Hydrological and Morphometric Characterization of Anambra-Imo River Basin Using Remote Sensing

Abstract

Abstract Environmental problems related to flooding, water management and landslide often emanate from disruption of river basin within a geographical locality. In this study, the Anambra-Imo River Basin which drains the five southeastern states of Nigeria and a part of Kogi State in the northcentral was studied by combining the remote sensing technique and GIS. With the aid of digital Elevation Model (DEM) of the geographical region, the linear and spatial morphometric attributes of the basins such as Drainage density (Dd), Drainage texture (Dt), Circularity ratio (Rc), Elongation ratio (Re), Constant of channel maintenance (Cm), Form factor (Rf), Infiltration number (If), Stream frequency (Sf), Length of overland flow (Lo), and Compactness index (Ci) were obtained. The results of the analysis showed that the basins have a well-developed dendritic and parallel type drainage pattern with a NE-SW orientation suggesting a relationship between fracture orientation and physographic features. Anambra Basin is a 6th order basin having a total of 1462 streams with a length of 13682.9 km; while Imo River Basin is a 5th oreder basin having a total of 208 streams with a ttal length of 1320.57 km. Morphometric analyses yielded an infiltration number of 0.3 and 0.11, elongation ratio of 0.35 and 0.29, form factors of 0.26 and 0.54; compactness index of 1.4 and 1.06; length of overland flow of 0.46 and 2.18; Circularity ration of 0.49 and 0.84; constant of channel maintenance given of 0.93 and 4.34; Relief ratio of 0.61 and 0.35; and ruggedness number of 0.19 and 1.5 for Anambra and Imo river basin respectively. These results have thrown light on the underlying factors responsible to flooding and gullying in the study area as a combination of climatic and geological characteristics of the study area.