Geomorphic, morphometric and structural analysis of North West Benin Owena River Basin, Nigeria: implications for groundwater development

An approach detailing geomorphic, morphological and structural characteristics of a basin provides insight into groundwater development in data scarce regions. Remote sensing and GIS aids the identification, extraction and mapping of these characteristics. In this study, the geomorphic, morphological and structural parameters were delineated for North West Benin Owena River Basin (NWBORB), Nigeria towards its groundwater development. The basin was delineated from topographic maps. Five major sub-basins (SB I–V) were generated. Basin geomorphic characteristics were obtained from fundamental topographic information. Each sub-basin was quantitatively assessed of for their geomorphic, morphometric (linear, areal, and relief) and structural aspects. Geomorphic, morphological and structural parameters relevant to groundwater were utilized for sub-basin prioritization and identification of deficit/surplus groundwater zones. NWBORB is a sixth order basin. Dominated by rain fed lower order streams, it reflects late youth to early mature stage of development of the fluvial geomorphic cycle. It has a low stream frequency (F_s) and moderate drainage density (D_d) of 1.149. Bifurcation ratio (R_b) shows that the lower stream orders are surging through highly dissected, steep mountainous terrain that creates a seasonal low groundwater prospect, with exceptions occurring in the pediplains and flood plain areas. A comparison of the predominant orientations of the second, third and fourth stream orders with the lineament directions indicates structural control within the basin. Sustainable water conservation techniques are suggested locally within the drainage basin. SB-II is the most deficit zone, while SB-V is found to be surplus zone of groundwater potential.