Avaliação de cenários de uso e ocupação do solo em uma pequena bacia não instrumentada usando o modelo swat.

Abstract

In arid regions and semi-arid to spatial and temporal variability and rainfall, as alterations the use and occupation of ground, the kinds of ground and the adverse climatic conditions and the occurrence of intense rains with short duration, when associate the absence of conservationist practices, influence directly in generation of outflow and in the production of sediments into hydrographics basins. The present job have the objective of evaluate sceneries alternatives of occupation of ground into a small hydrographic basin not instrumented using a model SWAT (Soil and Water Assessment Tool) for environmental planning purposes. A sub-basin of experimental basin of Poço de Pedras with drainage area of 3,23 km2 was chosen to estimate the leak blade and the production of sediments considering four sceneries of use and the occupation of ground. The characteristics of the use and occupation of ground, kinds of ground, topography and morphology, were obtained by supervised classification of images of satellite LANDSAT 5. The results obtained to the annual loss of the ground through the production of sediments indicate that the small interventions in the area of the basin, as the rotation of areas intended to the pastures, will allow the natural recomposition of vegetation in the areas in fallow, with consequent reduction of production of sediments. When we compared the results of drain blades and productions of sediments obtained through three alternatives sceneries of use and the occupation of ground with the actual scenery , the scenery number one, presented a variation of – 89,6% for + 19,0% , for the blade drained annual, and – 100,0% for + 20,0% , for the annual production of sediments. Through the distribution spatial of production of sediments, we can identify areas with the greatest need of intervention.