Effects of enset-based land use system on infiltration rate and curve number of the soil in Meki river watershed, Western Lake Ziway Sub-Basin, Central Rift Valley of Ethiopia

Enset-based land use system (EBLUS) exhibits good carbon stock and infiltration rate equivalent to forest covered areas, which enhances infiltration rate and water holding capacity of the soil and it can also reduces the curve number (CN) of the soil but it was not considered in former studies in Meki river watershed. Therefore, this study was planned to articulate the influence of EBLUS on infiltration rate and CN of the soil and also to interpolate the CN matrix of EBLUS relative to other LUSs with established hydrological characteristics in the watershed. The soil type data collected from Ministry of Water, Irrigation and Energy (MOWIE) and verified by Harmonized World Soil Database (HWSD) was used to determine the Hydrologic soil group (HSG) of the watershed. Land cover considering EBLUS was classified using ERDAS Imagine 2014 while other watershed parameters were generated from Digital Elevation Model (DEM). Infiltration rate of the soil was measured using Amozi-meter (Hood infiltro-meter) under different LUSs and considered in EBLUS CN matrix interpolation. HEC-Geo-HMS model, Geo-statistical tool, SPSS and MS-Excel were used to interpolate CN matrix of EBLUS relative to other LUSs.

The field measurement results show that an infiltration rate of 12.9675, 11.1875, 10.375, 7.065 and 12.8125 mm h⁻¹ for Natural Forest LUS, Grassland and plantation LUS, cultivated LUS, Bare/built-up LUS and EBLUS, respectively. The resulting CN matrix of EBLUS was 39, 51.5, 58.3 and 61.6 for HSG of A, B, C and D, respectively. There was higher infitration rate and lower CN matrix in EBLUS relative to other land use systems with formerly established hydrological parameters.

The relatively high infiltration rate of the soil and a significant reduction in mean CN of the watershed shows the high role of EBLUS in water resources management. Therefore, escalating EBLUS will increase infiltration rate and reduce the CN of the soil which reduces runoff volume in the watershed and it ensures the sustainability of water bodies such as Lake Ziway by reducing sedimentation.