MT3D99 manual
Contents
1. O O OO WG L a W a OO Ww O OOO OOO O L Lo 1 NBLOCK 1151230 I1 12 Jl J2 IBZ In this example the model consists 3 layers 23 columns and 15 rows In the first layer there are five zones defined using the free format with zones 1 to 4 representing the north east south and west borders of the model respectively and zone 5 the model interior By defining the zoneation in this fashion it is convenient to calculate how much flow into or out of the model borders In the second layer there are only one zone Zone 1 could represent a mine pit or landfill In layer 3 All zone values are set to zero using the block format thus no subregional flow or mass budget computation will be done in that layer Chapter 7 Post Processing Programs 7 11 a Schematic illustration of three budget zones in a model grid 1 _ E H Z G S tt Bae ttt Ba LT a T E 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 Columns J Columns J Layer 1 consists of three zones Layer 2 consists of two zones b Representation of the budget zones in the budget zone definition file 103 IPCode for free format followed by Zone Numbers layer 1 ede Ld 3 3 3 3 bd ad ds 3 3 3 3 Tiitis 33 3 11131223 3 2222223 3 2222223 3 2222 2 2 33 Z Z Z 2 22 3 3 101 iPCode for block format followed Zone Numbers layer 2 2 nblock 1818 1 lil i2 jl j2 1B4 block 1 3 425 3 2 Figure 7 32. a modular 3d multispecies transport simulator User s Guide By Chunmiao Zheng in association with S S Papadopulos amp Associates Inc TABLE OF CONTENTS Introduction System Requirements and Installation 2 1 Executable Programs and System Requirements sccscssscsssssscssscssscssscssesscssscssscssesesesseess 2 1 2 2 Installation and Setup c ccsessscassessccsversesssvessersssoscessavessessovessossovacconssucscassusscansonscessgacaessscescessaveas 2 1 Enhanced Basic Transport Package 3 1 Automatic Restart Option csscssesscsscsscscsssssssssssscssscssessesssessssssssessessssssssnesssssessessesseseeses 3 1 3 2 Cell Dy Cell MASS lt s sicssssvssseccevassoasesssonssesssuscoassenscesveasesvasivuesuassons sbassbascasseaseahosasoonssuesbassenssesseessieess 3 3 Enhanced Reaction Package AL Monod Kinetics ieies cscsecescessecsasssceacceissccaesacsecsdusstacsonsctasa cbdescseseepacdasdoataveseesactnbatiebsseesoceassettetasoasecss 4 1 4 2 Instantaneous Aerobic and Anaerobic Biodegradation sssscessssscssscsescecscecesscssesssesesees 4 2 4 3 First Order Parent Daughter Chain Reactions sss ss sss seves vesse ssssss vesse sssess resserrer 4 5 Input Instructions 5 1 Basic Transport Package seves seves ssssss resse essere resserrer neson onnenn enesenn ennenen 5 1 5 2 Reaction Package csscssisssscsocsscsssssesesvessesssnsecessensessssessonssesdeasesdessesesveisnsesctssesesosvoasesssesasenssc
3. and Ypcr rcr 18 the yield coefficient for transformation from PCE to TCE The same conventions are used for species TCE DCE and VC Based on laboratory and field scale results Wiedemeier et al 1997 present representative first order biodegradation rates for chlorinated solvents ranging from 0 00068 Chapter 4 Enhanced Reaction Package 4 5 to 0 54 day for PCE 0 0001 to 0 021 day for TCE 0 00016 to 0 026 day for DCE and 0 0003 to 0 012 day for VC Clement 1997 lists the yield coefficients Y PCE TCE 0 79 Yrceipce 9 74 and Fue 0 64 The first order sequential kinetic reaction is implemented in MT3D for both dissolved and sorbed phases using either explicit and implicit schemes For explicit schemes a stability criterion associated with each reaction is calculated and the maximum transport stepsize allowed is determined For implicit schemes the iterative solver is used to solve the reaction terms with no stepsize limitation Chapter 4 Enhanced Reaction Package 4 6 5 Input Instructions 5 1 BASIC TRANSPORT PACKAGE This section describes the changes in the input instructions for the enhanced basic transport package Note that the enhanced basic transport package is backward compatible with the original BTN package as implemented in MT3D and MT3DMS Thus the BTN input file prepared for other versions of MT3D can also be read and used directly by MT3D Also note that the bold typefac
4. and MT3DMS can also be read and used directly by MT3D Note that the bold typeface indicates the new features implemented in y by MT3D while the underlined are the new features first introduced in MT3DMS FOR EACH SIMULATION El Record Format ISOTHM IREACT IRCTOP IGETSC 4110 ISOTHM is a flag indicating which type of sorption or dual domain mass transfer is simulated ISOTHM 0 no sorption is simulated 1 Linear isotherm equilibrium controlled 2 Freundlich isotherm equilibrium controlled 3 Langmuir isotherm equilibrium controlled 4 First order kinetic sorption nonequilibrium 5 First order kinetic dual domain mass transfer IREACT is a flag indicating which type of kinetic reaction is simulated IREACT 0 no kinetic reaction is simulated 1 first order irreversible reaction 2 Monod kinetics 3 first order parent daughter chain reactions and 1 instantaneous reaction among species IRCTOP is an integer flag indicating how reaction variables are entered IRCTOP 22 all reaction variables are specified as 3D arrays on a cell by cell basis lt 2 all reaction variables are specified as a 1D array with each value in the array corresponding to a single layer This option is mainly for retaining compatibility with the previous versions of MT3D Chapter 5 Input Instructions 5 2 e IGETSC is an integer flag indicating whether the initial concentration for
5. mass units of species k The instantaneous reaction model of equation 4 6 is implemented in MT3D sequentially in an explicit formulation i e the base species 1 first reacts with species 2 C t C C F 4 7a CU Le CUI CU Fo subject to constraints C t 1 0 ife c t F e c e COF S C 1 0 if c gt C F If the base species 1 is completely consumed by species 2 then all subsequent reactions involving species 3 4 k are terminated Otherwise what is left of the base species reacts with species 3 i e c 1 c C O F 2 4 8a C rt 1 C7 C F subject to constraints C 0 if CC gt C O F 1 13 4 8b C t 1 0 if C gt CW F where C is the modified concentration of the base species due to the previous reaction with species 2 The procedure is repeated until either the base species is completely depleted or no more reactants are left The reaction model as defined in equation 4 6 can be used to approximate the reactions between BETX electron donors and various electron acceptors such as oxygen nitrate manganese ferric iron sulfate and carbon dioxide For example the general formulation of 4 6 can be replaced by the following equations to model aerobic biodegradation of hydrocarbon H t 1 H 00 Fro OU 1 Oui H t Fo 4 9 Chapter 4 Enhanced Reaction Package 4 3 where H and O are concentrations of hydrocarbon and oxygen re
6. 1 e the value of IREACT For IREACT 1 RC1 is the first order rate coefficient for the dissolved or mobile phase unit TT For IREACT 2 Monod kinetics RC1 is the product of total microbial concentration M unit ML and the maximum specific growth rate of the bacterium u unit T Chapter 5 Input Instructions 5 4 Enter E6 for each species if IREACT gt 0 E6 Array RC2 NCOL NROW one array for each layer Reader RARRAY e RC2 is the second kinetic reaction parameter The use of RC2 depends on the type of kinetic reaction selected i e the value of IREACT For IREACT 1 RC2 is the first order rate coefficient for the sorbed or immobile phase unit TT For IREACT 2 Monod kinetics RC2 is the half saturation constant K unit ML Enter E7 if IREACT 1 or 3 E7 Array STOICH NCOMP 1 one array for all species Format RARRAY S STOICH is the stoichiometric ratio or yield coefficient dimensionless for multispecies reactions For IREACT 1 instantaneous reactions the first value in the array is for the reaction between species and species 2 the second value for the reaction between species 1 and species 3 and so on For IREACT 3 first order chain reactions the first value in the array is for the reaction between species and species 2 the second value for the reaction between species 2 and species 3 and so on 5 3 ANOTE ON THE GCG SOLVER PACKAGE If the GCG solver package
7. 2 System Requirements and Installation 2 1 3 Enhanced Basic Transport Package 3 1 AUTOMATIC RESTART OPTION In the previous versions of MT3D including MT3DMS the procedure to restart a previous simulation run is not straightforward particularly if a transient flow field is involved A new option has been added to MT3D to make it much easier to restart a previous run The new restart option involves two changes in the Basic Transport BTN Package First MT3D saves all the information needed for a restart run including time counters global mass budgets and concentrations of all species in a default binary file named MT3D RES MT3D updates this file at the same user specified frequency as it writes to the unformatted concentration files Next to restart a run activate the restart option by setting the 10 element of the transport option array i e TRNOP 10 to T True in the BTN input file see Figure 3 1 MT3D will then prompt the user for the name of the restart file or the MT3D RES file saved in the previous run Once the restart file is read in MT3D starts the new simulation using the concentrations saved in the restart file as the initial condition and automatically resets the time counters and global mass budgets to continue from the time recorded in the restart file If the flow field is transient MT3D automatically skips those time steps of the flow solution that are prior to the restart time Thus there is
8. Chapter 6 New Benchmark Problems 6 2 6 2 INSTANTANEOUS AEROBIC BIODEGRADATION The example problem considered in this section is similar to that described in Section 7 3 of the MT3DMS manual involving two dimensional transport from a continuous point source in a uniform flow field The model grid consists of 46 columns 31 rows and 1 layer and is aligned with the flow direction along the x axis see Figure 6 2 The flow model is surrounded by constant head boundaries on the east and west borders and no flow boundaries on the north and south borders The head values at the constant head boundaries are arbitrarily chosen to establish the required hydraulic gradient One injection well is located at column 11 and row 16 The injection rate is sufficiently small so that the flow field remains approximately uniform The model parameters used in the simulation are listed below Cell width along rows Ax 10m Cell width along columns Ay 10m Layer thickness Az 10 m Groundwater seepage velocity v 1 3 m day Porosity 6 0 3 Longitudinal dispersivity 10 m Ratio of transverse to longitudinal dispersivity 0 3 Volumetric injection rate 1 m day Simulation time t 730 days 2 years Assume that the injected water contains hydrocarbon species 1 with a constant concentration of 1000 ppm Further assume that the background concentration of oxygen species 2 in the aquifer is 9 ppm The background oxygen concentration is
9. Ld K 1000 mg L Case 2 Mw 2x10 mg L d K 1 mg L and max Case 3 M Maa 2x10 mg L d K 0 001 mg L Note that these reaction parameters are intended for demonstration purposes only and have no Chapter 6 New Benchmark Problems 6 1 particular physical relevance For Case 1 the Monod kinetics should approach a first order reaction since K is three orders greater than the maximum concentration in the aquifer Indeed the calculated concentration profile with the Monod kinetics is nearly identical to the analytical solution for the same transport problem but assuming a first order reaction with the rate coefficient A M U nax K 2x10 day Case 2 with K in the same order as the aquifer concentrations shows the mixed order characteristics of the Monod kinetics In Case 3 the Monod kinetics approaches a zero order reaction i e 0C dt M M nax Since K is max negligible compared to the concentrations in the aquifer First order analytical E Monod Case 1 A A Monod Case 2 Monod Case 3 0 8 0 6 C Co 0 4 0 2 Figure 6 1 Calculated concentrations for one dimensional transport from a constant source in a uniform flow field The solid line indicates the analytical solution assuming first order kinetics while the symbols represent the numerical solutions assuming Monod kinetics with different coefficients
10. are used by HCComp if no data inclusion window is defined y Columns Istart_Include 2 Iend_Include 4 b Only observation data points inside the data inclusion window are used by HCComp Figure 7 2 Definition of the data point inclusion window for HCComp Chapter 7 Post Processing Programs 7 5 7 2 2 Observation data file The observation data file contains well identification names observation well locations and observed values of head drawdown or concentration These data should be arranged in the following order For each observation time interval where NW KPER KSTP TOTIM WELLID 1 X 1 Y 1 LAYER 1 OBS 1 WELLID 2 X 2 Y 2 LAYER 2 OBS 2 WELLID NW 1 X NW 1 Y NW 1 LAYER NW 1 OBS NW 1 WELLID NW X NW Y NW LAYER NW OBS NW NW is the total number of observation points wells an integer KPER and KSTP are the stress period and time step numbers for the calculated heads or drawdowns with which the observed heads or drawdowns are compared integers TOTIM is the total elapsed time for the calculated concentrations with which the observed concentrations are compared WELLID is the well identification name a character variable X and Y are the x and y coordinates of the observation point in the global coordinate system LAYER is the index of the model layer where the observation well is located an integer and OBS is the observed value of head drawdown or concentrati
11. no need to modify the flow model input files Similarly if there are multiple stress periods of sinks sources defined for the transport simulation MT3D will automatically read and discard the input data for those stress periods that are prior to the restart time Note that if it is desirable to save the restart file from a previous run it should be copied and renamed because each time MT3D is run the default restart information file MT3D RES will be overwritten Chapter 3 Enhanced Basic Package 3 1 TRNOP Element Number 1 2 3 4 5 6 7 8 9 10 Sample TRNOP Input Record TRNOP T T T F T F F F F T Element Number 1 2 3 4 5 6 F 8 9 10 Note 1 The Advection Option is used an input file is needed for the Advection ADV Package 2 The Dispersion Option is used an input file is needed for the Dispersion DSP Package 3 The Sink amp Source Option is used an input file is needed for the Sink amp Source Mixing SSM Package 4 The Chemical Reaction Option is not used an input file is not needed for the Chemical Reaction RCT Package 5 The Generalized Conjugate Gradient Solver is used an input file is needed for the Generalized Conjugate Gradient GCG Package 6 9 Reserved for future add on packages 10 The Restart Option newly implemented in MT3D is used Figure 3 1 Specification of the transport components solver and restart option to be included using the logical TRNOP array The TRNOP array i
12. the sorbed or immobile phase of all species should be read when nonequilibrium sorption ISOTHM 4 dual porosity mass transfer ISOTHMS S is simulated IGETSC 0 the initial concentration for the sorbed or immobile phase is not read default it is assumed to be in equilibrium with the dissolved concentration ISOTHM 4 or zero for ISOTHMSS gt 0 the initial concentration for the sorbed or immobile phase of all species will be read Enter E2 if ISOTHM gt 0 E2 Array RHOB NCOL NROW one array for each layer Reader RARRAY e RHOB is the bulk density of the aquifer medium unit ML if ISOTHM 1 2 3 and 4 RHOB is interpreted as the immobile porosity i e the ratio of disconnected pore spaces filled with immobile fluids over the bulk volume of the aquifer medium if the simulation is intended to represent a dual domain system i e if ISOTHM S Enter E2A for each species if IGETSC gt 0 E2A Array SRCONC NCOL NROW one array for each layer Reader RARRAY e SRCONC is the user specified initial concentration for the sorbed or immobile phase For ISOTHM 1 2 3 or 4 SRCONC is the initial concentration for the sorbed phase of a particular species unit MM For ISOTHM 5 SRCONC is the initial concentration for the immobile phase if unit ML Enter E3 for each species if ISOTHM gt 0 E3 Array SPI NCOL NROW one array for each layer Reader RARRAY S SPI is the first sorption parameter The us
13. Example for specification of budget zones in a model grid Chapter 7 Post Processing Programs 7 12 7 3 4 Output file FMBUDGET prints out flow or mass budgets for every zone defined in the zone definition file at every time period saved in the unformatted flow transport link file or cell by cell mass file If a single zone is defined across several layers the budget is computed and printed layer by layer Note that the groundwater flow budgets are presented in flow rates dimension LT not in total flow volumes The unit for flow rates used by FMBUDGET is the same as that used in MODFLOW The conventions for IN and OUT used by FMBUDGET are also the same as those in MODFLOW That is in terms of flows across zone side boundaries IN means into the target budget zone from other zones whereas OUT means out of the target budget zone to other zones In terms of vertical flows IN from TOP means downward flow into the target layer from the layer immediately above whereas OUT to TOP means upward flow from the target layer to the layer above On the other hand IN from BOTTOM means upward to the target layer from the layer immediately beneath it whereas OUT to BOTTOM means downward flow from the target layer to the layer beneath In terms of storage various sink source terms IN means sources with flow entering the target budget zone whereas OUT means sinks with water leaving the target budget zone The terms TOTAL IN TOTAL OUT and ABSOLUTE DISC
14. KPER is the number of the stress period and TOTIM is the total elapsed time at which heads drawdowns or concentrations being compared are saved 7 3 Flow MassBUDGET FMBUDGET FMBUDGET calculates total flows across and within arbitrarily defined flow budget zones or subregions in any model layer based on the unformatted flow transport link file saved by LinkMT3D package added to MODFLOW It also calculates total masses both dissolved and sorbed in any user specified subregions in any model layer based on the unformatted cell by cell mass file saved by MT3D FMBUDGET is useful in many routine tasks such as providing a layer by layer summary of flow and mass budgets or calculating total groundwater flow into or out of a structure such as a landfill represented by a group of model cells In addition to the unformatted flow transport link file or the cell by cell mass file FMBUDGET requires a user specified budget zone definition file For output FMBUDGET saves detailed summaries of flow and mass budgets for every zone at each time period saved in the unformatted file 7 3 1 Unformatted flow transport link file The unformatted flow transport link file is saved by the LinkMT3D package added to MODFLOW The flow transport link file contains detailed cell by cell flow terms and must already exist before MT3D can be run The flow transport link file is similar to the cell by cell flow file created by MODFLOW Note that FMABUDGET only works w
15. LH KH Gn LH L KH GH woo KH aA LH Ln Ln Ln Ln Ln Ln Ln Ln Ln Ln Ln Ln LH Ln Ln Ln Ln Ln Ln Ln Ln Ln Ln Ln a Ww Ln LH LH Ln Ln Ln LH Ln Ln Ln Ln Ln we Ww Ln LH LH Ln Ln Ln LH Ln Ln Ln Ln LH Ln e w KH n GH L KH GH Ln L KH GH GH n une Ww Ln LH LH Ln Ln Ln LH Ln Ln Ln Ln Ln Ln e w KH KH GH L KH GH LH L KH LH GH M we Ww Ln LH LH Ln Ln Ln LH Ln Ln Ln Ln Ln une w KH n GH L KH GH Ln L KH GH GH n we Ww Ln LH LH Ln Ln Ln LH Ln Ln Ln Ln Ln Ln e Ww Ln LH LH Ln Ln Ln LH Ln Ln Ln Ln LH Ln e Ww Ln LH LH Ln Ln Ln LH Ln Ln Ln Ln LH Ln LA Ww Ln LH LH Ln Ln Ln LH Ln Ln Ln Ln Ln une Ga B NY NY NY NY NY B NH NY NH B NH NH KF 3 3 3 3 LAYER 2 00000 0 lt 0 0 0 0 00000 011111 T ES ao E a S 0 0 0 E G E a Se gt IE T E SS a gt SO SS E G Ea gt ET ET E E SS co Sa Sl T ee SS T E G E E EE IE G E G E G G E E G E EE E E E L E T E T E L T E G Os E E EA eS E FS Os G G C E Gila SE gt EE T E IE E SL L E L G gt E G E E E SU SS A gt G IE G E E E G E ET E E I L E G IE Se Se SS E G IE E EE IE G E G E G E E E Gal Se gt EE T E IE Ce Sa So T E L E G E E E IE SS A gt G IE G E E E G H ET ET E I D E E IE T ET G E E gt IE ET EE IE G E G E E E E E Se gt EE T E IE Sa So T E E G o E G E E E IE G E G E G EE E E 9 ET P G E T E Ce Sa SS Sa E G o E G E E A E 0 0 1 I 4 4 4 4 4 4 4 4 4 4 4 4 4 3 10 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 10 LAYER
16. ND where FN_ModelConfiguration is the name of the model configuration file It is automatically created after MT3D is run if the SAVUCN option is set For more information on this file refer to the documentation for PM FN_Computed is the name of the unformatted head drawdown file saved by MODFLOW or unformatted concentration file saved by MT3D Chapter 7 Post Processing Programs 7 2 FN_Observed is the name of a text file containing information on the observation points see Section 7 2 2 FN_Output is the name of the output file containing HCCOMP calculation results see Section 7 2 3 XMIN_ Grid is the x coordinate of the lower left corner of the model mesh in the global coordinate system see Figure 7 1 YMIN_Grid is the y coordinate of the lower left corner of the model mesh in the global coordinate system see Figure 7 1 ROTATE_Grid is the angle of the model mesh rotated counterclockwise in degrees from the x axis of the global coordinate system see Figure 7 1 Jstart_Include is the starting column J number of a window within which data points are to be included for use during model calibration see Figure 7 2 By default Jstart_Include 0 is equivalent to Jstart_Include 1 Jend_Include is the ending column J number of the data point inclusion window see Figure 7 2 By default Jend_Include 0 is equivalent to Jend_Include NCOL NCOL is the total number of columns Istart_Include is the starting row I nu
17. REPANCY are sums of all inflows all outflows and actual discrepancy between them not percentage For transport mass budgets only total dissolved and or sorbed immobile masses in each budget zone are computed and printed Note that if an inconsistent unit such as ppm has been used for concentration the mass calculated by MT3D and hence FABUDGET based on the inconsistent concentration unit must be converted if the absolute mass magnitude is important The mass is calculated in MT3D as product of volumetric flow rate times concentration multiplied by time stepsize Chapter 7 Post Processing Programs 7 13 References Alexander M 1994 Biodegradation and Bioremediation Academic Press San Diego Calif pp 302 Borden R C and P B Bedient 1984 Transport of dissolved hydrocarbons influenced by oxygen limited biodegradation 1 theoretical development Water Resour Res 13 1973 1982 Clement T P 1997 RT3D A Modular Computer Code for Simulating Reactive Multispecies Transport in 3 Dimensional Groundwater Aquifers PNNL SA 28967 Pacific Northwest National Laboratory Richland Washington Lunn M R J Lunn and R Mackay 1996 Determining analytical solution multiple species contaminant transport with sorption and decay Journal of Hydrology 195 210 Monod J Annu Rev Microbiol vol 3 p 371 394 Widdowson M A and D W Waddill 1997 SEAM3D A Numerical Model for Three Dimensional Solute Transport and Se
18. al Multispecies Contaminant Transport Documentation and User s Guide Technical Publication U S Army Corps of Engineers Waterways Experiment Station Vicksburg Mississippi References 8 2
19. ange in the substrate concentration can be written as follows Rifai et al 1997 oC C LIC MM ot C M nas K C S 4 5 where M is the total microbial concentration ML The total microbial concentration is difficult to estimate and dependent on availability of many chemical and biological factors In MT3D M u a and K are implemented as input parameters and are assumed to be constant over time In addition the Monod kinetics is implemented only for the dissolved phase of an organic compound Both explicit and implicit formulations are used for numerical solution 4 2 INSTANTANEOUS AEROBIC AND ANAEROBIC BIODEGRADATION Following the approach of Borden and Bedient 1986 and Rifai et al 1989 and 1997 an instantaneous reaction model is implemented in MT3D to simulate the biodegradation of common hydrocarbon contaminants including benzene touluene ethylbenzene and xylene BTEX The general expression for this type of instantaneous reactions can be written as cl I Cc C O F CU NE CTE CU Le CUI CUF CUL CUI CV E 4 6 E 1 C t C t F where C is the concentration of the base species 1 which reacts sequentially with one or more species represented by concentrations C through C and F is the stoichiometric Chapter 4 Enhanced Reaction Package 4 2 ratio for the reaction between species 1 and k i e one mass unit of the base species reacts with F
20. cient Lanczos ORTHOMIN acceleration scheme and enables the user to solve a wide array of problems using much less computer time TVD Solution Scheme MT3D combines three major classes of transport solution techniques in a single code namely the standard finite difference method the particle tracking based Eulerian Lagrangian methods and the third order finite volume TVD total variation diminishing method The new TVD method for solving the advection term is mass conservative and minimizes numerical dispersion and artificial oscillation Dual Porosity Option The optional dual porosity dual domain advection diffusion mass transfer model provides a more effective approach than the standard single porosity advection dispersion model for simulating solute transport in fractured media or extremely heterogeneous porous media Nonequilibrium Sorption and Monod Kinetics The nonequilibrium sorption model enables the user to examine the role of sorption in solute transport and remediation processes without the restrictive local equilibrium assumption In addition to the first order kinetics MT3D supports zero order and mixed order Monod kinetic reactions Chapter 1 Introduction 1 1 Multispecies Reactions MT3D includes an enhanced reaction package to handle BIOPLUME type aerobic and anaerobic reactions between hydrocarbon contaminants and any user specified electron acceptors and parent daughter chain reactions for inorganic or
21. d oxygen assuming instantaneous reaction The hydrocarbon is assumed to be continuously injected from a point source into the aquifer with a background oxygen concentration of 9 ppm Chapter 6 New Benchmark Problems 6 4 6 3 FIRST ORDER PARENT DAUGHTER CHAIN REACTIONS The example problem considered in this section involves one dimensional transport of three species in a uniform flow field undergoing first order sequential transformation The equations for the reactive transport problem are as follows aC gC C R D XC J w OR 2 2772 2 v MC Y AC 6 1 3 2m3 3 n p y SNC FIAC where superscripts 1 2 and 3 indicate species 1 2 and 3 respectively The model parameters used in this example are identical to those used in Clement 1997 and are listed below Cell width along rows Ax 0 5 cm Cell width along columns Ay l cm Layer thickness Az 1 cm Longitudinal dispersivity a a 1 8 cm Groundwater seepage velocity v 0 1 cm hr First order reaction rate for species 1 a 0 05 hr First order reaction rate for species 2 2 0 03 hr First order reaction rate for species 3 3 0 02 hr Retardation factor for species 1 R 2 Stoichiometric ratio for reaction between species 1 and 2 Y 1 2 1 Stoichiometric ratio for reaction between species 2 and 3 U 2 3 1 Simulation time t 200 hours In the flow model the first and last columns are constant head boun
22. daries Arbitrary head values are used to establish the required uniform velocity In the transport model the first column is a constant concentration boundary for all species with the concentration values equal to 1 0 mg L for species 1 and zero for species 2 and 3 The last column is sufficiently far away from the source to approximate a semi infinite one dimensional flow domain The initial concentrations for all species are assumed to be zero Chapter 6 New Benchmark Problems 6 5 Figure 6 3 shows the calculated concentration distributions for all three species at the end of the 200 hour simulation period The calculated values agree closely with the analytical solutions of Lunn et al 1996 It can be seen that as species 1 is transported from the source its mass lost to decay becomes the source for species 2 some of which is in turn transformed into species 3 The fully implicit finite difference scheme is used for the solution with a transport stepsize multiplier of 1 1 Numerical Species 1 m Numerical Species 2 A Numerical Species 3 Analytical Solutions C Co 0 5 10 15 20 25 30 35 40 Distance cm Figure 6 3 Comparison of calculated concentrations of three species in a uniform flow field undergoing first order sequential transformation with the analytical solutions of Lunn et al 1996 Chapter 6 New Benchmark Problems 6 6 7 Post Processing Programs This chapte
23. e indicates the new features implemented in MT3D while the underlined are the new features first introduced in MT3DMS AS Al5 Record Format Record Format TRNOP 10 ADV DSP SSM RCT GCG XXX XXX XXX XXX RES 10L2 TRNOP are logical flags for major transport and solution options TRNOP 1 to 5 corresponds to Advection Dispersion Sink amp Source Mixing Chemical Reaction and Generalized Conjugate Gradient Solver packages respectively TRNOP 10 is the flag for the restart option If any of these options is used enter its corresponding TRNOP element as T otherwise as F TRNOP 6 to 9 are reserved for add on packages IFMTCN IFMTNP IFMTRF IFMTDP SAVUCN SAVCCM 4110 2L10 SAVCCM is a logical flag indicating whether the cell by cell mass for both dissolved and sorbed immobile phases should be saved in a default unformatted binary file named MT3Dnnn CCM where nnn is the species index number SAVCCMST the cell by cell mass of each species will be saved in the default file MT3Dnnn CCM SAVCCME F the cell by cell mass is not saved Chapter 5 Input Instructions 5 1 5 2 REACTION PACKAGE This section describes input instructions for the enhanced chemical reaction package implemented in MT3D Note that the enhanced reaction package is backward compatible with the original chemical reaction package as implemented in MT3D and MT3DMS Thus the reaction input file prepared for MT3D
24. e of SP1 depends on the type of sorption selected i e the value of ISOTHM Chapter 5 Input Instructions 5 3 For linear ISOTHM 1 and nonequilibrium sorption TSOTHM 4 SP1 is the distribution coefficient K4 unit LM For Freundlich sorption ISOTHM 2 SP1 is the Freundlich sorption equilibrium constant K unit depends on the Freundlich exponent a For Langmuir sorption SOTHM 3 SP1 is the Langmuir sorption equilibrium constant K unit LM For dual domain mass transfer ISOTHM 5 SP1 is not used but still must be specified Enter E4 for each species if ISOTHM gt 0 E4 Array Reader SP2 NCOL NROW one array for each layer RARRAY SP2 is the second sorption parameter The use of SP2 depends on the type of sorption selected i e the value of ISOTHM For linear sorption ISOTHM 1 SP2 is not used but still must be specified For Freundlich sorption ISOTHM 2 SP2 is the Freundlich exponent a For Langmuir sorption SOTHM 3 SP2 is the total concentration of the sorption sites available S unit MM For nonequilibrium sorption or dual domain mass transfer ISOTHM 4 or 5 SP2 is the first order kinetic mass transfer coefficient unit TTL Enter E5 for each species if IREACT gt 0 E5 Array Reader RCI NCOL NROW one array for each layer RARRAY RCI is the first kinetic reaction parameter The use of RC depends on the type of kinetic reaction selected
25. iduals M defined as 1 N M y cal obs N i where N is total number of active observation points 2 The standard derivation of residuals SDEV defined as 1 2 v In the above equation N 1 instead of N is used in the denominator based on the SDEV ae er obs a N 14 N I unbiased method of estimating the standard derivation of a sample out of the entire population 3 The mean of absolute residuals MA defined as 1 N M obs N La obs 4 The root mean squared residuals RMS defined as RMS R obs n N i 1 i RMS is similar to the standard derivation SDEV when the mean of residuals M is near zero and the sample size N is large In addition the correlation coefficient and the probability of un correlation between observed and calculated values are also computed and printed These statistical parameters can serve as indicators of the goodness of fit between the observed data and calculated values 7 2 4 Post data file In addition to the standard output file HCCOMP also prints out a separate data file for each model layer for the convenience of posting data points on contour plots These post Chapter 7 Post Processing Programs 7 8 data files have the default file names RESIDLxx DAT where xx is the layer index In each post data file there are ten columns arranged in the following order KPER TOTIM X Y XM YM OBS CAL RESIDUAL WELLID where
26. is used for implicit solution of the Monod kinetics or the first order chain reactions the maximum number of the outer iterations MXITER in the input file to the GCG package should be set to greater than one This is because these reactions involve nonlinear terms that need to be updated during iterations Chapter 5 Input Instructions 5 5 6 New Benchmark Problems 6 1 MONOD KINETICS The example problem considered in this section is similar to that described in Section 7 1 of the MT3DMS manual It involves one dimensional transport from a constant source in a uniform flow field The model grid consists of 101 columns 1 row and 1 layer and the model parameters used in the simulation are listed below Cell width along rows Ax 10m Cell width along columns Ay 1m Layer thickness Az 1m Longitudinal dispersivity a a 10m Groundwater seepage velocity v 0 24 m day Porosity 0 0 25 Simulation time t 2000 days In the flow model the first and last columns are constant head boundaries Arbitrary head values are used to establish the required uniform hydraulic gradient In the transport model the first column is a constant concentration boundary with a concentration value of 1 0 mg L The last column is sufficiently far away from the source to approximate a semi infinite one dimensional flow domain Three simulations are run using different parameters for the Monod kinetics as follows Case 1 M Mna 2 mg
27. ith a flow transport link file saved by Version 2 or later of the LinkMT3D package 7 3 2 Unformatted cell by cell mass file The unformatted cell by cell mass file is saved after MT3D is run if the SAVCCM option is set The cell by cell mass is saved at the user specified times and also at the end of each flow model time step If sorption or dual domain mass transfer is simulated both Chapter 7 Post Processing Programs 7 9 dissolved and sorbed immobile masses are saved Otherwise only dissolved mass is solved For more information on the content and structure of this file refer to Chapter 3 7 3 3 Budget zone definition file The budget zone definition file contains the location of the budget zones specified by the user It consists of a three dimensional integer array IBZ with one value for each model cell No negative zone numbers are acceptable Use zero for background where no zone is defined Number the zones starting from 1 and increase consecutively A zone can be as small as a cell and as large as an entire model The three dimensional IBZ array is input as a series of two dimensional arrays each of which represents a model layer staring from Layers 1 to NLAY total number of layers For each model layer the user must first specify an integer input code IPCODE of either 101 or 103 followed by zone numbers for the layer How zone numbers are input depends on the value of IPCODE If IPCODE 101 the zone number
28. mber of the data point inclusion window see Figure 7 2 By default Istart_Include 0 is equivalent to Istart_Include 1 lend Include is the ending row I number of the data point inclusion window see Figure 7 2 By default lend_Include 0 is equivalent to Iend_Include NROW NROW is the total number of rows Interpolation is a logical flag indicating whether interpolation is used to obtain the model calculated value at the observation point if it does not coincide with a nodal point If the flag is set to F the value at the observation point is set equal to the nodal value of the cell where the observation point is located If it is set to T bilinear interpolation is used to obtain the value at the observation point from neighboring nodal points in the same layer No vertical interpolation is done A default HCCOMP INI file is included in the directory where the HCCOMP program is located Copy this file to your working directory and make changes to the default file names and options as necessary for your particular simulation Chapter 7 Post Processing Programs 7 3 a XMIN_Grid 0 YMIN_Grid 0 ROTATE_Grid 0 y A Observation Point x y Sy td aE TET lt 70T HT Arad X b XMIN_Grid a YMIN_Grid b ROTATE_Grid o Figure 7 1 Definition of the global x y and local coordinate xm ym systems Chapter 7 Post Processing Programs 7 4 y Columns SMON LAJA a All observation data points
29. modeled by setting the initial concentration of species 2 to 9 ppm in all model cells and by assigning 9 ppm to the species 2 concentration of the inflow from the constant head boundary Hydrocarbon and oxygen are assumed to react instantaneously the stoichiometric ratio for the reaction is approximately 3 0 The calculated concentrations for hydrocarbon and oxygen at the end of the two year simulation period are shown in Figure 6 2 The maximum concentration of hydrocarbon is approximately 50 ppm at the injection point Figure 6 2a The oxygen plume is depleted Chapter 6 New Benchmark Problems 6 3 where the concentration of hydrocarbon is above zero Figure 6 2b For this example the TVD scheme is chosen for solving the advection term while all other terms are solved by the explicit finite difference option The mass balance discrepancies for both species are less than 107 The calculated hydrocarbon and oxygen plumes are nearly identical to those calculated using BIOPLUME II Rifai et al 1987 and RT3D Clement 1997 It should be pointed out although only two species are demonstrated in this example MT3D can handle as many species as needed a Hydrocarbon 20 fo wdd uo nenuasuos Q 200 200 A w 4 k 150 Axig 100 b Oxygen 20 wdd uonesus9u05 Q 200 200 0 50 K y Axis 00 v m 50 Figure 6 2 Calculated distributions of hydrocarbon an
30. on These data are entered using free format As a result WELLID a character variable should be entered with single quotation as in OW EPA3 To separate input variables within each input record use either blank space or comma An example of the observation data file is as follows 13 1 1 0 Well 170 543478 9 5044505 0 5 33 1 Well 170 543478 9 5044505 0 7 18 5 Well 391 542304 1 5043993 0 4 0 Well 391 542304 1 5043993 0 7 3 2 Well 140 541261 6 5044101 0 5 0 Chapter 7 Post Processing Programs 7 6 Well 140 541261 6 5044101 0 7 2 0 Well 903 542237 7 5043639 0 4 0 Well 903 542237 7 5043639 0 7 3 0 Well 907 542868 1 5043631 0 5 0 Well 907 542868 1 5043631 0 7 3 8 Well 135 541528 6 5044917 0 7 2 0 Well 132 542315 6 5044703 0 7 8 2 Well 165 543315 1 5044225 0 7 5 8 For flow simulation the observed heads or drawdowns are compared with the calculated values at a specific stress period KPER and time step KSTP both set to one for steady state simulation because with MODFLOW the user can only save the heads or drawdowns at the end of time steps within each stress period The discretization of time steps is controlled internally in MODFLOW based on the number of time steps and the time step multiplier specified by the user With MT3D the user can specify the exact times at which the concentrations should be saved thus the observed concentrations can be compared with the calcula
31. organic compounds This enables MT3D to analyze natural attenuation and bioremediation without using a third party add on reaction package The multispecies reactions are fully integrated with the MT3D transport solution schemes including the implicit solver Automatic Restart Option MT3D supports a new automatic restart option to greatly facilitate the continuation run from a previous simulation Complete Mass Budgets MT3D computes and saves cell by cell mass budgets This enables the user to compile a detailed mass budget for any subregion of the model grid Postprocessing Programs MT3D includes several useful and flexible postprocessing programs PostMT3DIMODFLOW for creating 2D or 3D data files for any graphic and visualization software package including Surfer and Tecplot HCComp for computing residuals and summary statistics between observed and model calculated heads and concentrations and FlowIMassBUDGET for calculating detailed groundwater flow and solute mass budgets in any user specified subregion of the model grid Note that this manual is only intended to serve as a supplement to the MT3DMS Documentation and User s Guide Zheng and Wang 1998 to provide information specific to the new features implemented in MT3D For details on the theoretical numerical and application aspects of MT3DMS refer to Zheng and Wang 1998 which is included as an attachment of this report Chapter 1 Introd
32. quential Electron Acceptor Based Bioremediation in Groundwater Draft Report to the Army Corps of Engineers Waterways Experiment Station Vicksburg Mississippi Rifai H S P B Bedient R C Borden and F J Haasbeek 1987 BIOPLUME II Computer Model of Two Dimensional Contaminant Transport under the Influence of Oxygen Limited Biodegradation in Ground Water Version 1 User s Manual Rice University Texas Rifai H S C J Newell J R Gonzales S Dendrou L Kennedy and J Wilson 1997 BIOPLUME III Natural Attenuation Decision Support System Version 1 User s Manual Air Force Center for Environmental Excellence Brooks AFB San Antonio Texas Wiedemeier T H M A Swanson D E Moutoux E K Gordon J T Wilson B H Wilson D H Kampbell J Hansen and P Haas 1997 Technical Protocol for Evaluating References 8 1 Natural Attenuation of Chlorinated Solvents in Groundwater Air Force Center for Environmental Excellence Brooks AFB San Antonio Texas Zheng C 1990 MT3D A Modular Three Dimensional Transport Model for Simulation of Advection Dispersion and Chemical Reactions of Contaminants in Groundwater Systems Report to the U S Environmental Protection Agency Robert S Kerr Environmental Research Laboratory Ada Oklahoma Zheng C 1996 MT3D User s Guide and Input Instructions S S Papadopulos amp Associates Inc Bethesda Maryland Zheng C and P P Wang 1998 MT3DMS A Modular Three Dimension
33. r contains user s guides for several post processing programs intended for use in conjunction with MODFLOW and MT3D including PosIMT3DIMODFLOW HeadlConcentrationCOMPARE and FlowIMassBUDGET 7 1 PostMT3D MODFLOW PM PM can be used to extract the calculated concentrations from the unformatted concentration files saved by MT3D and other versions of MT3D within a user specified window along a model layer or cross section 2D or within a user specified volume 3D at any desired time interval The concentrations within the specified window or volume are saved in such formats that they can be used by any commercially available graphical package such as Golden Software s Surfer and Amtec Engineering s Tecplot to generate 2D 3D contour maps and other types of graphics Note that that PM works equally well with the unformatted head drawdown file saved by MODFLOW For instructions on how to use PM refer to Appendix D of the MT3DMS Documentation and User s Guide 7 2 Head ConcentrationCOMPARE HCCOMP HCCOMP calculates the differences or residuals and associated summary statistics between observed and calculated heads drawdowns from MODFLOW or calculated concentrations from MT3D at observation points for use during model calibration The operation and input output structures of HCCOMP are documented in this section HCCOMP operates on the unformatted head drawdown file generated by MODFLOW or the unformatted concentration file generated b
34. ration file MT3Dnnn UCN Chapter 3 Enhanced Basic Package 3 3 4 Enhanced Reaction Package 4 1 MONOD KINETICS In MT3DMS only first order kinetics is included for modeling radioactive decay or biodegradation Showing only the dissolved phase the first order kinetics is expressed as eae LC l C 4 1 ot where L C represents the operator for all non reaction terms including advection dispersion fluid sinks sources and A is the first order rate coefficient TT A more general approach for modeling biodegradation is Monod kinetics Monod 1949 C 4 2 K C Sa u u where u is the specific growth rate of the bacterium TT u a is the maximum specific growth rate TT C represents the substrate concentration ML and K is a constant that represents the substrate concentration at which the rate of growth is half the maximum rate ML Alexander 1994 The Monod kinetics approaches a first order or zero order reaction depending on the value of the half saturation constant K relative to the concentrations in the aquifer If K gt gt C equation 4 2 can be simplified as u u 4 3 Chapter 4 Enhanced Reaction Package 4 which is equivalent to the first order kinetics with the first order rate coefficient of u K If K lt lt C equation 4 2 becomes a zero order kinetics 1 e H lt l 4 4 Relating the Monod growth function to the decrease of an organic compound the ch
35. s are read using the block format which consists of a record specifying the number of blocks NBLOCK followed by NBLOCK records of input values specifying the first row 11 the last row I2 the first column J1 the last column J2 of each block as well as the zone number IBZ value to be assigned to the cells within the block as shown below and also in Figure 7 3 If two or more blocks overlap one another the subsequent blocks overwrite the proceeding ones If IPCODE 103 the zone numbers are read using the free format Values are separated either by a space or by a comma as shown below and also in Figure 7 3 The input must start at Row 1 sweeping from the first column on the left to the last column on the right After Row 1 is completed proceed to Row 2 and so on until the final row is reached One row of input values can occupy as many lines as necessary Also note that the free format input permits the use of a repeat count in the form n d where nis an unsigned nonzero integer constant and the input n d causes n consecutive values of d to be entered Chapter 7 Post Processing Programs 7 10 Example of the budget zone definition file 0 LAYER Lra w A H Ln L KH GH L 0 A LH L M K aA Ww Q LH An Ln M KH GH H M KH LH H M une Ww Ln LH LH Ln Ln Ln LH Ln Ln Ln Ln LH Ln e Ww Ln LH LH LH Ln Ln LH Ln Ln Ln Ln LH Ln LA Ww Ln LH LH Ln Ln Ln LH Ln Ln Ln Ln LH Ln e LJ Ln LH LH Ln Ln Ln LH Ln Ln Ln Ln Ln Ln e Q H
36. s entered in the input file to the Basic Transport Package Chapter 3 Enhanced Basic Package 3 2 3 2 CELL BY CELL MASS The cell by cell mass output option first introduced in MT3D is maintained in MT3D A utility program FMBudget has been added and included with MT3D to post process this file see Chapter 7 The content and structure of the unformatted cell by cell mass file one for each species are shown below MT3Dnnn CCM unformatted For each transport step saved Record 1 KPER TIME2 TEXT1 NCOL NROW NLAY Record 2 DMASS J I K J 1 NCOL 1 NROW K 1 NLAY If sorption or dual domain mass transfer is simulated Record 1 KPER TIME2 TEXT2 NCOL NROW NLAY Record 2 SMASS J I K J 1 NCOL I 1 NROW K 1 NLAY where KPER TIME2 TEXTI TEXT2 NCOL NROW NLAY DMASS SMASS is the stress period at which the mass is saved is the total elapsed time at which the mass is saved is a character string character 16 set equal to SOLUTE MASS is a character string character 16 set equal to SORBED MASS is the total number of columns is the total number of rows is the total number of layers is the calculated solute mass in each cell unit M is the calculated sorbed immobile mass in each cell unit M The CCM file is saved by setting the SAVCCM option to T True in the BTN input file The frequency of output to this file is the same as that to the unformatted concent
37. se 10 57 10 75 10 89 10 89 10 78 10 82 Iron 21 48 21 85 22 13 22 13 21 90 22 20 Sulfate 4 62 470 476 4 76 4 71 4 73 Carbon Dioxide 2 12 2 15 2 18 2 18 2 17 2 17 Note Average arithmetic average Average mass weighted average Chapter 4 Enhanced Reaction Package 4 4 4 3 FIRST ORDER PARENT DAUGHTER CHAIN REACTIONS MT3D incorporates a first order parent daughter chain reactions as follows showing only the dissolved phase 1 L C NC dC 2 272 Al sre XC FY NC 4 11 k L C A C Y an A CT where L C represents the operator for the non reaction terms including advection dispersion fluid sinks sources XM is the first order reaction coefficient for species k and Y _ the yield coefficient between species k 1 and k which can be computed from the stoichiometric relationship between the two species The first order sequential kinetic reaction model as defined in equation 4 11 can be used to model radioactive chain reaction and biodegradation of chlorinated solvents For example the transformation of perchloroethene PCE trichloroethene TCE gt dichloroethene DCE vinyl chloride VC may be expressed as ac Lc et JEEE C PCE ot ac gt L C TEES an VICE TCE ne Yoona EC 6 PCE aC DCE 4 12 5 Ler PEC DCE 4 Yoa k eG t ace F HC ECYC AES a O where C is the concentration for PCE 4 is the first order reaction coefficient for PCE
38. spectively Fy is the stoichiometric ratio for the reaction between hydrocarbon and oxygen F is approximately equal to 3 1 i e one gram of hydrocarbon reacts with 3 1 grams of oxygen see Table 4 1 For a six species system involving hydrocarbon oxygen nitrate ferric iron sulfate and carbon dioxide as considered in the Bioplume III code Rifai et al 1997 the general formulation of 4 6 can be replaced by H t 1 H t Ou E NOY Fay Felt Fur SO Fas CO Fac O t 1 O t HG Fo N t 1 N t A t Fay Fe t 1 Fe t H t Fyre S S HQ F CU 1 C t H t F yc 4 10 where N Fe S and C are concentrations of nitrate ferric iron sulfate and carbon dioxide respectively and F Fyre F ys and F are stoichiometric ratios for reactions between hydrocarbon and electron acceptors i e nitrate ferric iron sulfate and carbon dioxide respectively see Table 4 1 While it is conceptually simple and computationally straightforward the instantaneous reaction model represents a great simplification of complex biologically mediated reactions occurring in natural systems Therefore this type of modeling approach should be considered as a screening level approximation Table 4 1 Stoichiometric ratios for reactions between BTEX and common electron acceptors after Rifai et al 1997 B T E X Average Average Oxygen 3 08 3 13 3 17 3 17 3 14 3 15 Nitrate 4 77 4 85 4 91 4 91 4 86 4 88 Mangane
39. sssesseosas 5 2 5 3 A Note on the GCG Solver Package essessesoossesessossesoossesoossesessossesoossesoessesessossessossesoessesessosses 5 5 New Benchmark Problems 6 1 Monod Kimetics sccccsscsscsesscssensssssesscessssssssessnsssssscscessssssscessessescsssnssssssessessessessosssessssneseeses 6 1 6 2 Instantaneous Aerobic Biodegradation ssesessossesoossesessoesessossesoesoesessoesessossesoesoesessossessossessesse 6 2 6 3 First order Parent Daughter Chain Reactions scsccsssscsssssssssssscsssssssssssssesssssscessssssseeee 6 4 Post Processing Programs 7 1 PostMT3DIMODFLOW PMD 7 1 7 2 Head ConcentrationCOMPARE HCCOMD sccssssscssssssscessssccessssccscssscscesssccccssseccscssseecess 7 1 7 3 FlowIMassBUDGET FMBUDGET uussssssssssssssssssssssssessesssssssssssssssssesssssssssssssssscesssscussussssesscesenses 7 9 References Attachment MT3DMS Documentation and User s Guide 1 Introduction MT3D is a new version of the modular three dimensional contaminant transport model MT3D distributed by S S Papadopulos amp Associates Inc since 1996 MT3D builds on the strengths of the new public domain MT3DMS code Zheng and Wang 1998 and includes significant new enhancements to expand the functionality of the MT3D and MT3DMS codes The key features of MT3D include Implicit Solver The iterative solver is based on generalized conjugate gradient methods with the highly effi
40. ted values at exactly the same time 7 2 3 Standard output file HCCOMP creates a standard output file which lists all information for each observation point in the following order WELLID X Y XM YM COL ROW LAYER OBS CAL RESIDUAL where XM and YM are the transformed x and y coordinates of the observation point in the local model coordinate system whose origin is at the lower left corner of the model mesh and whose x and y axes are along a model row and column see Figure 7 1 If XMIN_Grid YMIN_Grid and ROTATE_Grid are input as zeroes XM and YM are equal to X and Y input by the user COL and ROW are column J and row J indices of the model cell where the observation point is located as determined by the HCCOMP program It is imperative that the user check these COL and ROW indices to ensure the correct transformation is performed from X Y to J D CAL is the model calculated value at the observation point If no interpolation is used CAL is set equal to the nodal value at cell J I LAYER Otherwise CAL is interpolated from four neighboring nodal points and Chapter 7 Post Processing Programs 7 7 RESIDUAL is the difference between calculated and observed values Positive RESIDUAL indicates over prediction whereas negative RESIDUAL indicates under prediction A number of statistical parameters for the residuals are calculated and printed following the well list These parameters include 1 The mean of res
41. uction 1 2 2 System Requirements and Installation 2 1 EXECUTABLE PROGRAMS AND SYSTEM REQUIREMENTS The executable programs were compiled with the Lahey LF90 FORTRAN 90 compiler Version 4 0 to run on PCs with a 80486 or higher CPU in 32 bit protected mode using extended memory The compiled programs use the dynamic array allocation feature of FORTRAN 90 and will allocate the exact amount of memory that is required for a particular problem at run time If the memory required by the problem exceeds the total amount of physical memory that is available a message NOT ENOUGH MEMORY will be printed and the execution aborted The executable programs run under Microsoft DOS or Windows v3 x 95 NT in the DOS compatibility box 2 2 INSTALLATION AND SETUP To install for the first time create a subdirectory on the hard drive with a name such as MT3D99 and then copy all the files in the Bin subdirectory of the distribution CD ROM to the new subdirectory Make sure to modify the AUTOEXEC BAT file to place the MT3D99 subdirectory on the PATH statement File LF90 EER contains the Lahey compiler s run time error messages When a run time error occurs the executable program will first search the current working directory and then all directories specified in the PATH statement to locate file LF90 EER before it can print out the error message For more information refer to the README DOC files included with the distribution CD ROM Chapter
42. y MT3D Therefore before using HCCOMP MODFLOW or MT3D must have been run and an unformatted head Chapter 7 Post Processing Programs 7 1 drawdown or concentration file saved The unformatted file may contain records for only one or multiple time periods To save the unformatted head or drawdown file in MODFLOW specify the desired time steps and stress periods through the Output Control options With MTS3D the user can specify the exact times at which the results should be saved through the input file to the BTN package Note that HCCOMP will work properly only if heads drawdowns or concentrations are saved for every model layer even though MODFLOW permits the user to save heads or drawdowns for selected model layers only 7 2 1 Input Output I O options file HCCOMP INI When HCCOMP is executed it first searches the current directory to find a file named HCCOMP INI which contains default input output options If HCCOMP INI is not found the program will prompt the user to enter the name of the I O options file The structure and content of the HCCOMP INI file are shown below the bold faced letters indicate the keywords that should not be modified amp HCCOMP_IO_OPTIONS FN_ModelConfiguration mt3d cnf FN_Computed mt3d001 ucn FN_Observed HCCOMP dat FN_Output HCCOMP out XMIN_Grid 0 YMIN_Grid 0 ROTATE_Grid 0 Jstart_Include 0 Jend_Include 0 Istart_Include 0 Iend_Include 0 Interpolation F amp E
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