUSE TRAP deals with the transport and transformation of a number of chemical compounds and biological constituents found in sewer systems These constituents are first of all organic material measured as biological or chemical oxygen demand BOD and COD respectively which can affect the oxygen content of the water Other compounds are the nutrients ammonia and phosphate the heavy metals and various other organic or inorganic pollutants Bacteria from human and animal wastes can also potentially be found in the sewers The determinants that can be analyzed using the MOUSE TRAP WQ module are BOD COD organic matter and oxygen Ammonia and phosphate Heavy metals Bacteria total and faecal coliform and streptococci Pollutants attached to sediments The WQ module is coupled to the AD module This means that while the AD module simulates the transport process the WQ module deals with the simultaneous transforming processes of the com pounds in the sewer The AD module is running in parallel to the WQ module when the WQ module is activated The WQ module for MOUSE TRAP has been constructed to be as flexible as possible This has resulted in a structure where the determinants mentioned above can be studied individually or rather in the groups indicated abov
36. modelling Surface Runoff Quality SRQ Module The primary role of the Surface Runoff Quality SRQ Module is to provide a physically based desctiption of the relevant processes associated with sediments and pollutants due to surface runoff and then provide surface runoff sediment and pollutant data for the other pipe sewer network sediment transport and water quality modules The following processes can be accounted for 1 Build up and wash off of sediment particles on the catchment 2 Surface transport of pollutants attached to the sediment particles 3 Build up and wash out of dissolved pollutants in potholes and stilling basins Pipe Sediment Transport ST Module Sediment deposits can greatly reduce the hydraulic capacity of sewer pipes by restricting their flow area and increasing the bed friction resistance The MOUSE TRAP Pipe Sediment Transport ST Module can account for these problems by simulating pipe sewer network sediment transport including deposition and erosion from non uniform graded sediments Contributions from rainstorm wash off and dry weather wastewater flow can be included The ST Module runs in conjunction with the dynamic flow routing thereby simulating dynamic deposition of sediment and providing feedback due to the change in pipe area and resistance caused by sediment deposition The following issues can be addressed 4 Prediction of sediment deposit locations and associated pollutants and metals in the s
37. mosphere and oxygen demand from eroded sewer sediments This allows realistic analysis of complex phenomena related to water quality in sewer systems The WQ Module includes diurnal variation of foul flow discharges and user specified concentrations of foul flow components The sediment types included in the interaction with the WQ Module are foul flow organic sediments and fine and course mineral in pipe sediments originating from catchment runoff potholes and stilling basins The WQ Module can account for 7 Decay of BOD COD in bio film and water phase Hydrolysis of suspended matter 9 Growth of suspended biomass 10 Oxygen consumption from decay of BOD COD bio film and erosion of sediment 11 Re aeration 12 Bacterial fate 13 Interaction with sediments for nutrients and metals Software Implementation MOUSE TRAP is an add on module to both MOUSE Runoff and MOUSE HD Pipe Flow Model The MOUSE TRAP functionality can be accessed i e a pollution and or sediment transport simulation can be executed only after the MOUSE license has been extended to include MOUSE TRAP For details about the DHI s copy protection system and the license update procedure please refer to the MOUSE Installation and Update Guide MOUSE TRAP utilizes the standard MOUSE Menu System with on line HELP facility which has been extended to accommodate functions related to MOUSE TRAP This implies that the documentation related to the standard version of
38. n selected position the cursor at the relevant group no and press lt Enter gt the lower level menu for that group will be displayed These menu are presented in the following section The processes are described theoretically in the MOUSE TRAP Reference Manual Here a general explanation of the processes and inventory of the required input parameters are given in connection to the discussion about relevant data forms TRAP WQ BOD COD DO The determinants included in this group is the BOD COD and dissolved oxygen The BOD is modelled as two fraction the dissolved and readily degradable BOD and the suspended BOD that is degraded slower and of which a part is the heterotrophic bacteria responsible for the degradation of a part of the dissolved BOD The dissolved BOD can also in some cases besides the degradation by the bacteria be degraded in a biofilm at the inside of the sewer pipe and at the water surface The processes included are shown in Figure 4 1 Reareation Oxygen Heterotrophic BOD ety BOD BS Suspended ES Dissolved J 790055 Deposition Erosion Erosio Biofilm Sediment BOD BOD oxygen LC demand Interstitial Liquid Sediment Figure 4 1 The processes included in the modelling of BOD COD dissolved oxygen problems in sewer pipes in MOUSE TRAP The general parameters for the BOD COD DO processes are inserted through the data dialog shown
39. ndary conditions at all inflow boundaries In order to chose the morphological sediment transport model type check the checkbox UPDATE THE BED LEVEL on the dialog TRAP ST Model and Formula The Transport Formulae Short Description The following four non cohesive sediment transport formulae are implemented in MOUSE TRAP ST e Engelund Hansen Ackers White e Engelund Freds e Deigaard e van Rijn Short descriptions of the sediment transport formulae are given below No general guidelines can be given for the preference of one formulation over another as the applicability of each depends on a number of factors All these formulae demonstrate that the sediment transport is a highly non linear function of the flow velocity depending on the formulation the sediment transport is proportional to the velocity raised to the power from 3 to 5 Hence the user should be very careful in the description of the hydrodynamics in the model setup The Ackers White formulae The formulae determine directly the total sediment transport The formulae are semi empirical based partly on dimensional analysis and partly on physical arguments The Engelund Hansen formula The formula determines the total sediment transport directly It has been derived from consideration of the work done by the flow on the sediment being transported Originally the formula was derived for a dune covered bed but it was found ap
40. nt Pollutants The PPC values can be specified for each pollutant component TP gives the total amount of pollutant in grams per litre wet sediment The parameter Fine sediment gives the percentage of the TP which is attached to the fine sediment fraction The parameter Coarse sediment gives the percentage of the TP which is attached to the coarse fraction For surface sediment the sum of the parameters Fine sediment and Coarse sediment must be equal to 100 The dialog for the specification of the PPC values are shown in Figure 2 2 In Figure 2 2 the values have been specified for component BOD SRQ Surface SEDIMENT and POLLUTANTS Glob Elei ID 5 1 Close Pollutant partitioning coefficients TP fa 000 Component BOD g Fine Sediment s 000 Insert Coarse Sediment 44 000 Ix 56 000 44 000 Figure 2 2 The Surface Sediment and pollutants Global data dialog The data supplied to the Gully pot model facilitate description of the build up of dissolved pollutants in the gully pots during dry weather and the wash out of dissolved pollutants from the gully pots during storm events DHI Software 19 Sc 20 The data which describe the gully pots in the modeled area can be comprised to 1 Land use type 2 No of pots per ha 3 The average pot volume liter 4 Inflow concentration of dissolved oxygen mg l MOUSE TRAP Additionally data for description of the build up o
41. on period The SEDIMENT DATA are only used if a given fraction is to be modelled with the ST module Connecting Time Series from the Time Series Database to the Network Model Sediment data time series are connected to the network model in the same way as the hydrodynamic data For the sediment data it is possible to interpret the connected time series as either sediment transport 1 5 or as concentrations g m3 This is controlled by the number in the Model Connection Type field Type code 1 represents transport 1 s and type codes 2 and 3 represent concentration For type codes 2 and 3 the specified concentration is converted into transport by use of the relative densities given in the TRAP ST Model and Formula dialog according to the following e Type code 2 The relative density is used e code 3 The relative density for fine sediments is used The user must be careful when selecting the concentration because in reality suspended sediments exhibit a vertical concentration gradient i e concentration is a function of depth This means that when the concentration time series is converted into transport internally for computation then the resulting transport is dependent on the sampling depth of the sediment concentration IMPORTANT For Type codes 2 and 3 an Identifier MUST be specified identical to the one specified in the NODE 2 field of the discharge connection in order to connect the
42. opriate The parameters Theta critical and MIN MAX should not be altered unless the user is familiar with the consequences For a more detailed description of these parameters refer to the related equations in the Technical reference documentation ST MODEL PARAMETERS E c x Ges te Figure 5 2 The ST Model Parameters data dialog TRAP ST Calibration Factor These are multiplication factors for the calibration linear scaling of the sediment transport models In a simulation including both bed and suspended loads the bed load is scaled by the Total Load Bed Load factor and the suspended load is scaled by the Suspended Load factor If only the total load is calculated Ackers White and Engelund Hansen the total load is scaled by the Total Load Bed Load factor and the Suspended Load factor is not used DHI Software 39 Sc 5 5 5 MOUSE TRAP ST CALIBRATION FACTORS Global x Calibration factor for Total Load Bed Load Close ho Help Calibration factor for Suspended Load Figure 5 3 The ST Calibration factors Global data dialog TRAP ST Graded Sediment This dialog allows for the specification of the input data required for the simulation of graded sediment transport and sediment sorting The bed material is represented by two layers an active layer overlying an inactive passive layer Each layer is divided into an equal number
43. ording to the following expression where D 1 00 u 3 2 u the flow velocity m s The dispersion coefficient may in the simulation vary between the limits 0 00 lt D lt 10 00 DHI Software ADVECTION DISPERSION AD 3 2 4 Advection Dispersion Specific Data _ Inl xl Fast Query Close From Help ID 051 Insert Dispersion factor 000 Exponent 0 000 Minimum dispersion coefficient 0 000 m2 s Maximum dispersion coefficient I 0 000 0 000 0 000 10 000 Figure 3 5 The Advection Dispersion Specific Data dialog TRAP AD Initial Concentrations Initial conditions i e the concentrations of each component at the start of the simulation can be specified both as Specific and Global data The specific data are given for individual nodes while the Global data define uniform initial conditions over the entire model except for these nodes and the adjacent links where specific data are given Initial conditions within the links adjacent to the nodes with specific initial conditions are obtained by linear interpolation If the specification of initial concentration for a certain component has been omitted a zero concentration is automatically applied It should be noted that the units used for initial concentrations of various components correspond to those specified in the Components definition dialog The Initial Concentration Global and Specific data dialo
44. ould be sufficiently small in order not to generate instabilities in the hydrodynamic calculations If both the sediment transport module and the advection dispersion module run at the same time and an interaction takes place between the two modules then the time step should be the same for the sediment transport and the advection dispersion computations 46 DHI Software
45. plicable to the upper regimes plane bed and anti dunes as well The Engelund Fredsoe Deigaard formulae The formulae calculate the total transport as the sum of the bed load transport and the suspended transport The sediment transport is calculated from the skin friction i e the shear stress acting on 36 DHI Software SEDIMENT TRANSPORT ST se 5 3 4 5 4 5 5 5 5 1 5 5 2 the surface of the bed In this formulae it is possible to describe the development of sand dunes in pipes and hence include the resulting friction into the computations The total bed resistance is then calculated as the sum of a contribution from the skin friction acting on the dune and an expansion loss behind the dune The van Rijn formulae In the van Rijn sediment transport formulae the sediment transport is divided into bed load and suspended load The bed load is calculated from the saltation height the particle velocity and the bed load concentration The bed load computations follow the approach of Bagnold 1973 which assumes that the motion of the bed load particles is dominated by the gravity forces When the bed shear velocity exceeds the fall velocity sediment is transported in suspension The suspended load is calculated as the depth integration of the local concentration and flow velocity The method uses the reference concentration computed from the bed load transport The formula has been verified for particles in the range 200 2000 Um
46. tensive reference on using MOUSE TRAP data dialogs DHI Software 5 MOUSE TRAP 6 DHI Software 3 1 3 2 3 3 MOUSE TRAP USER SUPPORT Product Support If you have questions or problems concerning MOUSE TRAP please consult the documentation Installation and Update Guide and MOUSE TRAP User Manual first Secondly look in the README files that came with your installation If you have access to the Internet you may also have a look under Frequently Asked Questions or Problems amp Work arounds on the MOUSE Home Page The MOUSE Home Page is located at http www dhisoftware com mouse If you cannot find the answer to your queries please contact your local agent In countries where no local agent is present you may contact DHI directly by mail phone fax or e mail DHI Water amp Environment Agern All 5 DK 2970 Horsholm Denmark Phone 45 45 169 200 Telefax 45 45 169 292 e mail software a dhi dk When you contact your local agent or DHI you should prepare the following information The version number of MOUSE that you are using The type of hardware you are using including available memory The exact wording of any messages that appeared on the screen A description of what happened and what you were doing when the problem occurred A description of how you tried to solve the problem DHI Training Courses DHI software is often used to solve complex and complicated problems which requ
47. tion refer to the MOUSE TRAP Technical Reference Manual TRAP ST Initial Sediment Depth The initial depth of the sediment deposits the bed shear stress caused by the sediment deposits and variation of the critical bed shear stress as a function of the initial sediment depth are specified in the dialog TRAP ST Initial Sediment Depth The various parameters can be specified either globally or locally The depth of the initial sediment deposits should be specified relative to the bottom level of the pipe The bed shear stress from the sediment deposits can be specified in three ways e bed shear stress is calculated from the local mean grain diameter according to DHI Software 41 amp 5 lt MOUSE TRAP 42 25 4 _ 5 2 2 5ed j where d is the mean grain diameter e the bed shear stress is the Manning s M taken from the form the bed shear stress is the Manning s n 1 M taken from the form The variation of the critical bed shear stress can be given as a function of the initial sediment depth as long as only erosion occurs If deposition occurs the critical bed shear stress is set equal to the Shields critical bed shear stress specified in the dialog TRAP ST Model and Formula This value of the critical bed shear stress will be used as long as the depth of the sediment deposit is larger than the maximum depth to which the initial sediment deposit has been eroded This can be summ
48. ts The location of the open boundaries in the model are specified in the AD Open Boundary Condition dialog see Figure 3 9 SS AD OPEN BOUNDARY CONDITION xl ID Node omg 7 Boundary Concentration zl Insert K mix os Show Select List gt 0 500 Concentration Figure 3 9 The AD Open boundary condition data dialog Special consideration must be given to the open boundaries in the Advection Dispersion model i e at an open boundary a boundary time series containing either transport or concentration in the receiving waters must be specified A proper type is selected from the Boundary Type combo box If the flow is directed out of the model the concentrations or transport at the boundary are computed from the concentrations or transport within the model area In this case the concentration or transport outside the model area is assumed not to influence the conditions in the model area If a flow reversal takes place so that flow is directed from the receiving waters into the model area the specified time series of boundary concentrations or transport are used and assumed to be unaffected by the previous outflow from the model area A parameter K mix is used to ensure a smooth transition between the calculated concentration or transport at the boundary before the flow reversal and the specified time series of boundary concentrations The description of K
49. ure 4 4 The WQ Bacteria data dialog TRAP WQ Sediment Pollutants Data needed for modelling pollutants attached to sediments are specified in the data dialogs shown in Figure 4 5 The sediment attachment is based on the PPC concept see MOUSE TRAP Technical Reference Therefore the total pollutant load g pollutant liter of wet sediment are specified under TP DL Fine sediment Coarse sediment is the TP value partitioned in to a dissolved a fine sediment and a coarse sediment fraction respectively These are specified in percentages of TP and must sum to 100 An example is given in Figure 4 5 with the recommended values for partitioning BOD into fractions 32 DHI Software WATER QUALITY WQ Figure 4 5 The WQ Pollutants Attached to Sediments Global data dialog DHI Software 33 MOUSE TRAP 34 DHI Software 5 2 5 2 1 5 2 2 SEDIMENT TRANSPORT ST General Overview MOUSE TRAP permits the computation of non cohesive sediment transport from four different sediment transport formulae Each of the sediment transport formulae can be used in any of the sediment transport models available in MOUSE TRAP ST The sediment transport models are of different levels of complexity The most simple model calculates only the hydraulic resistance from sediment deposits in the pipes and the most complex model is a full morphological model for graded sediment The sediment transport models
50. urring microorganisms are factors involved in the decay of pathogenic bacteria in the marine environment Eschericia coli E coli is one of the dominant species in faeces from human and warm blooded animals The organism itself is normally considered non pathogenic but is very often used as indicator organism for faecal pollution and hence a potential of real pathogenic organisms eg other bacteria and vira Infections obtained from bathing waters are most often caused by vira protozoas Shigella and Campylobacter Enteric bacteria die off can be modelled very well by a first order decay reaction However the die off constant or decay rate is highly variable due to interaction by environmental factors on bacterial die off The main factors are suspected to be light temperature and salinity variations In sewers the only relevant factor among these to include is the temperature Other less important factors are e g predation sedimentation and the amount of available nutrients For each bacteria group a first order decay rate at 20 C has to be specified together with a temperature coefficient This is done in the dialog seen in Figure 4 4 WU Bacteria Faecale Coliforms Close Help 1st order decay rate _ Temp coeff for decay io 5 Total Coliforms 1st order decay rate po Temp coeff for decay ro Streptococci 1st order decay rate oso Temp coeff for decay io 5 Fig
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