地下水文学计算题.docx

'1.Aconfinedaquiferis18.5mthick.Thepotentiometricsurfaceelevationsattwoobservationwells822mapartare25.96and24.62m.Ifthehorizontalhydraulicconductivityoftheaquiferis25m/d,determinetheflowrateperunitwidthoftheaquifer,specificdischarge,andaveragelinearvelocityoftheflowassumingsteadyunidirectionalflow.2.Aunconfinedaquiferinastratumofcleansandandgravelhasahydraulicconductivityof0.01cm/sec.Fromtwoobservationwells200mapart,theobservedwatertableelevationsare11and7mmeasuredfromthebottomofthestratum.Determinethedischargeperunitwidthoftheaquifer. 3.Aunconfinedaquiferofcleansandandgravelislocatedbetweentwofullypenetratingrivers,andhasahydraulicconductivityofk=0.01cm/sec.Theaquiferissubjecttoauniformrechargeof1.6m/year.ThewatersurfaceelevationsinriversAandBare8.5mand10m,respectively,abovethebottom.Estimate(a)themaximumelevationofthewatertableandthelocationofgroundwaterdivide,(b)thetraveltimesfromgroundwaterdividetobothrivers(ne=0.35),and(c)thedailydischargeperkilometerfromtheaquiferintobothrivers.4.Twoobservationwellshavebeenconstructedintheunconfinedaquifershownbelowandthepiezometricheadsinthewellsare13mand10.5mrespectively.Iftheflowrateqis0.02m3/hr/unitwidth,determineK2? 5.Followingfiguredemonstratesastratifiedmaterialinanalluvium.Hydraulicconductivityandspecificyieldfortheupperlayerare5.5m/dand0.1,respectively.ThicknessofthelowerlayerMis33m,withahydraulicconductivityof10.8m/d.Riverstagesinthebothsidesoftheaquiferkeepsteady,andtheyare97.5mand89mforriversAandB,respectively.Thedistancebetweenthebothriversis1.2km.Theriverlengthis7km.Iftheprecipitationrechargeandgroundwaterevaporationlossareignored,wewouldliketoknow:（1）Thetotalwaterflowingfromtheleftrivertotherightriverin30days.（2）Waterstorageamountintheupperaquifer.（3）Fromatimet0,riverstagesvaryinmathematicalfunctionsgA(t),gB(t)forriversAandB,respectively.ExpresstheGoverningequation,BoundaryConditions,andInitialConditionsofthemathematicalmodel. 6.Awellthatpumpsataconstantrateof0.5m3/sfullypenetratesaconfinedaquiferof34mthickness.Afteralongperiodofpumping,nearsteadstatecondition,themeasureddrawdownsattwoobservationwells50and100mfromthepumpingwellare0.9and0.4m,respectively.(a)Calculatethehydraulicconductivityoftheaquifer,(b)estimatetheradiusofinfluenceofthepumpingwell,and(c)calculatetheexpecteddrawdowninthepumpingwelliftheradiusofthewellis0.4m.7.Apumpingwellof0.5mdiameterfullypenetratesaunconfinedaquiferproducesataconstantrateof80m3/hr,theinitialwatertableis33m.Afteralongperiodofpumping,nearsteadstatecondition,thedrawdowninaobservationwell18mfromthepumpingwellis1.8m.Thedrawdowninanotherobservationwell45mfromthepumpingwellis1.1m.(a)Calculatethehydraulicconductivityoftheaquifer,(b)theexpecteddrawdowninthepumpingwell,and(c)theradiusofinfluenceofthepumpingwell. 8.Awellinaconfinedaquiferwaspumpedatarateof680m3/d.Theaquiferwas18mthick.Time-drawdowncurveforanobservationwell118mawaywasgiveninthefigurebelow.FindT,K,andS.9.Awellpenetrationaconfinedaquiferispumpedatuniformrateof2500m3/d.Time(t)anddrawdown(s)foranobservationwell60mawayareplottedonsemi-logarithmicpaperasshowninthefigurebelow.Astraightlineisfittedthroughtheobservationpoints.Iftheconfinedaquiferthicknessis25m,findTransmissivityT,hydraulicconductivity(K)andstoragecoefficientμ*.'