Akagera River Avulsion Study Workshop
An exchange of information workshop was organized on 19th October, 2021 at Rusumo Project site office, Kirehe District, Rwanda to present and discuss the outcome on Assessment and Mitigation of Akagera River Avulsion. The study was conducted by Hydroc company.
This study was conducted to analyse the impact of the Akagera River avulsion on Regional Rusumo Falls Hydroelectric Project’s energy generation and assess the impact of changes in sediment discharge due to the avulsion on the plant and energy generation and how it may be managed. The avulsion was found to have formed between March and July 2014. While a direct connection between Lake Rweru and Akagera River already existed before this time, it was in 2014 when the avulsion became visible, and its delta started to grow.
In the consultant’s opinion the most likely explanation of the 2013-2014 avulsion is a retreat of the lake shore in combination with papyrus jams blocking the flow during floods. The favorable point of the avulsion at the end of an outer bend might have added to this.
The potential avulsion-induced changes of the Regional Rusumo Falls Hydroelectric Project’s energy generation were quantified by an extensive model study. A hydrological model was developed for the Akagera River basin, which allows to simulate the water balance of Lake Rweru and the inflow to the Regional Rusumo Falls Hydroelectric Project in daily time-steps for the period 1971 to 2020. The model was calibrated with observed discharge data at several gauges. At Lake Rweru the modelling of the inflow and outflow relationships were based upon the results of a hydraulic model and calibration with observed lake levels.
