WATER TRANSMISSION SYSTEMS DESIGN : AN EVALUATION

Abstract

The importance of water supply and sanitation facilities is now being recognized by the public not only for healthful living, but also for improving the social and economic conditions. The provision of water, supply facility for a city involves a sizeable amount of money. Water supply facility is broadly classified in two parts, first part consists of source of water, its treatment and storage in overhead reservoir and supply main; and distribution system forms the second part. A substantial amount of research has been done on the optimization of distribution system but very little attention has been paid by the designers on the water transmission systems. The conventional method of design of the trans-mission system consists of designing rising main and arbitrarily fixing the height of overhead reservoir. For designing the rising main for a particular discharge, three diameters are considered, frictional head losses are calculated in each by Hazen-Williams formula, and the diameter for which the sum of costs of power and pipe line is least,is adopted as the 'Optimum" a diameter. The above method has following limitations. (1) Hazen-Williams formula has several limitations and does not estimate the true value of head loss in the pipe line. It may be due to this reason that in some cases in the field the crater does not reach the overhead reservoir or else the conven- tional method gives an overdesign of the transmission system...............