Author(s)

C. Espoz-Alsina, S. M. Navone & A. Maggi

Abstract

The Santa Maria river basin in the province of Catamarca, Argentina is showing the first symptoms of desertification. The objective of this study was to develop an effective desertification assessment method that uses a Geographic Information System for this valley capable of: 1) combining various data such as field observations, aerial photographs and Landsa/Radarsat images used to obtain four basic maps of the area: Soils, Slope Degree, Vegetation Cover and Land Use; 2) digitally processing the database to obtain Desertification values; and 3) simulating future scenarios. The determinant processes of desertification considered were the deterioration of the vegetative cover, water erosion, wind erosion, salinization, human pressure, and animal pressure. Each of these processes was spatially represented in the four basic maps of the area. The risk of desertification posed by each of these processes was quantified with values between 0 (no risk) 4 (maximum risk) for each respective mapping unit of the basic maps. The value of Desertification for a given location was defined as the sum of the values of Total Water Erosion Risk, Total Wind Erosion Risk, Total Salinization Risk, Human Pressure and Animal Pressure derived from the spatial intersection of the soil, slope, vegetation and land use maps. The values of Desertification were categorized into five levels ranging from 0 (None) to 4 (Very Severe) by applying specially designed filters on the output database. The desertification map obtained using this methodology reflected accurately conditions observed on the ground.

Keywords