Evaluation of Sediment Generation and Transport: A Case Study of Thwake Dam in Kenya
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Date
2024
Authors
Maiyo, Gilbert Chumo
Ndiba, Peter Kuria
Odira, Patts M.
Nyangeri, Ezekiel
Journal Title
Journal ISSN
Volume Title
Publisher
IWA Publishing
Abstract
The study aimed to evaluate sediment generation, transport, and deposition into the Thwake reservoir. This research sought to assess sediment transport patterns and their potential impact on the reservoir using regional and numerical techniques. The Thwake River basin
constitutes 30% of the dam’s catchment area and experiences high soil loss due to its semi-arid climate, steep slopes, and lack of vegetation.
The river system in the sub-basin is ephemeral, with the riverbed remaining dry throughout most of the year and experiencing tidal flow only
during storm events. Bed material samples were collected from selected reaches, and sediment properties were evaluated. The study
involved analyzing datasets on the reservoir, catchment, and sand-bed channel. Numerical models assessed hydrological and sediment
transport information by considering interacting variables and predicting deposition patterns and sediment yield estimates. The findings indicated that sufficient bed material from sub-basin 3E would be deposited into the reservoir, resulting in delta formation approximately 5 km
downstream of the tail waters at minimum dam operating level. The mass cumulative sediment inflow from 3E into the reservoir was estimated between 14 and 26.3 metric tons per annum, representing reservoir loss and useful life under 50 years.
Description
Article
Keywords
climate change, sediment generation, transport, sand dams
Citation
Maiyo, G. C., Ndiba, P. K., Odira, P. M., & Nyangeri, E. (2024). Evaluation of sediment generation and transport: a case study of Thwake Dam in Kenya. Journal of Water and Climate Change, jwc2024040.