Wetlands are important sources of renewable fresh water for human basic needs. Renewable water resources can be found at the surface or underground. Indeed, water supply comes from an array of inland wetlands, including lakes, rivers, swamps (surface water), and groundwater aquifers (renewable and fossil groundwater).
In the Mediterranean, water resources are limited and unequally distributed. Pressure on water is increasing in the Mediterranean, especially in summer and in coastal areas, where population, tourism and other activities concentrate. These pressures are expected to increase along with demographic growth, economic and social changes and climate change. Especially, the water-poorest territories may be the most heavily affected: by 2100, precipitations are foreseen to diminish by 20 to 30% in the Southern countries and by 10% in Northern countries.
Overuse of surface water provokes surface wetlands disappearance and decrease water tables recharge. The combined effect of this and of groundwater overexploitation speeds up the drying of groundwater tables. This impacts not only the quantity of available resources but also its quality (intrusion of seawater in coastal aquifers for instance). General water quality deterioration occurs in many parts of the Mediterranean region, due mainly to contamination (waste, fertilisers), mismanagement during irrigation practices and overexploitation of coastal aquifers.
The purpose of measuring the indicator “Supply of water” is to assess the role of wetlands in providing water for human consumption. This MWO indicator has yet to be developed.