O processo erosivo na Bacia do Alto Paraguai

The Pantanal Matogrossense can be subdivided into three physiographic provinces, Planaltos, Pantanais and Morrarias, characterized by peculiar geologic, geomorphologic, hydrologic and pedologic features. On the Planaltos province, large extensions of florestas and cerrados, have been submitted to deforestation and were replaced by farming and cattle raising activities from the 70's years. In the process of transformation, the deforestation is normally done by burnt or extracted trees with the use of weight agricultural machines. As a consequence of that activity, the erosive process suffered a great acceleration, taking to loss portions of productive lands and flooding of low areas in the Pantanal basin. The aim of the present paper is to evaluate the changes on the use and occupation of the soil in the last thirty years and theirs consequences on the erosive process of the region. It has been analyzed in three different moments : 1966, 1985 and 1996. Statistical analysis of multitemporal data base were carried out to compare the land cover changes in these provinces. The 66's data was available from the DSG/IBGE (Geographic Division of Brazilian Army and Brazilian Institute for Geography and Statistics); the 1985 and 1996 data have been obtained from Landsat TM images interpretation. Four pilot areas were chosen for detailed study: the Taquarizinho basin, located southern from Coxim, the Arica-Açu and Arica-Mirim basins, on the northern part of Alto Paraguai Basin, the Pedro Gomes region and the rio Correntes / Itiquira Chapada. The laminar erosion on the first three areas was calculated with the application of the Universal Soil Loss Equation, aided by Geographic Information System and Remote Sensing techniques. The results obtained put in evidence the environmental dynamic occurred on the Pantanal region in the last thirty years.