Summary: Costa Rica introduced a wide variability microclimatic, with average rainfall between 1300 and 8500 mm and an ambitious environmental policy, with 27% of the territory under some protective figure. However, the inappropriate use of land and population increase in the headwaters of the basin, represent a series threat to the sustainable management of water resources and soil in the country. The river basin Birrís part System Hydroelectric Birrís, which caters to a large portion of the province of Cartago. The company JASEC, presented the electric service, has decided to intervene in the tributary basins to that system, backed by legislation costarricens to promote land management that allows the use hydroelectric compatible with the sustainability of farming activities in the watershed. To do so, JASEC proposed internalization of environmental benefits through an environmentally adjusted electric rates to finance the operations of a management plan for territorial these goals. The thesis examines the relationship between land uses and ecological status of water in the river basin Birrís, from the standpoint of sustainability, in order to build and validate a methodology for analysis of the interrelationships between those uses and the production of environmental services hidrícos. This has been modeling processes erosión-sedimentación and water balance in the basin, based on the existing data records. Simultaneously, there have been experiments in the field, by installing microparcelas runoff to determine the hydrological response of the Land Use scale farm. There has been a two-year monitoring of the ecological status of water, assessed at its three dimensions: biotic, physico and hidro-morfológica. The fieldwork has completed a survey of a representative sample of producers in the basin, in order to characterize the energy and economic system of production in the watershed. With data from the modeling and field work have been developed and selected proxy indicators of sustainability in social, economic and environmental quality of the watershed. It has also collected the views and preferences of the social groups involved in land management of the watershed: electrical generators, planners, academics, environmentalists and producers. It has conducted a survey of preference in accordance with the methodology AHP (Saaty,
1980) and has been extracted and social group weights assigned to each criterion Spatial. We have evaluated three policies or scenarios Basin (reforestador, agrarista and balanced) in two lines: biophysics and social, from sustainability indicators selected in the first phase and preferences of social groups. Fruit of work has been characterized relations between the socio-economic variables, land use and water at the basin. The variables that express the ecological status of water are estrechame 8 nt real 508 cionadas one another and jointly respond to the impacts of inappropriate uses of land in the basin studied. The ecological status of water is a good indicator of the impacts of uses indadecuados territory in the watershed study. The ecological status delas water is a good indicator of these impacts on watersheds with intense tropical farming. Based on this thesis, we recommend testing sustainability plans spatial especially when providing for the adoption of new ways to use the territory.
