Morphopedologic approach for diagnosis and control of erosion

Abstract

This paper describes a morphopedological approach applied to the Sapo River sub-basin to support territorial management for soil and water conservation. The approach follows the conception of the morphopedological compartment presented by Salomão (1994), which considers terrain homogenous units based on soil, relief and geological substrate. Three thematic maps of 1:50,000 scale were made to characterize the morphopedology. Afterwards, spatial analyses techniques were developed in GIS to outline the morphopedological compartments considering the hydraulic functions of the relief inclination. As a result, 11 compartments of the physical environment with specific characteristics have been identified. Relatively smooth terrains predominated, formed by sandy soils in 76.41% of the studied area, represented by the MP-06 and MP-08 morphopedological compartments. These two units, together with the Quartzarenic Neosol, the MP-10 compartment with erosive amphitheaters of drainage head waters, the colluvial slopes and slope talus from the MP-07, and the median and low mountain sides of median hills of the MP-05 compartment, constitute the regions most vulnerable to erosion. Erosion occurs predominantly at the bottom of fluvial valleys from MP-05 and MP-06 and at drainage head waters, resulting in direct impacts on soil and waters of the basin due to silt build-up, hydromorphism losses and decrease of the water level. It was concluded that preventive actions are necessary to control erosion, especially in the most fragile areas.