Nearly all urban centres in Kenya including Nairobi, have a water shortage. But the water supplies to Kenya’s towns and households could be further strained due to sedimentation of water sources such as dams and reservoirs. Nairobi in particular, is predicted to suffer this predicament, a new study has revealed. The study conducted at Ruiru dam indicates that the dam’s volume has reduced by 10% to 2,564,590 cubic metres, most of this loss happening over the last 20 years. This revelation comes in the wake of continued water stress in urban dwellings with only 40% of Nairobi residents receiving water on 24-hour basis. Ruiru dam which was commissioned in 1949, supplies up to 21,000 cubic metres of water per day to Nairobi City.
The research conducted jointly by the JKUAT based Water Research and Resource Center (WARREC) and Nairobi City Water and Sewerage Company (NCWSC),was the first among a series of surveys to be conducted on a number of reservoirs to establish ground level of siltation.
Speaking during the launch of the study, NCWSC Managing Director, Eng. Philip Gichuki had expressed optimism the survey could lead to knowledge based decision making in the country’s water sector.
Scientists at JKUAT deployed a remote sensing equipment to determine depths, topography and water storage volumes of the dam. It is the first study of its kind to be conducted on Kenyan reservoirs.
According to the Principal Investigator, Dr. Joseph Sang, sedimentation can be attributed to human activities along rivers servicing the dams. He called for targeted conservation measures to cushion the critical water installations from siltation.
A similar survey is currently underway at the Ndakaini dam which supplies 85% of Nairobi City’s water needs. Through the partnership, JKUAT will also help NCWSC build human capacity and resident knowledge in relevant areas. Two staff of NCWSC are part of the team undertaking the survey.
While lauding the survey, WARREC Director, Prof. Bancy Mati said time had come for the water sector in Kenya to interact with researcher and make use of scientific knowledge for decision making. She added the Centre which is a Vision 2030 flagship project, was keen on actualizing research undertakings that could form a fulcrum of policy orientation in Kenya’s water value-chain. The bathymetric survey equipment used to assess sedimentation of Ruiru and Ndakaini dams, uses cutting–edge scientific tools, to improve knowledge on reservoir sedimentation, enabling better planning for water supplies to Nairobi and its environs.