18 th World IMACS / MODSIM Congress, Cairns, Australia 13-17 July 2009 http://mssanz.org.au/modsim09 Participatory analysis of the Jucar-Vinalopo (Spain) water conflict using a Decision Support System Andreu, J. 1 , M. A. Pérez 1 , J. Paredes 1 , and A. Solera 1 1 Instituto de Ingeniería del Agua y Medio Ambiente (IIAMA), Technical University of Valencia (UPV), Valencia, Spain E-mail: ximoand@upv.es Abstract: New water policies around the world are demanding more integrated, participatory, sustainable, efficient, and equitable planning and management of water resources. All this considerations introduce a higher degree of complexity into the already complex task of integrated water resources management. In the process of making good decisions, information must be managed and analyzed about the feasible alternatives, their impact on the multiple objectives, the tradeoffs among them, as well as risks associated with them. To elaborate and analyze such information, sound science, technology, and expertise have to be involved. Moreover, tools for data management and analysis, and models are needed in order to cope with the complexity, the basin scale scope, and the huge amount of information, alternatives, and scenarios. But frequently, decision makers, stakeholders and general public, that is, Policy Making Actors (PMA), are not prepared to produce and understand such information. Therefore, a transfer of technology and ideas from scientist to PMA is needed. This has to be an effective transfer in the sense that PMA must be able to apply the technology easily and in a repeatable and scientifically defensible manner. One of the best ways to conduct this transfer, and to build a shared vision of the basin, is through the joint development of Decision Support Systems (DSS). Furthermore, DSS are essential for the purpose of providing integration, easiness of use, sensitivity analysis, and risk assessment. In this contribution, their use in the participatory analysis of the Jucar-Vinalopo Project (JVP) water conflict is presented. The JVP is a transfer of water from the Jucar Basin to the Vinalopo Basin, both in Eastern Spain, which was approved in a Basin Plan in 1998. The project included an intake in a reservoir located the middle part of the Jucar river, and after a lift of 500m and 80 km of canals and pipes, it should deliver water to San Diego artificial reservoir, in the Vinalopo basin. Construction started in 2002, and in summer 2004, environmental organizations and traditional irrigation farmers of the lower Jucar Basin obtained from the newly elected Spanish government an opportunity to re- examine the project. A Participatory Technical Committee (TC) including all Policy Making Actors and experts in the subjects was working for 4 months in joint development of a DSS (including basic data). In order to simulate the alternatives, all data and scenarios were agreed. The TC obtained as results the trade- offs between demand water deficits and environmental requirements at Jucar River and Albufera wetland, and between potential average transfer and environmental requirements. A complete report was elaborated, including all agreements, disagreements and results, summaries and synthesis. The results were presented to a Broader General Committee including additional representatives of the Regional Governments, National Government, and European Commission. Finally, it was decided by the Ministry of Environment to modify the project to set up the intake of the transfer in La Marquesa small dam (close to the mouth of Jucar river by the Mediterranean Sea). Now, the new JVT project is under construction, and it will be finalized by 2010. DSS for JVP has been developed using AQUATOOL DSS shell developed at Technical University of Valencia (UPV), facilitating the development and use of the DSS. In fact, every one of the parties was able to use the resulting DSS in their PC, so that they could perform simulations on their own, or verify results offered by other parts. In this way, they were able to differentiate the objective elements from the subjective opinions on the alternatives and the results. Keywords: Decision Support Systems (DSS), Water Conflict Resolution, Integrated Water Resources Planning and Management, Spain 3230