USING SATELLITE IMAGERY TO ESTIMATE THE RATE OF VEGETATION COVER IN THE WATERSHED OF CHOTT CHERGUI -WILAYA OF EL BAYADH (HIGH STEPPE PLAINS OF ALGERIA)

Abstract

Several factors influence the extent of water erosion: the length and the gradient of the slope, soil texture, the extent of vegetation cover. However it is the soil cover that remains the dominant issue on the effective response against erosion by protective the surface facing the erosive forces of raindrops and runoff. Our work aims to estimate the rate of vegetation recovery using satellite imagery in a semiarid region of the watershed of the Chott Chergui within the wilaya of El Bayadh. It is estimated the overall rate of recovery of vegetation on the site and its linking with the values of the normalized difference vegetation index (NDVI) corresponding to the image. The result has developed a map of three classes of vegetation cover, the first is completely denuded of vegetation, it is sandy areas, with rocky outcrops, or areas of buildings. The second vegetation with a less than 10 %, which corresponds to natural vegetation growing at altitudes moderately important to mountainsides. The third class has a recovery rate above 10% representing the agricultural parcels along the banks of the wadis, or reforested areas (that cover more than 30 %).