Modelling and optimisation of water loss management strategies in a water distribution system: a case of Moshi Urban Water Supply and Sanitation Authority (MUWSA)

Abstract

Water loss in water distribution systems (WDS) is a serious problem in developing countries. A lot of water is lost on its way from the sources before reaching the consumers due to leakage, illegal use, and theft of infrastructures among others. The effect of water loss in the WDS includes reduction of revenue, water shortage, disruption of water quality, and inflation of operation and maintenance cost of the water authorities. The control of water loss in the WDS is closely dependent on the commitment of the decision-makers, the strategies used and budget set for water loss management (WLM). This study presents a combined model of Multi-Criteria Decision Making (MCDM) and Integer Linear Programming (ILP) methods which may help decision-makers to prioritise and select the best strategies for WLM. The MCDM family methods; the MAVT, SMARTER, SAW, and COPRAS were used to evaluate and prioritize the strategies, while ILP was used to select the best strategies. Additionally, the study compared the SAW and COPRAS methods in prioritising and selecting the strategies. The data used were collected at MUWSA. The results show that the COPRAS and SAW methods rank the given alternatives differently while when integrated with the ILP technique, the formulated models select the same portfolios of alternatives. Thirteen alternatives which cost 97% of the total budgets set for WLM were selected. Furthermore, the ILP models showed robustness in selecting the portfolio of alternatives as they select the same alternatives despite the ranking of alternatives and change of weights of evaluation criteria. Finally, the study proposed the decision model framework which can be used by decisionmakers to evaluate and select the best strategies for WLM in WDS. URI