Land-use change and impacts

The Mediterranean basin has been characterized by intense human presence and landscape transformation for centuries. Recent land-use changes point to a general expansion of shrub and forest cover in low-productive mountain areas, especially in the countries on the northern side of the Mediterranean, as a consequence of farmland and grazing abandonment. However, strong urbanization and agriculture intensification are occurring in valleys and coastal areas, particularly on the southern and eastern rims of the basin that are affected by rapid population growth. Extensive revegetation on formerly cultivated land can reduce notably runoff generation and deep water percolation, with important consequences for freshwater supplies. The expansion of irrigated land and urban areas, often accompanied by tourism development, greatly increases water consumption, which may also lead to decline in river discharges and aquifer overexploitation. Projected future decline in the availability of freshwater resources and increased water demand, exacerbated by the present context of changes in climate conditions, make it urgent to establish sustainable land and water management strategies. These require deep understanding of the impact of land-use changes on water resources. Any significant advance in understanding the water cycle requires field observations and measurements accompanied by hydrological modeling approaches that simulate hydrological changes under different land-use and climate scenarios.