Mapping rangeland degradation by using rainfall and remote sensing data, North-Eastern Region, Sudan

Climate factors in conjunction with Satellite imagery and aerial photographs provide an opportunity to undertake routine natural resources monitoring for mapping land degradation over large areas such as pasture lands. These facilities provide efficient decision making instruments for resources management and implementation of applicable control measures. To explore climate change in terms of rainfall and its impact on the rangeland conditions in north-eastern part of Sudan, annual time series (1940 to 2004) for two weather stations across the area were analyzed. Aerial photographs for three selected sites in the study area were used to produce maps using grey tone, drainage pattern, vegetation cover and land use. These maps were overlaid with the Landsat images for 2000 to map out land degradation. The analysis of the rainfall data showed a significant decrease in annual rainfall during period 1940 to 2004. From remote sensing data, the map showed that during the 1960s there was active rain-fed agriculture and dense trees and bare soil in the area. When these maps were overlaid with Landsat 2000, it was noticed that the eroded and bare soil area had increased considerably but there were some areas covered with grass which was an indication of bush encroachment. The results suggest that the different ecosystems in the area were subjected to various forms of site degradation. These have led to sand encroachment and increased water erosion in the northern part of the area. Degradation is however reversible in many parts of the study area provided organized control measures are introduced.