Isolation Valve Density of a Water Distribution System for Varying Water Usage Options in the Dhaka District Metered Areas

摘要

Available methods for determining optimum isolation valve density in water distribution systems have so far not been applied considering the variability of water usage during a water outage or emergency shutdown. Here, we developed a valve density criteria combining three different methods (based on value of undelivered water, value of water services and GLUMRB criteria) considering various plausible emergency water usage scenarios and applied it in the case of 30 District Metered Areas of Dhaka city. With the existing number of valves in the network, the 20-liter DWASA waterjar (priced at 19.31 $/m~3) was found to be more preferable emergency water option compared to bottled water due to its affordability,better accessibility to consumers and wide coverage potential for the most essential water uses of the consumers.While analyzing for adequacy of satisfactory ranges of valves in the water distribution system, it was found that the optimum range of valve density varies from 4.5 to 9.3 valves/km. It can be envisaged that heterogeneities in water usage and willingness-to-pay of the consumer, available infrastructures and modalities for water supply in densely populated urban areas in developing countries can affect the required isolation valve density.