Water resources and environmental change in Spain. A key issue for sustainable integrated catchment management

Abstract

There are many evidences of water resources diminution in different parts of Spain for the period 1921-99, representing in average a 0.4% per year. This diminution has been claimed to be the result of the increasing irrigation and the climate variability. The main land use and cover change in Spanish mountain areas has been, since the middle of the XX century, the afforestation subsequent to land abandonment, both spontaneous and supported by Spanish and European policies. The causal links between the increase in forest land cover and decrease in water yield have been largely demonstrated at the experimental catchment scale, although there is less evidence of these links at the operational scale. The analysis of the water balance of several Spanish catchments during the last 50 years, showed that the main part of the observed decreases in flow are not explained by increases in water consumption by irrigation or by climate variability, but should be attributed to a change in the response of the headwaters. The relationships between change in forest cover and water flow decrease for these catchments were found similar to the relationships described elsewhere as experimental results. The management of land cover should be therefore taken into account for a true integrated catchment management.