NJHS-vol 4 Summary

NIGERIAN JOURNAL OF HYDROLOGICAL SCIENCES

Vol. 4 September, 2016 ISSN: 2315-6686 Abstract

NJHS Summary of Vol 4

Discharge and Sediment Redistribution in the Lower Niger Delta and Implications for Pollutant Evacuation in Tidal Estuaries

T. K. S. Abam

Institute of Geosciences and Space Technology,

Rivers State University of Science and Technology, Port-Harcourt, Nigeria

groundscan@yahoo.com, abam.kingdom@ust.edu.ng

Abstract

The Niger Delta is the ultimate receptacle of the waters and sediments transported by the Niger and Benue River systems; receiving more than 26,000 m3/s during peak flows. Analysis of historical Niger River discharge distribution between 1953-2014 implicate the morphormetrics at the Asamabiri bifurcation into Forcados and Nun Rivers, the effects of which are manifested in changes in flood depth, water and sediment distribution, standing period of floods, changes in coastal erosion patterns, freshwater-saline water interfaces. The paper assesses the impact of dredging which disproportionately deepened the Nun, thereby increasing the bathymetric cross-sectional area and as a consequence allowed for a larger share of the Niger River discharge. The trajectory of flood water emanating from the Niger River through Orashi River to Sombreiro River at peak flow was explored for its benefits in flood impact mitigations. The relationship between sediment load and discharge for rivers in the Niger was analyzed, leading to empirical descriptive equations that correlate both. Ebb and flood tidal discharges for major river estuaries in the Niger delta were utilized in developing a flux efficiency index which determined the efficiency of coastal rivers in disposing of pollutants.

Keywords: Niger delta, discharge distribution, flux efficiency