Wetlands play a major role in the regulation of water flow, attenuating both the number and the intensity (peak) of extreme events like floods and droughts.
Floods and droughts are common in the Mediterranean basin due to highly variable rainfall regimes. They lead to important human and economic damage each year. For instance, between 2000 and 2009, more than 2 million people were affected by drought in the Mediterranean countries and more than 1.1 million by floods, of which, more than 2,000 lost their lives. Meanwhile, the cost of these damages was evaluated at nearly 3 billion USD for drought and more than 16 billion for floods. The economic, social and psychological impacts of flood damage can be disastrous.
There is an increasing demand by societies for natural hazard and water regulation, and especially for flood protection. Two factors may explain this demand: (1) the increase of urbanisation in the valleys, especially with the concentration of cities and human activities close to rivers, and (2) the reinforcement of the legislation on risk management (EU Flood Directive, 2007). Moreover, climate change is expected to exacerbate the risk of droughts and floods in the Mediterranean region. Meanwhile, river regulation, urbanisation and floodplain destruction have resulted in reduced flood retention capacity of wetlands and higher level of run-off. Hence, the risk and severity of floods has increased. This negative trend has continued since 1950.
The sustainable management of flooding risks thus involves combining several activities such as flood control works, appropriate urban planning and the protection of natural wetlands’ regulatory functions. Using the natural capacity of wetlands to attenuate floods is another complementary, cost-effective way to reduce flooding risks. It involves the conservation and restoration of crucial ecosystems like wetlands and floodplains.
The indicator “Attenuation of flood and drought” aims at measuring the specific role of wetlands in the regulation of the river flow variability as well as disaster mitigation. This MWO indicator has yet to be developed.