Title: Effects of water hyacinth on water quality of Winam Gulf, Lake Victoria

Author(s): Wilfred M. Osumo
Final project
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Supervisors: Steingrimur Jonsson


Lake Victoria is the second largest freshwater body in the world by surface area. It is important for the livelihood of people living in the area. The lake is currently facing many problems, one of which is macrophyte encroachment mainly the water hyacinth, Eicchornia crassipes. Winam Gulf is a large inlet from Lake Victoria that extends into Kenya. In order to study the effects of water hyacinth on water quality in the gulf, measurements of water properties were made in the north-eastern corner of the gulf, when the area was covered with hyacinth in March 2000. The hyacinth was then cut and dumped on the bottom during the period June to beginning of August when all water hyacinth had been removed with measurements being made again in July. Water properties were again measured in November to see the changes made by the cutting of the hyacinth. The oxygen levels in the gulf were found to increase significantly (2-4 mg/l) after the shredding of the hyacinth. The largest changes occurred in the bottom layers. This happened quite soon after the shredding was completed.

Current measurements were also made and they indicate that the wind is the main driving force of currents in the area. They also show that the circulation in the gulf is mainly horizontal rather than vertical.

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