Evaluation of Irrigation Development based on Rain Water Harvesting at Jemma Sub-Basin, Upper Blue Nile River, Ethiopia
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Date
2026-02
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Addis Ababa University
Abstract
In Ethiopia, where rain-fed agriculture is the major livelihood in the Jemma Sub-Basin, climate variability and water shortages persist as a continuing challenge. To address this problem, the present Research develops a geospatial and hydrological modelling solution for irrigation development assessment. This sustainable alternative can be achieved through rainwater harvesting (RWH). The approach included;
In the sub-basin, a GIS-based analysis of multiple criteria was used to find 6983.70 km2 of irrigable land. Consideration should be given to components such as slope, soil type, and water accessibility.
The Topographic Wetness Index (TWI), and the Normalized Difference Vegetation Index (NDVI) models was used. Subsequently, 2,274 potential sites were identified for water harvesting and storage combined, which can hold about 45.1 million cubic meters.
The next step involved using the CROPWAT model to compute the irrigation water duty. The Dega zone was found to have a value of 90.07 ha/cumec and Weyna Dega zone 67.07 ha/cumec. The investigation revealed that the demand for irrigation water is 191.54 cumec for all identified suitable lands.
Calibration of HYPE model was done, in order to assess the water availability in the catchment, three hydro-gauging stations have been established. It is evident that total available water in the Jemma Sub-Basin is 206.222 cumec. It is more than sufficient to meet total irrigation water demand.
Thus, water availability does not pose a limitation. This confirms that irrigation development based on rainwater harvesting is a feasible and sustainable strategy to enhance agricultural production and water security in the area.
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Keywords
Rainwater Harvesting, Irrigation Suitability, GIS, AHP, NDVI, TWI, HYPE Model, Hydrological Modeling, Crop Water Requirement, Jemma Sub-Basin, Upper Blue Nile, Ethiopia.