Study on Water Distribution Network Rehabilitation and Expansion Planningin Developing Countries

-ABSTRACT\ud \ud Water supply is of crucial importance for sustainability of human life. According to the World Health Organization (WHO), water-related diseases are the most common cause of illness and death among the poor in developing countries. In 2010, about 780 million or 11 per cent ofthe global population did not have use of an improved source of water and 1.9 billion were without water service coverage. Since most of the population growth will be in developing countries, the number of people who lack access to safe water is likely to increase further.Even today, the provisioning of water supply facilities is not sufficient to meet the increasing water demand with rapid population growth and the advance of commerce and industry. Moreover, poorly laid-out pipelines and deterioration result in numerous leakage incidents as well as impacting the daily lives of citizens with inadequate water pressure. Developing countries are confronted by two main problems relating to the water supply system, namely, how to optimize the distribution network for achieving cost-effectiveness and at the same time how to meet increasing water demand. A water distribution network being the most expensive componentof a water supply system, the overall planning, installation, and rehabilitation processes should be implemented accurately and carefully. Developing countries should devise suitable pipeline upgrading plans that are economically feasible within their financial constraints.To deal with these issues, this research develops a new approach to rehabilitation and expansion of the water distribution network.\ud Chapter 1 provides the research background. It also introduces previous studies relating to the design and rehabilitation of pipe distribution networks.\ud Chapter 2 reviews a report on the global water market, and examines municipal water markets from all over the world. This chapter also looks at Indonesia???s water market structure and strategic drinking water management, comparing these with others countries in the East Asia Pacific Region (EAP). The analysis indicates that global water markets are expected to increasein the future and will be dominated by rehabilitation network investment. The EAPregion, with the largest population, requires a substantialbudgetforbuildingand maintaining water infrastructure. Strategic pipe management in this region appears to consist mainly of efforts to rehabilitate the water distribution network, with the exception of Indonesia, Thailand and New Zealand. Strong economic and populationgrowth make Indonesia a country witha favorable water market.It is supported by an abundance of water resources. Since water service coverage only reached around 31% of the total population in 2010, water utilities should pay more attention to expanding and rehabilitating the water distribution network and achieving World Bank targets in the drinking water sector.\ud Chapter 3 focuses on the study area, reviewing an existing water supply system, and considering problems occurring in the water supply sector. Inadequate alignment of distribution pipelines, low water pressure, and high water losses are major problems in the study area. At the same time,many old pipes are still in use, while smaller mains of polyvinyl chloride pipes are installed in newly developing areas.These pipes are 100-150 mm in diameter, and are not sufficient to achieve stable and continuous water supply. Water demand forecasts point to rapidly increasing water demand in the future. Although the water authority recognizes the urgent need for rehabilitation and reinforcement of the existing distribution pipe network, it is not capable of allocating sufficient funds. In undertaking the upgrading of water pipelines in the study area, anappropriate planning strategy is needed from the following two standpoints. One is to satisfy the hydraulic constraints of the water distribution network in order to meet future water demand increases. The other is to reduce life cycle costs.\ud In Chapter 4, optimization models for the water distribution network (WDN) design are proposed. This study uses TMR as an abbreviation of trunk/limb mains reinforcement. The purpose of this chapter is to show that the TMR concept is necessary for making possible ???selection and concentration??? of the upgrading process. The optimization models used in this studyare based on a hybrid genetic algorithms model (HGA), which builds a pipeline network analysis program into the GA.The aim is to determine suitable diameters that will meet future water demand while minimizing the pipe material costs and meeting the hydraulic constraints.To this end, the study applies three types of HGA models. The objective of applying HGA-I, focusing on the final goal of 2090, is to determine sufficiently large pipe diameters so as to handle the growing water demands of the future.HGA-II(a) is used to apply a process of selection and concentration on the proposed plan obtained by means of HGA-I, from the standpoint of improving cost performance. The purpose of applying HGA-II(b) is to determine appropriate diameters for interim plan years (2030, ???50, ???70). It is revealed thatthe optimization models can select 43 pipelines making up the main pipeline network from the target network consisting of 77 pipelines in all.\ud In Chapter 5, life cycle cost analysis (LCCA) covers the following four items;1) material cost, 2) civil work cost, 3) leakage cost, and 4) demolition cost.When pipes with short life cycle are selected, the design will meet water demands for the time being and diameters can be upgraded in phases. This approach, however, comes with the burden of frequent upgrades. Selecting long life cycle pipes at an early stage in the project, on the other hand, requires laying pipes with large enough diameters to meet expected future demand increases and may result in an uneconomical design. This study considers the combinations for upgrading to pipe materials with different life cycles. The results shows that the combinations for minimizing total LCCA in the project period are different for each pipeline. Furthermore, this chapter proposes a Multi-Step (MS) pipeline upgrade planning model that takes into account budget constraints in each project period. This model takes ???improvement of the inadequate pressure problem??? as a measure of the effectiveness of upgrading under budgetary constraints, and sets as an objective function the maximization of average water pressure across all nodes.The upgrading plan devised using the MS model was able to reduce costs by approximately 12% in comparison with the case where budget constraints were not taken into account. The study shows that this model not only solves hydraulic problems but contributes greatly to improving the cost-performance of a pipeline upgrading project.\ud Chapter 6 summarizes the main conclusions of each chapter and contribution of this research