Multi-scale analysis of surface runoff and water-harvesting dams in a semi-arid region : a case study in Tigray (Ethiopia)
(2014)
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- Abstract
- This research integrates the runoff generation from subcatchment, runoff storage in the reservoir, inflow to the reservoirs, and the hydrological connectivity between runoff source area and storage structures using multi-scale data in carbonate dominated area. The first part aims at the hydrologic design approach of two reservoirs. Inflows to the reservoirs can be quite low and time of concentration quite long in catchments with soil and water conservation measures, such as check dams. Reservoir water loss could be as high as 24.3 mm day-1 due to permeable lithology at the dam site and if water is stored for a long time. In the second part a detailed assessment was made. In the source area runoff coefficients could be more than 0.40 and SCS-CN provides reliable estimates of the runoff once the CN is calibrated and a low initial abstraction ratio is used. The lower runoff coefficient (below 0.20) at catchment scale was explained by the transmission loss between the source and storage area. This indicated that the hydrological connectivity between runoff source areas and storage structures should be taken into account for a realistic estimate of the inflows to irrigation reservoirs in semi-arid regions. The water losses from limestone dominated irrigation reservoirs could reach up to 26.0 mm day-1. Such losses can be avoided when hydrologic and geophysical investigation is combined in the design of water-harvesting dams.
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Teka, D. (2014). Multi-scale analysis of surface runoff and water-harvesting dams in a semi-arid region : a case study in Tigray (Ethiopia). https://hdl.handle.net/2078.5/55332