A GIS Evaluation of the Hypsometric Analysis of Woji River Basin, Port Harcourt, Nigeria

The management of river basins requires full understanding of the several factors and processes responsible for the evolution and development of such basins. Hypsometric analysis which is the measurement of relationship existing between land area and elevation of basins has been applied to understanding processes controlling hydrological behavior of river basins. Geographical information system provides the modern platform to obtain hypsometric data which helps to understanding different parameters that make up landforms; determine the geological and erosional stages of river basins and temporal changes that have occurred in structure of landscape. The hypsometric analysis of Woji River Basin has been carried out using the DEM of the region and ArcGIS 10.4.1 with the aim to determine the geological stages of development and assess the erosional status of the Woji River basin. The study area was classified into three sub-basins for the purpose of the study. The hypsometric curve of the entire basin and its sub-basins exhibit remarkably concave curve which indicate that the bulk of the watershed area and soil masses resides at relatively low elevation and the basin is in equilibrium or mature stage. The hypsometric integral of Woji river basin is 0.45 while its sub-basins ranged from 0.41 to 0.46, an indication that the entire basin has only 45% of its land area yet to be eroded. Although the overall hypsometric analysis of the entire basin reveals that the basin is not highly susceptible to erosion, the rapid increase in built-up area and decrease in vegetation suggest that human-induced changes are significantly impacting the basin’s environment, leading to increased soil erosion, sedimentation, and runoff. Sustainable urban planning and environmental monitoring and management practices to mitigate the adverse effects of human activities on the basin’s natural environment is highly recommended.