School of Civil and Environmental Engineering

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Browsing School of Civil and Environmental Engineering by Author "Abate, Setogn"

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    Assessment of Surface Water Potential and Demands in Tekeze River Basin, Northern Ethiopia
    (Addis Ababa, 2015-12) Abate, Setogn; Sahilu, Geremew (PhD)
    Tekeze river basin is located in the northern part of Ethiopia. The objective of this paper is to assess surface water potential using SWAT model and estimation of water demands using the Water Evaluation and Planning (WEAP) model in the Tekeze River Basin. According to the result obtained from SWAT model, the basin receives a mean annual rainfall of 976.4 mm which is 80.9BM3. The mean annual actual evapotranspiration is 9.5BM3 or 11.8% of the mean annual rainfall of the basin. The mean annual surface runoff that leaves from the basin is 7.8BM3 which corresponds to 93.97 mm. Out of the mean annual rainfall of 80.9BM3; the remaining 40.1BM3 is lost due to percolation for the recharging of the aquifer and 23.5BM3 as lateral flow or subsurface flow. For calibration, the model was run for a period of five years and the monthly calibration results for R2 and NS were 0.82 and 0.81 respectively which are beyond the acceptable ranges. According to SWAT developers in Santhi et al (2001), the daily stream flow calibration result (i.e. R2=0.54 and NS= 0.53) was found to be unsatisfactory which failed to meet especially the requirement of R2 > 0.6 For model validation, the model was run for a period of three years and the model validation results on monthly time step shows a good relationship between measured and simulated results and the results of R² and NS values were 0.7 and 0.63 respectively. However, unsatisfactory performance of SWAT model in daily validation was obtained which failed to meet statistical model efficiency criteria with R2 and NS values of 0.47, 0.41 respectively. The water demand estimation portion of this study was done for one water supply, three hydropower and four irrigation large scale projects in the basin. The model results showed that, for the reference scenario from year 2012 to 2030 are 18.4Bm3, 18.3267Bm3 and 73.3 Mm3 for water demand, supply delivered and unmet demand respectively. The annual average water demand, supply delivered and unmet demand are 969Mm3, 965.14Mm3, and 3.86 Mm3 respectively for the proposed large scale projects. Generally, comparing assessment of surface water potential result (i.e. average annual of 7.8BM3) and average annual water demand (i.e. 969Mm3); the basin has sufficient surface water potential that can be used for the selected planned and ongoing large scale projects. Keywords: Water Evaluation and Planning, Soil and Water Assessment Tool, Water Demand, surface water potential, Tekeze River Basin