ORIGINAL ARTICLE Multi-objective, multiple participant decision support for water management in the Andarax catchment, Almeria N. Van Cauwenbergh Æ D. Pinte Æ A. Tilmant Æ I. Frances Æ A. Pulido-Bosch Æ M. Vanclooster Received: 10 November 2006 / Accepted: 1 May 2007 / Published online: 27 June 2007 Ó Springer-Verlag 2007 Abstract Water management in the Andarax river basin (Almeria, Spain) is a multi-objective, multi-participant, long-term decision-making problem that faces several challenges. Adequate water allocation needs informed decisions to meet increasing socio-economic demands while respecting the environmental integrity of this basin. Key players in the Andarax water sector include the municipality of Almeria, the irrigators involved in the intensive green- house agricultural sector, and booming second residences. A decision support system (DSS) is developed to rank differ- ent sustainable planning and management alternatives according to their socio-economic and environmental per- formance. The DSS is intimately linked to sustainability indicators and is designed through a public participation process. Indicators are linked to criteria reflecting stake- holders concerns in the 2005 field survey, such as fulfilling water demand, water price, technical and economical effi- ciency, social and environmental impacts. Indicators can be partly quantified after simulating the operation of the groundwater reservoir over a 20-year planning period and partly through a parallel expert evaluation process. To predict the impact of future water demand in the catchment, several development scenarios are designed to be evaluated in the DSS. The successive multi-criteria analysis of the performance indicators permits the ranking of the different management alternatives according to the multiple objec- tives formulated by the different sectors/participants. This allows more informed and transparent decision-making processes for the Andarax river basin, recognizing both the socio-economic and environmental dimensions of water resources management. Keywords Decision support Á Stakeholder involvement Á Sustainability indicators Á Water management Á Multi-criteria analysis Introduction Water scarcity is one of the most important causes for societal problems in arid or semi-arid regions. It is not as much the physical scarcity, but rather the mismanagement of the water resource, that is at the basis of these water problems and the imminent water crisis (Llamas 2004). This situation also applies to the Andarax river basin in the province of Almeria, situated in the south-east of (Fig. 1), one of the most arid regions in Europe. This river basin is the test site for the EU project ALERT, which aims at achieving sustainable water use without compromising the quantity and quality of the groundwater stored in the Andarax aquifer. Special attention is given to the problems of saltwater intrusion currently experienced in the aquifer. The Andarax river basin (Fig. 1) comprises an alluvial valley of about 250 km 2 and a mountainous area around 2,000 km 2 consisting of four mountain ranges: Sierra Alhamilla, Sierra de Filabres, Sierra de Gador and Sierra N. Van Cauwenbergh (&) Á D. Pinte Á M. Vanclooster Agricultural Engineering Unit, Catholic University of Louvain (UCL), Place Croix du Sud 2, Bte 2, 1348 Louvain-la-Neuve, Belgium e-mail: vancauwenbergh@geru.ucl.ac.be A. Tilmant UNESCO-IHE Institute for Water Education, P.O. Box 3015, 2601 DA Delft, The Netherlands I. Frances Á A. Pulido-Bosch Grupo de Investigacion de Recursos Hidricos y Geologia Ambiental, Universidad de Almeria (UAL), Edificio CITE II-B, 04120 Almeria, Spain 123 Environ Geol (2008) 54:479–489 DOI 10.1007/s00254-007-0847-y