Characteristics of Spanish Reservoirs

摘要

Sau Reservoir was first filled in 1963 in a middle stretch of the Ter River, as part of a multi-use scheme, including hydroelectric power, agricultural irrigation, domestic and industrial water supply to metropolitan areas, and also recreational activities. Since it was built, the reservoir has experienced a process of increasing eutrophication (Vidal and Om 1993), from moderately eutrophic during the first years after filling, to severe eutrophication in the late 1980s. Several human activities in the basin fed the process: intensive use of fertilizers, pig and stock farming development, proliferation of industrial areas and changes in land use (Sabater et al. 1990; Sabater et al. 1991; Vidal and Om 1993; Sabater et al. 1995; Espadaler et al. 1997). To improve the quality of water supplied by the reservoir, wastewater treatment plants were built in main urban and industrial areas during the early 1990's (Vidal and Om 1993). Limnological characterization of Sau Reservoir started in 1963, conducted by the local water supply company ( Aig es Ter- Llobregat , ATLL). Since 1995, this study is executed in collaboration with the Department of Ecology at the University of Barcelona, under supervision of Dr. Joan Armengol. Thus, a good database is available on both changes in the water body and on incoming materials through main inflows (the Ter River and the Major River, accounting for 85% and 8% of land drained by Sau Reservoir, respectively). The basic sampling frequency is monthly. Besides in-situ measured descriptors (i.e. temperature, conductivity, turbidity, dissolved oxygen concentration, pH, redox potential, and water transparency), chemical analyses are conducted on samples taken at several depths.