Risk-based principles for defining and managing water security.

2013·1.7 MB·English

by  Hall, Jim

Risk-based principles
for defining and managing
water security
JimHallandEdoardoBorgomeo
rsta.royalsocietypublishing.org
EnvironmentalChangeInstitute,UniversityofOxford,Oxford,UK
The concept of water security implies concern
Research about potentially harmful states of coupled human
and natural water systems. Those harmful states
may be associated with water scarcity (for humans
Citethisarticle:HallJ,BorgomeoE.2013
and/or the environment), floods or harmful water
Risk-basedprinciplesfordefiningand quality. The theories and practices of risk analysis
managingwatersecurity.PhilTransRSocA and risk management have been developed and
371:20120407. elaborated to deal with the uncertain occurrence
of harmful events. Yet despite their widespread
http://dx.doi.org/10.1098/rsta.2012.0407
application in public policy, theories and practices
of risk management have well-known limitations,
particularly in the context of severe uncertainties
Onecontributionof16toaThemeIssue
and contested values. Here, we seek to explore the
‘Watersecurity,riskandsociety’.
boundaries of applicability of risk-based principles
as a means of formalizing discussion of water
security. Not only do risk concepts have normative
SubjectAreas: appeal, but they also provide an explicit means
climatology,hydrology,statistics of addressing the variability that is intrinsic to
hydrological,ecologicalandsocio-economicsystems.
Weillustratethenatureoftheseinterconnectionswith
Keywords:
a simulation study, which demonstrates how water
watersecurity,risk,hazard,vulnerability,
resources planning could take more explicit account
exposure,decision
ofepistemicuncertainties,tolerabilityofriskandthe
trade-offsinriskamongdifferentactors.
Authorforcorrespondence:
JimHall
e-mail:[email protected] 1. Definingwatersecurity
Water security has acquired increasing prominence as
a concept and objective in global water policy, though
the extent to which it differs from previous framings of
globalwaterchallengesisnotalwaysclear[1].Certainly,
theoriginaldefinitionintermsofabroadaiminwhich
‘every person has access to enough safe water at an
affordable cost to lead a clean, healthy and productive
life, while ensuring the environment is protected and
2013TheAuthors.PublishedbytheRoyalSocietyunderthetermsofthe
CreativeCommonsAttributionLicensehttp://creativecommons.org/licenses/
by/3.0/,whichpermitsunrestricteduse,providedtheoriginalauthorand
sourcearecredited.
enhanced’[2,p.12]hardlyseemedtoaddvaluetoexistingglobalwaterobjectives,forexample
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articulatedintheMillenniumDevelopmentGoals.Yet,subsequentdefinitionshaveincreasingly
associated water security with the management of water-related risks. UN Water [3, p. 1]
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anacceptablequantityandqualityofwaterforhealth,livelihoods,ecosystemsandproduction’. ...iety
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forhumanhealthandwell-being,theeconomyandthenaturalenvironment.Weareconcerned
aboutwater-relatedoutcomesinwhichneedsforwaterservices(topeopleandtheenvironment)
arenotsatisfied.Theseareoftentimesassociatedwiththeextremesofthehydrologicalspectrum
(droughts and floods) and harmful water quality. Harmful outcomes are a consequence of
disastrousevents(the‘water-relateddisasters’oftheUNWaterdefinition[3]),butmayequally
well be the result of chronic conditions, for example associated with salinization, hypoxia
and waterlogging. Even in the absence of harmful physical aquatic conditions, individuals
and communities may risk a shortage of water or sanitation services because of deficiencies of
entitlementoraccess.
The possibility of harmful states of the aquatic environment (droughts, floods, harmful
water quality, etc.) can seldom be eliminated. The notion in UN Water’s definition [3, p. 1]
that ‘protection against...water-related disasters’ can be ‘ensur[ed]’ denies the random nature
of these events and the unbounded potential for some extremes. Risk management involves
weighinglikelihoodsandconsequencesofarangeofpossibleoutcomesandengaginginsocietal
discussionofthetolerabilityofrisksandthewillingnesstopayforriskreduction,recognizing
thatrisksaresociallyconstructedandthatthereisarangeoffactorsthatdetermineindividuals’
perception of risk [7]. Analysis of other risks to which society is exposed will help to place
water-relatedrisksincontextandtoidentifytheappropriatescaleandnatureofresponse.
The definition of tolerability of water-related risk is bound to be shaped by cultural and
economic contexts and the scale and range of other risks to which a society is exposed. The
thresholdoftolerabilitywillnotbeacrispone.Yet,instancesaboundwherethelikelihoodand
consequences of water-related risks have stimulated societal and political action, be it to cope
withthechroniceffectsofhydrologicalvariabilityontheeconomyofEthiopia[8],thedamaging
effectsoffloodsontheMississippi[9,10]orthedegradedaquaticenvironmentinEuropewhich
hasledtotheWaterFrameworkDirective[11].Therubricofwatersecurityoffersthepotentialto
bothanalyseandgeneralizetheseinstancesofriskmanagement.
Intheirdevelopmentofindicatorsofwatersecurity,Lautze&Manthrithilake[1]identifyfive
components that they consider to be critical to the concept of water security: (i) basic needs,
(ii)agriculturalproduction,(iii)theenvironment,(iv)riskmanagement,and(v)independence.
The ‘risk-management’ indicator is associated specifically with ‘prevention of water-related
disasters’.Inthispaper,wearguethatriskisthedefiningattributeofwatersecurity,thoughrisk
hasmultipledimensions.Thus,eachofLautzeandManthrithilake’sindicescanbetakenasan
indicatorofrisk(i)ofnotsatisfyingbasicneeds(forgivenproportionsoftimeandquantilesof
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the population), (ii) of inadequate agricultural production owing to water-related constraints,
(iii) of harmful environmental impacts, and (iv) to the reliability of water supplies from the
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Meanwhile,Cook&Bakker[12]identifyfourframingsofwatersecurity:wateravailability; ...iety
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ofgeneralframeworksformeasuringandmanagingwater-relatedrisks.Webeginbyanalysing ...sR
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deals with all dimensions of water-related risks, nor does it explore different actors’ attitudes
torisk.Itdoeshoweverdemonstratehowdifferentsourcesofuncertainty,includingthesevere
uncertainty in the outputs from climate models, can be incorporated in risk-based planning
decisions.Weaddresssomeofthecriticismsofarisk-basedapproachbeforeconcluding.
2. Whyfocusuponrisk?
(a) Theoreticalandempiricalobservations
While market values of water are typically lacking [13], theory and simulation studies yield
decreasing marginal values [14–16]. Water users and managers tend to be concerned with
avoidingundesirableshortages(orindeedextremefloodflows)uptoapointwhenasatisfactory
quantity of water is assured and the marginal value of water declines. In other words, water
usersareconcernedabouttheriskofwater-relatedneedsnotbeingsatisfied,ratherthanabout
maximizingconsumptionofwaterresources.Eventhoughinmanycountriesthemarginalcost
of domestic water supply is at or close to zero, domestic demand for water does not increase
inanunboundedway.Thereisalimittothenumberofcropsthatfarmerscancultivateinany
given year, so again their need for water is bounded and their concern is with water scarcity
threateningtheirobjectivesforagriculturalproduction.Similarly,inrelationtowaterquality,the
focusisuponachievingacceptablewaterqualitystandardswithinthecontextofgivenusesand
environments,ratherthanuponachievingthebestpossiblewaterquality.Theconcerniswiththe
riskofstandardsnotbeingsatisfied.
Thereareusesofwaterthatwillcontinuetoyieldbenefitinamoreorlessunboundedway.
Inelectricitymarketswherehydropowersubstitutesforlargerelectricitysupplieswithahigher
marginalcost,hydropowergeneratorscanalwayssellelectricity.Decisionmakersmaywellwish
tomaximizethesebeneficialoutcomes,butwedonotregardthisasameanstoachievingwater
security(thoughitmaybeameanstoachievingenergysecurity).Indeed,itmaybeathreatto
watersecurityifhydropowergenerationincreasesthewater-relatedriskstowhichotherpeople
andtheenvironmentareexposed.
It seems that water users are more concerned with satisfying an acceptable level of water-
related risks rather than maximizing returns. In an empirical study of 22 case studies of water
resourcesplanning,Rogers&Fiering[17]identifiedlimiteduseofoptimizationtechniques.On
contribution of
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water to growth
water and growth
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analysis of water resource management in the context of a changing climate [19–21]. Robust
satisficing responds to the often severe uncertainties to which decision makers often find
themselves exposed, by proposing that under such conditions decision makers should seek
options that satisfy minimum performance requirements under the widest range of future
conditions,ratherthanseekingtooptimizeaparticularperformanceobjective[22].
Parallelingthesearguments,atamacro-economicscale,Grey&Sadoff[5]identifyalevelling
offininvestmentinwaterinfrastructureandinstitutionsthataccompaniesatransitiontowater
security (figure 1). In ‘water insecure’ societies, water-related risks are intolerably high and
inhibit growth. As a consequence, resources for investment and institutions and infrastructure
tomanagetherisksareconstrainedandthesocietiesare‘hostagetohydrology’.Whenresources
are made available to manage water-related risks, the marginal benefits are high and risks are
rapidlyreduced.Asrisksgodown,themarginalcostperunitofriskreductionincreases,anda
pointisreachedwheretheS-curveflattensoff:largenewinvestmentsarenotjustifiedbecause
water-relatedrisksaretolerablylow—thecountryis‘watersecure’.Thestorydoesnotendthere
however,asinstitutionsandinfrastructurecanandwilldeteriorateifnotmaintained,expectations
with respect to risk to people and the natural environment are dynamic and the climate is
changingmeaningthatsocietiesthathadperceivedthemselvestobewatersecurearenowfacing
newthreats.
ResearchbytheJapanWaterForumandtheWorldBank[23]illustratesthistransitioninJapan.
ObservethisintheplotofdeathsversusfloodcontrolinvestmentinJapan(figure2).Flooding,
causedbyheavyseasonalrainsaswellastyphoons,hadmajoreconomicimpactsinJapanwhile
the country was recovering from World War II. Flood damages occasionally exceeded 10% of
grossdomesticproduct(GDP),andin1959TyphoonIsewanresultedinthedeathof5159people.
The risk to this rapidly growing economy was unacceptable and, from 1950 to 1975, some (cid:2)2
trillion was invested in river infrastructure (similar to the investment in railways). Since the
1970s, the impact of flood on the Japanese economy has not exceeded 1% of GDP in any year.
Theaverageannualdamageisroughly0.1%ofGDP.Thisfigureisreflectedelsewhere:theIPCC’s
Special Report on Extreme Events [24] (SREX) reported climate-related damages from extreme
events(ofwhichhydro-meteorologicalrisksarethelargestcontributor)of‘lessthan0.1%ofGDP
for high-income countries...during the period from 2001 to 2006’. Underlining the Grey and
SadoffS-curve,SREXreportedlossesof1%ofGDPformiddle-incomecountries,whichhavehigh
economicvulnerabilityandunder-developedriskreduction,whilethisratiohasbeenabout0.3%
no. people killed Soil Conservation and the Flood Control Urgent Measures Act flood control investment
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and missing by flood Flood Control Special Account Act (100millions of yen)
6000 40000
Typhoon Isewan
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p.3]notedhow‘extremenaturaleventstendtoachieveanexceptionalconvergenceofawareness
onthepartofmajorandminorwaterusers,aswellasonthepartofpolicymakers,legislators
andofinfluentialagents,forexamplethemedia’.Extremeeventsopen‘policywindows’[27]in
which policy imperatives and opportunities exist to respond to risks. This was the case in The
Netherlandswherethe1953floods(inwhich1836peopledied)stimulatedthemajorprogramme
of Delta Works, which was completed in 1997. However, as we have already noted, changing
societalexpectationsandachangingclimatecanstimulatere-evaluationoftolerablelevelsofrisk,
whichtookplaceinTheNetherlandsintheworkoftheDeltacommissie[28],whichadvocateda
10-foldincreasedstandardofprotectionagainstflooding.Astheeconomiccaseforsuchahigh
standardisatleastquestionable[29]andDutchsocietywashardlyclamouringforareduction
in risk (which is already so low as to be imperceptible to most citizens), we may speculate as
to why further investment of AC3bn per year was advocated. At a time when global business
confidenceissoweak,aboldstatementofwatersecuritythatTheNetherlandswillbeopenfor
business‘comewhatmay’wasperhapsmoreaimedattheinternationalinvestorcommunitythan
atdomesticaudiences.
The empirical cases in this exploration of the relationship between water risk and decision
making have focused upon flooding (in Japan and The Netherlands). Flooding is a tractable
case because the impacts can be relatively readily defined in economic terms and the costs of
mitigationarelargelyincurredbygovernmentssotendtobeavailable.Grey&Sadoff[5]provide
narrativesofthewatersecuritytransitioninthecontextofawiderrangeofwater-relatedrisks,
including drought risks to agriculture and salinization, with instances of countries at different
stagesofdevelopment.Ineachofthesecases,weobservehowchoicesandoutcomesatamicro-
and macroscale can be explained in terms of water-related risks and management response
tothem.
(b) Operationalizingwatersecurity
Having advanced some theoretical and empirical motivations for thinking of water security in
terms of risk, we now examine how a risk-based definition of water security can be helpful
inpracticalterms.
Risk brings particular focus to water management problems because it is concerned with
outcomesthatwevalue.Analysisofrisksprovidesessentialevidencetoenablechoicesbetween
alternativecoursesofaction.Inthatsense,riskisforward-looking,usinganalysisofrisksnow
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andinthefuturetoinformdecisionmaking.Specifically,andcrucially,riskrelatesthepotential
forachosenactionoractivity(includingthechoiceofinaction)toleadtoundesirableoutcomes.It
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other pressing needs)?’ [4]. It does imply the need to value undesirable outcomes, which in ...iety
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Proponents of IWRM [30] have argued how inclusive and flexible processes are essential to
managing the multiple demands placed upon water resources. Water security complements
IWRMbyarticulatingthewater-relatedoutcomesthatareofmostconcerntodecisionmakers.
ItisarguedthatIWRMprovidestheprocessthroughwhichthedimensionsofwatersecuritycan
beaddressedtogether[31].
Definitions of risk incorporate some combination of likelihood and consequence of sets of
possible outcomes as being a basis for decision making [32]. Inherent therefore is the notion
that there is a range of possible outcomes (some of which may not even be foreseeable [33])
andtheoutcome(s)thatwillinpracticematerializecannotbepreciselyforecast.Thisemphasis
uponunpredictability(atleastindeterministicterms)isparticularlyconstructiveinthecontext
ofwater-relatedhazards,becausenaturalvariability,ontimescalesfromminutes(e.g.forflash
floods) to decades (e.g. for groundwater reserves), as well as in space, is such a distinguishing
characteristic of water resources systems. Risk analysis encourages us to think about a whole
range of possible future conditions, from the everyday to the extremely unlikely. Analysis of
hydrological variability has long formed the basis for water resources management decisions,
forexampleinrelationtoinfrastructureplanningandoperation[34,35].Arisk-baseddefinition
ofwatersecurityembedsthemanagementofvariability(andassociateduncertainties)attheheart
ofwaterpolicy.
Traditional engineering approaches to dealing with variability have sought to identify a
‘designcondition’(forexample,areservoirstoragevolumeoradikecrestlevel)anddesignto
meetthatcondition[36].Arisk-basedapproachinvolvesconsideringthefullrangeofconditions
to which a system might be exposed, including those that exceed the ‘design condition’.
This places a focus upon system response to extreme conditions and the capacity to recover,
i.e.resilience.Attentionisdrawntothemodesbywhichsystemsmayfailandwhetherfailureis
catastrophicor‘graceful’.Warningsystemsandemergencyreliefhavebeenrecognizedasintegral
aspectsofthesystemicmanagementofrisks.
Arisk-basedperspectiveequallyemphasizestheprobabilityandtheconsequencesofharmful
events. It thus provides a mechanism to analyse the effectiveness of risk-management options
designedtoreducetheseverityoftheaquatichazardandtoreduceexposureandvulnerability,
the two factors which determine our ability to manage or adapt to hazards. Following SREX
[24,p.3],wethinkof‘vulnerability’asthe‘propensityorpredispositiontobeadverselyaffected’,
inotherwordsthesensitivityofthesystemtobeadverselyaffectedbyahazard.The‘exposure’
is the ‘presence of people; livelihoods; environmental services and resources; infrastructure; or
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economic, social, or cultural assets in places that could be adversely affected’. Thus measures
to reduce vulnerability, through the development of coping or risk-sharing strategies (e.g.
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Weconsidersomeappropriatespatialscaleofanaquaticsystem.Itneednotbeself-containedin
aquaticterms:therewillbefluxesovertheboundary.Thesystemwillalmostinvariablyhavebeen
modified,oftenprofoundlyso,byhumaninfluences.Thesystemisdefinedintermsofavectorof
statevariables,w(t),wheretdenotestimedependency,whichdefinetheaquaticattributesofthe
system:storagevolumes(aboveandbelowground),waterlevels,flows,waterqualityindicators,
soilmoisturecontents,precipitationandsoon.
DrawingupontheconceptualframeworkproposedintheMillenniumEcosystemAssessment
[43], we define a set of water-related services that the aquatic system performs, which are
associated with constituents of human well-being. Aquatic systems are dealt with extensively
intheMillenniumEcosystemAssessmentandarerecognizedfortheirroleinprovisioningwater
for use domestically, in agriculture and industry, regulating floods and assimilating waste and
culturalservices,forexamplerecreation.
Theattributesathatarevaluedintheaquaticsystemareafunctiongofasubsetofthesystem
states(whichmayincludeantecedentconditionsaswellas,orinsteadof,thepresentstate)anda
series of time-dependent auxiliary variables, x(t), which determine the human and biophysical
factors that go together with the aquatic system state variables to determine the ecosystem
servicesthattheaquaticsystemprovides.Eachattributeinthevectoraiscalculatedasafunction
ofthesystemstateandauxiliaryvariables.a(t)maybeafunctionofpast(timet−n)aswellas
i
present(timet)systemstates—itmay,forexample,besensitivetocumulativeeffects.Thus,
a(t)=g(w(t−n,...,t),x(t−n,...,t)). (3.1)
i i
Theseattributesathatarevaluedintheaquaticsystemmightinclude
— thefrequencyofwatershortagestodomesticorindustrialwaterusers,
— thefrequencyofviolatingwaterqualitystandards,
— countsofaquaticspecies,
— theoutputofirrigatedagriculturalland,and
— thedistributionofflooddamages.
We note that the relative influence of aquatic variables w and auxiliary variables x upon these
outcomes varies. We also note that the function g can be applied to future (uncertain) system
i
states,toestimatewhichoutcomewouldbeassociatedwithagivenvectoroffutureconditions.
(a) 8
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Fa()i .......ta.royals
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no. households flooded in a given year (a) ......org
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(b)70 rivers lakes ....ilTra
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10
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high good moderate poor bad
WFD ecological status
Figure3.Examplesofsummaryrepresentationsofwater-relatedattributesforpopulationsofactors.(a)Householdsflooded.
(b)EcologicalstatusofriversandlakesinEngland.(Onlineversionincolour.)
Giventhevariationintimeofwandx,thecorrespondingvariationinamaybedescribedbya
jointprobabilitydensityfunctionf(a).Wecanthereforecalculateexpectationsofa orprobabilities
i
ofa exceedinggiventhresholds,forgiventimeframes.
i
Attributesmaybedisaggregatedwithrespecttodifferentactorsinthesystem:someresidents
maygetflooded,othersmaynot;somefarmersmayhavewaterforirrigation,othersmaynot.
Particularlyinformativearefrequencydistributionsofthenumbersofactorswhodo,ordonot,
satisfysometargetforawater-relatedattribute(figure3).
Computing probability distributions of attributes across actors requires information about
the dependence between outcomes for different actors. Large-scale events, for example major
droughts, which impact upon multiple actors, are often highly correlated with space and
time. The incidence of correlated risk is of particular interest from the perspective of national
governmentsconcernedaboutwatersecurity,orinsurerswhomaybeprovidingcoverforwater-
related risks. Understanding spatial correlation is essential to understand how risks aggregate
with spatial scale. Countrywide risk estimates may conceal smaller locations of high risk, in
particularwhenpopulationsareconcentratedinareasofhigherrisk(figure4).Bythesametoken,
tolerabilityofriskwilldependonthesizeofpopulation,withsocietiestendingtobeaverseto
verylarge-scalelossestopeople[44].
Actors associate utilities with water-related attributes a. Their utilities will reflect both their
preferenceswithrespecttodifferentcombinationsofattributesettingsandtheirattitudestorisk.
This is only usually practical if it is possible to obtain a representation of the utility function
suchthat
u(a1,...,an)=h(h1(a1),...,hn(an)), (3.2)
40
9
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0106 country 104 102 1 ........publishin
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average element area (km2) .....org
.
Figure4.WaterstressinAfricaaspercentageofthepopulation,computedwithincreasingresolution[4].(Onlineversion ..Ph
incolour.) ....ilTra
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..R
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wherehk isafunctionofattributeak onlyandwherehhasasimpleform,forexampleadditive ...A3
oimhmraaspmrgobuirentleataninlptdulicitchsialcaitutiryvsasecae.tnedNdriaosrbtniioscekvstheoa,evflrewearstasshit,oeearnrwcf(eufihnngitccurtharieollent5oaa)d.loTtfuoohrreamdrseiifisgoknnf-iibtfithiacoisasnendtocyeffprwoaemfaddtieonerecgsrsoeeeafcnsuwairnabigttlyeemriusnaesrtcgetuoirrnmirateyslp:uordtfeielstcioetrnyleetarissat,iwbnalgoes ...........71:20120407
risk, and has long been regarded as a defining (and, for Adam Smith, puzzling) characteristic
ofwater[16].Riskaversion,inparticularinrelationtolow-probability–high-consequenceevents,
helpstoexplainwhygovernmentscontinuetoinvestincostlyhazardmanagementschemes,even
whentheexpectedriskisrelativelylow[16].
Risk-based decision making involves choices between alternative courses of actions on the
basis of their benefits in terms of risk reduction and their costs, aggregated through time over
some appropriate time horizon. All of these costs and benefits are aggregated into the utility
functioninequation(3.2),whichthenprovidestherationaleforestablishingapreferenceordering
overalternativecoursesofaction.
Although complete and coherent as an approach to decision making, two significant
reservationsshouldbenotedatthispoint.Thefirstisthepracticaldifficultyofelicitingutilitiesin
practicalsettings[45].Inpractice,theeconomicbenefitsofwaterservicesmaybequitediffuse
and embedded in many aspects of economic value, so are difficult to unravel [16]. Secondly,
the preference ordering of options may be sensitive to uncertainties in our understanding of
thesysteminquestionandtheutilitiesassociatedwithit.Severalauthorshavehighlightedthe
importanceofexhaustivesensitivitytestinginordertoidentifydecisionsthatareasfaraspossible
robusttouncertainties[37,46–48].
4. Aframeworkforindicatorsofwatersecurity
Riskisnotanobservablequantity,soifwebaseadefinitionofwatersecurityuponrisk,itmeans
that water security is not directly observable. This presents a problem if we wish to develop
indicators that will track risk through time and demonstrate the effectiveness (or otherwise)
of adaptations that are intended to reduce risk. A complete picture of risk can be constructed
fromacompositesetofindicatorsthattrackthevariousfactorsthatcontributetorisk(figure6).
Indicatorsofhazardwillincludethefrequencyofhydrologicalextremes,harmfulwaterquality
and so on. They may extend to indicators of deliberate water security threats such as terrorist
attack or dependence on hostile neighbouring nations. Indicators of exposure relate to the
numbers of exposed populations, businesses, species, etc. Indicators of vulnerability relate to
thesensitivityofspeciesandthecopingcapacityofindividualsandcommunities.Acomposite
oftheseindicatorscanbeusedtotrackchangethroughtimeandelucidatethefactorsthatmay
influenceorexplainchange.
(a)
10
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uautility, ()i ....................ta.royalsocietypublishin
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quantity of water available for use (a) ..R
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(b) ..37
..........1:20120407
a)j
u(
y,
utilit
s,0 probability of flooding P(a=1) s,1
ur= j ur=
caj caj
od oc0 i.e. od oc1 i.e.
o flo1)= flo1)=
n= =
aj aj
P( P(
Figure5.Utilityrepresentationofsignificantcharacteristicsofwatersecurity.(a)Decreasingmarginalvalueand(b)risk
aversion.
indicators of hazard
e
ng risk impacts
a at present
of ch and in future in the past
s indicators of
ver vulnerability and
dri exposure
Figure6.Componentsofrisk-basedindicatorsofwatersecurity.Observablequantitiesarehighlighted.(Onlineversionin
colour.)