ASTM_D_5610_-_94_2014.pdf

Designation:D561094(Reapproved 2014)Standard Guide forDefining Initial Conditions in Groundwater Flow Modeling1This standard is issued under the fixed designation D5610;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This guide covers techniques and procedures used indefining initial conditions for modeling saturated groundwaterflow.The specification of initial conditions is an essential partof conceptualizing and modeling groundwater systems.1.2 This guide offers an organized collection of informationor a series of options and does not recommend a specificcourse of action.This document cannot replace education orexperience and should be used in conjunction with professionaljudgment.Not all aspects of this guide may be applicable in allcircumstances.This ASTM standard is not intended to repre-sent or replace the standard of care by which the adequacy ofa given professional service must be judged,nor should thisdocument be applied without consideration of a projects manyunique aspects.The word“Standard”in the title of thisdocument means only that the document has been approvedthrough the ASTM consensus process.2.Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil,Rock,and ContainedFluidsD5447 Guide forApplication of a Groundwater Flow Modelto a Site-Specific ProblemD5609 Guide for Defining Boundary Conditions in Ground-water Flow Modeling3.Terminology3.1 Definitions:3.1.1 aquifer,confinedan aquifer bounded above and be-low by confining beds and in which the static head is above thetop of the aquifer.3.1.2 conceptual modelan interpretation or working de-scription of the characteristics of the physical system.3.1.3 fluxthe volume of fluid crossing a unit cross-sectional surface area per unit time.3.1.4 groundwater flow modelan application of a math-ematical model to represent a groundwater flow system.3.1.5 hydraulic conductivity(field aquifer tests),the vol-ume of water at the existing kinematic viscosity that will movein a unit time under unit hydraulic gradient through a unit areameasured at right angles to the direction of flow.3.1.6 hydrologic conditiona set of groundwater inflows oroutflows,boundary conditions,and hydraulic properties thatcauses potentiometric heads to adopt a distinct pattern.3.1.7 simulationone complete execution of the computerprogram,including input and output.3.1.8 transmissivitythe volume of water at the existingkinematic viscosity that will move in a unit time under a unithydraulic gradient through a unit width of the aquifer.3.1.9 unconfined aquiferan aquifer that has a water table.3.1.10 For definitions of other terms used in this testmethod,see Terminology D653.4.Significance and Use4.1 Accurate definition of initial hydrologic conditions is anessential part of conceptualizing and modeling transientgroundwater flow,because results of a simulation may beheavily dependent upon the initial conditions.5.Initial Conditions5.1 Initial hydrologic conditions for a flow system arerepresented by the head distribution throughout the flowsystem at some particular time corresponding to the antecedenthydrologic conditions in the aquifer system.3The specifiedheads can be considered reference heads;calculated changes inhead through time will be relative to these given heads,and thetime represented by these heads becomes the reference time.As a convenience,this reference time is usually specified aszero time or initial time.Time is reckoned from this zero timeor initial time.In more formal terms,an initial condition gives1This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcommittee D18.21 on Groundwater andVadose Zone Investigations.Current edition approved Aug.1,2014.Published January 2015.Originallyapproved in 1994.Last previous edition approved in 2008 as D5610 94(2008).DOI:10.1520/D5610-94R14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Franke,O.L.,Reilly,T.E.,and Bennett,G.D.,“Definition of Boundary andInitial Conditions in the Analysis of Ground-Water Flow SystemsAnIntroduction,”Techniques of Water-Resources Investigations of the United StatesGeological Survey,Book 3,Chapter B5,1987.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 head as a function of position at t=0;that is,h=f(x,y,z;t=0).This notation suggests that,conceptually,initial condi-tions may be regarded as a boundary condition in time.6.Procedure6.1 The following procedures and requirements are pro-posed for establishing initial conditions at a s