Application of hydrological indices and GIS for the detection of areas at risk of erosion - case study Oued Rhumel watershed, East Algeria

Abstract

Abstract In Algeria, the loss of water capacity in reservoirs is a major challenge in the face of a significant increase in water demand. This loss of resource is due to the sedimentation of reservoirs, one of the most serious consequences of erosion. The use of hydrological indices is widely recognised as a highly effective method of providing input data for the cartographic representation of erosion-prone areas within geographic information systems. In the present study, the hydrological indices essential for erosion modelling were obtained through meticulous processing and analysis of a digital elevation model. The various indices, including sediment transport index, composite topographic index and stream power index, were combined with other relevant issues such as slope, curvature, channel spacing and channel density, The results of the survey have shown that a significant part of the Oued Rhumel catchment, located in the eastern region of Algeria, i.e. 24.35% or 1,292.72 km2, is located in an extremely high or high erosion zone, which requires the immediate implementation of conservation measures. In addition, a total of 190.81 km2 or 2,024.47 km2 is located in areas with a moderate or low risk of erosion. It is therefore evident that the use of primary and secondary derivatives of the digital elevation model, as well as morphometric parameters, through the application of a spatial analysis tool, is an effective and comprehensive method for identifying erosion-sensitive zones. This approach can be used on a regional or continental scale to facilitate watershed management and monitoring.