Sub Watershed Prioritization for Integrated WatershedManagement Using GIS and Remote Sensing Techniques

Abstract

The main aim of this proposal is to prioritize the sub watersheds for integratedwatershed management and conservation measures and to evaluate the temporalchange of the land use/cover using GIS and Remote Sensing techniques. In additionto this study also assessed or estimates the amount of soil erosion in the catchmentarea through RUSLE model and map areas which are susceptible for soil erosion.Multi temporal satellite imageries LandSat ETM 2000, LandSat ETM 2005, 2010 andLandSat8 OLI/TIRS 2017 have been utilized for LULC change detection analysis. Andan average annual rainfall data, soil map (data), and DEM have been considered forsoil erosion risk analysis. The land cover map of 2000 and 2017 were used to producethe soil erosion risk maps and to estimate the rate of soil erosion and applied foranalyzing SI and DSI for sub watershed prioritization. As a result, LULC maps of 2000,2005, 2010, and 2017 and potential soil erosion risk map of the study area weregenerated.In the period 2000-2017, 3.76 km2 of Water body, 42.96 km2 swampy areas, 75.52km2 of grass land, 10.16 km2 bare land, 29.72 km2 Forest land, 73.66 km2 shrub land,234.75 km2 crop/cultivated land, and 143.14 km2 area of built up/settlement werechanged to other classes from their initial state. Within this period 6.54 km2 of Waterbody, 0.91 km2 swampy area, 14.32 km2 of grass land, 1.47 km2 bare land, 4.24 km2Forest land, 9.69 km2 shrub land, 842.99 km2 crop/cultivated land, and 38.15 km2built up/settlement area not changed to other classes of LULC.Generally in this time interval 613.67 km2 land out of the total area coverage hadbeen changed in this dynamics from one class to the other class. In the other handabout 918.31 km2 out of the total area coverage had not changed to other LULCclass, it was as its initial stateRegarding soil erosion risk assessment the result of annual soil loss of the study area(Upper Awash Basin) showed that the value range from 0 to 673.05 ton/ha/year in2000 and 0 to 866.02 ton/ha/year in 2017. The average annual soil loss rate in 2000was 20.86 t/ha/yr and in 2017 is 23.98 t/ha/yr.From the final result it’s identified that around four sub watersheds (45 rural kebeles)in very high priority class, five sub watersheds (46 rural kebeles) are in high priorityclass; two sub watersheds (27 rural kebeles) are in medium level priority class,around two sub watersheds (14 rural kebeles) are in a very low priority class andaround three sub watersheds (12 rural kebeles) are in low priority classTherefore detail assessment on micro watershed on prioritization, LULCmanagement, soil conservation practice are recommended.