Decision Support System for Drought Planning and Management in the Jucar River Basin, Spain

Most watersheds in East and South-East Spain can be classified as semi-arid or arid with large space and time variability in precipitation and river flows. Therefore, water resource systems planning and management must be done with emphasis on drought preparation and mitigation. Administration of water is performed at basin scale by Basin Agencies (Confederaciones Hidrograficas) since early in the 20th century, and water laws enforce the design and implementation of Basin Plans (BP), since 1985, and of Special Drought awareness and mitigation Plans (SDP) at basin and local scales, since 2000. The use of models and Decision Support Systems (DSS) has played an important role in the development of the Jucar Basin Plans for almost two decades, as well as for the development and implementation of the Special Drought awareness and mitigation Plans (SDP). The SDP's have been formulated according to a proactive approach to drought preparedness and mitigation. They include long term (planning), medium term (alert) and short term (emergency and mitigation) measures that are activated using Standardized Drought Monitoring Indicators (SDMI) based on the use of combinations of data provided by the ASAS on precipitation, storage in reservoirs, groundwater levels, and flows in rivers. The SDMI and the curves of thresholds for assessment of the drought situation have been calibrated by intensive use of DSS for drought risk estimation. Besides of the regular use of the SDMI, DSS are also permanently used at the real time management board meetings to assess drought risks and vulnerability at medium and short terms. When entering into a drought alert or emergency situation, DSS are a way to evaluate the effectiveness of the measures to modify the risks and to mitigate the impacts of the drought. This is of great help in the negotiations among the parties in the participatory drought committees set up in emergency situations. In this contribution, the experience using these tools during the 2005-2008 drought is reported. This is the most intense hydrological drought registered in the basin in recorded history (since 1940). Due to the highly stressed situation of the basin (ratio of used to renewable resources is around 0.7) situations like this threaten economic uses of water and environment, with big potential damages. Among the measures used during this drought we can find increase of efficiency in water use; improvement in control devises for surface water diversion, groundwater abstraction, and environmental flows; continuous monitoring and inspection of water use and environmental state; anticipated conjunctive use of surface and groundwater, direct reuse of treated wastewater, combined use of two neighbor basins, temporary water rights purchases, and emergency works to improve connectivity in the system. As a result, the worst drought in modern times has been passed with relatively low economic and environmental damages; urban supply was always fulfilled; and conflicts among users solved in an atmosphere of transparency, and cooperation fostered by the mentioned methodologies. DSS for Jucar Basin has been developed using Aquatool DSS Shell developed at Technical University of Valencia (UPV), facilitating the development and use of hydrological, management, water quality and risk assessment models by the Basin Agency professionals.