USGS

Finite-difference Model for Aquifer Simulation in Two Dimensions With Results of Numerical Experiments

U.S. Geological Survey, Techniques of Water-Resources Investigations, Book 7, Chapter C1

By P.C. Trescott, G. F. Pinder and S. P. Larson


Table of Contents

Abstract

Introduction

Theoretical development

Ground-water flow equation

Finite-difference approximations

Source term

Leakage

Evapotranspiration

Computation of head at the radius of a pumping well

Combined artesian-water-table simulation

Transmissivity

Storage

Leakage

Test problems

Numerical solution

Line successive overrelaxation

Two-dimensional correction to LSOR

LSOR acceleration parameter

Alternating-direction implicit procedure

Strongly implicit procedure

Comparison of numerical results

Considerations in designing an aquifer model

Boundary conditions

Initial conditions

Designing the finite-difference grid

Selected references

Attachment I, notation

Attachment II, computer program

Main program

Subroutine DATA1

Time parameters

Initialization

Subroutine STEP

Maximum head change for each iteration

Subroutine SOLVE

SIP iteration parameters

Exceeding permitted iterations

Subroutine COEF

Transient leakage coefficients

Transmissivity as a function of head

TR and TC coefficients

Subroutine CHECK1

Subroutine PRNTAI

BLOCK DATA routine

Technical information

Storage requirements

Computation time

Use of disk facilities for storage of array data and interim results

Graphical display package

Modification of program logic

Fortran IV

Limitations of program

Attachment III, data deck instructions

Attachment IV, sample aquifer simulation and job control language

Attachment V, generalized flow chart for aquifer simulation model

Attachment VI, definition of program variables

Attachment VII, program listing



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