Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , France) and the 2 1 9247 9248 , and B. Grouillet 2 , A. Dezetter 1 erentiate the impacts of climate- and human-induced changes on ff erent combinations of climatic and water use scenarios for the mid- , Spain) basins. Natural streamflow was evaluated using a conceptual ff 2 , D. Ruelland 1 This discussion paper is/has beenSciences under (HESS). review Please for refer the to journal the Hydrology corresponding and final Earth paper System in HESS if available. CNRS, HydroSciences Laboratory, Place Eugene Bataillon,IRD, HydroSciences 34095 Laboratory, Montpellier, Place France Eugene Bataillon, 34095 Montpellier, France Abstract This paper assesses the sustainability ofunder planned multiple water climate uses in change mesoscalecauses scenarios, river and basins of contributes unsustainability. to Weter determining management propose the issues, possible an withlocal assessment water water management grounded agencies. scenarios in Furthermore builtlate real-world we in to present wa- collaboration management an with goals analysisresults, and through furthering present indicators the the that implicationsframework re- significance integrating of of hydro-climatic climate and uncertainty our humantions for dynamics study between and our for resource accounting and water forferent interac- demand management. scales was and A developed with and modeling contrasting applied water in uses: two the basins Herault of (2500 km dif- 1 2 Received: 30 July 2015 – Accepted: 12Correspondence August to: 2015 J. – Fabre Published: ([email protected]) 10 September 2015 Published by Copernicus Publications on behalf of the European Geosciences Union. Ebro (85 000 km hydrological model. A demand-drivenaccount reservoir for management streamflow model regulations wasestimated from designed from to the time main seriesronmental dams. of flows Human demographic, were water socio-economicwithdrawals accounted demand and were for climatic was strictly by data. limited. defining Envi- mand Finally at streamflow indicators strategic comparing thresholds resource water underapplied and availability under which demand to di nodes de- were computed. This framework was 21st century to di streamflow and water balance.flows Results would showed be that guaranteed objectiveareas in monthly this current could environmental climate imply conditions limitingimpact human in water of both uses the basins, more yet tested thanquestion in once climate the every several projections five water years. on allocations The the both and water coming environmental availability decades. requirements and Waterand currently demand shortages intense, planned could and for for the human pressure use on could water become resources and more aquatic frequent ecosystems could in- Sustainability of water uses inhydrosystems: managed human- and climate-induced changes for the mid-21st century J. Fabre Hydrol. Earth Syst. Sci. Discuss.,www.hydrol-earth-syst-sci-discuss.net/12/9247/2015/ 12, 9247–9293, 2015 doi:10.5194/hessd-12-9247-2015 © Author(s) 2015. CC Attribution 3.0 License. 5 10 15 25 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | n ffi s between environmen- ff ordable cost to lead a clean, healthy ff erent concepts, which many authors have ff 9250 9249 erence between Integrated Water Resources Management as prescribed ff cient water availability or excessive water demand), and/or through pressures on ffi In this context, projections of water availability and demand at the river basin scale Studies that address the issue of water demand satisfaction at the river basin scale In this setting water sharing plans, when not already enforced, are currently being et al., ,2015 e.g.).on However hydro-climatic achieving factors a (defining sustainablefactors, the use volume such of of as water resource) waterand resources but demand also depends transportation and on capacity), anthropogenic water determining management infrastructures the (e.g. availability storage of water resources (Gri under scenarios of climateperspective and to water water use changes sharingwater are plans. management essential To to date, are bringity studies mostly a (Schwank focusing long-term focused et on on climate al., impacts projections2014; on Bär of et water al., resource2015; availabil- Nkomozepi and, Chung 2014; Palazzoli decision makers and water managers toplanning look horizons further (Hallegatte, in time2009). andthe Moreover perhaps main as lengthen di underlined their by inLudwig the et WFD al.(2014) and climateof IWRM, change compared adaptation to is the the future focus focus on of current adaptation. and historic issues are scarce, evenence more of so human studies water that use account on streamflow for (one consumptive example use being and the the work influ- of Beck and et al., 2013; Menzel andsiderable, impacts Matovelle ,2010 on e.g.). irrigation Also, requirementsshould climate be (Döll, accounted change2002; for could inWoznicki prospective et have waterfocused con- balance al., only assessments.2015), Some on which studies water have demandflow requirements (Grouillet (Donley et et al., al., ,2015 tal2012, e.g.), flow e.g.), on requirements or fulfilling and on)(2015 environmental Wada one the considered tradeo type human of demand influencescale; (Kirby in however et projections they al., of did2014, future notof e.g.). drought considerWanders studies at possible and at future a the changes global the in capacity river to water basin satisfy use. scale current Aet demands assessed number al., (López-Moreno the2011, et e.g.), impacts al., orof2014; of future climatePulido-Velazquez hydrological planned change changes on demands agricultural without on water considering demand the (Milano possible et impact al., 2013a, e.g.). 21st century, due to climate andand socio-economic changes, Lloyd-Hughes (Heinrichs2014; et al., Milano2012; etArnell al., ).2013b These projections should encourage designed in many river basins.ble These with plans WFD are requirements, often i.e. focusedrecognized the on that 2015, the mid-latitude 2021 periods areas or compati- could 2027 horizons. experience However increased it water is stress widely along the and productive life, whilehanced”. ensuring This that definition comprises the manytried natural di to environment define is and grasp protectedincluded over and the in years en- the (Cook and ideasources, Bakker of2012). implies water One being of security able thepreserving is concepts to functional sustainability. satisfy A water-dependent current ecosystems sustainable and, ability (Gleick use future2000). of of human Thus water users it water re- implieswater demands to the resources, while find a a challenge(Vörösmarty at long-term et the al., balance heart).2012 between An ofitself imbalance integrated the between through water availability availability management the and and strategies demandsu incapacity can the express of use water of water-dependent supply ecosystems due to to excessive meet waterEuropean consumption demand Water by Framework (be human Directive use. it (WFD) The European (European because river Commission, basins of2000) to in- ecosystem requires reach health. a sustainable balance between human water use and tensify. The causes ofmost unsustainability areas vary results across are highly sub-basins dependent and on scenarios, the climate and change in scenario. 1 Introduction Water security was definedlowing: by “Water the security Global at any Waterperson level Partnership from has (GWP, the)2000 access household by to to the the enough global fol- safe means water that every at a 5 5 10 15 20 25 25 10 15 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ), 2 Syndicat Mixte du 9252 9251 water agency since 1964, and the Rhône-Méditerranée Corse The purpose of the present study is thus to assess the sustainability of planned wa- Uncertainties regarding anthropogenic climate change have been largely discussed Integrated modeling of water balance at the basin scale is an extremely complex located in the Souththe of France (Fig. 1a), has been part of the territory managed by 2 Study areas 2.1 Two water management units withThis contrasting water study uses was conductedtrasting in geographical two characteristics Mediterranean and water water management uses. units The with Herault con- basin (2500 km sustainability. We propose an assessmentissues, grounded with in water real-world management water scenarioscies. Furthermore management built we in present collaboration an analysis withgoals through local and indicators water present that relate the agen- to implicationssignificance management of of climate our uncertainty study for for water our management. results, furthering the ter uses in complexusing mesoscale a river conceptual basins modelling framework, under and multiple to climate determine change the scenarios possible causes of un- model comparison of climateavailable change estimate projections of may uncertainty. be the most pertinent currently in the literature. While some authorseling issued to recommendations better on serve how decision toimportance improve making mod- of (Milly et considering al. , climateadaptation,2008 solutions uncertainties e.g.) despite others this in have uncertainty the stressed2010, (Hallegatte, the e.g.). decision2009 ; DessaiPatt process, and et and Hulme(2004) al., to2005; recommended finding changing, Wilby testing probabilities the in sensitivity climatebust of to decision systems guide making adaptation. (Dessai Following and the2010), Hulme, framework2007; we ofDessai propose ro- et an al., given approach2009; byWilby covering a and a selection Dessai, wide of global range climate of models. possible As climate underlined by scenarios, (2007),Räisänen inter- (Kundzewicz and Stakhiv, 2010; , Wilby 2010).be However considered if as projections predictions of and changetructure used cannot dimensioning, directly models to decide can on beto water used determine allocations to the or understand possible infras- the causes system ofthis change under way, Blöschl (Letcher study et and and , al. Montanari(2010)2007 ; will recommended, Pielke help the2009, analyze e.g.). use the In of system,enough “simple” rather to models than that model complex models the(2006), that system “climate may with conditions never perfect be and accuracy. complete known system As dynamics a stressed that priori”. by could ModelingSmitinate be studies and problematic anthropogenic can Wandel are and help rarely flows climatic point were out impacts. more potential sensitive While to problemsof theKirby and diversion range et reallocation discrim- of scenarios climate al.(2014) change considered,drivers found projections other could than that studies have to found more river the that impact range nard anthropogenic than et al., climatic2014; driversVörösmarty (Beck et and al., Bernauer, 2000,2011 ; e.g.). Rey- task which necessarily comprises many biasesraised and on uncertainties. Questions the have confidence been that can be placed into projections of hydro-climatic changes Bernauer, 2011 ). Indeed watertion sustainability of must human be assessedenvironmental water instream through needs, uses. the This the satisfac- impliesmand level accounting of (i.e. for and pressure the distinguishingtual on amount water withdrawals, de- resources, of and consumptive and water use,upstream-downstream notably the that relations, in reservoirs respect users complex and river of would water basins transfers.papers withdraw In with a integrating numerous without number water of restrictions), uses, existing 2015; water ac- Shamir management et and al., waterment,2015 availability units, e.g.), such (Nam as the et individual systemscan al., reservoirs be under or found addressing an study water aquifer. were balance Towith our projections elementary in knowledge numerous complex, manage- fewer spatial mesoscale studies and river basins, temporalability (Collet interactions et between al., water2013, uses e.g.). and water avail- 5 5 25 20 15 10 20 25 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | C to over ) except in ◦ 2 − (CHE), which ) in the Herault and 2 − in the semi-arid central . Climatic conditions in ), located in the North of 1 km 1 2 − − 1 − (14 Ls 1 − s 3 C in the lower Ebro valley and from over ◦ er in their geographical characteristics. The 9254 9253 ff to less than 600 mmyr (Fabre et al., 2014), the main one is the Salagou Confederación Hidrográfica del Ebro 1 ff − (SMBFH) was created in the 2000s to ensure more local ) in the Ebro between 1971 and 2009. 2 − (Fabre et al., 2014). Irrigated areas, covering nearly 700 000 ha in C in the Pyrenees to 17 km ◦ ff 1 − in the western Pyrenees to less than 400 mmyr ), built in 1968 to supply water for irrigation but currently mostly used for 3 1 − 4 Ls 1 − s 3 C and from over 1600 mmyr ◦ The Herault and the Ebro basins di Figure 1 shows the main anthropogenic pressures on water resources in the Herault Ebro valley. Mean annual streamflow was 36 m a few urbanized areas such asdemand Zaragoza for or industrial Pamplona. Urban use water amounted demand to and comparable water volumes in2.2 2009. Conceptual representation of water availabilityA and conceptual water representation demand of water availabilitywater and uses demand was were set up groupedavailability in in nodes. each Water basin: water availability demand nodes wereat nodes represented the each either outlet linked by the of to surface a one flow or sub-basin, more or water by the volumes stored in the main dams. Thus each dam 102 hm recreational activities on the reservoiraround lake. the The Gignac main irrigated canalter areas which are of distributes concentrated nearly water fromhydrosystem 3000 ha the with of Herault a irrigable River total60 to % land. of of a The 234 total perime- Ebro dams, runo is currently amounting a to complex a and storage highly capacity regulated of 2009, are concentrated incanals the semi-arid linked Ebro to valley largeMountains. and storage The are population dams, supplied density most by is of a mostly network very which low of collect (under water 10 inhab. from km the Pyrenean Herault River flows 150 kma from crystalline Mont system Aigoual ofmiddle low (1565 part, m permeability a.m.s.l.) and in in an alluvial the theat valley the upstream north, in town part, of through the Agde. downstream a Thefrom part, karstic Ebro Fontibre into River system in flows the in the 910 Mediterranean km Cantabrian the it Sea along Range a forms north-west (1027 m a to a.m.s.l.), south-east large tothe axis delta. the north, town It the of Iberian is Tortosa range borderedHerault where in basin by the is south the characterized and Pyrenean by themountain range a Catalan range, coastal Mediterranean (up with range climate to in mild influenced 3383 the wet byitation m east. the a.m.s.l.) winters The follow Cevennes and in a hot dry north-to-south summers. gradient Temperature and in precip- the basin, ranging from under 8 age capacity of 8 % of total runo and the Ebro basins.low The upstream population part density of anda the sparse high Herault concentration agricultural river of areas basin urbanwhich is while and supplies characterized the agricultural urban by areas downstream water (Fig.one part to 1a). third coastal has The of areas Florensac total located transfer, watertion outside demand demand the in (mostly 2009. basin, for Water vineyards) accountedboth and demand for peaking urban is between demand highly July (increased seasonal, and because with of August. irriga- Of tourism) the five dams in the basin with a total stor- was created in 1926ment with but a now ensures strong a emphasisResources wider on Management role resource in and water and planning. management,issues These infrastructure in two and develop- line basins with could Integrated already belet Water have vulnerable et water to sharing al., climate2013; to changeMilano adapt (Bielsa to et future and, al. , García-Vera climate Cazcarro, ).2013 2013a; change However2015; Vargas-Amelin have these been and strategiesCol- are designedclimate Pindado, lacking in change2014 ). projections and both of Strategies sustainability basins the of (AERMC, impacts planned; 2014 of water uses. 15 330 m Bassin du Fleuve Herault management and in response towater issues availability that (SMBFH, are2005). specific The toSpain Ebro the (Fig. basin Herault (85 1b), basin, 000 is including km managed by the the Ebro basin areand the complex Mediterranean due Sea, tonees and the (Vicente-Serrano of and contrasting the López-Moreno, influences2006). threetion Annual of mountain range temperatures ranges, the and from particularly precipita- Atlantic 8 2000 the mmyr Ocean Pyre- 5 5 25 20 15 15 20 10 10 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ff ) inputs. A snow 0 T E data that were consid- ff )(Ruelland et, al. 2011, 2014) was acti- T 9255 9256 ) and potential evapotranspiration ( P ciency of supply networks and irrigation techniques. UWD referred ffi At each demand node, water demand was defined for human water uses (human wa- In the Ebro basin the links between reservoirs and irrigation systems were accounted In the Herault basin the surface flow at the outlet of each sub-basin was considered module based on mean basin temperature ( vated in the sub-basinsthe with a snow snowmelt module regime.period adds GR4j 1981–2009 relies three and on more validated fourused parameters. parameters, over in and the The the period model two 1971–1980. was The basins calibrated hydro-climatic are data described over in the Fabre et(2015). al. To assess natural runo in each sub-basin, the model was calibrated only against runo 3 Method 3.1 Integrative modeling of the balance3.1.1 between water availability and Modeling demand water availability and demand Natural streamflow was assessed inbasins the in six the sub-basins Ebro inrun the using at Herault a GR4j and daily (Perrin time themodel et step 20 relies and al., sub- calibrated/validated on),2003 at precipitation a a ( 10-day conceptual time step. hydrological The model hydrological the withdrawals that wouldconsidering enable the users e to have access to optimal amounts of water connected to municipal networks incalculated the according Ebro basin. to Water anthropogenic demand for drivers human (e.g. use population was and irrigated area dy- ter demand) and for environmental requirementstypes (environmental of water demand). human Three water demandtural were water considered: demand urban (AWD), water demand andwas defined (UWD), other as agricul- water the demands amount (OWD). of Human water that water users demand would withdraw without restrictions, i.e. to water demand forto domestic municipal use networks. and AWD for wasered commercial defined negligible and in as industrial the water uses Herault demand connected basin, for OWD irrigation referred use. to Consid- water demand for industries not ered to be natural, i.e.et not al., 2015). influenced by withdrawals or dam management (see Fabre cases such as thewater Ebro uses, and valley, water surface availability flow wasthe is considered sub-basin to regulated in be which by the waternodes dams surface is flow presented upstream extracted. at Note from here, the that outlet a the apartthe of demand Ebro, from grouping node the the eight was water mainpaper uses defined demand not we in connected will each to present the ofeight the large the main balance irrigation demand 20 between systems. nodes. water In sub-basins this demand of and availability only for the for and eight main demand nodes,defined corresponding (Fig. to 1b). eight In main cases irrigation wheredam, systems, the were water irrigation availability systems was were considered directly to linked be to the a volume storage stored in the reservoir. In other sub-basins of the Saint-Laurent and Lodeve. to represent water availability for allbasin water (Fig. uses 1a). supplied The by southern withdrawalsurban inside section withdrawals the of sub- and the Herault aand basin its high (Agde) irrigated has level areas both were ofis the isolated agricultural in highest low the water and Herault demand. mostly at Gignac agricultural The sub-basin. in Gignac Water the demand canal Laroque sub-basin, and minimal in the upstream basin was divideddemand into nodes. sub-basins, The accounting conceptual mappinggradients for of and the water both use hydrosystems water contrasts accounted2014). (for supply for more The climatic to details Herault see basin oneFabre was et or divided, al. into; 2015 more sixCollet sub-basins et and al. , the Ebro into 20 (Fig. 1). 5 5 10 20 25 15 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | erent ff was then constraint . For exam- 1 , considered MIN − s Q OBJ 3 OBJ Q Q and ). (and 1 − MIN s Q MIN 3 Q erence between water demand ff values were defined by local authorities and, accordingly, OBJ 9257 9258 5 A Q MN as simulated by the model at the gauging station Q , the minimum monthly flow not exceeded one year and 5 5 A value observed at this station. Therefore MIN MN MNA 5 Q A Q Q MN Q constraint for the Ebro at Zaragoza and a 100 m ered between the two basins, according to the local management 1 ff − s , was defined as the streamflow under which withdrawals for human 3 MIN ) were defined at the outlet of each sub-basin as 10 % of the mean an- in this study. This monthly minimum flow is not enforced as such but is Q MIN OBJ Q values were defined downstream from storage dams and at specific locations Q streamflow ective water withdrawal. Only a part of the water withdrawn was considered to ff natural water resources and their availabilityand considering infrastructures; water management rules the ability to satisfy water demands throughout the basin; MIN – – Q Two types of environmental water demand were considered in this study. The first A demand-driven dam management model adapted from Fujihara et al.(2008) pre- equal to ple, the minimum flow definedof by Gignac local is authorities 70 for % the ofdefined Herault the at as the 70 gauging % station of of Gignac the over the the period 1981–2009. In the Ebro basin (such as a 30 m based on variations around users can be limitedflow to or guarantee aused minimum as monthly a average planning flow,adjusted called objective. to In objective guarantee the the respect Herault of basin this for flow at example, least water eight allocations years are out of ten. out of five in pastas measurements. simulated Thus by in the theet present model al., study in)2015 the each was influenced used sub-basin streamflow to over calculate the period 1981–2009 (see Fabre nual natural streamflow (simulated as1981–2009 described (or 5 in %Fabre of et mean al., annual2015 ) flow over if the it exceeded period 80 m rules. In the Herault basin, for the Ebro at Tortosa,each see CHE, sub-basin,),2013 under and which thresholdthese withdrawals values thresholds were were di forbidden. set The at the method outlet used of to define mand for all types of humanmand, water demand. then If restrictions water availability were was lower appliedwere than first to water de- applied limit to withdrawals for AWD,dustrial then human and OWD, urban uses. then demand Restrictions UWD. before No agriculturaldemand. withdrawal Water restrictions shortage restrictions were reached was imposed calculated 100 % through on of the in- di Water availability and demand wereof compared priority at for each water water usesequal demand was to considered, node. or higher as An than defined order water in demand, Fig. then 2. water If withdrawals water were availability equal was to water de- 3.1.2 Comparing water availability and demand and simulating influenced and e be actually used (consumptivethe use), sub-basin the outlet as remainingsimulated: return part flow was (see consideredFabre to et return, al. 2015). to Thus the modeling chain type, called water use are no longer allowed.stream This type from of a minimum flow dam canwater or also uses be a enforced downstream down- pumping and site,type a of for environmental example, minimum flows to was flow guarantee considered,objectives: for in availability in the line for water with aquatic other planning sharing environment. and plans, water A the allocations second total volume of water allocated to the di sented in Fabre etoperations(2015) al. of was each run damthe (the to Ebro Salagou simulate basin). dam streamflow The in regulation modelday the time computes and Herault step, the basin storage accounting water and for balance waterinitial 11 demand, of reservoir major entering level. the dams Considering streamflow, reservoirs evaporation, in minimum and atreservoir and the each level, target the 10- reservoir volume levels, it ofthe calculates water the river released downstream in from associated the canals dam (if during applicable) and each in 10-day time step. namics) and climatic driversdata (only used for and agricultural the water modellingand demand).Fabre of More et water details al.(2015). demands on can the be found in Grouillet et al.(2015) 5 5 25 15 20 10 15 25 10 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 0 T T E ciency) ffi 8 km grids whose × ciency of the potable water network ffi 8 km grid (Dezetter et al., 2014; Fabre × 9259 9260 ciency, touristic activity, and unit allocations of the 2000s. ffi ciently in both basins (Fabre et al. , ). 2015 ffi at a daily time step. 0 T E 8 km grids presented in Fabre et al.(2015). For the Herault basin, climatic data (over the reference period 1971–2005) of the cells of the 8 × the influenced streamflowpogenic resulting pressures (water from withdrawals, hydro-climatic return flows conditions and dam and management). anthro- P – In order to cover a wide range of possible climate projections and thus limit over- All simulations of climate change were based on the historical Representative Con- As part of planning for the respect of the European Water Framework Directive, lo- The modeling chain was calibrated over the period 1981–2009 and validated over els (see Table 1) fromUsing the a Coupled large Model setmate Intercomparison of projections Project GCMs stems Phase is mainly from indeed 5Hulme, the recommended (CMIP5). climate2007). since models The the (Arnell mid-21st et dispersion centurya, al. between2004; (2036–2065) compromise cli- Dessai was and between chosen local fornecessity projections to projections through use of climate watertinguished projections uses from in climatic which (generally variability. a for signal 2030) of and climate the change could be dis- was built based on these projections (e.g. for irrigated areas and irrigation e reliance on a limited numberfuture climate of scenarios climate were projections built based (Wilby on and the Harris, outputs),2006 from nine eighteen Global Climate Mod- centration Pathway (RCP) overand the 8.5 reference over the period future (1976–2005) periodtracted (2036–2065). and from The the the outputs from IPCC RCPs thegenerated Data 4.5 nine using Distribution GCMS a were Center. change ex- Climate factoret method change (Déqué, al., scenarios2007; 2012, wereMilano e.g.). et then the, al. For reference2013b; each andRuelland future GCM climatic grid simulations cell, were the applied to monthly the variations observed obtained series between of Water uses were considered throughand two a scenarios trend in scenario eachirrigated for basin: areas, current 2050. network water e Current uses water uses were definedcal with agencies the make population, projections of changes in water uses by 2027. The trend scenario and center was included within the said GCM grid cell. 3.2.2 Water use scenarios et al., 2015). The Hargreavesused empirical to equation calculate Hargreaves ( and Samani, 1985) was was calculated using theEbro FAO basin, Penman–Monteith daily formula temperature (Allen andtions, et precipitation respectively, al., were measurements1998). interpolated from For on 264 the an and 8 818 sta- and the continuation of the2050. trends in The these changes projections (e.g.rent applied for and population to growth) the the until trendtions main water were drivers use based of scenarios onin water are the France, demand presented median INE in between scenarios ina Table the of study 2. Spain). the cur- of Population Unit water national projec- allocations usesthe statistic in Ebro. for institutes the In urban (INSEE region the for water Heraulttic the basin, demand unit HeraultRinaudo(2011) consumption were and suggested from between a takenchanges projections 12 the from % and by 2000s decrease improved the and in control CHEever domes- 2050, in of projections linked water also with consumption suggest forecasted byand an household behavioral gardens increased appliances. connection and How- rate commercialincrease of water of small uses urban industries, to unit parks allocation potable by water 21 networks, %. inducing The a e total the period 1971–1980 at ainfluenced 10-day streamflow time e step, and simulated water supply capacity and 3.2 Climate and water use scenarios3.2.1 for the mid-21st century Climate scenarios Climate scenarios covered a reference periodtative (1976–2005, of considered current to climatic be variability) represen- andFor each a basin future daily period climate centeredthe forcings on over 8 2050 the (2036–2065). period 1976 to 2005 were extracted from came from the SAFRAN meteorological analysis system (Vidal et al., 2010) and 5 5 25 20 15 10 15 20 25 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 10 D erent for was then ff AN described in D OBJ Q 9262 9261 erence between natural and influenced streamflow ff ciency, irrigated areas and industrial activity were di ffi cient. A prospective study was led in the Herault basin within the ffi erentiate the impacts of climatic and anthropogenic changes on water ff : average annual deficit. : average deficit at a 10-day time step; 5 % of UWD or AWD); water resources : frequency of years with at least one significant deficit at a 10-day time step 10 AN > D D F ( – – – For each combination of scenarios the level of anthropogenic pressure on water These indicators inform us on the frequency and magnitude of water shortages. The dam management model was run with the hydro-climatic and water demand Natural streamflow in the reference climate was simulated by running the hydrolog- resources was calculated: the di was calculated by averaging the non-null deficitswater (i.e. demand) water computed shortage at as a a 10-daywere percentage time of step summed over for the whole each period.total year Water annual shortages and demand the that annualcalculated could deficit by not was averaging be defined the satisfied asindicators non-null by the were available annual percentage resources. computed deficits of separately overwater for the demand urban whole (AWD). water period. demand The (UWD) three and agricultural was calculated at thethe outlet 30 year of period. each Theage basin level of at of a anthropogenic natural pressure 10-day streamflow.each was time Finally, combination expressed influenced step, of as and scenarios monthly a averaged to streamflow percent- over the was monthly compared environmental for flows As detailed in Sect. 3.1.2, watereach shortage type was of calculated demand, at at eachwater a demand demand node 10-day was and time then for step. characterized The by satisfaction three of indicators: urban and agricultural nario (future uses under pastminimum climate levels and remained future unchanged uses for under the future other climate). dams. Target and 3.3.2 Indicators of water demand satisfaction and anthropogenic pressure on storage capacity, a project currently underlevels way were in changed the accordingly Ebro basin. in Thus combinations target regarding reservoir the trend water use sce- inputs corresponding to eachalso combination include of changes scenarios. in Future dam water management use such scenarios as the doubling of the Yesa dam’s water sharing plan, in whichless an of inventory available of resources). local These irrigationEbro projections projects basin were was irrigated made used areas (regard- in werethe the CHE considered trend (CHE, to scenario.).2013 reach In Changes their the water in maximum population consumption (permanent extent were and defined applied touristic) by network uniformly and and unit to irrigation urban all e demandeach nodes, demand whereas node. changes in Morefound in detailsGrouillet on et the(2015). al. trend water use3.3 scenarios for Analysis 2050 of can the be relative impact3.3.1 of climate and water Combinations use of scenarios climate and waterThe use modeling scenarios framework was applied underscenarios four combinations to of di climate and water use input data from each ofeters the obtained 18 by climate calibration over scenarios 1981–2009 described were in kept Sect. identical 3.2.1. in The all param- simulations. ical model withstreamflow climate over input the data period from 2036–2065, 1976 the to hydrological 2005. model For was run the with simulation climate of natural was considered to varytional in policy the to reduce Herault losses,considered according and already to remained e constant local in objectives the in Ebro, line where networks with are a na- supply capacity. These combinations and theirin corresponding Table 3. objectives are presented 5 5 20 25 15 10 25 10 20 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | C ◦ 4 to − 4.8 40 and + + 53 % in the + 57 %) than in the Ebro ( are linked to an increase in de- − 3 15 %); however changing climate − 14 to 5 % in the Ebro basin. Nevertheless, − + 11 % in the Laroque section to 15 to 9264 9263 + − , of which 10.4 hm 3 C in the Ebro basin). Precipitation projections are more ◦ 4.6 + 57 % or 14.8 hm er among the 18 scenarios. Annual precipitation changes range from ff + ciency in the water use trend scenario leads AWD to decrease by 50 % ffi 7 % in the Herault and from + AWD is projected to increase in all sections of the Ebro basin and in all scenarios, These climatic scenarios result in changes in simulated natural discharge: while sce- 13 to 36 %) basin. In the Ebro basin discharge changes at the beginning of spring (April) are 57 % in the Saint Laurent and Salagou sections respectively). UWD is pojected to uncertain and di − spring and summer precipitation arebasins; projected in to the decrease already or drycrease slightly in months increase precipitation. of in June, both July and August all scenariosnarios project diverge in a fall, de- winter andlow spring, flows, all slightly 18 scenarios more result marked− in in a the decrease in Herault summer ( uncertain, with a possible increase inwhile discharge all due scenarios to lead increased to and earlier a snowmelt, decrease in spring4.1.2 discharge in the Water Herault demand basin. changes under waterIn use and the climate Herault scenarios basintrasted between projections the of upstream water and demand downstream for sections the (see mid-21st Fig. century 4a). are Although de- con- except in the Bardenas,the Alto climate Aragon change and scenariosthe Ebro lead water Valley to irrigated use a areas trend decreaseparticularly where scenario, in in some irrigated AWD the with Segre of areas andscenario current are is Lower water stronger Ebro projected uses. than areas. to the In In impactIn increase these of the some areas in scenarios Bardenas, the all of impact Aragon climate basins, projected of y change the (see to Catalunya, Fig. trend Jalon have 4b). and asin Guadalope much the areas or trend climate more changelargest scenario. impact in is The the on Aragon uncertainty AWD and Catalunya, on than Segre, the the Jalon and changes impact Guadalope in areas; of it water climate is use lowest change in on AWD is + increase in the upstream sections,Salagou from section. conditions have a dominant impact and cause an increase in AWD (up to mand is expected to increase inprojected some upstream agricultural sections such demand asGignac remains Laroque and and low Lodeve, Agde. Depending relatively on tois the found water the in use downstream scenario the considered,crease sections downstream the in sections of highest of e AWD Gignac or Agde. In the Gignac section the in- despite a 65 % increasein in the irrigated trend areas, scenario because whereas ofimpact AWD a in of 90 the % projected increase Agde climate in sectionanthropogenic change irrigated doubles areas. changes on In (in AWD both is the sectionsUWD the comparable most increase to pessimistic ( the climate impact change of scenarios). projected Note the mands outside the basin) inUWD the in Agde the section, which waterjected concentrates use climate 83 % trend and of scenario.same anthropogenic the In basin’s order changes the of on upstream magnitude.trend agricultural sections In scenario water the the causes demand Saint impacts a are Laurent of slight of and pro- decrease Salagou the in sections, AWD the ( water use Sect. 3.1.1 and theflows was frequency calculated. of non-compliance with these monthly environmental 4 Results 4.1 Hydro-climatic and water demand changes 4.1.1 Projections of hydro-climatic changes forFigure the mid-21st 3 century shows thejected changes by the in nine temperature, GCMs precipitation and1976–2005 two and reference RCPs period natural for in the discharge periodtions the pro- 2036–2065 show Herault in a and comparison clear the to increasing the Ebro trend, basins. particularly Temperature projec- marked in the summer (up to in the Herault basin and 5 5 25 20 15 10 10 15 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 45 %) and Lower 185 % in the Ebro + + 30 %), Segre ( + 9266 9265 erent climate change scenarios. ff 100 % in Aragon and Catalunya to + cient to meet water demand in the downstream sub-basin, ffi ected by climate change except in the Gignac area, where the annual agricul- ff 50 %) areas. OWD is projected to double or more in all sections except the + The water use trend scenario under reference climate variability results in a signifi- Combined with current water uses, climate change scenarios induce an increase in The trend water use scenario in a reference climate only impacts the satisfaction Considering current water use in climate change scenarios, water demand and avail- Finally, results for planned water uses under climate change scenarios show that of AWD in thethe Agde area. frequency Despite of a withdrawalUWD significant restrictions decrease increase is in not in AWD projectedAWD the in and to the Agde no decrease, Gignac upstream area. due area, priorityif Indeed to was streamflow the UWD given high to was was AWD insu considered in Gignac of over first UWD priority in Agde. over Thus ability become out of balancehighly in dependent all on sections the ofter climate the shortages: scenario, Herault particularly depending basin. regarding on Howevershortages the the results in frequency are climate the of scenario, wa- Gignac the frequency area of reaches agricultural three water to eight years out of ten. Despite some Valley). 4.2 Water demand satisfaction under climate4.2.1 and water use scenarios Water demand satisfaction in theConsidering Herault current basin water uses inpear the reference less climate than variability, water once shortagesGignac every ap- and five Agde years areas, in where(Fig. agricultural all water 5a). sections shortage In of occurs the two thetural Saint years Herault water Laurent out basin demand of and except five at Lodeve in a sectionsless 10-day the the severe time average in step restriction reaches the onAgde, nearly agricul- nearing other 100 20 %, sections. % while of The restrictions agricultural annual water are demand. deficit is highest in Saint-Laurent and agricultural withdrawals upstream were limited. Ebro ( Segre and Lower Ebro (from storage capacity is projected toter lead shortages, to from a every decreasesystems year in to the of three frequency Guadalope, of years Jalon, agricultural out wa- of and ten. the In Ebro the Valley, already and out in of balance the balanced systems of cant improvement of the balancenas between system, water for demand both and urban and availability agricultural in water the uses. Barde- The increase of the Yesa dam’s the frequency of shortagesthe in Bardenas, the Ebro Alto valley Aragon andalso and right increases Lower bank Ebro the systems areas for magnitudeEbro. for UWD. of The Projected AWD, annual and impacts climate are in change deficits most exceptthat uncertain water in demand in the satisfaction the in Ebro Altochanges the Valley Aragon Segre in and and is water Lower Lower not uses Ebro bearea. occur. areas. impacted It Note by climate is change also if hardly no impacted in the Aragon and Catalunya 4.2.2 Water demand satisfaction in theIn Ebro the basin combination of currentthat water the uses Bardenas, and Ebro reference climate Valleyof and variability, results balance, right show with bank agricultural systems water (Jalonthe shortages and Ebro Guadalope) every Valley are year and out andrespectively annual Bardenas, (see deficits Fig. and of 5b). 60 30 Also,bank % shortages and systems. in at 70 Urban % a water 10-day in shortages time also the step appear are Jalon frequently higher and in in these Guadalope the areas. right areas possible high increases in theare frequency not of a water shortages, the average annual deficit projected climate change has asections higher of the impact Herault than basin. thescenario In water amplifies the use the sections trend impact of of scenario Gignac the in and di all Agde, the water use trend tural water deficit reaches 30 % under the most pessimistic climate change scenarios. the Lower Ebro area. Althoughare AWD also stays dominant projected inincreases to all are increase scenarios, found UWD in in and the all OWD Aragon areas and in Catalunya ( the trend scenario. The highest UWD 5 5 25 20 15 10 20 25 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | erences be- ff , thus leaving a larger 1 − s 3 are reached more than eight OBJ Q for the Ebro delta. This environmental flow ciency of this adaptation strategy quite un- 1 ffi − 9267 9268 s 3 set by climate change in some of the scenarios. Thus the range of climate change Figure 6b shows the high impact of storage on streamflow in the Ebro basin: the an- Figure 7 shows that monthly environmental flows The combination of the water use trend scenario and climate change scenarios lead ff thropogenic impact is highest inwithdrawals spring are and at fall, and theirin decreases highest. in the summer This when reservoirs, can water which and be aims due to at securing to the a withdrawals flow operation being of of 100 made m the mostly Mequinenza, Ribaroja and Flix dams with an earlier and more25 marked peak to than 45 in % the (depending reference30 on climate. to the This 50 peak climate % reaches change with the scenario) water with use climate trend change scenario only, under and climate change. constraint also explains thescenarios: decrease although of natural streamflow anthropogenic decreases impact inoutflow the under from climate climate change the scenarios, change the dams was kept at a minimum of 100 m tween the areas. The benefitso of the dam enlargement inscenarios the tested Bardenas in area this are study partly makes the e percentage of natural flowreaches at 38 % the of outlet. annualnatural flow Anthropogenic under streamflow pressure current under on conditions the and watersult water increases resources use in to trend 45 an % scenario. increase ofwater Climate annual uses in change and scenarios anthropogenic from re- 43 pressure, to ranging 52 % from when 36 combined with to the 44 water % use with trend current scenario. to significant water shortages in the entire Ebro basin, with marked di Segre and Aragon and Catalunyater the water demand use satisfaction. scenario Finally hasincrease the little in increase to all no in types impact AWD of onan in water wa- increase the demand in Alto in the Aragon theUWD area frequency Lower shortages Ebro and of to in the AWD appear the in shortage trend the in scenario Lower Alto induces Ebro. Aragon and causes AWD and certain. In the Ebro valley andan the increase right bank in systems, the projected climateurban magnitude change water of causes shortages. water However in shortages thesereside and areas in the an the main increase causes current in ofdeterioration conditions, the imbalance in water seem frequency already to use of imbalanced andcombination systems. climate of In changes projected the only water Lower causingwater use Ebro a shortages and and slight in climate Segre both changes areasthe areas lead the Segre) (every to and year to frequent in urban agricultural the water Lower shortages Ebro, in eight the4.3 years Lower out Ebro. of Anthropogenic ten pressure in on water resources In the Herault basin simulated anthropogenicat pressure an on annual water resources time remainsthe step: low trend it water increases use from scenario,and 2 and 3 to it 3 to reaches % 2 4 betweencombination % to the of 3 under % current current under a water water climatewater use combination uses resources change and and at of scenarios the reference water outlet climate, ofthe use the anthropogenic end trend Herault pressure of basin and on reaches July 20 (Fig. climateural % 6a). streamflow of scenarios. natural at Anthropogenic streamflow In the pressure at same the increaseschange period and scenarios under reaches consumptive the use 27 % water is of use projected nat- trend to scenario. increase Under slightly climate earlier in the year, years out of tenuses in and all reference sub-basins climate variability. of However theincrease the water in Herault use the trend and scenario frequency Ebro causesrior of basins, an to unsatisfactory under environmental years current objectives) (when at water influencedthe the outlet streamflow respect of is of the infe- environmental Ebroeas. flows basin. Conversely, Climate in it change improves the scenarios Gignacflows lead (Fig. to in 7a) a and the non-compliance Bardenas Lodeve,areas with (Fig. Saint-Laurent except monthly 7b) the and environmental ar- Cinca Gignac andbination areas the of of Segre the the sub-basins trend in waterhave Herault a use the basin high scenario Ebro impact and and basin. on in climate Finally, the the change all compliance com- scenarios with environmental is flows projected in to the Ebro at Tortosa. 5 5 10 15 15 20 25 20 25 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ected by any decrease in ff erent areas of the Herault basin. Never- ff 9270 9269 culties in the analysis of results, the breadth of uncer- ffi The comparison of the Herault and Ebro basins shows that the regulated systems In most areas, results were highly dependent on the climate change scenario. Al- In some areas the plans to increase water use, rather than the decrease in availability regulation such as the Herault basin should be directly a on the left banka of certain the level Ebro in could agricultural be water only demand, whereas slightly systems impacted with by limited climate streamflow change, up to eas water stress shouldbasin. be Our induced results mainly showed bysatisfied, that climate even the change, with fixed notably also environmental innatural frequent flows the low limitations could Herault flows, of frequently the waterat be question their withdrawals. arises un- current Facing whether level. decreasing Then regulatoryunder again, minimum climate increased change flows consumptive scenarios use can could as bewarmer further shown temperatures, impact kept by ecosystems lower simulations already flows, perturbed and by quickly changing conditions. summer low flows. Although anthropogenicmuch pressures higher on in resources the were Ebroremain shown than to in in be the balance Heraultregulated with basin, demand water some of nodes availability. the However wereheterogeneous, main in water studied; in the uses water the could Ebro stress same basin within way only as each the the area large, di may be quite tainty in future climatesclimate must be change considered, scenarios and istain characterizing essential projection the and to range thus limit of thesensitivity possible risk the to of risk climate maladaptation uncertainties of, (Pielke 2001; was over-relianceexample, Wilby shown in on).2010 to the Also, one vary the Herault between uncer- basin, thehave demand comparable the nodes. frequencies areas For of of water Laroque,ferent shortage sensitivities Saint-Laurent to and in climate Lodeve, reference uncertainties which conditions, (see exhibited Fig. dif- 5). though this may induce some di theless both scales of studymanagement remain and planning. pertinent, since they each match a scale of water should be satisfied inpear current over a climate longer conditions. term,by under Yet a a then changing risk to climate. of reduce However note water water that demand, stress it may than could be to ap- harder curb its increase from now on. In other ar- under climate change scenarios,availability: should in cause four an areas of imbalanceand the between Lower Ebro water basin Ebro), use (Alto current and Aragon, waternarios. Aragon uses In and could these Catalunya, be Segre areas sustainable if under water climate uses change change sce- according to local plans, water demands 5 Discussion and conclusion 5.1 Significance for water management The purpose of this studyan was ensemble to of assess climate the change sustainability scenariosto of using planned determine a water conceptual the uses modeling under framework, possible and was causes appraised of through unsustainability. The theover sustainability risk the of long of water term imbalance uses (severalwater between decades), water use i.e. the availability while possibility andtainable keeping to demand levels. satisfy withdrawals The demands and sustainability for human water of consumptive demand planned use satisfaction water and at uses theclimate environmentally was pressures variability assessed sus- of over by water 30 simulating usesshowed year that on periods, objective resources monthly in considering environmentalmate water flows would conditions use be in and guaranteed in both climatewater current uses basins. scenarios. cli- more Yet Results than in onceto every several lower five areas years, water which this availability, implies or couldet a “doing al.(2010). imply need Moreover better to the limiting with adapt impact human water what ofability uses the and we tested demand have” climate could as projections questioncurrently suggested on the planned both by water for water allocationsMolle the avail- and coming decades. environmentalscenarios Indeed, constraints under water climate shortages change and for waterand use human the use pressure on could water become resources more and aquatic frequent ecosystems and could intense, intensify. 5 5 10 15 25 20 25 10 15 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ciency in the Gignac area ffi 9272 9271 erent downscaling techniques, hydrological models ff erent in areas experiencing more frequent years of ff erentiating the impacts of climate change from those of socio-economic ff orts were made to account for uncertainty in future water stress by using ff This prospective study was based on debatable assumptions regarding the station- The indicators used in this study to characterize the balance between availability arity of hydrologicalpartly processes unrealistic. and Notably, keeping of theby parameters water calibration of management, over the hydrological which 1981–2009non-stationarity. The model may in robustness obtained of all be conceptual hydrologicalmatic simulations seen models and under raises as anthropogenic changing drivers cli- the isto question an published essential of research, question it hydrological for seems impactical in studies. model the According range parameters of could climateMoreover, be change climate transposable studied projections (Coron here, at hydrolog- etchanges, the due al., to 2050; 2012 the horizonVaze downscaling method. etbuilt only Also, with al., note accounted constant that2010). anthropogenic for the drivers water mean40 over use years 30 monthly scenarios years, (Fabre were while et simulations over, al. ings the was2015) past a showed key element thatargue to the be that non-stationarity considered since in of hydrological the anthropogenic modeling. sequence However forc- one of could wet and dry years from the reference period was 5.3 Limitations and uncertainties Although e (Jiang et al., ; 2007 Jones etReynard al. , et,2006 e.g.), al., or water2014 ; useaShamir scenarios wider (Purkey et range et al. , al., of; 2008 uncertainty.2015,many climate Note e.g.) change that could scenarios. only However be the onehere trend used, water not water for use use as scenario scenario example, a should to washorizon, projection be compared cover seen for but to water rather managers aswater of demand a what associated water quantification with uses (with themanagers could included demographic the be in and expected at their socio-economic the modeling planning trendsuse 2050 documents that uncertainties) scenario for local the should of mid-term. be Thusof considered the adaptation as trend measures. a water reference state on which to base the design a wide range ofcompletely climate covered in scenarios, this study. Di the full range of uncertainties was far from being 5.2 Contributions of the integrated modelingThe framework integrated modeling framework enabledthe us to two account for studied manythrough interactions hydrosystems. the within Upstream-downstream simulation interactions ofactions water were between withdrawals, considered water return uses flows wereis and also mostly consumptive accounted agricultural use. for: and Inter- while thusdeficit, water in water demand the shortages in Herault are basin the agriculturalpriority mostly Ebro water given caused withdrawals to can by UWD. be In a limited this hydro-climatic because way of the the increase in irrigation e help anticipate undesirable situations, asenabled recommended by usJuwana et to al.(2012).qualify assess They the the vulnerability frequency offuture and the changes magnitude studied will of hydrosystems indeed to deficits, be water di and stress. thus The helped impacts to of and demand were sensitive to the dynamics of anthropogenic pressures, and should should not lead tothe an increase improvement in UWD of ofFinally AWD the by satisfaction Agde di if area, it asand occurs suggested demographic concurrently in trends, the the with modeling trenddrosystems’ framework water vulnerability helped use to assess scenario. water thenari stress, cause (2010), which, of is as an the underlined essential hy- valuethe by of drivers Blöschl climate of and change water impact stress Monta- studies. inalso The basins at identification facing the of rapid heart climatic of anddecade the anthropogenic of changes challenges is put the forward IAHSet in al., the (International2014). Panta Association Rhei hydrological of scientific Hydrological Sciences) (Montanari shortage of the same magnitudesin (see areas the exposed upstream to areas increasedthe of annual Herault the basin deficits Herault or (such basin), the asan than Alto the increased Aragon Gignac deficit area and (such of Agde as the the areas Ebro Gignac of basin) area). or to shortage events with 5 5 20 25 15 10 20 10 15 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | erent set by ff ff ective in reducing ff ciency in Gignac would not nec- erent combinations of climate and ffi ff erent climate scenarios over multi-decadal ff 9274 9273 erent scenarios that counts the most. Neverthe- ff orts regarding irrigation e ff This work was carried out as part of the GICC REMedHE project funded ective over the long term in non-stationary climate conditions (Hallegatte, 2009). ff erent systems may not react in the same way to similar water shortage frequency The next step of this work, currently underway, is thus to assess the sensitivity of fu- Finally, some authors have questioned the use of indicators to assess and predict ff to propose scenarios of sustainable changes in water uses, both e ture changes in water demand satisfaction to variations in the water use scenarios, and water use scenarios helpedunder to answer climate- the and question human-induced ofshortage the risks. changes, sustainability This and of study toprove water enables the uses determine us sustainability the to of approach causes watermanagers possible uses will of adaptation for have water each options to studytions to address area. between im- the In water satisfaction the uses ofstudy Herault and UWD, basin, showed between while water that upstream accounting the and for e downstream. interac- For instance this climate change. 5.4 Prospects Applying this integrated modelling framework in di Hidrográfica del Ebro fordata providing for the the necessary Ebro basin dataknowledge was and provided the by documents World the for Agencia Climate this Estatalwhich Research de study. is Meteorología Programme’s Climatic responsible (AEMET). Working for We Group ac- CMIP, and on we Coupled thank Modelling, the climate modeling groups (listed in Table 1 of by the French Ministry2015. of The Ecology, authors Sustainable thank Development the Syndicat and Mixte Energy du for Bassin du the Fleuve period Hérault and 2012– the Confederación essarily induce an increaseof the in priority the given satisfactionthe to Ebro of the adaptation local satisfaction will of most agriculturalmanagement urban likely demand could relate water to because have demand agricultural an further waterhowever impact downstream. demand. caution on Modifying In is dam the needed balancebe between while e demand considering and long availability, This term was well investments, illustrated which in thisof may study the not by Ebro the basin, case where of the the benefits Yesa dam of in the the dam Bardenas enlargement area could be partly o the gap between water demand and availability andAcknowledgements. robust to climate uncertainties. scenarios: rather than thechanges absolute in values of their the values indicators between in di each scenario, it is the kept in climate projections, ittion and might irrigated not areas, make consideringis more that sense unpredictable. the to Thus climate consider to variabilityture varying over account scenarios, popula- the for it 30 the year would period variabilityuse seem of more scenarios anthropogenic pertinent and pressures to to in use confront fu- a them large to range di of stationary water may give accurate information,unclear. they In argue the that present study the we added used value indicators to of facilitate using the indicators comparison of is di less the question remainsof of hydrosystems the use to of waterconsidered these as stress. indicators harm The indicators, to quantifying represent indicatorswater changes shortage the in used for the vulnerability human in frequency use. and They thiswhich, magnitude do according of paper not to completely(2011),Hinkel could grasp cannot the ina be notion measured. bottom-up of fact Complementary vulnerability, approach, studies be using focusinget on al., ; 2014 socialBurton vulnerability et al., andbe; 2002 needed adaptiveFarley to et capacity al., assess (Bhave 2011; thedi Wilby vulnerability and of Dessai, 2010, these e.g.) two would river basins to water stress. Indeed summer withdrawals. Furthermore, aquatichigh ecosystems value, in therefore this environmental area flowsagriculture are are and fragile of thus and particular economic of interest.limitations activity However, of the is water local highly withdrawals may dependent question on this irrigation, activity. and frequent water stress (Molle andgate, Mollinga reality and,2003 even e.g.),concede out arguing that spatial indicators that and calculated indicators at temporal tend a heterogeneities. local to Although level aggre- the and resulting authors from a complete study or intensities. In the Laroqueare area sensitive of to the Herault climatic basin, variability, for with example, no summer low storage flows capacity to lessen the pressure of periods. 5 5 20 25 10 15 15 20 10 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ect ff n, S.: Climate ffi 9275 9276 tation priorities: the shaping of adaptation policy, Clim. Policy, 2,cuenca 145–159, del 2002. Ebro,9273 Memoria,9257, available9261 at: ,www.chebro.es last access: October 2014,to 2013. assess long-term waterTotal Environ., supply 461–462, capacity 528–540, of 2013. a9251, meso-scale9253 Mediterranean catchment,of Sci. climatic variability andranean human catchment, activities Hydrol. on Sci. the J., water 59, resources 1457–1469, 2014. of a9255 Hughes, meso-scale J., Jones, Mediter- C. 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I.: A frameworkWoznicki, for S., Nejadhashemi, assessing A., uncertainties and Parsinejad, in M.: climate Climate change change and im- irrigation demand: 5 10 20 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 18 % 27 % 4 % 0 % 95 % 46 % 9 % + + + + + + + uses undervariability reference climate uses under climate change uses undervariability reference climate uses under climate change 39 %74 %38 468 % 675 NA21 % 554 241 5 % 109 NA NA80 % 111 22 % 658 500 NA NA 60 961 400 65 + + + + + + + Herault Ebro Climate Aim of the assessment 9286 9285 2000s 2050s Trend 2000s 2050s Trend uses ) 97 117 1 − yr 1 ciency (%) 60 75 − ffi inhab. 3 ciency (%) 75 80 ffi Transfers (inhab. outside the basins) 186 620 234 676 Touristic activity Unit allocation (m Network e Network and irrigation e Main drivers of water demand at the scale of the Herault et and Ebro basins in the Four combinations of climate and water use scenarios applied in the Herault and the CombinationCurrent uses under past climate 2000s 1976–2005 Water Sustainability of current water Current uses under future climateFuture 2000s uses under past climate 2036–2065Future 2050 uses under future climate Sustainability of 1976–2005 current 2050 water 2036–2065 Sustainability of planned water Sustainability of planned water UWD Permanent population (inhab.) 350 417OWD 440 Industrial 651 AWD water allocation Irrigated areas (ha) NA NA 4754 NA 8502 NA NA Table 3. Ebro basins. Table 2. current and the trend water use scenarios. NA: Non Applicable. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | the Herault (a) 9288 9287 Integrative modelling framework applied at each resource and demand node of the Location, main water uses and water management characteristics of the Ebro basins. In the Herault basin, 6 sub-basins matching 6 demand nodes were (b) Herault and theon Ebro climatic basins. and Water anthropogenicthrough demand drivers. the and Anthropogenic simulation influence natural ofmand on streamflow demand-driven satisfaction streamflow dam was were was assessed management simulated assessed by and comparing based consumptive demand use. to availability. Water de- Figure 2. defined. In the Ebroand basin, 8 20 demand sub-basins nodes were matching selected the main for irrigation the systems simulation were of defined. water resources and Figure 1. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | the Herault (a) the Ebro basins under (b) the Herault and (a) 9289 9290 Average temperature, precipitation and natural discharge over the reference period Water demands for human activities in the Ebro basins. Natural discharge is simulated with the hydrological model over the (b) Figure 4. and four combinations of water use and climate scenarios. reference and future period. Figure 3. 1976–2005 and under 18 climate change scenarios at the 2050 horizon in Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | the Ebro basin. Anthropogenic pressure (b) 9292 9291 the Ebro basin under four combinations of water use and climate erence between natural and influenced streamflow at the outlet of the Herault basin and ff (b) (a) Water demand satisfaction indicators for urban and agricultural water demands in Anthropogenic pressures on water resources under four combinations of climate and the Herault basin and each basin, expressed as a percentage of natural streamflow. is computed through the di Figure 6. water use scenarios in Figure 5. (a) scenarios. Each radar chart presentsvalues range the from results 0 for (no one deficit) demand to node. 1 For (maximum all frequency three or indicators intensity of deficit). Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | the Ebro basin. (b) the Herault basin and (a) in 9293 OBJ Q Frequency of years (out of ten) with monthly influenced streamflow inferior to the objective monthly environmental flow Figure 7. Frequencies are considered acceptable under two years out of 10.