Three Dimensional Velocity Distribution Modelling of Nun River in Nigeria

Desmond U. Nwoko; Ify L. Nwaogazie; Charles C. Dike

Desmond U. Nwoko Centre for Occupational Health, Safety and Environment, University of Port Harcourt, Nigeria.
Ify L. Nwaogazie Department of Civil and Environmental Engineering, University of Port Harcourt, Nigeria.
Charles C. Dike Centre for Occupational Health, Safety and Environment, University of Port Harcourt, Nigeria.

Keywords: Modelling, velocity, erosion, sediment, three dimensions, Nun River, Niger Delta

Abstract

In this study, hydrodynamics and sediment concentration equations of partial differential in 3-dimensions were solved using finite difference methods, the Crank Nicolson procedure to predict both sediment concentration and velocity profile of Nun River. The computer software (EKU2.8) which is a modification of the Navier Stokes equations was employed for discretization of Nun River stretch of 2,000 m into 2,245 rectangular meshes and simulation of the rivers flow velocity distribution. The code was validated by using the field water current measurements obtained from a selected stretch of the river. Average predicted velocities of 0.85 m/s, 1.542 m/s and 0 m/s compared favorably with 0.8 m/s, 1.475 m/s and 0.09 m/s obtained from field measurement for upstream, midstream and downstream boundaries. The predicted results have approximate correlation coefficients of 0.96 for velocity distribution using Pearson product-moment method. The model proved very useful in predicting the velocity distribution of Nun River; higher versus lower velocities at inner and outer bends, with resultant effect of erosion and sediment deposition accordingly. The result of this study may be considered an important contribution to the improvement of sediment and erosion risk management.