Modelling of an Optimized Intermittent Water Supply Network in Kampala City.

Abstract

In most of Uganda’s major towns with piped water supply networks, water is supplied to the consumers for less than 24 hours a day due to the increased water demands resulting from population growth and insufficient quantities of water at most of the sources. This study was carried out on the Mulawa borehole network which is an isolated network located in the Bulindo sub branch of the major Kyaliwajjala distribution network so as to develop a model of an isolated water supply network with optimized intermittent conditions. A study was carried out to identify parameters of intermittency within the network. Due to the existence of a rationing timetable used by NWSC to alternatingly supply water to Mulawa hill and Bulindo estates for two days each due to insufficient availability of water, consumers were propelled towards acquiring storage tanks in order to cope with the intermittent supply thus signifying the existence of intermittent water supply. Design parameters of the existing network were collected and used in modelling the existing network in Epanet 2.0 software. The load of the consumers was applied to the model and an extended period analysis was made in order to critically understand the characteristic performance of the existing network. Model calibration was made by measuring field pressures at a selected junction Ju1 for 63 hours using a pressure logger. The pipe roughness and demand at junctions were adjusted until simulated pressures were close to the measured pressures. After an analysis of the calibrated network, several optimization strategies like changing pipe diameters, addition of a tank in the network, changing the pumping schedule and addition of air valves with in the network were examined. In conclusion all the three specific objectives of the study were successfully achieved thus ensuring development of an optimized intermittent isolated water supply network.