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| dc.contributor.author | SISAY, MENGISTIE ESHETIE | |
| dc.date.accessioned | 2021-08-19T08:39:55Z | |
| dc.date.available | 2021-08-19T08:39:55Z | |
| dc.date.issued | 2021-01-30 | |
| dc.identifier.uri | http://ir.bdu.edu.et/handle/123456789/12502 | |
| dc.description.abstract | Understanding River morphology process is essential for River management, restoration and sustainable mitigation measures. Nowdays, Rivers are under immense morphological change due to various natural and planned and unplanned anthropogenic activities. Hence, this study assessed the anthropogenic activity impact on River morphological change on Ribb River, Lake Tana Basin, Ethiopia for about 20 Km length starting from Bahir Dar-Gondar main Asphalts Road and to Lake Tana. Primary data (volume of sand, dyke dimension, River cross-sections and grain sizes) were collected through questionnaires, surveying using standard measuring equipment‟s (total Station, GPS) and laboratory analysis. Secondary data (stream flow, sediment, rainfall and climatic) were also collected from MoWRIE. For data preparation and analysis, Arc GIS, HEC-RAS and BSTEM tools were used. River bed changes have been studied from 2005 to 2014 period. Model calibration and verification were done using both primary and secondary data. The Englend-Hansen formula showed good agreement with field data. The grain size analysis result showed that the river bed is dominated by sand (D50 <4.75mm), and it is classified under G5c stream type. By considering the dyke along the river banks, the steady flow analysis result showed the conveyance capacity of the considered reach was not sufficient for the discharge of 100 years return period; flood depth raises a maximum of 1.2 m from normal floodplain level and the flood inundation extends more than 600 m wide without the dyke on both sides. The river is affected by back water from the lake for about 1.5 km and this and other anthropogenic activities resulted in an average annual rate of erosion and deposition of 0.22 m and 0.1 m respectively. The maximum lateral bank retreats were 0.08 m/yr for upper and 0.25 m/yr lower reaches and the lower reach is more stable than upper with factor of safety (Fs) 8.79 and 7.2 respectively. Local communities, sand miners and energy office reported that more than 319,680-ton sand is excavated each year. Generally, this study showed that the morphological change of the specific study reach is a contribution of planned and unplanned human interference. Hence, to minimize the negative aspects of change, the government and other responsible stakeholders should give much emphasis the type of developmental interventions on the river system and should control illegal interference. | en_US |
| dc.language.iso | en_US | en_US |
| dc.subject | CIVIL AND WATER RESOURCE ENGINEERING | en_US |
| dc.title | IMPACTS OF HUMAN INTERVENTION ON RIVER MORPHOLOGY CHANGE IN THE LOWER RIBB RIVER, TANA BASIN, ETHIOPIA | en_US |
| dc.type | Thesis | en_US |
