Effects of dam construction on the planimetric changes of downstream rivers

Chalachew Abebe-Mulatu, Alessandra Crosato, Arthur Mynett, Michael Mehari

Tuesday 30 june 2015

13:03 - 13:06h at Oceania (level 0)

Themes: (T) Sediment management and morphodynamics, Poster pitches, (ST) River morphodynamics

Parallel session: Poster pitches: 5B. Sediment - River

The construction of dams affects water and sediment supply to the downstream river reach, which then adjusts itself to the new state by changing its slope, planimetry, reference width, and water depth. This work deals with the assessment of the long-term planimetric adaptation of meandering rivers after upstream dam construction. In particular, the work, which is now in its preliminary phase, aims at anticipating the changes that will occur on the meandering Ribb River (Ethiopia) a long time after the completion of the Ribb Dam. To analyze the effects of dams and generalize the results, two additional case studies are considered: the Tana River (Kenya) and the Blue Nile River (Sudan). These two rivers have been affected by dams for a long time already, whereas more dams are planned or in construction. The effects of large dams on these three rivers will be analyzed and compared, and based on the findings a methodology for the prediction of the effects of planned dams on the downstream river planimetry will be developed. The method includes field and historical investigations, GIS, image analysis and numerical modelling.