Hydrological Significance of Enset-Based Land Use System and its Role in Water resources and Watershed Management in Meki River Watershed, Lake Ziway Sub-Basin, Central Rift Valley of Ethiopia
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Date
2023-09
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Addis Ababa University
Abstract
Modeling the hydrological significance of Enset-Based Land Use System is critical for estimation, planning, management and sustainability of current and future water resources. The main objective of this study is to model the hydrological significance of EBLUS and its contribution for water resources and watershed management in Meki River Watershed, Lake Ziway Sub-Basin, central Rift Valley of Ethiopia. This work pursued: EBLULC change detection and dynamics analysis using Remote sensing softwares and evaluated it’s significance on soil erosion control using RUSLE model and Geo-statistical and statistical tools; it invoved measurement and analysis of infiltration rate of the soil using Amozi-meter and collection of organic carbon stock data; it seeks to interpolate the Curve Number matrix for EBLUS with respect to other land use systems with predetermined CN matrix; it presents the impact of EBLUS on magnitude of surface runoff using HEC-HMS and it evaluates the implications of EBLUS for the water resources and watershed management for sustainability of water bodies. As a result an increase in EBLUS over the last thirty years by 11.2% was observed without much loss (stable), the difference in soil loss for nonenset growing zones and enset growing zones were evaluated as 1.405t ha-1yr-1 . Higher mean infiltration rate in EBLUS (12.8125 mmhr-1 ) next to Forests (12.9675 mmhr-1 ) caused in the lowest average CN of EBLUS (52.6). Calibration (NSE=76.25) and validation (1990-1994) (NSE=62%) results confirmed that the adequacy of the HEC-HMS model for runoff simulation. 11.26% of surface runoff infiltrated due to the presence of EBLUS. The high surface runoff in the lower subwatersheds than the upper sub-watersheds indicates the contribution of EBLUS is high in the watershed despite the area coverage of EBLUS was low (10%). Generally, EBLUS increases the canopy cover of the watershed, decrease the truction power of rainfall, reduce the soil loss in the watershed, increase infiltration rate of the soil and reduce the magnitude of surface runoff and contribute to the sustainability of water bodies. Therefore, expanding the coverage of the EBLUS can improve the hydrological components to enhance water absorption into the ground water system and contribute to the water resources and ecological sustainability of the surrounding in addition to its social, economic, food security, environmental and microclimatic importance of the watershed which have a direct influence on water resources and watershed management in Meki river watershed.
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Enset, Infiltration, CN, Amozi-meter, Geostatistics