Downstream hydraulic geometry across headwater channels in Upper Ogun River Basin, Southwestern Nigeria

ABSTRACT

Hydraulic geometry is widely applicable in different environments and is quite essential across different channel units. In this study, downstream hydraulic geometry was used to ascertain differences in exponents across headwater channels within a Basement Complex in a humid tropical region. This study was conducted within the Upper Ogun River Basin, Southwestern Nigeria. The basin is approximately 200 km in length and 140 km wide. Eighty-three (83) reaches were sampled across third-order basins within the Upper Ogun River Basin. Hydraulic geometry variables were measured and derived at bankfull using appropriate techniques and basic hydraulic equations, respectively. For the six-individual basins covered, it was found that the exponents (b, f and m) of the downstream hydraulic geometry relations for Q_bf covered a range of: b = −0.12–0.51; f = 0.44–0.67; m = 0.04–0.46. The channels of four basins out of six becomes progressively narrowed and deepened downstream while that of the remaining two becomes progressively wider and shallower downstream.

KEYWORDS:

• Downstream Hydraulic Geometry
• Tropical region
• Headwater channels
• Upper Ogun River Basin

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Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Olusola Adeyemi

Olusola Adeyemi, PhD, is a Lecturer at the Department of Geography, University of Ibadan, Ibadan, Nigeria. He specializes in Tropical rivers and Ecohydrology.

Fashae Olutoyin

Fashae Olutoyin, PhD, is a Senior Lecturer at the Department of Geography, University of Ibadan, Ibadan, Nigeria. She specializes in Geomorphology and GIS.

Onafeso Olumide

Onafeso Olumide, PhD, is a Lecturer at the Department of Geography, Olabisi Onabanjo University, Ago-Iwoye, Ogun State, Nigeria. He specializes in Earth System Modelling.