Dam operations, local rainfall, changing settlement growth pattern and flooding in the Niger Delta, Nigeria

Abstract

Since 1968 when the Kainji dam was built on the R. Niger in Nigeria, many other large dams, and more than 10 formal, large-scale irrigation schemes have been constructed in the R. Niger drainage basin. By the early 1990s, a perception had developed in the Niger Delta, the floodplain and tidal region comprising the terminal distributaries of the R. Niger, that the operations of these dams and upstream land use have caused a marked reduction in river discharges in the Delta. Concurrently with the dam construction era (1964–1995), there was a 30-year (1968–1998) drought particularly in the Sudan-Sahel Zone of West Africa, a significant section of the R. Niger drainage basin. This negatively impacted the flow regime in the Delta. The long-term low flow regime appears to have influenced the direction of settlement growth in the region. Rainfall started reverting to pre-drought levels circa 1995, promoting spate flows on the R. Niger, its tributaries and the Delta. The consequence has been debilitating quasi-annual flooding also perceived in the Niger Delta as another result of dam operations. This study attempts to elucidate the cause of flooding in the Niger Delta, and particularly the roles of dam operations, local rainfall, and direction of settlement growth on the flooding phenomena. Flooding and flood impact mitigating solutions are proffered.