A decision support toolbox for optimal design of water supply systems.

Abstract

This study focused on intermittent water supply, where customers receive water for less than 24 hours a day or only a few says a week commonly caused by the errors in the design process such as over-sizing or under-sizing of pipes, pumps and tanks whih result from the subjective nature of traditional design methods that are complex and rely heavily on the designer’s experience.The study aimed to develop a toolbox that enables Water Supply System Designers to achieve optimal design and perform automated financial analysis of water supply systems. The toolbox consists of an automated financial analysis tool, an optimal transmission network design tool, and an optimal distribution network design tool, all intended to enhance efficiency, accuracy, and decision-making during the design phase. The financial analysis was conducted by costing the sized transmission and distribution networks, using detailed cost estimates for equipment, installation, and operational expenses. Optimization was performed using Genetic Algorithms (GA) to ensure optimal sizing of pipes, pumps, and tanks in both transmission and distribution networks. The toolbox was validated through hydraulic simulations in EPANET Matlab Toolkit and tested on real-world case studies to assess its performance in comparison to traditional design methods. The toolbox successfully generated detailed cost estimates for system components, including transmission and distribution networks. Key financial metrics, such as Net Present Value (NPV) and Design Present Cost (DPC) were also obtained. The optimal transmission desin tool was able to design a pump head and flow. Pipe diameters of 250mm, 160mm and 140mm were obtained for the distribution main. Results from the case studies showed that the automated financial analysis tool produced results quickly and efficiently, significantly reducing the time required for cost evaluations compared to manual methods. The optimization reduced over-sizing by leading to a reduction in lifecycle costs through improved design and reduced operational expenses. Additionally, the optimized designs enhanced hydraulic performance, improving water pressure and distribution, thus contributing to a more reliable and sustainable water supply system.