Design of sustainable water distribution systems in developing countries

This paper concerns the development of international guidelines for the design of urban water distribution systems in developing countries where intermittent supplies are unavoidable for the foreseeable future, in order to sustain adequate and safe supplies. The development of these guidelines has been funded by the Department for International Development (UK). The available water sources throughout the world are becoming depleted and this has brought into focus the urgent need for planned action to manage water resources effectively for sustainable development. The problem of water scarcity in urban areas of developing countries is of particular concern and as the water quantity available for supply generally is not sufficient to meet the demands of the population, water conservation measures are employed. One of the most common methods of controlling water demand is the use of intermittent supplies, usually by necessity rather than design. It is evident from literature surveyed that the design of distribution networks operating intermittent supplies has in general been based on the assumption of continuous supply; the concepts and methods used are identical with those used in developed countries. This has resulted in severe pressure problems and great inequities in the distribution of water. Clearly there is a need to develop more appropriate design tools which recognise the particular features of intermittent systems. This paper describes a novel approach to the design of water distribution systems in developing countries. An alternative approach to design has been developed which employs a modified network analysis procedure and utilises formal optimisation techniques to ensure the maximum uniformity in supply. The conventional approaches to network analysis will be described and discussed with respect to their suitability for simulating conditions of water shortage. The modifications required to model such conditions have been identified and incorporated into a modified network analysis simulation tool. The simulation tool has been verified using data obtained during extensive field surveys performed in Kerala, India. In addition to the simulation tool, optimisation techniques to identify the least cost design of distribution systems, while achieving the most equitable distribution of water have been developed. These optimisation routines in combination with the simulation tools, have been applied to the design of an urban network in Kerala, India, and construction of this network is to begin in the next few months. Copyright ASCE 2004.