The ecological importance of groundwater modellisation making use of different grid sizes
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Publication Editor
Hemminga, MartenKazungu, Johnson
Jurgen, Tack
Mtolera, Matern
Ron, Johnstone
Domingos, Gove
Jose, Paula
Date
1998
Metadata
Show full item recordAbstract
Several studies illustrate the conflicts between water resource management and the quality of estuarine habitats. Nichols et al. (1986) describe how, in California (U.S.A.), the flow from two major tributaries to San Francisco Bay (San Joaquin and Sacramento rivers) has been reduced to less than 40% of historic levels. Most of the historic flow upstream in the watershed is now hold in reservoirs for use by agricultural and urban consumers during dry California summers. The projects upstream have resulted in three major ecological impacts: (1) collapse of the salmoid fisheries which is directly attributable to the construction of the Shasta Dam, (2) reduced freshwater inflow together with overfishing resulted in the decline in abundance of sturgeon, sardines, flatfish, crabs, and shrimp, and (3) the diminished freshwater inflow is probably responsible for the reduction of the capacity of this estuary to dilute, transform, or flush contaminants that are diluted into San Francisco Bay (Nichols et al., 1986). Even when changes in volumes of groundwater discharge are small, alteration of timing of freshwater flow can result in negative impacts in the estuarine ecosystems. Since 1900 twenty eight dams have been constructed on the Columbia River (U.S.A.). Management policies have reduced springtime freshwater flows to 50% of former levels, while fall discharges have been artificially increased by 10-50% (Simenstad et al., 1992). These changes had a negative effect on salmon fisheries in the region.Page Range
pp.105-113Title of Parent Book or Report
Anthropogenically induced changes in groundwater outflow and quality, and the functioning of Eastern African nearshore ecosystems (GROFLO)- INCO-DC: International Cooperation with Developing Countries (1994-1998) Contract number: ERBIC18CT960065 - GROFLO Final Report Part 2 -- Individual Partner ReportsPublisher or University
Netherlands Institute of Ecology, Centre for Esturarine and Coastal EcologyCollections