SPATIAL AND TEMPORAL MODELING OF WATER EROSION IN DYSTROPHIC RED LATOSOL (OXISOL) USED FOR FARMING AND CATTLE RAISING ACTIVITIES IN A SUB-BASIN IN THE SOUTH OF MINAS GERAIS

Diogo Olivetti,Marx Leandro Naves Silva,Ronaldo Luiz Mincato,Joaquim Ernesto Bernardes Ayer,Nilton Curi

doi:10.1590/s1413-70542015000100007

Abstract

Water erosion is one of the most important soil degradation processes and it can be intensified by land use and vegetal covering changes. Thus, water erosion modeling studies associated to multi temporal analyses of land use are effective in assessing how changes in land cover affects sediment yield. Therefore, considering the modifications in the land use from 1986 to 2011, the aim of this study ranged to estimate water erosion rates and compare them to the soil loss tolerance (SLT) limit in the Latosols (Oxisols) at Ribeirão Caçús sub-basin, in the South of Minas Gerais State, Southeast Brazil, by means of the Revised Universal Soil Loss Equation (RUSLE) in association with the geographic information system (GIS), and geostatistical techniques. So, for each year mapped, soil loss averages were compared by t test at 5% significance to assess the soil degradation stage. The results indicated that, in the period, the soil loss average rate was from 2.4 to 2.6 Mg ha-1 year-1 and the areas with soil loss above the limit of SLT were around 8.0%. The t test demonstrated there was no considerable difference among the soil loss averages (p = 0.18). In consequence, the area of degraded soils did not increase. Thus, the RUSLE model in GIS is a simple and useful tool to estimate the soil loss and help define soil conservation and recovery measures.

Highlights

Soil is one of the most important environmental resources on Earth
Digital soil classification was carried out with ArcGIS 10.0 software using the State of Minas Gerais Soil Map (UFV et al, 2010) and the classes of relief obtained from the declivity map starting with digital elevation models (DEM) derived from the Shuttle Radar Topography Mission (SRTM) according to procedures by EMBRAPA (2006)
From the Revised Universal Soil Loss Equation (RUSLE) parameters, the erosivity value for the study area is of 6,500 MJ mm ha-1 h-1 year-1 (Aquino et al, 2012)

Summary

Introduction

Soil is one of the most important environmental resources on Earth. It holds a peculiar position in the hydrological and nutritional cycles and has influence on several forms of terrestrial life, besides storing and releasing greenhouse gases, and filtering and remediating pollutants. Soil conservation and recovery are some of the great challenges for humanity in the XXI century. In this scenery, water erosion accelerated by anthropic activities is one of the main soil degrading processes, with impacts on farming and cattle raising productivity and on natural resources, since recovery rates is not fast enough to compensate for soil loss associated to erosion (Needelman, 2013).

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Results