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South‐east Spain is a drought prone area, characterized by climate variability and water scarcity. The Jucar River Basin, located in Eastern Spain, has suffered many historical droughts with significant socio‐economic impacts. For nearly a hundred years, the institutional and non‐institutional strategies to cope with droughts have been successful through the development of institutions and partnerships for drought management including multiple actors. In this paper, we show how the creation and institutionalisation of Multi‐Sector Partnerships (MSPs) has supported the development of an efficient drought management. Furthermore, we analyze the performance of one of the suggested instruments by the partnership related to drought management in the basin. Two methodologies are used for these purposes. On one hand, the Capital Approach Framework to analyze the effectiveness of the governance processes in a particular partnership (Permanent Drought Commission), which aims to highlight the governance strength and weakness of the MSP for enhancing drought management in the Jucar River Basin. Through a dynamic analysis of the changes that the partnership has undergone over time to successfully deal with droughts, its effectiveness on drought management is demonstrated. On the other hand, an econometric approach is used to analyze the economic efficiency of the emergency drought wells as one of the key drought mitigation measures suggested by the Permanent Drought Commission and implemented. The results demonstrate the potential and efficiency of applying drought wells as mitigation measures (significant reduction of economic losses, around 50 M€ during the drought period, 2005–2008).

Abstract. Climate and land use change (global change) impacts on groundwater systems cannot be studied in isolation. Land use and land cover (LULC) changes have a great impact on the water cycle and contaminant production and transport. Groundwater flow and storage are changing in response not only to climatic changes but also to human impacts on land uses and demands, which will alter the hydrologic cycle and subsequently impact the quantity and quality of regional water systems. Predicting groundwater recharge and discharge conditions under future climate and land use changes is essential for integrated water management and adaptation. In the Mancha Oriental system (MOS), one of the largest groundwater bodies in Spain, the transformation from dry to irrigated lands during the last decades has led to a significant drop of the groundwater table, with the consequent effect on stream-aquifer interaction in the connected Jucar River. Understanding the spatial and temporal distribution of water quantity and water quality is essential for a proper management of the system. On the one hand, streamflow depletion is compromising the dependent ecosystems and the supply to the downstream demands, provoking a complex management issue. On the other hand, the intense use of fertilizer in agriculture is leading to locally high groundwater nitrate concentrations. In this paper we analyze the potential impacts of climate and land use change in the system by using an integrated modeling framework that consists in sequentially coupling a watershed agriculturally based hydrological model (Soil and Water Assessment Tool, SWAT) with a groundwater flow model developed in MODFLOW, and with a nitrate mass-transport model in MT3DMS. SWAT model outputs (mainly groundwater recharge and pumping, considering new irrigation needs under changing evapotranspiration (ET) and precipitation) are used as MODFLOW inputs to simulate changes in groundwater flow and storage and impacts on stream-aquifer interaction. SWAT and MODFLOW outputs (nitrate loads from SWAT, groundwater velocity field from MODFLOW) are used as MT3DMS inputs for assessing the fate and transport of nitrate leached from the topsoil. Three climate change scenarios have been considered, corresponding to three different general circulation models (GCMs) for emission scenario A1B that covers the control period, and short-, medium-and long-term future periods. A multi-temporal analysis of LULC change was carried out, helped by the study of historical trends (from remote-sensing images) and key driving forces to explain LULC transitions. Markov chains and European scenarios and projections were used to quantify trends in the future. The cellular automata technique was applied for stochastic modeling future LULC maps. Simulated values of river discharge, crop yields, groundwater levels and nitrate concentrations fit well to the observed ones. The results show the response of groundwater quantity and quality (nitrate polPublished by Copernicus Publications on behalf of the European Geosc...

Water pricing policies have a large and still relatively untapped potential to foster more efficient management of water resources in scarcity situations. This work contributes a framework for designing equitable, financially stable and economically efficient urban water tariffs. A hydroeconomic simulation model links the marginal value of water, which reflects water scarcity given its competing uses, to water supply reservoir levels. Varying reservoir levels trigger variations in the second block of the proposed twoblock increasing-rate tariff; these variations then reflect water's value at that time. The work contrasts the two-block scarcity tariff with a constant volumetric rate for the city of Valencia, Spain, and the drought-prone Jucar basin, where most of 430,000 households are equipped with smart meters. Results show urban consumption is reduced by 18% in the driest years, lowering basin-wide scarcity costs by 34%.