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| dc.contributor.author | Assefa, Kidist | |
| dc.date.accessioned | 2020-03-19T10:09:40Z | |
| dc.date.available | 2020-03-19T10:09:40Z | |
| dc.date.issued | 2020-03-19 | |
| dc.identifier.uri | http://hdl.handle.net/123456789/10725 | |
| dc.description.abstract | Low flow analysis provides vital information for the planning and design of many hydraulic structures and risk assessment in hydrological index analysis and environmental flow management. However, there were no much studies in understanding the situation in low flow trends and with the occurrence of frequency. Therefore, the objective of this study was to evaluate the trends in low flows and regional low flow analysis in the Blue Nile Basin, Ethiopia. In order to carry out this study, 15 sub-basins in the Blue Nile was selected based on the long term availability and quality of data. The 3 day -sustained low flow (3dslf), the 7 day sustained low flow (7d-slf) and the 14 day sustained low flow (14d-slf) models were used to extract the data from the daily stream time series data of each sub basin. Trends in low flow for the selected flow stations were analyzed separately by using Mann-Kendall trend test. Low flow frequency analysis was also used estimate the long term low flow quantiles. In addition, regional analysis for estimating the quantiles for ungagged catchments was also developed. The results indicated that the all three models of low flow have indicated no significant difference for each station at 95% Confidence interval. Out of the selected stations 12 of stations has indicated decreasing trend while remaining one increasing 3 within know trend. This decreasing trend could be due to land cover and climate change which results in increasing runoff and evapotranspiration respectively. Weibull distribution, GEV and LGN was found appropriate fit based on the L-MRD. Hence quantiles were estimated based on this probability distribution and indicated diminishing magnitudes of low flow quintiles for 2 and above return periods. Area and rainfall followed by slope were the most sensitive parameters in relating the low flows with catchment characteristics for estimating low flow quantiles for ungagged catchments with regional growth curve. In general, the study indicated that there needs to a new water management scenario and adaptation mechanism for climate change and land cover situation to utilizing water resource sustainably in the Blue Nile basin. | en_US |
| dc.language.iso | en | en_US |
| dc.subject | Hydraulic and Water Resources Engineering | en_US |
| dc.title | Low flow trend and frequency analysis in the Blue Nile Basin, Ethiopia | en_US |
| dc.type | Thesis | en_US |
