Improving equity in intermittent water supply systems

The problems of limited financial resources and water scarcity in urban areas of developing countries are of concern to water managers following growing demand–supply imbalance. As a result, an intermittent supply is widely adopted as a measure for controlling water demand among consumers. However, ensuring equitable water distribution at low cost in intermittent water supply systems becomes a challenge. Most intermittent water supply systems fail to achieve both objectives and how to improve equity remains a complex task for water managers. There is little research in this area and therefore a need to develop more appropriate optimisation techniques that recognise this unique feature of intermittent systems in developing countries. The paper proposes a simple multi-objective optimisation model to measure and improve equity and minimise cost in intermittent distribution networks, under water scarcity condition. A simple network is subjected to intermittent supply to demonstrate the model, in which both locations and capacities of source tanks/reservoirs are subject to optimisation. A simulation model is used to model intermittent systems as pressure-dependent through the use of consumer storage tanks. The paper reveals that equity under intermittent supply conditions is measurable and can be improved through optimal location and sizing of elevated source reservoirs.