Downstream Geomorphological Response of Kano and Chalawa Channels to Dam Construction in the Savanna Zone of Northern Nigeria
Abstract
An assessment of the downstream geomorphological responses of two channels to dam construction in the savanna zone of northern Nigeria reveals significant changes from pre-dam to post-dam conditions. The changes are reflected both in the post-dam channels geometrical (i.e. width, depth, cross sectional area and abandoned width) and non-geometrical variables (i.e., silt + clay percentage and mud layer thickness). Reduction in the channels effective sizes, erosion in terms of incision of post-dam depths into pre-dam channels and development of lesser and finer deposits in the post-dam channels, overbank and floodplain zones are characteristic channel changes identified to be due to dams construction. Development of abandoned tracts of land that gradually evolve into farmlands and areas of vegetation colonization are the observed consequences of the changes.
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