Improving the maintenance and storage capacity of runoff dependant earth dam reservoiurs :

Abstract

Water is the most essential natural resource on the planet earth and it is as well one of the basic needs of human life. Thus it should be carefully monitored, accessed, assessed and purified to make it potable and fit for its various purposes. In Uganda water is mainly abstracted from ground and surface water sources which are prone to high level of pollution and depletion. The surface water sources are majorly replenished by precipitation. In March 2016, the reservoir of Oyitino earth dam which is 4.6m high and supplies a population of 46,400 people in the municipality dried up unexpectedly which left the municipality with a severe water crisis for a period of One month prompting a 20 litre jerry can of water to be sold as high as 1,500 Ugandan shillings. The drought was attributed to changes in the climatic condition (prolonged dry spell) in the region, the water demand exceeding the supply due to inadequate storage capacity of the reservoir resulting from its size and siltation level This project has therefore addressed the problems by delineating and characterizing the catchment of the reservoir, carrying out hydrological analysis of the catchment to assess the availability of run off to feed the reservoir, carrying out structural re-design of the earth dam, design of a silt chamber to control the volume of silt in the reservoir and assessing the economic viability of the project. This therefore project therefore emphasizes that increasing the dam wall height from 5.8m to 10m and designing of the silt chamber consequently increases the reservoir capacity from 4440 m3 per day of supply to 62,436m3 per day of supply which is adequate enough to supply the population of 625,9 13 people in the municipality by 2064 given the fact that the volume of the surface runoff from the catchment area that ends up in the reservoir is in the range of 57,121,727m 33,7I3,421m3 which is adequate enough to feed the reservoir with the volume water required to meet the water demand up to 2064.