Susceptibility and risks to water erosion in the upper of Araguaia River Basin (GO/MT), Brazil

Abstract

erosion, the most important cause of the accelerated loss of properties on agricultural lands by reduction of fertility, desertification and increase of recent sedimentation in the hydrical channels. The laminar erosion is a common form but no evident signs are visible, except when the roots appear on the cultures and pastures. It is caused by runoff, mainly in the tropics. Some soils have high susceptibility and risks to this form of erosion, frequently the fine sandy soils after deforestation of their original cover and replacement by intensive agricultural an pasturage activities without conservational practices. This article presents the results of the laminar erosion in the Upper Araguaia River Basin situated in the Central Plateau of Brazil, an important area of recharge level of large rivers, in part situated under states of Goias and Mato Grosso and covered by the savannah named Cerrado in Brazil. This area is suffering an intensive and indiscriminate deforestation of the original dominant savannah (83%) in the landscape in the last 40 years, resulting in rapid substitution by soy and cotton cultures and pasturages, near 45% of total of area in 1999. This process are is propagated from the high plateau where the clayey soils and smooth relief are predominant corresponding to a high land use capacity, to the lowered dissected zones that contour it, covered by fine sandy soils, non-cohesive, with fine porosity, lower fertility and organic matter too (Quartzarenic Sandy Sols in Brazilian Soil Taxonomy) (equivalent Inceptsols in the USA Soil Taxonomy) without conservational practices. In addition, the tropical climate have an annual precipitation concentrated in the summer, about