transportinporousmedia,GW,30(1),P78-86.
SubsurfaceFreshwaterAbstractionandSaltwaterIntrusion
ProtectioninanIsland
GuominLi
InstituteofGeologyandGeophysics,ChinaAcademyofSciences
AbstractUndernaturalconditionsintheaquifersystemofanisland,astateofequilibriumis
maintained,withastationaryfreshwater-seawatertransitionzoneandalotofrainfallthatenters
theflowsystemremainsintheupperaquifers,moveslaterally,anddischargestothesurrounding
saltwaterbody.Thereexistsarelationshipbetweentherateoffreshwaterdischargetotheseaand
theextentofseawaterintrusion.Underthedisturbedconditions,thefreshwaterdischargestothe
seaisthedifferencebetweentherateofnaturalandartificialdischargeandthatofpumping.Two
phenomenacanleadtoadeteriorationofthefreshwaterresources:thelateraladvanceofthe
saltwaterfronttowardsthecostalwellsandtheupcomingofunderlyingsaltwateralloverthe
island.Itisclearthatthemaximumallowablerateoffreshwaterabstractionisafunctionofthe
sitting,screening,andpumpingratesofthewells.Analysisanddiscussesarecarriedoutwiththe
objectivesofunderstandingthemechanismofsaltwaterintrusionandlearningtocontrolitin
ordertoimprovetheyieldoftheaquifersysteminanisland.Anexampleisexaminedforthe
managementofthefreshwaterlensofWeizhouIsland,China.
Keywords:Island,freshwaterlens,groundwaterfluctuation,saltwaterintrusion,numerical
modeling
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