Land use and land cover change influence in the runoff and sediment yield in the Xingu River Basin region

Abstract

In the 70s the Brazilian government started a series of measures in order to promote the occupation and development of the north region of the country. These measures had as consequence great changes in the country economy, placing Brazil as one of the biggest agricultural powers in the world, mainly due to the agricultural expansion for these regions. This development however was responsible for a huge devastation of the Amazon forest. Changes in the vegetation cover as occurred in Amazon can create numerous social, economic and environmental problems. One of the environmental factors that are significantly affected is the hydrological cycle of the region, once the vegetation cover has direct and indirect relationships with phases of the cycle as evapotranspiration, infiltration and runoff. The increase of the runoff implies in a higher transport of sediments and nutrients for the rivers, causing several environmental problems as erosion, silting, and eutrophication. The magnitude and consequences of these problems in this region is not well known, however the development of new tools for hydrologic and erosion modeling are making possible a more efficient quantification and monitoring of this problem. The hypothesis of this work is that the deforestation of the Amazon forest in the last decades had as consequence the increase of the runoff and sediment yield in the region. In order to test this hypothesis runoff and sediment yield will be estimated by models for different dates. Land use and land cover for before the agriculture expansion, actual and future scenarios will be analyzed, these information will be obtained using satellite images and land use and land cover change simulation models. Several other parameters will be incorporated into the study and be considered constant along all the periods analyzed as soil maps, digital elevation model, and precipitation data. At the end of this work it is expected to understand in a more detailed way the impacts of the deforestation in the hydrological cycle and sediment yield in the study area, as well as to generate contributions for decision takes in areas where conservationist measures will have to be taken. (AU)