&nbsp; <p>In many Mediterranean coastal areas, agriculture, drinking water supply, tourism and industry strongly depend on groundwater resources. As a result of significant economic development over the last three decades along the Mediterranean coast (agricultural intensification, growth in tourism activities, population migration), abstraction from coastal aquifers has greatly increased. This has often resulted in a significant decline in water tables that has, depending on the local geological context, increased the risk of seawater intrusion (European Environment Agency, 2006; Nixon et al., 2003; Plan Bleu, 2005). </p><p>In a number of locations (in Spain, Italy and Greece for instance), although action is clearly needed to avoid any irreversible degradation of groundwater resources, pumping fever is not easily harnessed by the threat of salt water intrusion (Aguilera-Klink et al., 2000). As in many other &quot;Tragedies of the Commons&quot; (Hardin, 1968), this is often explained by the intensity of the interests at stake, the lack of appropriate institutions, the lack of effectiveness of existing instruments and an insufficient knowledge of groundwater resource functioning. More generally, groundwater management has appeared difficult to implement in situations of numerous individual users, such as farmers irrigating from boreholes and wells, both because of the difficulty of getting genuine representation of these users in the decision-making, and because of the high costs to measure water uses (Shah, 2007). Examples of success are rare and no blueprint emerges on the international staAlthough the impact of climate change on groundwater resource remains difficult to predict, the elevation of temperature and changes in precipitation patterns will strengthen the problems currently faced in these areas. In the Mediterranean region, increasing strong climatic seasonal contrasts (severe droughts and storms) have already been observed in the last century (EEA, 2004; Haas, 2002). These contrasts are likely to be exacerbated by global warming with more warm and dry summers and more precipitation during warmer winters despite shorter rainy seasons (Gibelin and D&eacute;qu&eacute;, 2003; Rowell, 2005; Wang, 2005). Uncertainties about the extreme rainfall events and droughts intensity in the future are still important (Neppel et al., 2003; Renard et al., 2006; Renard, 2006; Rowell, 2005), while some studies point out a variability increase (Diodato, 2004; Jones and Reid, 2001; Voss et al., 2002). The hydrological regime of rivers as well as the recharge of aquifers will be impacted: river discharges are expected to increase during fall and winter, snowmelt to take place earlier, periods of lower low flows to become longer and aquifer recharge to decrease (Booij, 2005; Caballero et al., 2006; Ducharne et al., 2003; Etchevers et al., 2002; Leblois, 2002; Merritt et al., 2006; Zierl and Bugmann, 2005). The reduction of river base flow will also result in a shift of agriculture water supply source from surface to groundwater, reinforcing the pressure on aquifers.</p>