Research On Performance Indicators For Leakage Control In Water Distribution Systems

Water loss management in water distribution systems is an important way to alleviate water scarcity in China,and it is also a way of improving economic efficiency of water supply enterprises and ensuring the safety of water supply.The first step in water loss management program involves conducting a water balance and performance assessment.However,research on the water balance method in China is not mature.There is no suitable performance indicator for real losses,even though these losses constitute the main component of overall water losses.The purpose of this study is to grasp the methodology and application of the water balance,to establish a reasonable performance indicator for leakage control,and to provide the theoretical basis and application experience for water loss analysis and evaluation for managers and researchers.Based on the top-down and bottom-up theory,this paper details the method of water balance analysis,studies the application of water balance analysis method through the analysis of specific cases and the calculation method of real losses.The effect of total water supply volume and average water supply pressure on the rate of water loss was studied,results show water loss rate is not a suitable performance indicator for national and international comparisons.By studying the leakage records of Y City,it was found that water in small diameter pipelines and service connections is more likely to be lost.There are limitations by using the indicator“water losses per km of mains”(diameter>75mm).By comparing the difference between international and Chinese urban construction and pipe network structure,it was found one service connection may have several users in China while one user abroad.Buildings have more floors in China than other countries.At the same time,the calculated Infrastructure Leakage Index(ILI)value of apartment zones is unreliable.So the Unavoidable Annual Real Losses(UARL)formula and ILI cannot be used directly.Background Losses Index(BLI)as the performance indicator for real losses was researched in this study.Multiple linear regression was used as a statistical technique to determine factors that contributed to background losses.Pipe length(km)and number of customer meters are the main contributors to background losses(m3/d)in house zones(R~2=0.96).Pipe length(km)and number of community meters are the main contributors to background losses(m3/d)of apartment zones(R~2=0.84).The effect of the number of community meters on background losses is more significant than that of the number of building meters.This study found that BLI was a more appropriate performance indicator for real losses.BLI is the ratio of the current annual real water losses and the unavoidable annual background losses(UABL)and has no units.It is effectively an indicator of how well a distribution network is being managed and maintained at the current operating pressure.It is more suitable for the comparison between different system.