Water

Water resources in the Mediterranean are scarce. They are limited, unevenly distributed and often mismatching human and environmental needs. Three quarters of the resource are located in the northern Mediterranean while three quarters of the needs are in the south and east. As a consequence, approx. 180 million people in the southern and eastern Mediterranean countries suffer from water scarcity (<1,000 m3 capita-1 yr-1). The main water user is agriculture, in particular on the southern and eastern rim. The percentage of irrigated land of the total cultivated area is 25% for the Mediterranean Basin and is currently increasing, likely with higher rates under even drier climate conditions in the future. Water demand for both tourism and agriculture peak in summer, potentially enhancing tensions and conflicts in the future. Municipal water use is particularly constrained in the south and will likely be exacerbated in the future by demographic and migration phenomena. In parallel, northern countries face additional risks in flood prone areas where population and urban settlements are rapidly increasing. Climate change, in interaction with other drivers (mainly demographic and socio-economic developments), has mainly negative consequences for the water cycle in the Mediterranean Basin, including reduced runoff and groundwater recharge, increased crop water requirements, increased conflicts among users, and increased risk of overexploitation and degradation. These impacts will be much more important for global warming higher than 2°C. Strategies and policies for water management and climate change adaptation are strongly interconnected with all other sectors (e.g., the Water-Energy and Food Nexus). Technical solutions are available for improving water use efficiency and increasing reuse. Seawater desalination is increasingly used as adaptation measure to reduce (potable) water scarcity in arid and semi-arid Mediterranean countries, despite known drawbacks in terms of environmental impacts and energy requirements. Promising solar technologies are under development, potentially reducing emissions and costs. Reuse of wastewater is a solution for agriculture and industrial activities but also recharge of aquifers. Inter-basin transfers may lead to controversies and conflicts. Construction of dams contributes to combat water and energy scarcities, but with trade-offs in terms of social and environmental impacts. Overall, water demand management, which increases water use efficiency and reduces water losses, particularly in urban environments, is crucial for a sustainable development. Maintaining Mediterranean diet or coming back to it on the basis of locally produced food and reducing food wastes may save water but also carbon emissions while having nutritional benefits.