Environmental Modelling & Software 18 (2003) 413–427 www.elsevier.com/locate/envsoft SINUSE: a multi-agent model to negotiate water demand management on a free access water table S. Feuillette a1 , F. Bousquet b,* , P. Le Goulven c a LIA-GEODE, IRD, 32 avenue Varagnat, 93143 Bondy, Cedex, France b CIRAD IRRI, Chatuchak, P.O. Box 9-159, 10900 Bangkok, Thailand c DIVHA, Maison des Sciences de l’Eau, IRD/MSE, BP 64501, 34394 Montpellier, Cedex 5, France Received 13 May 2002; received in revised form 2 December 2002; accepted 9 December 2002 Abstract Many water tables are currently overexploited throughout the world. This situation raises the question of their management. Integrated management of such systems, established in both supply and demand areas, calls for thorough knowledge of the func- tioning of both the water table and its users, so models are usually required. This study is based on the case of the Kairouan water table, located in Tunisia, which has been continuously and globally decreasing for more than 20 years, due to overexploitation by private irrigators. The field study led to the hypothesis that the dynamics of the system is heavily influenced by local interaction between the resource and its users, and by direct, non-economic interaction between the farmers. The literature shows that several kinds of model have already been used to represent interaction between a water table and its users but none of them are able to take this kind of social behaviour into account. The simulator of a water table and user interaction (SINUSE) based upon multi- agent systems enabled us to overcome these limitations. This model proved to be very useful for representing a complex and distributed system such as the Kairouan water table. It enabled us to explore the interaction between the physical and socio-economic components of the system and to conclude that local and non-economic behaviour do have a major impact on the global dynamics of the system and must therefore be taken into account. The management interventions simulated with the SINUSE model have raised interesting questions, leading to the conclusion that this model could provide a useful tool for negotiating the integrated management of the water table system. Though this model is rather specific, the approach developed could be transferred to other water table systems, to improve the knowledge of their functioning and examine the possible impacts of different management tools.  2003 Elsevier Science Ltd. All rights reserved. Keywords: Water table overexploitation; Irrigation; Multi-agent systems; Water demand 1. Introduction Groundwater is the most abundant fresh water resource directly available on earth. Nowadays, numer- ous water table systems suffer from overexploitation (Berkoff, 1994), which introduces a growing threat of non-viability. Indeed, such situations can provoke salt- water intrusion into the groundwater or massive increases in water extraction costs, leading to non-viable * Corresponding author. Tel.: +66-2-942-7025; fax: +66-2-561- 4894. E-mail addresses: feuillette.sarah@aesn.fr (S. Feuillette); bous- quet@cirad.fr (F. Bousquet); patrick.legoulven@mpl.ird.fr (P. Le Goulven). 1 Tel.: +33-1-43-73-01-52; fax: +33-1-48-47-30-88. 1364-8152/03/$ - see front matter  2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S1364-8152(03)00006-9 situations over the short-term. Moreover, even when such problems are not encountered, the continuous drop in a water table raises the long-term question of trans- mission of the resource to future generations. So it is important to think about the management of these systems. As acting upon the water resource—by replenishing the water table or supplying water from other sources—is increasingly difficult and costly, the capacity to control water demand becomes a key issue for the sustainability of these systems (Bhatia et al., 1995). Several kinds of tool are used to manage water demand (Montginoul, 1998) and have been applied to water tables: technical tools, such as microirrigation, to improve irrigation; economic tools such as fees, taxes (Kosciusko-Morizet et al., 1998), water charges (Blomquist, 1992) or water markets (Meinzen-Dick,