Development of a Simple Hydraulic Performance Model for Sasumua Pipelines of Nairobi Water Supply, Kenya

Abstract

Most of the major water supply systems in the modem cities of Eastern Africa are just within 50 years of operation. Due to the specific quality of raw water in the region, often with high concentrations of manganese, the treatment methods adopted and the type of conveyance systems in operation, there are unique operational problems. At certain periods in the life of their operations, these water systems need hydraulic performance assessments on the basis of which rehabilitation exercises may he undertaken. This paper describes hydraulic assessment after rehabilitation of Sasumua treated water mains of the Nairobi Water Supply system in Kenya. Swabbing or pigging was adopted as the most economical and cost effective method of rehabilitation under the prevailing circumstances. During and at the completion of the swabbing, the need for a simple and easy to apply hydraulic performance model became apparent. In this paper a simple hydraulic performance model is developed that utilizes local staff and equipment that should provide an affordable procedure not only for Nairobi but other upcoming urban centers in the East African region. A simple system uniformity coefficient that is based on the results of the model prediction is proposed. The procedure for conducting the field flow test in the determination of the Hazen William's friction factor is described by utilizing the set up and data of the field flow test carried out on 11th August 1988 on completion of the swabbing exercise. Journal of Civil Engineering, JKUAT (2001) Vol 6, 67-80