Flood vulnerability assessment of the upper Cross River basin using morphometric analysis

Abstract

Cross River, which originates from Cameroon, flows through several communities in Nigeria. The population upsurge and settlements near the river channel, however, portends the possibility of natural hazards such as floods. Floods within the upper Cross River basin (UCRB) have resulted in the loss of lives and property. The importance of flood studies, therefore, cannot be overemphasized. This study evaluated the influence of sub-basins on the flooding of the main channel in the UCRB using morphometric analysis. The UCRB was delineated into sub-basins using Shuttle Radar Topographic Mission Digital Elevation Model. The drainage network and morphometric parameters were extracted using QSWAT installed as a plugin in QGIS. Based on the compound factors computed from morphometric parameters that directly impact runoff, the UCRB was categorized into three flood vulnerability zones namely: high vulnerability (10.93–13.10), moderate vulnerability (8.75–10.92), and low vulnerability (6.57–8.74). The analysis revealed that sub-basins 18, 10, 8, 17, 1, 6, 15, and 13 have greater potentials to attain peak discharge in a short period, therefore, the instantaneous high runoff contribution of their tributaries to Cross River. The results of this study provide useful information for the effective mitigation and management of the flood vulnerabilities of the UCRB.

Keywords

• flood
• vulnerability
• cross river
• basin
• morphometric analysis
• assessment