Bathymetry Development and Flow Analyses Using Two-Dimensional Numerical Modeling Approach for Lake Victoria

Seema Paul,Roger Thunvik,John Mango Magero,Jesper Oppelstrup,David Ddumba Walakira,Vladimir Cvetkovic

doi:10.3390/fluids4040182

Seema Paul, Roger Thunvik + Show 4 more

Open Access

https://doi.org/10.3390/fluids4040182

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Journal: Fluids	Publication Date: Oct 10, 2019
Citations: 6	License type: CC BY 4.0

Affiliation: KTH Royal Institute of Technology, Makerere University

Abstract

This study explored two-dimensional (2D) numerical hydrodynamic model simulations of Lake Victoria. Several methods were developed in Matlab to build the lake topography. Old depth soundings taken in smaller parts of the lake were combined with more recent extensive data to produce a smooth topographical model. The lake free surface numerical model in the COMSOL Multiphysics (CM) software was implemented using bathymetry and vertically integrated 2D shallow water equations. Validated by measurements of mean lake water level, the model predicted very low mean flow speeds and was thus close to being linear and time invariant, allowing long-time simulations with low-pass filtered inflow data. An outflow boundary condition allowed an accurate simulation to achieve the lake’s steady state level. The numerical accuracy of the linear measurement of lake water level was excellent.

Highlights

Lake Victoria (LV) in East-Africa is the second largest fresh water body in the world and the largest in Africa, with a shoreline shared by three countries: Uganda, Kenya, and Tanzania
There is a need to understand the hydrodynamic processes of lake systems that are directly affected by chemical, biological and ecological systems as well as the physical processes of the lake system and their driving forces, which are crucial for the management of these systems [4]
Mean water level changes in the order of 1 m were small compared to the mean depth of the lake

Summary

Introduction

Lake Victoria (LV) in East-Africa is the second largest fresh water body in the world and the largest in Africa, with a shoreline shared by three countries: Uganda, Kenya, and Tanzania. It is a shallow water body with an average depth of 40 meters and a maximum depth of 80 meters, and a horizontal extent of 355 km [1,2]. Previous Lake Victoria model analyses [5,6,7,8], including thermodynamic and hydrodynamic characteristics, were based on the Princeton Ocean Model 3D simulations. Nyamweya et al [9] used the Regional Oceanographic Model System (ROMS)

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Conclusion