Las aguas subterráneas en Doñana y su valor ecológico

Abstract

Doñana is the coastal area situated between the lower tracts of the Guadalquivir and Tinto rivers, in the SW of Spain, which covers about 3400 km2. Climate is Mediterranean with Atlantic influence. A part of the area constitutes extensive temporal marshes, and the remaining part forms sandy areas covered with brush and occasional forest. The underground part constitutes the large Doñana aquifer. The Doñana aquifer, up to 300 m thick in their central position, although commonly less than 100 m thick, is a key element to the important ecological values of the area, and to the human needs as well. The inhospitable environmental of the area kept it little disturbed until the 1950’s, and especially the 1970’s, when timber forest was introduced, and then intensively irrigated fields with local groundwater, touristic developments and population growth, but also with the creation for conservation purposes of the Doñana’s Biological Station, the National and Natural Parks, and with a progressive awakening of authorities and population conscience of the natural values to preserve and of the goods and services they provide. Groundwater development, up to about 90 million m3/year, has had as a consequence the water–table drawdown, the reduction or disappearance of ravine flows, lagoons and phreatophyte areas, as well as chemical changes, still going on, due to the use of agrochemicals and the infiltration of agriculture and population wastes. Conservation has to solve the interest’s conflict between Nature and human water demand, which has to be changed from concurrence into complementarity.