EVALUATIO AND MODEL DEVELOPMENT . FOR OPTIMIZATION OF W TER SUPPLY SYSTEM COST AND SUPPLY PROBLEMS : THE CASE OF BUTAJIRA TOWN

Abstract

Currently Butaji ra town is inside the zone of critical water shortage . Besides the town water supply enterpri se is not in a position to cover the capital and operati on and maintenance costs. Accordingly this paper has set out to maximize the total revenue collected from customers and quantifies the unsatisfied demand so that investment i n new water supply scheme developments can be planned and scaled . The various methods employed includes review of existing system design , topographic survey data was collected and search for opt i mal diameter of pump i ng mains pipe lines is done , The present water supply deficit is calculated and the future water demand is forecasted by use of water use forecasting model, Hydraulic ana l ysis of the distribution system has been done using steady-state water distribution models, Linear programming technique concept has been used in the formulation of optimization problem , and several stakeholder consultations have been carried out with the major stakeholders . According to the results of water demand assessment the town has got 59%, 36% , 22%, 17% cover age in the current year, 2015 , 2020 and 2025 respectively . The annual production loss amounts to 25% . Based on the study of water sources ground water is more feasible currently. It is found that 1 OOmm, 11 Omm, and 150mm are the optimum pumping main sizes. The present minimum tariff rate in order to cover operation and maintenance cost is found to be 2 . 63birr/m3 , 2 . 92birr/m3 , 3 . 80birr/m3 and 4 . 36birr/m3 for the four consumption categories 1-5m 3 /month , 6-1 Om 3 /month, 11-30m 3 /month , and >30m 3 /month respectively . The tariff rate structure should be revised period i cally based on OM costs and the model here can be used to generate the tariff. An interactive FORTRAN program has also been developed which computes the total service charge . From th i s study it is concluded that currentl y the water that i s produced from all the existing sources of supply covers only 60% . From the current supply sources the water supply enterprise losses 233 . 28m3/day . The total revenue collected from the customers could not cover the operation and maintenance costs of the water supply system. The study shows that optimization modeling is a powerful approach for supporting and enhancing a sound decision-mak i ng process in water industry .