Summary of the project

Introduction

Lake Kyoga is part of the Kyoga lake complex which includes a set of lakes and numerous wetlands in Central Uganda, Eastern Africa. The catchment size is about 60,000 km2 while the open water area in Lake Kyoga averages out around 3750 km2. The main inflow to the lake is coming from Lake Victoria through the regulated Owen Falls Dam in Jinja, Uganda.

Abnormally heavy El Niño rains during years 1997-1998 led to a raising water level in Lake Kyoga and Victoria which dislodged the papyrus beds, floating suds, and water hyacinth mats. The weeds accumulated into the outlet of Lake Kyoga and fully blocked the outlet which led to even higher water level in Lake Kyoga. Within one year, the water level rose over two meters in the lake.

Methods

The 3D EIA Flow Model is set up for Lake Kyoga to simulate the hydrodynamic characteristics of the lake such as water levels and currents, and as well as studying the effect of the sudd blockage on the lake’s hydrodynamic and water level. With the model, different scenarios on managing the sudd and simulate the effects of those on the water levels, currents, and outflow were carried out.

The effects of sudd blockage on the hydrological characteristics is studied with the help of water balance calculations and hydrological analysis.

Results

Acording to the water balance calculations, we get 25.4 m³/s for the real water loss increase after the blockage which is 2% of the total outflow. This correlates very well with the calculated increased evaporation because of the increased lake surface area. Also, the relationship between Victoria Nile inflow and Lake Kyoga outflow has remained naturally also after the blockage.

The EIA 3D Flow Model was found to be able to model the Lake Kyoga in rather accurate and appropriate to use for scenario simulations. The removing of the sudd would decrease the water level towards the level before the blockage formation. By widening and clearing the channels and clearing would decrease the water level some 0.5 m compared to year 2002 situation while the total remove of the blockage would put the water level 0.9 m lower.

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Model grid and user interface. To see the photo larger, please click on the image below:

Last updated on Nov 10^th 2004