1、Designation: D5610 94 (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 o
2、f 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 groundwaterflo
3、w. 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
4、 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 thisdocu
5、ment 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 ContainedF
6、luidsD5447 Guide for Application 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 a
7、bove 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 rep
8、resent 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
9、 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 vis
10、cosity 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 init
11、ial 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 distributio
12、n 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 b
13、ecomes 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
14、 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, vis
15、it 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
16、 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 States1head as a funct
17、ion 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 specified time fort
18、he following conditions of model simulation.6.1.1 Defining Steady-State Initial Conditions for aTransient-State Simulation of Head DistributionSelect fieldconditions that represent, at least approximately, an equilib-rium condition. The steady-state head distribution must besimulated by modeling hyd
19、rologic conditions, includingboundary conditions3that produced the observed distributionof heads. Exact representation of the field prototype flowsystem is not possible to achieve in practice, but an acceptablyclose representation may be used as the initial condition (seeGuide D5447).NOTE 1The use o
20、f model-generated head values for initial conditionsfor the transient-state simulation assures that the initial heads and themodel boundary conditions and hydrologic parameters are consistent. Ifthe field-measured head values were used as initial conditions, the modelresponse in the early time steps
21、 would reflect not only the model stressunder study but the adjustment of model head values to offset the lack ofcorrespondence between model boundary conditions, aquifer hydraulicproperties, and the initial head values.6.1.2 Defining a Transient-State Initial Condition for aTransient-State Simulati
22、on of Absolute HeadSimulatetransient-state absolute heads for field conditions by simulatingboundary conditions and hydraulic properties of the flowsystem. This period of absolute head simulation must besufficiently long that antecedent stresses, that is, stresses on thesystem predating the simulati
23、on period, are insignificant. Thesimulation period must be for a sufficiently long antecedentperiod that transient heads prior to the selected initial time areacceptably close to the field heads. The transient-state headdistribution is used as initial conditions for absolute transienthead distributi
24、on with the new stress imposed.6.1.3 Defining the Initial Head for Steady- or Transient-State Simulation of Head Change in Response to a StressApply the principle of superposition and define the initial headin the flow system as zero. Superposition modeling predictsonly the water-level changes relat
25、ed to a specific stress anddoes not predict absolute heads (heads referenced to a commondatum). If superposition is applicable to the problem, absoluteheads can be obtained by adding the head change obtained bysuperposition analysis to field heads. Superposition may beapplied only to systems that ex
26、hibit a linear response to stress.47. Report7.1 Completely document the definition of initial conditionsfor model simulation. Such documentation will be a part of theoverall documentation of the model. Include the followingitems pertaining to the formulation of initial conditions in themodel report:
27、7.1.1 Describe the natural physical processes operating onthe system, and7.1.2 Describe the simulation of the system processes up tothe initial time (t = 0) representation of each boundary. Evalu-ate the sensitivity analysis of the boundaries and state theconditions of stress over which the modeled
28、boundary condi-tions are appropriate.8. Keywords8.1 aquifers; boundary condition; groundwater model;transmissivityASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly adv
29、ised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either
30、 reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. I
31、f you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Indivi
32、dual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ T. E., Franke, O. L., and Bennett, G. D., The Principle of Superpositionand its Application in Ground-Water Hydraulics, U.S. Geological Survey, Open-fileReport 84-459, 1984.D5610 94 (2014)2
