Desalination of deep groundwater aquifers for freshwater supplies – Challenges and strategies

2018·2.7 MB·English

by  Veera Gnaneswar Gude

Groundwater for Sustainable Development 6 (2018) 87–92
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Desalination of deep groundwater aquifers for freshwater supplies – Challenges and strategies
T
ARTICLE INFO ABSTRACT
Keywords: Groundwaterdepletionisacommonprobleminmostofthecountriesacrosstheworld.Thisiscausedbyexcess
Groundwater populationgrowth,improvedlivingstandards,andclimatechangeissues.Manyregionsacrosstheworldare
Desalination accessingdeepgroundwatersourcesformanagingwatersupplydemands.Thisresearcharticlepresentsissues
Climatechange relatedtoaccessingdeepgroundwatersourcesinregionslikeCalifornia,USA.Potentialenvironmental,tech-
Strategiesandmanagement
nological and governance related groundwater management issues associated with desalination of deep
Governancewaterreuse
groundwaterreservesarediscussedbriefly.Aconcisediscussiononglobalwatersupplyissuesandpotential
strategiestoovercomethepresentbarriersarepresentedforbothdevelopedanddevelopingcountries.
1. Introduction
About98%ofglobalfreshwatersourcesarestoredundergroundwhichisusedbyapproximately2.5billionpeopleworldwidefortheirdaily
needs(Margat,2008,MargatandvanderGun,2013).Thegroundwaterwithdrawalratesareincreasingby1–3%annuallyacrosstheworlddueto
populationgrowthandhigherlivingstandards.Thisincreasedlevelofabstractioncoupledwithgroundwaterpollutionhascausedmanyissuesfor
groundwater-dependentecosystems.Climatechangeanditsvariability,ontheotherhand,affectsthegroundwaterrechargerates(Tayloretal.,
2013).Thissituationhastriggeredmanycommunitiestoaccessdeepgroundwatersources.Thesesourcesareoftensalineinnatureandmaycause
additionalenvironmentalconcerns.Therefore,itiscrucialtodevelopandimplementeffectivemanagementpracticestoprotectandproperlyutilize
this rather finite source. Management practices may include both technical and non-technical approaches. Understanding the importance of
groundwatergovernanceanditproperimplementationtoefficientmanagementpracticescouldenhancetheaccessibilityofgroundwaterresources
forlong-termsustainability.
Thepurposeofthisarticleistwo-fold.First,adiscussionoftheglobalgroundwaterdepletionproblemsispresented.Next,afewcasestudies
detailingissuesandormanagementpracticesrelatedtosustainablegroundwatergovernanceanditsimplementationindevelopedanddeveloping
countriesarepresented.
2. Globalgroundwaterdepletionproblem
Groundwater depletion is a local, regional and global problem and increasing withdrawal of groundwater for domestic water supplies and
agricultural uses has become a major challenge for many local water management agencies. Despite the critical importance of the groundwater
source for sustainable development, insufficient management attention is given to these sources in comparison with surface water sources
(Famiglietti, 2014). Groundwater sources are often poorly monitored and managed and sometimes they do not receive any attention in some
developingcountries.
Groundwaterresourcesarefiniteanddepletewithcontinuedwithdrawals(“overdraft”),aphenomenonoftentermedas“watermining”forour
increasingdemands.Forexample,inUSA,groundwaterwithdrawalratesmorethandoubledintheperiodfrom1965to1995tosupplydomestic
consumption,withsubstantiallylargergroundwaterabstractionoccurringtosupportindustrysuchasminingandirrigatedcrops(Glennon,2002;
Doodyetal.,2017).Recently,43%oftotalglobalirrigationwaterwasextractedfromgroundwatersources,withAmericaandAsiaextracting48%
and 45% respectively (Siebert et al., 2010). Furthermore, approximately 25% of the world's population depend on groundwater pumping for
drinkingwater,manyoftheseinsemi-aridandaridzones(Glennon,2002).Somerecenttrendsofgroundwateraquifersdepletionratesareshownin
Fig.1.Itisevidentthatsomelevelofgroundwaterdepletionispersistentacrosstheworldinmajorgroundwaterreserveswhichhascausedwater
stressissuesintheseregions(Wadaetal.,2010).
3. GroundwaterdepletiontrendsintheUSA
Fig.2showstheregionsintheUSAwheregroundwaterdepletionishighlypronounced.Insomeregions,thoughtheywereoriginallywater-rich,
thedepletionratesareveryhigh(Konikow,2013).ThisisusuallyassociatedwithincreasedwithdrawalsforirrigationasinthecaseofMississippi.In
somecases,itiscompoundedbythewaterneedsduetoexcessivepopulationgrowth,forexamplethewatercrisisinCentralvalleyofCalifornia.
Asthequantitydeclinesinmanygroundwaterreserves,thequalityofthesourcebecomesunsuitableformanypurposesduetootherundesired
https://doi.org/10.1016/j.gsd.2017.11.002
Received23August2017;Receivedinrevisedform18November2017;Accepted21November2017
Available online 23 November 2017
2352-801X/ © 2017 Published by Elsevier B.V.
Groundwater for Sustainable Development 6 (2018) 87–92
Fig.1.Groundwaterdepletioninmajoraquifersaroundtheworld(Famiglietti,2014);(a)groundwaterdepthinmm/yrand(b)groundwatervolumeinkm3/yr.1.
Northwest SaharaAlgeria, Libya,Tunisia(2003–2013);2.California CentralValleyUSA(2003–2010);3.HighPlains(Ogallala)USA(2003–2013);4.Guarani
Argentina,Brazil,Paraguay,Uruguay(2003–2009);5.NorthernMiddleEastIran,Iraq,Syria,Turkey(2003–2009);6.ArabianIraq,Jordan,Oman,Qatar,Saudi
Arabia,UAE,Yemen(2003–2013);7.NorthwesternIndiaIndia,Pakistan(2002–2008);8.NorthChinaPlainChina(2003–2010)and9.CanningBasinAustralia
(2003–2013).
groundwater chemistry that could take place due to soil and water contact. In many parts of the world, ground water is not suitable for direct
consumption.Theyareimpairedeitherduetonaturallyoccurringhazardoussubstancessuchasuranium,fluorideandarsenic(Yarlagaddaetal.,
2011).Insomecases,theimpairmentiscausedbyillicitdischargesbyindustrialsectors.Often,thesegroundwatersalsocontainhighdissolved
solids leading to their categorization as brackish waters. Traditional treatment techniques are not adequate to remove the dissolved solids. For
instance,two-thirdsofthecontinentalUnitedStatesincludingNewMexicohaslargevolumesofsalinewatersources.Thetotalvolumeofground
waterinaquifersinNewMexicoisestimatedtobe20billionacre-feet,however,75%ofthegroundwateristoosaline(10,000–35,000ppm)formost
usesandtheremaining25%ofthegroundwatercontainsdissolvedconcentrationsoflowerthan2000mg/L.
4. Californiaasacasestudy
Excesswithdrawalofeasilyaccessiblegroundwaterreservescreatenumberofchallengesintheform ofwaterqualityimpairmentcausedby
inducedleakagefromthelandsurface,confininglayersoradjacentaquiferscontainingsalineorcontaminatedwater(KonikowandKendy,2005).
For coastal regions, this causes seawater intrusion into ground water aquifers. Many large cities in the coastal areas currently experience this
problem.Thissituationstemsinterestforexploringalternativewatersourcesforfreshwatersupplies.Inarecentstudy,KangandJackson(2016)
presenteddeepgroundwatersourcesasnewuntappedpotentialwatersourcesfordrought-strickenCalifornia.Thedeepgroundwatersourcemaybe
attractiveforthelocaladministratorstomeettheincreasingdemandsforwatersuppliesintheregion.Thisfindingignitesinterestinseveralsectors
includingacademia,industryandgoverningagenciesandappearstoprovideexcitingopportunitiesforresearchanddevelopment.Whilethisistrue,
threemajorissuesrelatedtoaccessingthedeepgroundwatersourcescanbelistedas1)environmentalresourcedepletionandassociatedvulner-
abilities, 2) Desalination and water reuse energy-water nexus and process feasibility and 3) new strategies and inclusive governance for new
groundwaterresourcemanagement.
4.1. Environmentalresourceevaluation
Between1960and2000,thepopulationinthecentralvalleydoubledreaching6.5millionpeoplein2005andthefuturegrowthisprojectedto
continue(Anon,2009).ThecentralvalleyofCaliforniagroundwatersourcehasalreadydepletedby31.0±3.0km3betweenthedroughtperiodof
2006and2010duetoexcessiveirrigationusage(Scanlonetal.,2012).Continuedandextensiveuseofgroundwaterandrelatedenvironmentalharm
(i.e.water-leveldrawdown,aquiferminingandpollution,saltwaterintrusion,streambase-flowreduction,andland-surfacesubsidence)impliesthe
difficultyofefficientlyandequitablydefining,allocating,andprotectingrightstothisnewwaterresource(Koundouri,2004).Impactsofintroducing
newwatersourcestothesurfaceonthereceivingwaterbodiesandthecoastalseawaterrisesshouldalsobeconsideredasrecentstudiesreportthe
contributionofgroundwaterdischargestoglobalsea-levelriseincreasedfrom0.02(±0.004)mmyr−1in1900to0.27(±0.04)mmyr−1in2000
(Wadaetal.,2016).
4.2. Desalinationandwaterreusetechnologyassessment
Althoughsalinityofthedeepgroundwatersourcesislowerthantheseawater,theenergyrequirementstotreatthesewaterscanposeachallenge
tolocalelectricgrids(Gude,2015,2016,2017).Variablesalinityfeedisalsopossiblewithcontinuedwithdrawalsinthisregion.Thechallengeof
providingreliablepotablewatersystemsincludesinventionsinthedesignofflexibledesalinationsystemstotakebetteradvantageofthecapital
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Fig.2.GroundwaterdepletionintheUnitedStatesbetween1900and2008(Konikow,2013).
equipmentinvestmentsinthesecoastalregions(Gude,2011).Inviewoftheaforementionedpotentialvulnerabilitiesandenergy-waternexusissues,
blendingboththeseawaterandgroundwatersourcesfordesalinationapplicationappearstomitigatethesubsidenceoflandsurfaceandprovide
rechargetimesforthegroundwaternaturallyfromprecipitationandotherdischarges.Asdeepgroundwaterbecomesthenewpotablewatersupply
source,treatedwastewatersaswellasproducedwatersfromoilandgasoperationsbecomepartoftheintegratedwatermanagementschemefor
thesedrought-strickenareas.Noveldesalinationtechnologiesthatcanutilizehighsalinityandhighhardnesscontainingproducedwatersasfeedare
yetbedevelopedtoaddresswaterscarcitymosteconomically(Mengetal.,2016).
Alternativelymoreaggravatedwaterreuseoptioncouldbe consideredintheseregionspriortoconsideringdesalinationoption(Gudeetal.,
2010).Tenpercentofthetotalavailablefreshwater,or3.5millionkm3,isconsumedaroundtheworld.Ofthisamount,about330km3aregenerated
globallyasmunicipalwastewater(NRC,2012).Forexample,ofthe32billiongallons—or121millioncubicmeters(m3)—ofmunicipalwastewater
dischargednationwideintheUnitedStateseachday,approximately45.5millionm3aredischargedtoanoceanorestuary—anamountequivalentto
6%oftotalwateruseintheUnitedStates.Reusingthiswaterwoulddirectlyaugmentthenation'stotalwatersupply.However,waterreusemaynot
beanaffordablealternativeinallscenarios.Readersarereferredtorecentcontributionsondesalinationandwaterreusetopicsfordetailedlistof
technological and management alternatives (Gude, 2015, 2016, 2017). Desalination processes are mainly classified into membrane and thermal
processes.Membraneprocessesarealsocommonlyusedforwaterreuseapplicationsaroundtheworld.Desalinationprocessesleaveaconcentrated
streamcalled“brine”whichisamajorenvironmentalconcern.Acomparisonofpossiblereuse,recoveryratesandrepresentativecostsfordesali-
nation, water reuse and concentrate management technologies are shown in Fig. 3. It can be noted that water treatment costs increase with
complexityoftheprocessandtheendwaterquality.Forrecyclingandreuseoptions,zeroliquiddischargeoptionsarebeingdevelopedwhichare
energy-andcost-intensiveatpresent.
4.3. Newstrategiesandinclusivegovernances
Understandingthedeteriorationofglobalgroundwatersupplieswillbethefirststeptowardsdevelopingasustainableframeworkforground-
water resilience. Most of the current water laws and policies in the developed world were developed in times, when the tight interconnections
betweensurfacewaterandgroundwaterwerepoorlyappreciated(Famiglietti,2014).Thissuggeststhatgroundwaterwellgovernancerequiresa
newparadigmshifttoprotecttheenvironmentalresources,theiroperationsandmanagement(Conradetal.,2016;deChaisemartinetal.,2017).It
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Fig.3.Desalinationandwatertreatmentoptionsandwaterreuseandconcentratemanagementoptionsandcost-recovery/reuserelationships(modifiedafterGE,
2015).
maybepossibletoexploitcurrentwellstoaccessdeeperaquifersornewwelldevelopmentmayberequiredinsomecases.Regardless,thisleadstoa
needfornewgroundwatergovernanceamongthegroundwatersustainabilityagencies(GSA).Well-coordinatedapproachesacrossvariousagencies
arecrucialforsustainabledevelopmentofthisnewwaterresource,giventhediverseportfolioofgroundwatermanagementacrossthestateandfor
similarsituationsaroundtheworld(NRC,2012).
Forexample,thestateofCaliforniahasintroducedasustainablegroundwatermanagementactin2014withtheaimofmanaginggroundwater
sources with consideration of long-term sustainability and reliability along with enhancement of economic, social, and environmental benefits
(Kiparskyetal.,2016).Thisactalsoinitiatedtheestablishmentofgroundwatersustainabilityagenciesbylocalgroundwateragenciesandparti-
cipatingstakeholders(groundwaterandsurfacewaterusers,representativesofcities,agencies,watercompaniesandenvironmentalscientistsand
planners).GSAsshouldbedevelopedbasedonthefollowingcriteria:scale,humancapacity,funding,authority,independence,participation,re-
presentation, accountability, and transparency. This approach is expected to accomplish a highly efficient governance of the groundwater man-
agementinmedium-andhigh-prioritygroundwaterbasinsacrossthestate.AsofJanuary2017,154GSAnoticeshavebeensubmittedforapproval
and88basinshavealreadyestablishedapprovedGSAsacross30countieswith57high-ormedium-prioritybasinsand31low-orvery-lowpriority
basins.Properimplementationofgovernanceincludesinstitutionaldesign(structuresandrulesformanagement),governance(processesandme-
chanismsandorganizationsthathelpdeveloppublicpolicies,lawsandregulationsalongwithadministrativeandorganizationalstructures),and
management(specificactionstodetermineuseandprotectionofgroundwaterresources).
5. Groundwatermanagementindevelopingcountries
Groundwatergovernanceandmanagementindevelopingcountriesisquitecomplex.Manydevelopingcountriesrelyheavilyonagriculturefor
theirfoodself-sufficiencyandtosustaineconomies.Inthiscontext,exploitationorevenoverexploitationofgroundwatersourcesisacommonand
inevitablepractice.Thefollowingparagraphsdiscusssomeofthenovelpracticesdevelopedtosustaingroundwatergovernanceandmanagementin
developingcountries.
InwesternpartofIndia(StateofGujarat),whenthegovernmenteffortsfailedincontrollingthegroundwateroverexploitation,localcommunitieshave
takenseveralinitiativesinspiredbylocalreligiousleaders(VanSteenbergenandShah,2003).Theseinitiativesincluderainharvestingduringmonsoon
seasonandgrassrootsmovement.Theseeffortsweresoonadoptedbyotherneighboringcommunitiesleadingtostatelevelrecognitionbytheauthorities.
Thisisanexampleforachievinggroundwatergovernancewithpublic-privatepartnershipandcooperationbetweengovernmentagencies.
SimilartoIndia,Chinaisalsodependentongroundwatersourcesforfoodsuppliesandtofosteragriculture-basedeconomy.Thiscountryalso
facesissuesrelatedtooverexploitationofgroundwatersources.IncontrasttoIndia,Chinahasacentralizedmechanisminwhicheachvillagehasa
localgovernmentemployed(paidbylocaltaxes)representativewhoisresponsibleforsettingthewaterusefeeandplanningandimplementationof
irrigationpractices(Shah,2005).
Considering the long-term and complex groundwater management issues faced at local, regional, national and international levels, a global
framework for action called “Groundwater Governance Project” was developed UNESCO-IHP recently (Groundwater Governance Project 2016a,
2016b,2016c;deChaisemartinetal.,2017).Thisprojectdevelopedasharedglobalvisionfortheyear2030whichincludesthefollowingworking
principles:
a) Groundwatershouldnotbemanagedinisolation,butconjunctivelyasappropriatewithotherwatersourcestoimprovewatersecurityandassure
ecosystemhealth.
b) Groundwaterqualityandotherresourcesshouldbeco-managed.
c) Vertical integration (central and local) between nationaland local level participation in theelaboration andimplementation of groundwater
managementandprotectionplansshouldbeconsideredasmuchaspossible.
d) Coordination should be established with other sectors such as agriculture, energy, health, urban and industrial developments and the en-
vironment.
Several other options can be considered to groundwater governance programs to be effective (see Fig. 4). These options are: education and
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Groundwater for Sustainable Development 6 (2018) 87–92
Fig.4.Strategiesforsustainablegroundwatermanagement.
outreach,incentives,removingbarriers,andmandatesandregulations(GE,2015;Gude,2017).EducationandOutreachmayincludeprogramsthat
promotecertificationprogramsandrecognitionawards.Programstodisseminatethescientificinformationandgeneralbenefitsandessentialfacts
relatedtogroundwaterprotectionandsustainableresourcemanagementbyeducationandoutreachefforts.Educatingtheusersonwaterwithdrawal
trends,consumption,dischargeandreusedataiscriticaltogovernanceimplementation.Anincentiveprogramincludingdirectsubsidies,reductions
inpaymentstothegovernment,paymentsforwaterreuse,adjustingpricingmechanisms,regulatoryreliefforrecycledwaterusers,government
procurementofwaterrecycling/reuseequipmentandstructuringofwaterrightstoreducetheuseofpotablewatercanbeconsidered.Regulatory
reliefsmayincludemodificationoflocalregulationsdependingontheapplicationespeciallyintermsofwaterqualitystandards,revisinglaws,and
permittingrequirements.Creatingmandatoryrequirementsshouldconsiderutilityplanningandmanagementtodevelopplansforrecycledwater,
restricting potable water tohuman or food-related uses,and requiring theuse of recycledwater for agriculture and other non-potable uses and
requiringwaterrecoverysystems.
6. Conclusions
Groundwatergovernanceanditssustainableimplementationdependsonvariousfactors,includingavailabilityofaccurateinformation,financial
support,policyframingandimplementation.However,anotherkeycomponentofgroundwatermanagementisbeingabletoforecastgroundwater
levelswithahighdegreeofaccuracy.Theprecisepredictionofgroundwaterlevelscanhelppolicymakersresolvethebestapproachtogroundwater
management problems.This article discussedissues related togroundwater depletion in both developed and developing countries and provided
recommendationsforproperimplementationofgroundwatergovernanceanditsmanagement.
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VeeraGnaneswarGude
DepartmentofCivilandEnvironmentalEngineering,MississippiStateUniversity,MississippiState,MS39762,USA
E-mailaddresses:[email protected],[email protected].
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