TY - JOUR
T1 - Morphodynamic trends of the Ribb River, Ethiopia, prior to dam construction
AU - Mulatu, Chalachew A.
AU - Crosato, Alessandra
AU - Moges, Michael M.
AU - Langendoen, Eddy J.
AU - McClain, Michael
PY - 2018/7/9
Y1 - 2018/7/9
N2 - The meandering Ribb River flows in northwest Ethiopia to Lake Tana, the source of the Blue Nile River. The river has already undergone changes due to several human interventions, such as embanking, sand mining, water extraction and lake level regulation for hydropower. At present, a dam and a weir are under construction to store and divert water for irrigation. This will strongly alter both water and sediment discharges to the downstream river reaches, causing adjustments to the morphology. Assessing the current morphodynamic trends is the first necessary step to study the future effects and find ways to mitigate them. This paper presents an analysis of the current and past river based on newly collected data, aerial photographs, SPOT and Google Earth images. The riverbed changes are derived from historical staff gauge height analysis. The effects of sediment mining and water extraction are assessed using the theory of morphodynamic equilibrium. The findings of the analysis show a reduction of sediment transport capacity in the downstream direction, which has resulted in intense sediment deposition, resulting in blockage of the Lower River reach and subsequent channel avulsion. The effects of Lake Tana level regulation on the observed processes appear to be minor.
AB - The meandering Ribb River flows in northwest Ethiopia to Lake Tana, the source of the Blue Nile River. The river has already undergone changes due to several human interventions, such as embanking, sand mining, water extraction and lake level regulation for hydropower. At present, a dam and a weir are under construction to store and divert water for irrigation. This will strongly alter both water and sediment discharges to the downstream river reaches, causing adjustments to the morphology. Assessing the current morphodynamic trends is the first necessary step to study the future effects and find ways to mitigate them. This paper presents an analysis of the current and past river based on newly collected data, aerial photographs, SPOT and Google Earth images. The riverbed changes are derived from historical staff gauge height analysis. The effects of sediment mining and water extraction are assessed using the theory of morphodynamic equilibrium. The findings of the analysis show a reduction of sediment transport capacity in the downstream direction, which has resulted in intense sediment deposition, resulting in blockage of the Lower River reach and subsequent channel avulsion. The effects of Lake Tana level regulation on the observed processes appear to be minor.
KW - Blue Nile Basin
KW - Damconstruction
KW - Lake Tana
KW - Ribb River
KW - River dynamics
KW - Rivermorphology
KW - OA-Fund TU Delft
UR - http://www.scopus.com/inward/record.url?scp=85049828490&partnerID=8YFLogxK
UR - http://resolver.tudelft.nl/uuid:c723ccfc-0a82-4576-be0d-d3ab7fb76255
U2 - 10.3390/geosciences8070255
DO - 10.3390/geosciences8070255
M3 - Article
AN - SCOPUS:85049828490
VL - 8
JO - Geosciences (Switzerland)
JF - Geosciences (Switzerland)
IS - 7
M1 - 255
ER -