| It is pay enough attention to the leakage problem of urban water distribution system with the continuous expansion of the scale of urban water supply,as well as the problem of water shortage is becoming more and more serious and the problem of poor water resource utilization rate in many domestic areas.Through the water balance of the International Water Association,it is important to study the method of distribution leakage assessment,which solves the problem that the distribution leakage in domestic is difficult to assess.Thus,it provided technical support for distribution leakage assessment and a reference method for assessing the degree of leakage in the management area of the water supply industry.In this paper,by analyzing the limitations of the current assessment method,the existing shortcomings can be overcome.Combination of the IWA recommended non-revenue water and real losses performance indicator,it divided distribution leakage assessment into economic assessment and operational capability assessment indicators.Each category was divided into three levels according to the progressive relationship.The first-level indicators had nonrevenue water rate,real loss rate and management loss rate.The second-level indicators had unit connection point leakage amount,unit pipe length leakage amount,physical loss at unit connection point and physical leakage of unit pipe length.The third-level indicators had nonrevenue water cost rate and Infrastructure Leakage Index.Based on this,two types of three-level-nine-indicator comprehensive evaluation system for distribution leakage assessment were established.It could better assess the leakage of water distribution system.The water losses of water balance system can be divided into real losses,metering losses and other losses.In which,the inaccuracy of the calculation of metering losses is another difficulty in domestic distribution leakage assessment.It is mainly reflected that different types of water meters often produce different errors as the service life increases.Therefore,how to determine the water meters’ error is difficult in research.In this paper,there are two factors(water use model and water meter error curve)that affect the calculation of error to consider.Six different types of users were selected for continuous flow monitoring.The water use model is determined according to the proportion of water used under different flows.And then,reconstruction of the water meter error curves.Finally,the water meter error was calculated by considering the weighted error calculation method of the starting flow and the error calculation method under the characteristic flow.It is found that the calculation of the water meter error is basically in accordance with the requirements without considering the starting flow,but the experience shows that the error is often higher under the initial flow.The calculated results for the initial flow rate were-0.25%,-4.10%,4.59%,-2.03%,-5.74%,and-0.34% for the types I,II,III,IV,V,and VI,respectively.The method which considers the initial flow is more accurate.It provides a reference method of water meter error calculation for the domestic water supply industry and has a positive meaning.After a detailed study on the method of distribution leakage assessment and the calculation of water meter error,it is applied to an example of water supply system in a certain district of Suzhou.To collect and calculate each component of water consumption in the water balance,it can establish the water balance from 2013 to 2017.The components of water losses are more clearly visible after preliminary analyzing the proportion of water consumption and water losses.Finally,the system leakage status of the research area is assessed by the leakage performance indicator and the water loss rate.From the results of leakage performance indicator analysis,the leakage was mainly concentrated on the physical leakage caused by the pipe network.The leakage of the three areas of Fen hu,Tao yuan and Ping wang is serious,and Song ling and Sheng ze were relatively good.In water loss rate assessment,the measured leakage rate in the study area varies from 23% to 30%,and the measured loss rate ranges from 20% to 30%.The extent of leakage in the assessment study area for the past five years has not yet met the national standards.Finally,based on the evaluation results,several specific leakage control measures are proposed. |
