Sustainable management of water resources using remote sensing and geographical information systems at the Reventazon Basin

An integration of digital elevation modelling, satellite remote sensing and geographic information systems of land-cover and land-use in the Reventazon Basin in Costa Rica has been used to identify deforestation trends and possible sources of enhanced sediment erosion. The Reventazon Basin has currently two hydropower complexes in operation for a total installed capacity of 120 MW. Additionally, the basin is a major source of drinking-water for San Jose, Costa Rica's capital city. A good understanding of lan-use change/hydrologic relationships is necessary for sustainable development of the region. Drainage basins boundaries and slope distribution maps were extracted from a Digital Elevation Model (DEM) generated from 1:50,000 topographic maps. A stratified approach for land use identification using four aggregated land use classes (forest, pasture, urban areas, and agricultural lands) was developed and applied to Landsta Thermatio Mapper scenes from 1986 and 1991. The techniques described in this paper quantify the occurrence and spatial distribution of specific land use categories as a function of slope for the basins. The remote sensing and DEM information was later combined through a Geographic Information System (GIS). The results provide a framework for designing focussed field measurements and policy programs related to soil conservation, and for protecting water resources. In the Reventazon Basin these techniques could help to resolve conflicts between agriculture, hydropower generation, and water quality that are affecting the sustainable management of the basin at several reservoir sites.