Modelling and mapping of erosion potentiality watersheds using AHP and GIS technique: a case study of Alamata Watershed, South Tigray, Ethiopia

Next to population growth soil erosion are the second most environmental challenges which causing water worsening, land deprivation and desertification. This problem on the environment includes loss of soil fertility, reduction of the depth of water body (lakes, ponds, reservoirs etc), high water turbidity, flood hazard problems etc. This study focus on mapping of soil erosion-prone areas in Alamata watershed (area 534.380km(2)). This study leads where the most effective soil conservation strategies should focus in the area. Based on GIS with the integration of the analysis of analytical hierarchy process (AHP), curvature, stream power index, topographic wetness index, slope, elevation, soil, and land use were used as factors to have a fruitful decision to fulfill to the stated objective. MCEA and AHP are used to quantify hotspot area for erosion which created through pairwise comparison. Based on the analysis of MCE model and AHP tells that out of total watershed area, 0.01km(2) (0.003%), 29.42km(2) (5.506%), 162.80km(2) (30.466%), 341.52km(2) (63.910%) and 0.61km(2) (0.114%) areas are very high, high, medium, low and very low prone to soil erosion respectively. This gives as insight to a watershed decision maker and planners to minimize soil erosion problems.