Abstract
The synergistic enforcement of the hydrographic behaviors of Kereke and Ukoghor river basins on the river Benue have been identified as the major contributors of the replete episodic flood hazard of Makurdi town. It is on this note that this study aims at analysing and comparing two categories of morphometric parameters; areal and linear/relief which influence runoff/discharge volumes and time lag of Kereke and Ukoghor river basins hydrograpghs respectively. This analysis provides a better understanding of their hydrographic characteristics and vulnerability to the flood hazard. The potential hydrographic variables examined include: runoff, peak flow, time to peak, infiltration, and overland flow. This was achieved using topographical maps of Makurdi sheet 251 NW and 251 SW on scale 1:50,000 published by Federal Survey of Nigeria (1965). These morphometric parameters were evaluated using ArcGIS 10.2 platform. Results indicated that both basins are 5th order basins with dendritic pattern. Kereke and Ukoghor basins have basin area 261.28 km2 94.82 km2, basin length 26 km/10.79 km, basin perimeter 76.28 km/40.15 km, bifurcation ratio 3.51/3.09, length of overland flow 0.56 km/ 0.42 km, form factor 0.39/0.85, circulatory ratio 0.56/0.70, relief ratio 0.45/0.91, drainage density 0.91/1.20, elongation ratio 0.40/ 0.60 and infiltration number 0.53/1.32 respectively. A comparison of the results of linear/relief parameters indicate that Okoghor drainage constitute fast peak flow and concentration time of shorter duration and hence higher flood vulnerability than Kereke drainage basin. On the other hand a comparison of areal aspects of morphometry Kereke river basin constitutes more vulnerability to flooding in Makurdi town than Ukoghor river basin with regards to hydrograph volume regimes. The outcome of the study is fundamental for prioritizing proactive and sustainable urban flood management, appropriate land use planning and zonation especially along their flood liable areas, storm water management and other general urban environmental degradation management.
Highlights
Morphometry represents the topographical expression of land by way of area, slope, shape, length, etc
Oyatayo Kehinde Taofik et al.: A Comparative Analysis of Drainage Morphometry on Hydrologic Characteristics of Kereke and Ukoghor Basins on Flood Vulnerability in Makurdi Town, Nigeria still stand valid following [1], [3], [4], [5] and [6] who reported that the Morphometric analysis of drainage basins provides an elegant description of the landscape, and serve as a powerful means of comparing the form and process of drainage basins that may be widely separated in space and time
This study has attempted to examine the morphometric characteristics of Kereke and Ukoghor Drainage Basins, Makurdi, Nigeria, with a view to assessing the influence of area, linear and relief morphometric parameters on the hydrological processes within these basins
Summary
Morphometry represents the topographical expression of land by way of area, slope, shape, length, etc. These parameters affect catchment stream flow pattern through their influence on concentration time [1] cited [2]. These landscape parameters are significant because stream flow can be expressed as a general function of geomorphology of a watershed. Morphometric analysis defines more clearly and precisely the general form of the basin landform as represented on a map and serve as a basis for demonstrating the effect of environmental control on fluvial system and for predicting the basin output variables such as discharge [7]
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