ASSESSMENT OF EROSION HAZARD IN TORRES MUNICIPALITY OF LARA STATE (VENEZUELA) BASED ON GIS

摘要

The Revised Universal Soil Loss Equation (RUSLE) model was used to predict soil erosion hazard in the Torres municipality, Lara, Venezuela. Rainfall-runoff erosivity (R) values indicated low erosion potential. The soils have moderately low to high erodability (K), it being larger in the agricultural zone. The values of the LS factor are relatively low, since the study area is mainly morphologically flat. Cell-by-cell multiplication of the maps of R, K and LS factors resulted in a map of potential erosion. A similar procedure, adding the factors crop and management (C), and conservation practices (P) was used to estimate actual erosion. The smallest actual erosion values of soil losses were registered in forest zones and where agricultural practices are carried out. Actual ero-rnsion had a range of 0-2558t·ha~(-1) per year, but more than 72% of the area is under very low water erosion hazard, and is highly suitable to rain fed agriculture. Areas susceptible of erosion with a soil loss >12t·ha~(-1) per year are found primarily in the higher basin, or where there is sparse cover. The percentage of high sustainability for agricultural purpose amounted to 100% in the agricultural area. In accordance, the zone can be used continuously with annual mechanized cultivations without conservation practices. The results support that the RUSLE under GIS environment, coupled with digital elevation model (DEM) data and remote sensing, are powerful tools for both qualitative and quantitative assessment of soil erosion in a hydrographical basin.