
Research Article
Lake Level Fluctuation Impact on River Morphology Change
@INPROCEEDINGS{10.1007/978-3-030-93712-6_7, author={Sisay Mengistie Eshetie and Mengistie Abate Meshesha}, title={Lake Level Fluctuation Impact on River Morphology Change}, proceedings={Advances of Science and Technology. 9th EAI International Conference, ICAST 2021, Hybrid Event, Bahir Dar, Ethiopia, August 27--29, 2021, Proceedings, Part II}, proceedings_a={ICAST PART 2}, year={2022}, month={1}, keywords={Lake Tana River morphology Ribb River HEC-RAS model}, doi={10.1007/978-3-030-93712-6_7} }
- Sisay Mengistie Eshetie
Mengistie Abate Meshesha
Year: 2022
Lake Level Fluctuation Impact on River Morphology Change
ICAST PART 2
Springer
DOI: 10.1007/978-3-030-93712-6_7
Abstract
In the recent time Ribb River is under immense morphological change due to various natural, planned and unplanned anthropogenic activities such as, lake level regulation for hydropower production, embanking, sand mining, and water extraction. In the present time, Lake Tana level is raised (kept fairly constant) after the Chara-Chara weir construction and Belese Hydropower operation. These will strongly alter both River regime water and sediment discharge to downstream reach and causing morphology adjustment. Hence, this study assessed Lake level fluctuation impact on River morphological change on Ribb River, Lake Tana Basin, Ethiopia for about 20 km. The objectives of this study were to assess lake level impact on river cross-sections of Ribb River and investigate back water extension length and its consequent for River training structures. Primary data (River cross-sections, dyke dimensions and grain sizes) were collected through, surveying using standard measuring equipment’s (total station, GPS) and laboratory analysis. Secondary data (stream flow, Lake level, sediment, rainfall and climatic) were also collected from MoWRIE. For data preparation and analysis, Arc GIS and HEC-RAS were used. River bed change has been studied from 2005 to 2014 period and the result show that the reach exhibit both aggradation and degradation. The study reach is affected by back water for about 1.5 km length and this back water effect caused an average annual rate of 0.22 m deposition.