Soil loss and sediment transport during the storms and landslides of may 1988 in Ruhengeri prefecture, Rwanda

In early May 1988, five prefectures in western Rwanda experienced catastrophic levels of precipitation, landslide and flooding activity that resulted in a severe loss of life, property, and livelihood. Using data from runoff plot and hydrological monitoring stations of the Ruhengeri Resource Analysis and Management project, the events and circumstances leading to these phenomena are reconstructed. The Nyamutera River, which drains the impacted area, delivered 567000 tons of suspended sediment toits mouth between 7 and 13 May. This corresponds to a basin-wide lowering of 12600 t/Km, or more than half of the basin'a annual suspended sediment yield. Theoretical distributions of maximun 24 h precipitation events suggest that Nyakinama and other regions in Ruhengeri are particulary prone to similar high volume events, exacerbating an already serious soil loss problem throughout the prefecture. Because contemporary land use practices directly contributed to the severity of the 1988 event, further applied research that identifies technologies capable of reducing soil loss, augmenting soil fertility and minimiizing the impacts of high magnitude and high volume rainfall is greatly needed (AU)