Hydrologic soil group based curve number matrix modeling for Enset-Based land use system in Meki River Watershed, Western Lake Ziway Sub-Basin, Central Rift Valley of Ethiopia

Abstract Background Enset-Based land use system (EBLUS) exhibits good carbon stock and infiltration rate equivalent to forest covered areas, which enhances infiltration and water holding capacity and it can reduce the curve number (CN) of the watersheds but it was not considered in former studies. Therefore, this study is planned to model the hydrologic soil group (HSG) based CN matrix of EBLUS relative to other LUSs with established hydrological characteristics in the Meki river watershed. The soil data is used to determine the HSG of the watershed collected from Ministry of Water, Irrigation and Energy (MOWIE) and verified by Harmonized World Soil Database (HWSD). A Model is developed for CN of EBLUS relative to other LUSs (Alemu’s formula). The model considers both infiltration rate measured using Amozi-meter and carbon stoke of soil weighed as 85% and 15% respectively. HEC-GEO-HMS model is used to consider the CN of EBLUS as a separate LUS to verify the developed CN matrix model to generate CN of the sub-watersheds. Result The field measurement results show that an infiltration rate of 12.9675,11.1875,10.375,7.065 and 12.8125mm hr -1 for Natural Forest, Grassland and plantation, cultivated, built-up and EBLUS respectively. The model is: and the resulting CN matrix of EBLUS is 39,51.5,58.3 and 61.6 for HSG of A,B,C and D respectively. Conclusion Significant reduction in mean CN of the watershed that shows the role of EBLUS in managing the water resources and flood is high. Therefore, escalating EBLUS will reduce the CN of the watershed which reduces runoff volume in the watershed and it ensures the sustainability of Lake Ziway by reducing sedimentation.