Influence of Groundwater Exploitation for Urban Water Supply on Temporary Ponds from the Donana National Park (SW Spain)

摘要

Groundwater fluctuations were monitored in several temporary ponds from the Donana National Park (SW Spain) throughout five hydrological cycles from October 1989 to September 1994. These ponds are fed by a shallow water table and rainfall. They are located sequentially towards the pumping area of a neighbouring tourist centre on the coast. In general, the water table in the ponds varied according to rainy periods, except in the closest pond to the pumping area where water table levels have followed a continuous decline since summer 1992. The lack of any significant recharge in this pond after rainfall for more than two years suggests that the water table beneath this pond has been damaged. The average levels of the water table declined each year at a rate that was significantly correlated to the altitude of each pond as well as to the distance of each pond from the pumping area. Maximum variation of water table levels from winter 1990 to summer 1994 was also correlated with the distance of each pond to the pumping area. As a result ponds closer to the pumping area have recently experienced larger drawdowns and longer dry periods. Consequently, the present rate of groundwater extraction for urban water supply in the neighbouring area is damaging the conservation of temporary ponds from the Donana National Park.