Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , 2 1 12316 12315 , and B. Grouillet 2 , Spain) catchments. Natural streamflow was evalu- 2 ectiveness of adaptation policies aimed at maintaining ff , A. Dezetter 1 , 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 ability in the Ebro basinon appears water to be resources. more The critical, proposedsess owing modeling water to framework high stress is agricultural under pressure currentlyresearch climatic being will used and investigate to the socio-economic as- the e prospective balance scenarios. between water Further use and availability. ter management strategies over time.by Observed separating changes in human discharge and20 were hydro-climatic explained and pressures 3 % onhuman-induced of water changes. resources: the Although respectively decrease keyhighly areas in sensitive of to the hydro-climatic the Ebro variability, the Herault and balance basin between the were water shown uses Herault and to discharges avail- be were linked to for through a widely applicable demand-driventhe reservoir largest management dam model in applied the to Heraultter basin demand and was to 11 estimated major fromWater dams demand population in for and the irrigation Ebro monthly basin. was unitclimatic Urban computed water wa- forcing. from consumption irrigated Finally, data. area, a cropmand series and at of soil strategic data, indicators resource and comparing andVariations in demand water water nodes supply stress were and in computedmodeled, each water taking at into catchment de- a account over 10 climatic the and day past anthropogenic time pressures 40 step. and years changes were in successfully wa- The aim of this studyity was and to its assess spatial the and balanceFrance) between and temporal water variability the demand from Ebro and 1971 (85ated availabil- 000 to using km a 2009 conceptual in hydrological the model. The Herault regulation (2500 km of river flow was accounted Abstract Hydrol. Earth Syst. Sci. Discuss.,www.hydrol-earth-syst-sci-discuss.net/11/12315/2014/ 11, 12315–12364, 2014 doi:10.5194/hessd-11-12315-2014 © Author(s) 2014. CC Attribution 3.0 License. 1 2 Received: 30 September 2014 – Accepted: 15Correspondence October to: 2014 J. – Fabre Published: ([email protected]) 4 November 2014 Published by Copernicus Publications on behalf of the European Geosciences Union. Simulating long-term past changes inbalance the between water demand and availability and assessing their main drivers at the river basinscale management J. Fabre 5 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , , , ) ). ). 2011 2011 2013 , Varela- , , ; ) or char- cient data Füssel and ffi Collet et al. ) underlined March et al. 2011 ; Iglesias et al. ; , ; 2013a 2006 Pulido-Velasquez , ( Arnell et al. 2011 2011 2009 , , ). In other cases, wa- , Koutroulis et al. ). Strategies are thus re- ), which compared water 2013 , Varela-Ortega et al. 2012 Krol et al. 2013 Milano et al. , , Hallegatte Farley et al. n et al. ffi Pulido-Velasquez et al. ; Gri Varela-Ortega et al. ; 2011 , ). This limits the possibility of analyzing the Heinrichs et al. 12317 12318 Koutroulis et al. ; 2008 ; , 2013 2004 , , 2013 ), and an increasing number of studies that tackle this , ). Indeed before looking into complex future changes, Arnell 2011 2013 ). However they often take a static view of the water balance , Purkey et al. , n et al. ffi Beck and Bernauer Gri 2013a ; , 2011 López-Moreno et al. Collet et al. Ludwig et al. , ; ; 2011 2006 Milano et al. , ; ). Such strategies need to be based on a thorough understanding of the vulner- ). The vulnerability of a hydrosystem to climatic and anthropogenic pressures , ected by future anthropogenic and climate changes. In some studies, water demand is simulated based on human and climatic factors, Many authors have underlined the need for integrative assessments of the impacts Studies that compare water demand and resource at the basin scale incorporate an- ff quantifying the water volumes associated (e.g. or for the design of water management plans, which requirethropogenic a and long-term climatic perspective. driversstudies of water generally uses focus and ontions. availability In to simulating some varying water cases, extents. water resources uses The are under tackled varying by looking climatic at condi- population changes, without resources and demand with the aim of optimizing water allocation in given conditions, In recent decades, climatic andcreased anthropogenic in pressures many on regions watereconomic of resources changes, the have mid-latitude in- world. areas According couldcourse of experience to the increased projections 21st water of century stress ( climate in and the socio- 1 Introduction acteristic situations such asIn particularly the dry or context wet of years anthropogenic ( and climatic changes, demand for irrigation waterConsequently, is studies that not do always not taken fullyresources into incorporate and account human demand and ( may climatica not drivers fully of water grasp the ways in which hydrosystems couldand be is compared tomanagement water availability rules based (e.g. on climatic2013 variability and changing water accounting for average conditions over several years ( ter demand is notet simulated al. but isdrivers simply of used the as variability inputon of data demand withdrawals (e.g. in are space availablelated and to and over its account time, variations even for over when time this su accounted variability. for, If the impact water of demand climate is variability on simu- the Ortega et al. we need to be ablenon-stationarity to of represent human long-term and dynamics, physical which factors. implies accounting for the the importance of correctly representingmand, the which, to long-term our dynamics knowledge, ofthe few resources studies study and have by achieved de- so far (one exception being river basin scale (e.g. combined human andregions hydro-climatic that data may be from most vulnerable globalat to the water databases, stress. river However basin and to management assist identifiedto scale, decision account a making the for closer the look spatial must anddemand, be temporal taken storage dynamics at capacity, of each etc.). water hydrosystem In resources this and uses mindset, (types recent of studies were conducted at the also depends on itsconditions. ability Understanding to vulnerability to faceassessment of particular water water stress dry demand and thus events,interactions availability, and requires or between an water the to appropriate uses representation quantitative adapt and of resource. to the new climatic of climate change on theKlein balance between water useissue and can availability be (e.g. found in the literature. Studies at a global scale (e.g. ability of hydrosystems towater climatic stress. and Vulnerability anthropogenic to pressures climateexposure to and change climatic of is variability the not but mayof only drivers be a of climate due to consequence change a of and combination2012 a of of bio-physical system’s anthropogenic impacts pressures ( 2011 quired to adapt water management to these changes ( 5 5 20 10 15 25 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , Allen 2012 Collet ). , ; 8 km grid × 2014 2011 , , ectively to future ). Potential evap- ff Milano et al. 2008 ( Asefa et al. 8 km grid provided by Me- × Varela-Ortega et al. erent perspectives. It can be repre- ff erent water uses ( ff er in their geographical characteristics. The Quintana-Segui et al. ff 12320 12319 ) defined indicators as a statistical concept, provid- ) included indicators that represent the ability of sup- erent scales, stakes, and water management issues. ). In some cases, statistical components are included in ff 2005 ( 2013a 2011 , , ) was calculated using the FAO Penman–Monteith formula ( 0 Milano et al. ). For the Ebro basin, daily temperature and precipitation measurements ; Sullivan and Meigh erent past drivers of water stress. The need to better understand and represent 1998 2013 ). Increasing anthropogenic pressures in river basins in particular in the Mediter- ff , , The Ebro basin is located in the north of Spain (Fig. 1b). The Ebro River flows The first step in designing appropriate adaptation strategies for water resources man- Our review of the literature thus underlined the need to better understand the drivers Finally, water stress can be considered from di Pulido-Velasquez et al. Pyrenean range (up tothe 3383 Catalan m a.s.l.) coastal range in in the the north, east. the2.2 Iberian range in Hydro-climatic the and anthropic south datasets and Daily climate forcings for thefrom Herault the SAFRAN basin meteorological for analysis the system,teo period an France 8 1969 km and to validated 2009 over were France extracted by a karstic system in thethe Mediterranean middle Sea part, at and the an town alluvial of valley Agde. in the910 km downstream in part, a into north-west(1027 m to a.s.l.), south-east to direction the from town of Fontibre in Tortosa where the it Cantabrian forms Range a large delta. It is boarded by the 2 Study areas 2.1 Geographical context The Herault and theHerault Ebro basin catchments is located di in theCevennes South Mountains. of The France Herault (Fig. River 1a). flows 150 Itin km is from the boarded Mont in Aigoual north, the (1565 north m through a.s.l.) by the a crystalline system of low permeability in the upstream part, ability of current waterapplied uses. in The two integrative contrasted Mediterranean modeling catchmentsthropogenic framework facing pressures: was increasing developed climatic the and and Herault an- constrains its basin conception (France) to and di the Ebro basin (Spain). This period; and (ii) use this framework and appropriate indicators to assess the sustain- sented by indicators thatnesses. account for the hydrosystem’s water balance and its weak- otranspiration (ET et al. from 264 and 818 stations, respectively, were interpolated on an 8 km satisfaction of water demand,to: in (i) space combine and human over andrepresent time. hydro-climatic water The data stress aim in and an its of spatial integrative this modeling and study temporal framework was dynamics to over thus a past multi-decadal ply to meet demand (e.g.level water of demand satisfaction anthropogenic rates pressuretios). or These on supply indicators reliability) water usually and account resources the ( for (e.g. the average withdrawal water to balancethe in resource a analysis, ra- hydrosystem such as the return period of undesirable events ( ranean region call for bothof the its quantification spatial and of temporal water dynamics. demand, and the understanding agement is developing a modeling approach able to represent past variations in the and dynamics of the balancei.e. between at water uses the and scale waterclimatic of availability and in water anthropogenic river management changes, basins, plans. wethe need To di be to able understand the tointeractions interactions adapt between between e resources andof human demand and and physical to factorswhich is faces account significant particularly for climatic pronounced variability, the rapid inopment, population the non-stationarity and growth Mediterranean and increasing region, economic competition devel- between2013b di et al. ing an indirect wayson of over measuring time. a Indicators givenunder should quantity study. be or Some dynamic state, studies and and of account allowing for the for changes compari- water in balance the ( system 5 5 25 20 15 10 10 25 20 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) 1 − s 3 1985 , ) in the Martínez- 2013a ( Conseil Général C/1000 m and of ◦ 6.65 in the semi-arid central . Climatic conditions in − 1 extraterrestrial radiation, 1 − C in both basins between − = ◦ Milano et al. at the scale of the Ebro basin ) in the Herault and 330 m García-Vera and Martínez-Cob 2 Hargreaves and Samani 0 − , based on observations from the 17.8) (1) ) and km MIN + T C in the summer in the period 1971– 1 (MEDDE, 2010) for the Herault basin ). Annual temperatures and precipita- ◦ − 2014 ( MOY ciency of water supply networks and of ). Upstream sub-basins in the Pyrenean T and C in the lower Ebro valley and from over ( ffi ◦ 2006 × , (14 L s MAX 2010 ). Since additional data (e.g. wind and humid- 1 12322 12321 T 0.5 − , ) 0.0020 otherwise, Ra s to less than 600 mm yr 3 = MIN 2014 T 1 , ω Banque Hydro Collet et al. − − of the Center of studies and experiments on hydraulic MAX ) in the Ebro valley was applied to the whole basin using C in the winter to 20 T ◦ at a daily time step. The calibration proposed by ( 0 × Bejarano et al. ) 2004 ( /λ Dezetter et al. C in the Pyrenees to 17 ◦ in the western Pyrenees to less than 400 mm yr Anuario de aforos ) in the Ebro between 1971 and 2009. The Herault and its tributaries have 1 2 ) and by the CEDEX for the Ebro basin. − 0.0023 in windy areas, − (0.0864Ra = × km C/1000 m (for the Pyrenean and Cantabrian range, respectively) were applied ω ω between 1971 and 2009. ◦ 1 Vicente-Serrano and López-Moreno ) based on available wind speed data. − ff = C and from over 1600 mm yr latent heat flux. ◦ 0 Mean annual streamflow was 36 m Statistical breaks in temperature and discharge series were detected in both basins Population data were provided by national statistics institutes (INSEE for France and Daily streamflow data were extracted from the French Ministry of Ecology and Sus- 4.16 = 2004 nees ( 2009; average annualprecipitation precipitation follow was a north-to-south 1100 mm gradient15 in over the basin, the ranging basin. fromthe under Temperature Ebro 8 and basin to over areand the complex Mediterranean due Sea, to and the of contrasting the influences three of mountain ranges, the particularly Atlantic the Ocean Pyre- temperature ranged from 6 − over 1000 m a.s.l. for the interpolation1969–2009 of period ( using the inverse distance weighted method. Lapse rates of by 10 % in the1981–2009. Herault Seasonal basin disparities and were by identifiedter 12 in precipitation % the decreased in precipitation by the trends:creased approximately Ebro by while 40 21 basin % win- % over between in the 1971–1980 bothclimatic Herault basin and basins, trends and fall by were 12 precipitation detected % in- over by the Ebro basin. Similar hydro- a typical Mediterranean regime, whilenival hydrological regimes to in Mediterranean the ( Ebroand basin vary the from Cantabrian rangesruno produced an average of 47 % of theduring Ebro the period basin’s natural 1971–2009.1971–1980 Temperature increased and 1981–2009 by and 1 discharge1979 decreased and by 1980–2009 41 at and the 37though % outlet no between of statistically 1971– the significant Herault break and was the detected, Ebro annual basins respectively. precipitation Al- decreased 1969–2010 and 1957–2002 periods in the Herault and Ebro basins respectively. tion range from 8 2000 mm yr Ebro valley. (4 L s ity) were too scarce tofrom 1969 calculate to Penman–Monteith 2009, ET the Hargreaves empirical equation ( 2.3 Hydro-climatic context The Herault catchmentthe is Cevennes characterized mountain by range, a with Mediterranean mild climate wet influenced winters by and hot dry summers. The INE for Spain),extracted and from information agricultural concerning censuses.irrigation irrigated The systems e areas and and datawere relating crop provided to by dynamics unit the water was local consumption water and management agencies. industrial activities ( where λ tainable Development’s database and from the systems (CEDEX, 2012) forprovided the by the Ebro General basin. Councilde of Reservoir l’Hérault the levels Herault and administrative outflow region ( data were Cob and Tejero-Juste Eq. (1). Windy areas in the Ebro basin were defined by ET was used to calculate ET 5 5 25 20 10 15 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , Fabre ( Lecina ff Syndicat ). Studies ). Irrigated Collet et al. 2005 orts have been 2014 , ff , ), which applies to 2000 , ). ) except in a few urbanized 2 Fabre et al. − ( ), built in 1968 to supply water 3 ) and supports a dynamic agro- ff 2011 (CHE) was created in 1926 with , 2011 ers significantly from the south, with , ff since 1964. The local agency CHE 12324 12323 Salvador et al. European Commission ; (SMBFH) was created in the 2000s to ensure more ciency and increase demand management ( ffi 2010 , ciency of the system barely reached 7 % but increased ffi Syndicat Mixte du Bassin du Fleuve Hérault ). The Ebro basin concentrates 60 % of Spain’s fruit production Lecina et al. ; 2011 Confederación Hidrográfica del Ebro , 2002 for each type of demand on average between 1980 and 2010 ( , ), the main one is the Salagou dam (102 hm 1 CHE − yr 2014 3 ). The Florensac transfer, which supplies urban water to coastal tourist areas lo- , In both basins, hot dry conditions in summer lead to a peak in irrigation water de- The Ebro is a complex and highly regulated hydrosystem with a total of 234 dams, increased by 30 % in theThe Ebro) EU and Water drier Framework conditions Directive have led ( to water shortage events. underway since 1927, the twoBilbao main and ones Tarragona, underway being since urban 1975 and and industrial 1989 water respectively. transfers to mand associated with low flows.(since In the the 1970s, recent the past, population increasing has demand in doubled both in basins the Herault and irrigated areas have areas such as Zaragoza or Pamplona. Transfers to cities outside the basin have been cultural and urban use40 hm inside and outside the basin amount to comparable volumes: Figure 1 shows the mainEbro human basins. pressures In on the waterlow resources Herault population in density basin, the and the Heraulttration sparse north and of agricultural the urban di areas and in agricultural the areas north in and the a south (Fig. high 1a). concen- Water demands for agri- 2.4 Water management issues underway to improve networkand e Playán local management and in responsecluding to water issues availability that ( areon specific the to balance the Herault betweenauthorities basin, water in in- demand the and HeraultIn availability basin contrast, have and the been should lead launchedthe to by aim a of local increasing water irrigation sharing anda plan water strong resource for emphasis management on the in the basin. development thethe of Ebro CHE the basin, has resource with a and wider of rolemanagement infrastructure. in Nowadays and water water management, sustainability in line as with a Integrated whole. water resources Since the 2000s, e both basins, has alsoenvironmental flows. been The the Herault basin sourceAgence has of de been l’eau new part Rhône-Méditerranée constraints ofMixte the du Corse through Bassin territory the du managed Fleuve regulation by Herault the of industrial sector. Together with waternuclear demand power for plants, the industrial open-airpopulation water cooling density demand systems is is mostly of similar very two to low urban (under 10 water inhab. km demand. The 2014 and 30 % of the country’s meat production ( cated east of thedemand basin, accounted is for highly one seasonal, thirddemand of with (increased total irrigation because water demand of demandthe (mostly in tourism) five 2009. for dams both Water vineyards) in peaking and the between urban basin July with and a August. total Of storage capacity of 8 % of total runo areas are concentrated incanals the semi-arid linked Ebro to valley largeMountains. and storage are In dams, supplied 2007, most bydemand agricultural of a ( network water which of collect demand water represented from 92 % the Pyrenean of the total water et al. for irrigation but currently mostlyirrigated used areas are for concentrated recreational around activitiesthe the on Herault Gignac the River canal lake. to which The an distributesholders, main irrigable water until from perimeter the of 1990s nearly theto 3000 e 20 ha. % According in to the local late 2000s. stake- amounting to a storage capacity of 60 % of total runo 5 5 20 10 15 25 10 20 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Collet ect water ff cient water availability. ffi uent. ffl ects natural streamflow and water de- ff 12326 12325 ciency of the water supply networks. Anthropogenic drivers ffi ). It accounted for the north–south climatic gradient separating the milder 2013 ( availability Water withdrawn from a river isWater no withdrawals can longer also available for be users limited directly in downstream. the case of insu Although water that is withdrawnof is it not available is directly actually downstream,urban only and used. a irrigation The part supply remaining networks or water as returns treated e to the river through leaks in Winter flows and springas snowmelt a are result, kept the in regimemodified. reservoirs of for rivers summer downstream withdrawal, from storage dams may be strongly – – – Mapping the Ebro hydrosystem was mainly guided by the existence of extensive Our map of the Herault hydrosystem (Fig. 3a) was adapted from the work of vulnerability of each studybasins area accounting to for water the shortage.basin was water Each divided supply basin into to six was sections divided one and into or the sub- Ebro moreet into demand 20 al. (Fig. nodes. 3). The Herault and colder decade (1971–1980) and a warmer and drier3.1.2 period (1981–2009). Mapping resource and demand management The spatial distribution of resource vs. demand was mapped to correctly determine the based on data availability in both basins. This nearly 40 year period includes a wetter dynamically in space andbetween over water time resources to evaluate andsumptions: changes water in demand water are stress. accounted Interactions for by the following as- This integrative modeling frameworkpast was variability applied in to climatic a and long human period conditions. The of 1971–2009 time period to was capture chosen A modeling framework includingcounting hydro-climatic for and interactions between anthropogenic water dynamicsstep resources was and and designed ac- water (Fig. demand 2).mand Climatic at (mainly variability a a through 10 crop day irrigation time demand requirements), through while human population activities growth, a industrialirrigated activity, crops, irrigated and areas the and e of the water types balance include of localand water canals. management These rules through climatic the and operation anthropogenic of drivers dams were distributed and combined 3.1 Modeling approach used to assess the balance between water demand3.1.1 and Integrative modeling framework 3 Method were selected to accuratelytwo represent main the right correspondingheterogeneous bank climatic freshwater systems and availability. hydrological were The conditions also in the selected, Ebro as basin. they are representative of the wetter upstream catchments from the warmerchosen drier based area on downstream. Sub-basins their were similarlow and water mostly withdrawal agricultural characteristics. in Water thebasins withdrawals Laroque are of sub-basin, and Saint-Laurent minimal in andisolated the in Lodeve. upstream the sub- The Herault Gignac at(Agde) Gignac canal has sub-basin. both and The the its southern highesttural urban section irrigated water withdrawals of demand. areas in the the were Herault basin basin and a high levelirrigation of systems agricul- managed in association within large Fig. storage dams 3b). (see The black triangles Pyrenean catchments influenced by a snowmelt hydrological regime 5 5 10 20 15 15 10 20 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , ) 2011 ( CHE ciency index ciency of wa- Grouillet et al. ffi ffi ) was added and e e ff ) inputs. A snow mod- 2014 0 European Commission , 2011 , ), a conceptual hydrological model run at Ruelland et al. 12328 12327 2003 , were not used to calculate the goodness-of-fit cri- 1 produced in each downstream sub-basin was com- − ff in each sub-basin, the model was calibrated only against 10 days ff Perrin et al. ) and potential evapotranspiration (ET 3 ). It combined a random draw of parameter sets and the suc- P 2014 ( , in accordance with deficit irrigation techniques. Data on readily available C ). data that were considered to be natural, i.e. not influenced by withdrawals or ) and averaged over each sub-basin. ff Dezetter et al. To assess natural runo Figure 4 shows how AWD was calculated based on irrigated crops, climate con- OWD was not taken into account in the Herault basin because of the very limited in- The UWD of each municipality was assessed by multiplying a unit water allocation 2014a Streamflow was assessed inin the the six sub-basins Ebro in using the GR4j Herault ( and the 20 sub-basins is limited to a fewto minor satisfy turbines, agricultural while water demand. in the Ebro basin3.2.2 dams are operated primarily Modeling spatial and temporal dynamics in natural streamflow study areas were scarce. Moreover, in the Herault basin, the production of hydropower water use, (ii) agricultural waterdemands demand (OWD) (AWD) linked for crop toDetails irrigation industrial concerning and processes the (iii) and reconstitution otherthe water of to Herault and past power the water Ebro plant basins demand cooling between at 1971 systems. and the 2009 sub-basin can be scale found in in 3.2.1 Modeling spatial and temporal dynamicsThree of types water demand of watercluding domestic demand water were consumption, considered: irrigation (i) of parks urban and water gardens demand and (UWD), commercial in- 3.2 Simulation of water demand and natural streamflow a daily time step andrelies calibrated/validated at on a precipitation 10 day ( timeule step. The based hydrological on model mean basin temperature ( the drier period (1981–2009) andmatic validated calibration using of the the wetter model period wasin (1971–1980). performed using Auto- a three-step algorithm as described puted at a 10 dayat time step the by outlet subtracting of thewas greater ingoing the than streamflow section. from 0.1 hm The theteria; streamflow time hence the steps model for was which only calibrated simulated on agricultural natural demand flow periods. In the downstream activated in the sub-basinsand with the a snow snowmelt module regime. adds GR4j three relies more on parameters. four The parameters, model was calibrated using dam management. Withdrawals upstreamto from be the negligible, Pyrenean so damsentering all were the streamflow considered dams data werewas not were directly computed used available, based for so calibration. on streamflowoutflow, upstream Data and a from on evaporation. balance the Runo discharge between dams inflow, variations in the reservoir level, cession of Rosenbrock andfunction simplex aggregating algorithms three aimed goodness-of-fit at(NSE), criteria: the minimizing the cumulative a Nash–Sutcli volume multi-objective error (VE) and the mean annualruno volume error (VEM). at the municipality scale byeach assigning industrial a water sector. allocation Energy per demandto employee in the and the per volume Ebro year of basin for actors. water was Hydropower assumed evaporated demand to by was correspond the not open-air accounted cooling for system in of this the study nuclear as re- data for our two 80 % of ET water (RAW) were extracted from the2004 European soil database ( dustrial activity. In the Ebro basin, industrial demand was estimated by the ( culated from available urban waterdepend withdrawal on and the water population consumption data.ter rates These supply of allocations networks, urban and activities were andAnnual on assumed changes the in to population e remain over stable timedynamics throughout were due the taken to into study summer account, period. tourism as in were the the seasonal Herault basin. ditions and irrigated areas.maximum In irrigation the requirement case (MIR) was of considered irrigated to be vineyards the in water the required to Herault meet basin, the per capita by the population at each 10 day time step. Unit water allocations were cal- 5 5 10 25 20 15 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , is tar ff PR) R + in V in the Ebro dam are 3 erent sub-basins can also be ff 12330 12329 ; (ii) if the reservoir exceeds the target level min ) was set up and applied to the Salagou dam in the R 2008 ( produced between the dam and the users (i.e. between the ff erent sub-basin. The volume of water released from the dam depends ff Fujihara et al. Because dam management rules are driven by the demand associated with each Target levels were defined for each 10 day time step according to maximum ob- As shown in Fig. 5, the water balance of the reservoir was computed at each 10 day modeled in this study: the Alto Aragon and the Aragon and Catalunya areas (Fig. 3b). of dam also releasesminimum water flows. directly Lastly, the downstream managementsupply for of a downstream particular two users irrigation or or system.regulate more The to dams flows dams may respect from may be be upstreamAna coordinated located to dams to on downstream the on (e.g. same thethe river the Cinca Noguera and Escales, River, Ribagorzana see Canelles Riverlarge Fig. and dam or 3b), Santa located in the downstream. which Mediano Twooperated dams case jointly: and located they if Grado in were the di dams simulated totalcan volume as be on of supplemented if by water they the demand were second. cannot This one be is met the by case the of two first systems dam, in it the Ebro basin outlet of the EbroIn dam other cases, and a theand canal beginning Yesa dam) is of and directly the transports associatedlocated Lodosa water in with from canal a the the di in dam reservoiron the (e.g. to the the Ebro irrigated demand Bardenas areas system). associated that Canal with may the be canal and on the capacity of the canal. This type the lake. individual dam, simulation of damof operations is resources highly and dependent on demand.irrigation accurate In mapping in the a Herault clearlyare basin, delimited much the area more Salagou (Fig. complex. dam 1a). Someriver for dams, In supplies downstream including the water users. the Ebro for The Ebrodemand basin, volume and dam, dam of on release water operation the water released rules runo into depends the on the associated kept as a safetykept reserve as for a a particular safetyabove water water the use supply elevation (e.g. of to 100 a hm inlet the canal in city the inlet of Barasona (e.g. dam). Zaragoza) elevationimum In of or the elevation the case of to of Aragon 137 maintain m the and a.s.l. reservoir Salagou Catalunya is dam levels canal maintained in the to Herault enable basin, tourist a recreational min- activities on the minimum level observed over the period. The minimum levels of the reservoirs are 3.3.1 Modeling dam management Accurate simulation of dam management isability indispensable for simulations in of water highly avail- equippedadapted from hydrosystems. A demand-driven dam management model riods. The modelproduced, was which thus allowed for calibrated the on natural flow the to time be3.3 simulated steps for when the whole Comparing most year. resource of and demand the considering runo water management rules sections, the 10 day periods left out of the calibration data correspond to low-flow pe- Data on the level ofreservoir level the variability reservoir after of 1980, soriods the target 1971–1980 Ebro levels were dam, and defined for 1981–2009. separatelyin example, Minimum for revealed charge the levels a pe- were of change provided dam in by operations the or, stakeholders if the information was not available, were defined as above the defined minimum level additional water is released from the dam into theserved river downstream. levels over alar. given Changes in time dam period operation in rules which were accounted the for dam throughout operation the rules study were period. simi- ciated canals (if applicable)10 and day time into step. the river downstream from the damtime step, during accounting each for watertial demand, reservoir entering level. streamflow, Infiltration evaporation, was andwater not the release from included ini- the in dams the wereand the water following: subtracting balance. (i) evaporation after from The adding the rules entering initial guiding flowsisfy reservoir ( level, demand water and/or can be minimum released flow to requirements sat- as long as the reservoir level remains Herault basin and to 11The major model dams outputs or were groups of the dams reservoir in level, the the Ebro volume basin of (see Fig. water 3). released into asso- 5 5 25 20 10 15 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) indicates the F ) was expressed by F , on modified streamflow. LF erence between natural and ff 12332 12331 ) was represented by the average number of consecutive time L uent. The volume actually used was calculated by subtracting losses from ffl availability Last, the current sensitivity of the two basins to water stress was evaluated: water Second, water shortage for each type of demand was characterized by the magni- The return flow rate from losses from urban and irrigation supply networks was es- length of withdrawal restrictions, shows how quickly withdrawal restrictions were lifted. in 2009. Five indicatorsterize (see Fig. the 2) balance were betweenbasins computed water with at uses their each and current demand human waterwith node activities availability to the and in water charac- climate the management variability Herault practices,as and and of the faced Ebro the maximum simulated recentand annual past. was considered irrigation Maximum to water shortagean be shortage (MS) annual the irrigation rate was rate water and of defined shortagefrequency reliability occurrence below of of (Rel) 50 occurrence %. satisfactory of Shortage years,at irrigation frequency i.e. a ( water years 10 with withdrawal day restrictions time of step, more and than resilience 50 (Res), % computed as the inverse of the average demands faced water shortage, including industrial demands. demand corresponding to the sizeactivity of in the the population, year the 2009climatic irrigated was conditions compared areas, in to and the water industrial period availability 1971–2009, under using the the prevailing dam hydro- management rules applied the number of yearson out irrigation of water withdrawals fivea exceeded including water 50 shortage at % event of ( least thesteps one demand. with time-step restrictions The exceeding in average 50 % which lengthexceeding of 5 of restrictions the % demand. of Years the with demand urbanThese during water years shortage at least corresponded one toapplied 10 day critical to time step situations non-agricultural were in also users,restrictions identified. pointing which are applied to withdrawal to restrictions potential urban also water water sharing withdrawals, conflicts. this means When that all three types of be satisfied due toa lack 10 of day available time wateracceptable step. was According as computed to long for each the asshortage type local analysis they of stakeholders, concentrated did demand withdrawal mostly notder at restrictions on of exceed agricultural were priority 50 demand % (Fig. since of 2). it The AWD was frequency and last of in 95 withdrawal % or- restrictions of ( UWD. Water variability between 1971 and 2009. The percentage of water demand that could not tude, frequency, and average lengthcators of were withdrawal calculated restrictions for (see each Fig. demand node 2). considering These hydro-climatic indi- and anthropic First, anthropogenic and climatic pressures onpogenic water resources impacts were on assessed. Anthro- streamflow weremodified estimated streamflow. Comparing as changes the in di 1971 natural and and 2009 modified enabled climate streamflow variabilitysure between to as be causes distinguished from of anthropogenic the pres- decrease in streamflow observed in both basins. timated for the Heraultaccount basin for as soil a and geological whole heterogeneities.1 and Return with for flow a each rates step were sub-basin of testedNSE of 0.1 from on the and 0 low to Ebro were flows calibrated (July basin, by to to optimizing September goodness-of-fit included), noted criteria3.3.3 NSE including Sustainability indicators for the balance between water demand and generally urban activities was consideredtreated to e return to thethe outlet supply of the network basin from section withdrawals.was Second, as considered part of to the return losseswas to considered from to the supply return networks sub-basin to outlet.supply the networks For sub-basin was outlet. OWD, considered For 80 to % AWD, onlyavailable return of for part to crop withdrawn of the irrigation the sub-basin water was outlet. losses considered All from to the water be actually used by the crops. At each time step,simulated water water withdrawals were demand, considered(iii) and according AWD. the to Return following water flows availability, orderflows were were of considered. also priority: First, taken 80 (i) % into of UWD account. the (ii) For volume UWD, OWD actually two used and by types domestic of and return more 3.3.2 Modeling the influence of water uses on streamflow 5 5 25 20 10 15 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ). ). For 2003 C , Fowler et al. ; 1982 , Hashimoto et al. 12334 12333 ciency of the modeling chain ffi Simulations of the Salagou reservoir level led to scores of 0.53 for NSE and 1 % for In the Herault basin NSE values were over 0.80 and volume error (VE) was neg- The simulated natural streamflow in the Ebro basin was in good agreement with ob- their management, the variationsreproduced, in with the NSE levels values of of the 0.689 and and Yesa and 0.56 8 %. respectively, Grado and dams mean volume were errors well of VEM for the periodAs 1990–2009 can (reservoir be levelvariability seen data in in were 1986, only Fig. whichwith available 6a, is increasing after the water consistent 1990). demand reservoir with for irrigation the level since start-up started the of 1990s. showing a significant hydropower seasonal turbine and 4.1.2 Simulation of dam management Figure 6 shows the resultssonal of dam the operations were simulation well oflated represented reservoir interannual for levels variability the in majority of the of theobservations two dams. reservoir (e.g. basins. Moreover, levels Sea- the simu- were Ebro, in Sotonera rather or good Tranquera agreement dams). with Despite the complexity of scores. This can be explainedflow, leaving by very the few high data level forthree of calibration. The influence sub-basins simulation of of of withdrawals natural theHowever, on streamflow the stream- semi-arid in climatic these Ebro and valley topographicsuggest conditions was that of the thus the contribution considered of middlethe to these study, and the areas be lower contributions to Ebro of unreliable. totalEbro valley sub-basins discharge River 13, were is 14 set minor. and to For 20 zero. the to rest the natural of discharge of the Ribagorzana sub-basin upstream from thedams Santa-Ana (Escales, dam. Canelles In and this sub-basincation Santa of the Ana) Santa three were Ana simulated (see Sect.of as 3.3.1), the one thus natural large multiplying discharge possible dam at errorsMequinenza in Santa in and Ana. the the Tortosa, In calculation see lo- sub-basins Table 1) 13, results 14 indicated and poor 20 calibration (Ebro and at validation Zaragoza, 18 % over the calibration and validation periods, with the exception of the Noguera bility, and resilience werethe based performance on of water the supply metrics systems ( used in previous studies to evaluate The definitions of maximum shortage (also called vulnerability in the literature), relia- served streamflow in the sub-basinsthe that Pyrenean contribute sub-basins most and to discharge thebasins, at Ebro NSE the upstream values outlet, from were i.e. the above Aragon 0.60 River. and In VEM these and sub- absolute values of VE were below upstream Saint-Laurent and Laroque sub-basins, NSEwere values over slightly the lower validation period (0.79 andslightly. The 0.72 lack respectively), of and observed volume streamflowsub-basins errors in the prevented tended validation 1970s to in of increase the natural Gignac, streamflow Salagou simulations and in Agde these areas. Calibration and validation results for thein simulation Table 1. of natural Overall, streamflow the arein results presented were which satisfactory except discharge forquently was some available downstream significantly on sections natural modified streamflow.model and However, performed the few poorly sections generally calibration of producedin the data only the a basin were basin. small where proportion conse- the of total streamflow ligible over the calibration period in all sub-basins except in the Agde section. In the 4 Results 4.1 E 4.1.1 Simulation of natural streamflow The final indicator was theeach frequency indicator, of an occurrence acceptable of rangecriteria water of in sharing the values conflicts local was basin ( defined agencies. according to management 5 5 25 20 10 15 20 25 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) 1 re- − 1 yr − 3 36 %). yr + 3 6 % respectively in the 1970s to − 1 − , see Sect. 3.3.2) val- yr 3 8 %) in the fall. In sub- LF + between the 1970s and the 1 − yr and from 320 to 950 hm 3 1 − yr 3 12 % over the validation period. The in- − 12336 12335 in the 2000s over the whole basin), particularly 1 − yr 3 39 % respectively) and increased in the fall ( − ) mainly because of a significant increase in UWD (from 1 − yr 3 30 and − 23 % respectively) and increased slightly ( 52, − in the 2000s, with the biggest increase in the 1970s and the 1980s. − 1 in the 1970s to 36 hm − 1 yr − 3 29 and yr − 3 21, At Agde, the natural streamflow of the Herault river decreased in the winter, spring Total demand in the Ebro basin increased from 4330 hm Results at the outlet of the Ebro basin (see Fig. 8) showed that the influenced dis- The functioning of some dams was less well simulated. In the case of the Caspe and − basins influenced by a snowmelt regime such as the Cinca and Segre catchments, streamflow at the outlet1981–2009. decreased by approximately 20 % between 1971–1980and and summer ( Similar changes were observedstreamflow in in summer upstream at sections, Laroquestreamflow with and of the Gignac a Ebro (47 river bigger and at( decrease Tortosa 48 also % in decreased respectively). in the The the winter, natural spring and summer 4.2.2 Impact of climatic variability onSimulated natural streamflow changes inbasins natural are streamflow illustrated at inlarly the Fig. dry outlet 9. compared of The to the the 1980s 1970s, and Herault mainly 2000s and in appear the the to Ebro Herault have basin. been In particu- both basins, natural 6820 hm As shown in Fig.Aragon 10b, irrigation the systems main (from increase 400spectively between to in the 880 1970s AWD hm and occurred theand 2000s). in In Segre the the systems, Ebro Bardenas AWD valley, Aragon increased and(or and between even Catalunya Alto slightly the decreased 1970s in and theAWD the case remained of 1980s almost the and unchanged, Ebro stabilized with valley) after a 1990. peak On in the the right 1980s bank, in the Jalon sub-basin. AWD decreased in theIn 1990s the due other upstream to sections, agriculturalremained AWD very decline increased low. significantly, The and but simulated volumes stabilized increase nevertheless to in in AWD warmer the over and the 2000s. Herault drier basin conditionsAWD is in from mostly due the the Gignac 1980s area on, (see which Fig. led 10a). to a threefold increase in 2000s) with heterogeneities throughout the basin. In the Laroque upstream section, for the Florensac transferFig. 10a). in Total AWD the also Agde increased (from section 6 where to 17 UWD hm more than doubled (see 4.2 Changes in water demand and4.2.1 natural streamflow Variations in water demand underTotal anthropogenic water and climate demand variability inand the the 2000s Herault (5318 basin hm hm doubled between the 1970s (24 hm over the calibration period,fluenced and discharge of in 0.64 the and Cincawith and NSE Segre values systems under was 0.50ues moderately over and the well negative calibration reproduced, low period. Streamflow flowenced in NSE by the (NSE outflows downstream Segre from sub-basin themanagement is rules. Santa influ- Ana, Talarn and Oliana dams, which have complex Influenced streamflow was accurately reproducedNSE in the values Herault basin above (seeexcept 0.80 Fig. 7) at in with the all outletsimulated sub-basins of by the for the Salagou the dam damdam calibration management to where model. streamflow and the at However, validation outflow the the outlet was periods, contribution of only of the moderately the basin well charge is Salagou in very this low. complex hydrosystem wasat rather the well basin simulated: outlet aggregated simulations led to NSE and volume error scores of 0.68 and Talarn dams, this may befurther due upstream, to which the were existence not of included other in dams this that4.1.3 study. regulate streamflow Simulation of influenced streamflow 5 5 25 20 10 15 20 25 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | orts to improve the ff ) in the Ebro basin be- ff ) in the Herault basin and from ff 12338 12337 (24 to 38 % of mean annual natural runo 1 − yr 3 (1 to 2 % of mean annual natural runo 1 − yr 3 availability C annual increase in temperature. ◦ ciency of the Gignac canal, water shortage events continued to occur three years Figure 10b shows the results of the simulation of water shortage for the eight main Simulating natural and modified streamflow made it possible to distinguish anthro- Although the annual anthropogenic impact was higher in the Ebro basin, it reached The changes in natural streamflow simulated in both basins are in agreement with ffi Ebro, between 1971 and 2009,faced only shortages the exceeding Ebro valley, 50 Bardenas % and of Alto demand. Aragon areas In the case of the Bardenas irrigation canal, while user conflictswas may indeed appear notable in the forcerning downstream tensions the Agde around use area. water of Thewater resources, water from year and with the 2005 special strict Salagou negotiations dam regulations to that con- compensate led for to low the flowsmanagement release in systems the of in Herault additional the River. posed Ebro to water basin. shortage, The particularly systems thetural Guadalope on water sub-basin. withdrawal the Although restrictions some right may agricul- bank have been are applied very in ex- all areas except the lower out of five. In Agde, increasingRestrictions UWD on and AWD agricultural continued and to urban beThese water satisfied results withdrawals until are appeared the consistent 2000s. in with 2005,occurrence the a of information dry water provided supply year. by problems local instakes stakeholders the concerning on Herault the the basin supply in of the agricultural past water 40 years: are the concentrated main around the Gignac 4.3.1 Simulation of water shortages overFigure the 10 period shows 1971–2009 the waterand shortages simulated the between Ebro 1971 and basins.of 2009 the Results in the Herault are Herault basin, onlydid as presented not they for identify concentrate most any thequent of water Gignac occurrence the shortage and of water in Agde agricultural uses theon. sections and water Although other our AWD shortages sub-basins. decreased simulations Figure in slightlye in 9a the the shows Gignac 2000s the area due fre- to from recent the e 1980s basin and a decrease in anthropogenic pressure in the4.3 Segre sub-basin). Sustainability of the hydrosystems: balance between water demand and throughout the basin (75–25 % in the Aragon sub-basin, 50–50 % in the Cinca sub- between 1971–1980 andand 1981–2009 20 was % due to to an a increase natural in decrease anthropogenic in pressure, streamflow and these proportions varied and August, when withdrawals were made from reservoirs. pogenic impacts on streamflowupstream variability sections from of the the impactshown) Herault of basin the climate (Saint-Laurent, decrease variability. Laroque In ina and the streamflow Lodeve, natural between data decrease 1971–1980 not in andand 3 1981–2009 streamflow % was only, of due whereas theimpacts. to decrease in Eighty in Gignac percent annual and influenced of streamflow Agde, the was respectively decrease linked 1 to in anthropogenic discharge at the outlet of the Ebro basin in the 2000s. 30 % of natural flowmid-August at in a the 10 2000s dayin (Fig. time the 9a). step summer in While inclearly the the the Herault Herault visible impact basin, in basin of the Fig. between human storage mid-July 9b: activities role and in was of the highest reservoirs Ebro in basin, the anthropogenic Ebro impacts basin decreased is in July 4.2.3 Relative impact of anthropogenic andFigure climatic 9 conditions on also streamflow shows1971 that and the 2009 impact into of 27 both hm water basins. use Average3830 on to total streamflow 5000 water hm increased consumption between tween increased 1971–1980 and from 2000–2009. Annual 11 water consumption in both basins stabilized decreased in spring and summer. the climatic trends describedan in increase Sect. in 2.3., falla i.e. precipitation 1 a between decrease 1971–1980 in and 1981–2009, winter associated precipitation with and peak flow occurred one month earlier (May instead of June) after 1980, and streamflow 5 5 25 15 20 10 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | . In 3 on average 1 ciency of the − ffi yr 3 0.2), even though, between the 1970s = 1 − yr 3 75 % and Res = 12340 12339 with shortages one year out of five on average, with 1 ciency as today and under the same climate conditions − ffi yr 3 0) due to very low UWD. is planned in this area. = recent past 3 C A combination of human and hydro-climatic data based primarily on the mapping of According to the results shown in Fig. 12, the Aragon and Catalunya, Ebro valley, resource and demand nodes enabled us to account for heterogeneities in water uses The purpose of thiswater study was stress to and (i) its(ii) combine assess dynamics human the and in balance climatic space betweencontrasted drivers water and catchments uses to subject over and represent to availability time anthropogenic andpresented in its and in sustainability climatic a in variability. this past The two paper approach basins 40 year enables that period, are better likely and identificationdecades. to of face the rapid drivers climatic and of anthropogenic water changes stress in in the coming Jalon ( 5 Discussion and conclusion 5.1 Outcome shows that the currentavailability uses in the of hydro-climatic water conditions in ofand the water the recent management Bardenas past. and under system With unchanged itscould would climate current face not variability, water many in use long match the severe future, water shortage thisgenerally events area (MS speaking, the systema can total still deficit be over consideredyears 50 to % (see be occur Fig. reliable 12). in sinceunbalanced Finally, our years the (see simulations with Jalon Fig. less and 12), frequently Guadalope even than though areas once no appear every conflicts to five between be users particularly have arisen in the to the storage capacityreduces of annual the agricultural Oliana water dam.dam shortage The without combined rates the operation (Fig. additionalthe of 11b) storage expansion the compared of capacity two to irrigated of dams to the areas Rialb have Oliana in contributed (Fig. the to 10b). Bardenas the On and increase the Alto in other Aragon water hand, systems stress appears revealed in Fig. 10b. Figure 11b system due to the construction of the Rialb dam in the early 2000s, which was added the range of variabilityand as 11b that observed shows in an the improvement recent in past. the Comparison of water Figs. balance 10b in the Segre-Urgel irrigation available water resources (see Fig.and 9a). availability Figure are 12 better shows that, balancedfrom on in the the the Salagou whole, Herault area water than with use Agde in a the area maximum Ebro with shortage hydrosystem. a of Apart demand 70 resilience % nodes of and of 0.3, resilience the the of Herault 0.3 indicators basin. and remain the in anSegre-Urgel acceptable and range Lower in Ebro all tainable sections balance in the between Ebro water basin use appear and to have availability found if a climatic sus- conditions remain in and shortages occurred inwould only three have years been out 4the hm of same irrigated five areas in and e (Fig. the 11a). 1990s However (see water Fig.with shortages the 10a), would warmer AWD and have drier become conditionsdue of more to the increasing frequent 2000s, evapotranspiration owing and and both decreasing intense to precipitation, an and increase to in a demand reduction in The construction of new400 hm storage facilities to increase the4.3.2 storage capacity by Sustainability about of current water uses in the hydro-climatic conditions of the In the Gignac areacanal of in the the 2000s Herault (see Sect. basin, 2.3.) the is clear: impact while of AWD reached the 13 hm improved e storage capacity of thethe Yesa Alto dam Aragon is system, thesince currently Sotonera 1982, being which and increased helped Grado improve dams bydespite the have a about balance been significant between 600 increase managed hm water in together demandand demand and (from the availability 320 2000s). to However 950 hm agricultural water shortage periods did occur in the 2000s. system, the increase in water shortage mirrored an increase in water demand. The 5 5 20 25 10 15 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , ) DHI 2014 ( ciency in ffi Collet et al. ) or Mike BASIN ( ); in each unit, a local 2007 2011 ) did not distinguish between , , 2011 CHE , ( also has an operational model of the 12342 12341 Sieber and Purkey Varela-Ortega et al. ; ), WEAP ( Juntas de Explotación 2011 , 1996 , ). Threshold values were set to define undesirable situations in 2012 ( Confederación Hidrográfica del Ebro Andreu et al. ). However, beyond the use of a particular integrated modeling tool, the core issue In the Herault basin, the irrigation needs of vineyards increased and were subject Because the indicators used to measure water stress were defined with local stake- We were able to distinguish between hydro-climatic and human-induced dynamics One may note that integrated tools for the simulation of water balance at a basin Pulido-Velasquez et al. several decades at the fine scale used in this operationalholders, model. they weresensitive appropriate to for the spatial water and temporalhelp management dynamics anticipate issues. of anthropogenic undesirable These pressures, situations andJuwana indicators should and/or et are make al. projections, as recommended by nicipal scale, to provide inputnode. data The for the model atEbro a basin 10 day using time Aquatool. step Itcan and takes simulate per into demand demand account satisfaction all atwould the a not storage fine enable dams spatial a and scale. thorough canals, Nevertheless calibration and data of availability water resource simulation over a period of demand stems from the processing of raw data on irrigated crops and areas at the mu- nized in 17 sub-units, the availability were identified by isolating theault catchments basin that and contributed the most snowmeltthe in dominated the dams catchments Her- most in important thement for Ebro was the basin, taken and satisfaction into by of account. defining for water Our the demands. maps Local main of water irrigation the manage- systems: Ebro basin resource isolated management management in units the basin is currently orga- and management practices in the two basins. The main heterogeneities in resource the 2000s succeeded in limitingAgde agricultural section, water shortages an in imbalance thebecause between Gignac of demand area. In and the the availability combined appeared increase in the in 2000s AWD and UWD and the decrease in natural to great variability (standard1971–2009). deviation Urban reached water 60 demand % also ofstarted increased the significantly, to and mean water appear water usesensitive in demand conflicts to over the hydro-climatic basin. variabilitythe AWD (the 2000s satisfaction 1970s were in warmer were and wetter the drier). whereas Gignac However the the area improvement 1980s in appears and irrigation to e be each hydrosystem. The indicators cansults be to seen characterize as aover the four way dynamics of decades. interpreting Including of human simulationdistributed the and re- modeling balance approach physical enabled drivers between us inmand demand to a correctly satisfaction and spatially reproduce in and changes availability the in temporally the water Herault situations de- and described the byto Ebro local analyze basins: managers. the the Our simulated impactsmanagement practices simulation trends of on matched results climate the balance made variability between it and demand possible and variations availability. in water uses and water in assessing water stress liesing more data in to spatial and buildperiod temporal a processing of dynamic and time. representation in For combin- of example, water the uses added and availability value over of a the long simulation of agricultural water 2003 spite the complexity ofsimulation of the influenced systems streamflow represented,tween produced the particularly satisfactory types in of results.discharge the pressure Distinguishing in Ebro gave both be- us basins, basin, which awho the confirmed attributed better the the understanding preliminary observed of works decreasein of observed in precipitation changes discharge and in of an thecontrast, increase Herault studies River that in to focused evapotranspiration on a( over only decrease the a Herault few years catchment. in In the past and/or future projections water management committee adjustsdemand water nodes allocations in on our awater allocation yearly study is basis. represent discussed. Thus, actual the management units, theby scale simulating natural at streamflow which and the influence of regulations and withdrawals. De- term drivers of water stress. scale have already beenTOOL ( developed and described in the literature, such as AQUA- hydro-climatic and human dynamics, which hindered their understanding of the long- 5 5 25 20 10 15 25 10 15 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , ). In cult. ffi 2011 , Junta de Ex- Grouillet et al. erent uses was ff Salvador et al. erent users at the beginning ff ect downstream users. Also, despite ff 12344 12343 . Likewise, in the Ebro basin each ff can decide on the water volumes allocated to di ). Finally, the simulation of UWD, OWD and AWD does not provide a comprehensive Simulations of water shortages at a 10 day time step should be interpreted with cau- Although key areas of the Herault basin were highly sensitive to hydro-climatic vari- to the lack of appropriateseasonal distributions, data and on past withdrawals. dynamics Nonetheless, appearwere to the available be orders as in of agreement well with magnitude, as the data with that the knowledge of local managers (see validation of water demand simulations in space and over time was not possible due would be expected. Although theduced long-term valuable information reconstitution that of was past not water available using demands regular pro- data sources, accurate Aragon systems in the Ebro basin. 5.2 Limitations Our integrative modeling chain includesterpretation, uncertainties and stemming modeling from uncertainties. data Ininfluence use the on and Ebro streamflow basin, in- made widespread calibration anthropogenic Setting and the contribution validation of of the naturalimprovement semi-arid streamflow Ebro of di valley the sub-basins at simulations zero but led to also a to general the underestimation of total volumes, as and fodder crops grown in thea Ebro yearly basin, basis where cropping toof patterns adapt can our them be integrative adjusted approach to on enabled thestakes us for hydro-climatic to maintaining conditions. identify or The theAgde reaching most spatial water areas vulnerable distribution balance areas: in the are the main concentrated Herault in the basin, Gignac and and on the right bank and the Bardenas and Alto ability, the balance between water usesmore and critical, availability owing in to the high Ebroter agricultural basin demand pressure appears on and to water be availability resources. werebasin All shown such the to as same, be wa- the inconcentrate Ebro 60 balance Valley, % Aragon in of and large the water Catalunya, systemscomparison, demand Segre, of water from and the demand the Lower Ebro large in irrigation Ebro, theAWD systems which over Gignac in the area the Herault represented, basin. basin In onHerault over average, the basin 70 past % may 40 of years. be total What more is vulnerable more, the to vineyards an in the unreliable water supply than the cereal pared to AWD. TheEbro main was driver the of increaseexceeded the in the demand decrease water triggered in supply by waterstorage capacity the capacity). demand in expansion satisfaction of some in irrigated areas the land, (under which current management and streamflow. Although UWD also increased in the Ebro basin, it remained very low com- operation of dams fordownstream the streamflow and production hence of significantly a the hydropower can increasing attention have paid a to major environmental impact flows, on these the flows were not included in of water management. view of water uses. Notablycounted the for demand through for reserved hydropower production flowsThis was at only could the partly dams be concerned ac- a for major the source satisfaction of of AWD. bias in the modeling of influenced streamflow, as the plotación of the irrigation season,if based the on irrigation the seasonrestricted filling throughout begins level the of with season instead the lowimum of associated reservoir waiting level reservoirs. until levels, before the Thus, withdrawals limiting reservoirspatterns can are withdrawals. according at be Sometimes to their partially farmers the min- systems reservoir decide with level on no and/or storage their snow capacityault cropping cover like basin, ( the water Gignac shortages canal or mayreallocation the be should Agde be more section incorporated irregular. in in In the the future Her- model studies, to anticipated better water integrate the human aspects framework. Indeed, the orderfixed of in priority our model, for andbefore the agricultural no supply withdrawal restrictions restrictions of were reached wateruse imposed 100 restrictions to % on can of di industrial be demand. and decided Insupplies on urban real to in demand life, advance, irrigators to water are limit entirely non-essential cut urban o uses before 2014b tion, as no real-time water management adjustments were considered in this modeling 5 5 25 20 10 15 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ect ff 12322 Confed- 12320 (AEMET). 12341 and the , 12323 12341 , , ectiveness of adaptation ff (last access: February 2014), 12322 12327 , 12326 , 12317 12323 12319 , Agencia Estatal de Meteorología 12318 12346 12345 12319 Syndicat Mixte du Bassin du Fleuve Hérault for providing the necessary data and documents for this study as This work was carried out as part of the GICC REMedHE project funded (last access: October 2014), 2011. http://www.hercules.cedex.es/anuarioaforos/default.asp of climatic variability andranean human catchment, activities Hydrolog. on Sci. the J., water 59, resources 1457–1469, 2014. of a meso-scale Mediter- and their controlling factors in the Ebro basin (Spain), J. Hydrol., 385, 323–335, 2010. water availability in the Zambezi river12317 basin?, Global Environ. Change, 21, 1061–1072, 2011. at: to assess long-term waterTotal Environ., supply 461–462, capacity 528–540, of 2013. a meso-scale Mediterranean catchment, Sci. scenarios, Global Environ. Change, 14, 31–52, 2004. for water resources planning and12341 operational management, J. Hydrol., 177, 269–291, 1996. sources system under varying climaticyond, J. conditions: Hydrol., reliability, resilience, 508, vulnerability 53–65, and 2014. be- 2012. www.chebro.es of climate change on12317 global water resources, Global Environ. Change, 21, 592–603, 2011. puting crop water requirements, FAO Irrigation and Drainage Paper 56, FAO, 1998. Allen, R., Pereira, L., Raes, D., and Smith, M.: Crop evapotranspiration – guidelines for com- References simulate and compare the impacts ofof socio-economic possible trend future scenarios climates. and Further a wide researchmeasures range will in assess reducing the water e stress anduses achieving and a availability. sustainable balance between water 5.3 Prospects Despite the limitations mentioned above,able the the approach identification described of the inclimatic drivers this of and paper water will anthropogenic stress en- changes inextremely basins in that useful the are coming to likely to decades. policyThe face Such rapid next makers information step when will of designing be thisGICC-REMedHE work, water project, which consists plans is in for currently using being coming the conducted proposed decades. in integrative modeling the chain framework to of the sidering the time depth ofhave the been limited study, one by environmental could concerns arguefuture during that studies, the water majority environmental withdrawals of flows would thesustainability should not study of be period. a In taken hydrosystem’s into water balance. account when assessing the this study, except for reserved flows at dam outlets in the Ebro basin. 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Optimal values of NSE, VE and VEM are 1, 0 and 0 respectively. Vicente-Serrano, S. and López-Moreno, J.: Influence of atmospheric circulation at di Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 12354 12353 The Herault and the Ebro basins: location of the main human pressures on water General framework for the integrative modeling chain developed and applied to the Herault and the Ebro basins at a 10 day time step over the 1971–2009 period. Figure 2. Figure 1. resources (urban and agricultural areas, main storage dams and water transfers). Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 6 (a) 12356 12355 20 sectionsfor simulation of water resources and 8 demand nodes that matched (b) Maps of the main physical and human spatial characteristics of the two basins: Agricultural Water Demand (AWD) simulation model. Figure 3. sections were selected for simulationault of basin; water resources andthe water main demand irrigation nodes systems in were the selected in Her- the Ebro basin. Figure 4. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | the Herault basin ) and volumes re- R (a) , if applicable) were calculated at a 10 day canal V 12358 12357 ) and into the canal ( out V . Demand driven dam management model. The reservoir level ( Simulated and observed reservoir levels of the main dams in t the Ebro basin. Optimal values of NSE, VE and VEM are 1, 0 and 0 respectively. (b) and Figure 6. Figure 5. leased downstream ( time step Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | (low flow NSE), VE (cumulative volume error), LF 12360 12359 (low flow NSE), VE (cumulative volume error), and LF ciency index), NSE ffi e e ciency index), NSE ff ffi e e ff Simulation of influenced streamflow in the Herault basin from 1971 to 2009: results Simulation of influenced streamflow in the Ebro basin from 1971 to 2009: results for Figure 8. calibration (Cal: 1981–2009) and(Nash–Sutcli validation (Val: 1971–1980) periods. Optimal values of NSE Figure 7. for calibration (Cal: 1981–2009)NSE (Nash–Sutcli and validation (Val:and VEM 1971–1980) (mean periods. annual volume Optimal error) values are 1, of 1, 0 and 0 respectively. VEM (mean annual volume error) are 1, 1, 0 and 0 respectively. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | the Ebro river. (b) 12362 12361 in the Ebro basin. (b) the Herault river and on (a) in the Herault basin and Frequency and intensity of agricultural and urban water shortage in the period (a) Comparison of natural vs. influenced streamflow: anthropogenic impacts (water con- 1971–2009 considering the spatialconditions and temporal dynamics of water uses and hydro-climatic Figure 10. Figure 9. sumption and water storage) on Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | in the Herault (a) the Ebro basins: frequency of agricultural ) in years out of 5 years, resilience (Res), C (b) 12364 12363 the Herault and (a) ) and of water use conflicts ( F in the Ebro basin. Frequency and intensity of agricultural and urban water shortage under current Sustainability of current water uses (2009) under the hydro-climatic conditions of the (b) maximum agricultural water shortage (MS),catchment. reliability Only (Rel) demand at nodes thethe main with radar demand charts. at nodes least of one each non-null indicator value are represented in Figure 12. recent past (1971–2009) for water shortage ( Figure 11. water uses (2009) andbasin and hydro-climatic conditions in the period 1971–2009