ASTM_D_5611_-_94_2016.pdf

Designation:D561194(Reapproved 2016)Standard Guide forConducting a Sensitivity Analysis for a Groundwater FlowModel Application1This standard is issued under the fixed designation D5611;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 that should be used toconduct a sensitivity analysis for a groundwater flow model.The sensitivity analysis results in quantitative relationshipsbetween model results and the input hydraulic properties orboundary conditions of the aquifers.1.2 After a groundwater flow model has been calibrated,asensitivity analysis may be performed.Examination of thesensitivity of calibration residuals and model conclusions tomodel inputs is a method for assessing the adequacy of themodel with respect to its intended function.1.3 After a model has been calibrated,a modeler may varythe value of some aspect of the conditions applying solely tothe prediction simulations in order to satisfy some designcriteria.For example,the number and locations of proposedpumping wells may be varied in order to minimize the requireddischarge.Insofar as these aspects are controllable,variation ofthese parameters is part of an optimization procedure,and,forthe purposes of this guide,would not be considered to be asensitivity analysis.On the other hand,estimates of futureconditions that are not controllable,such as the recharge duringa postulated drought of unknown duration and severity,wouldbe considered as candidates for a sensitivity analysis.1.4 This guide presents the simplest acceptable techniquesfor conducting a sensitivity analysis.Other techniques havebeen developed by researchers and could be used in lieu of thetechniques in this guide.1.5 This guide is written for performing sensitivity analysesfor groundwater flow models.However,these techniques couldbe applied to other types of groundwater related models,suchas analytical models,multi-phase flow models,non-continuum(karst or fracture flow)models,or mass transport models.1.6 This guide is one of a series on groundwater modelingcodes(software)and their applications,such as Guide D5447and Guide D5490.Other standards have been prepared onenvironmental modeling,such as Practice E978.1.7 The values stated in inch-pound units are to be regardedas standard.The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.8 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.9 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 for Application of a Groundwater Flow Modelto a Site-Specific ProblemD5490 Guide for Comparing Groundwater Flow ModelSimulations to Site-Specific InformationE978 Practice for Evaluating Mathematical Models for theEnvironmental Fate of Chemicals(Withdrawn 2002)31This guide is under the jurisdiction of ASTM Committee D18 on Soil andRockand is the direct responsibility of Subcommittee D18.21 on Groundwater andVadose Zone Investigations.Current edition approved Jan.1,2016.Published January 2016.Originallyapproved in 1994.Last previous edition approved in 2008 as D5611 94(2008).DOI:10.1520/D5611-94R16.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.Terminology3.1 Definitions:3.1.1 boundary conditiona mathematical expression of astate of the physical system that constrains the equations of themathematical model.3.1.2 calibrationthe process of refining the model repre-se