Aquifer Recharge, Storage, and Recovery - Southwest Hydrology ...

An ASR PrimerCortney C. Brand – R.W. Beck Inc.streambedvadosezone wellrecharge basinsvadose zonerecharge/recoverywellThat Which We Call ASR...…others may not. In preparing this issue,Southwest Hydrology polled numerousexperts for the best term to describethe process of recharging aquifers (by avariety of means using a variety of sourcewaters), storing water (for short to longperiods), and then recovering water (fromthe same or other wells). We receivedmany opinions and no clear consensus.The top candidates, none of which include“recharge,” “storage,” and “recovery,” are:Aquifer Storage and Recovery (ASR):To some, this means strictly rechargeand recovery from the same well. Othersbelieve it is the most widely recognizedterm—at least in the Southwest—to referbroadly to all forms of aquifer recharge,storage, and recovery.Managed Aquifer Recharge (MAR):Has the greatest international use; lesscommon in this country. The originaldefinition referred to intentional bankingand treatment of water in aquifers.Managed Underground Storage ofRecoverable Water (MUS): Introduced in2008 by NRC’s Committee on SustainableUnderground Storage of RecoverableWater to define “purposeful recharge ofwater into an aquifer system for intendedrecovery and use as an element of longtermwater resource management.”Southwest Hydrology is using the broaddefinition of ASR.Most water resourcesprofessionals have heardof ASR, or aquifer storageand recovery, but it can mean differentthings to different people. ASR can meanartificial recharge, groundwater recharge,managed aquifer recharge, undergroundwater storage, conjunctive use, or acombination thereof. For purposes ofthis and accompanying articles, ASRis a water management technique thatencompasses the purposeful rechargeand temporary storage of water in anaquifer with the intent to recover all ora portion of the water from the sameaquifer in the future. Without the intentto, or act of, recovering recharged waterit is simply groundwater recharge.ASR is thought to have originated severalhundred years ago in the Kara Kum Plainof Turkmenistan and in Western India(Pyne, 1995), but is now conducted insome form on every continent exceptAntarctica. The motivators and potentialbenefits of ASR vary based on geography,hydrology, water chemistry, and waterpolicies/laws. A majority of the Southwestis arid or semi-arid, susceptible todrought, and characterized by declininggroundwater levels, unreliable surfacewater supplies, and overappropriatedrivers. As a result, the capture and storageof water when it is available is criticalto sustainable water management. Thetraditional approach has been to store wateraboveground by constructing dams andreservoirs. The benefits of abovegroundstorage include rapid fill and release,large storage capacities, straightforwardmeasurement and management, andopportunities for recreation. However,escalating costs and environmentalpermitting requirements associated withsurface reservoirs, as well as decliningavailability of land and suitable sites, havedriven water professionals to explore ASRas an alternative.Implementing ASRWhere feasible, storing water undergroundcan save money, increase yields, mitigatethe impacts of drought, firm up surfacewater supplies, improve water quality,and avoid evaporative losses. Thenecessary ingredients are 1) an aquiferof suitable character, 2) source water ofsuitable quality, 3) the means to transmitthe source water into the aquifer, and4) the means to recover it. ASR can beaccomplished in bedrock, alluvial, orlimestone aquifers as long as the formation16 • May/June 2008 • Southwest Hydrology