Estimation and mapping of gross erosion in the Seridó River watershed, Brazil

Abstract

The Northeastern backlands are currently subject to environmental damage, an intensifying of surface morpho-dynamic processes caused by intensive and inadequate (and ultimately erosive) soil use. Such interference results in complications for the socio-environmental relationship. Erosion and silting cause, among other consequences, socio-environmental and economic impacts, such as soil destruction, decrease in agricultural productivity, reduction in capacity for rivers and reservoirs, as well as water availability decrease. The present research sought to evaluate gross erosion of the Seridó River Basin (RN-PB, 10 thousand km2) in order to understand how erosion the basin. Primary and secondary data were applied to elaborate thematic maps, was elaborated a theoretical-methodological review of the object, being also used remote sensing in addition to geostatistical methods and sedimentological modeling. Estimating the gross erosion, the Universal Soil Loss Equation (EUPS) was applied to the 1992-2015 period. With this, it was possible to spatially interpolate the variables of interest for the whole basin. Maps were generated for rain erosivity, soil erodibility, topographic factor, use factor and soil cover. This information allowed the parameterization of the EUPS, which synthesizes the mean gross erosion of the basin. According to the results, the average gross erosion of the basin is 29 ton ha-1.yr-1, but at some critical points, the gross erosion exceeds 100 ton.ha-1.yr-1. The applied methodology allowed, therefore, a temporal and spatial evaluation of the sediment production in the basin.