Leakage Detection in Water Distribution Systems by Considering the Hourly Changes of Node Demands Using Harmony Search Algorithm

Water distribution networks are of the most important urban infrastructure for water supply. Given that water loss is currently a global concern, and water demand s increasing; This has made it necessary to manage demand and improve consumption patterns. One of the most important ways to manage consumption is to reduce unaccounted-for water. Leakage is one of the components of unaccounted-for water in the water supply networks. Also, due to population growth and water crisis in a large part of the world, the issue of leakage in urban water supply networks has become very important. Leakage in water distribution networks wastes energy and water resources, increasing damage to infrastructure, and contaminating drinking water. Water leakage in the water distribution systems (WDSs) varies between 5 to 55% of the total water. Therefore, leakage has an important effect on system performance. The importance of leakage can be found in issues such as water scarcity, optimal use of available resources and high costs of water treatment and distribution. In other words, in the discussion of water transmission and use, we are observing obvious and hidden waste, which is important in dry and semi-arid countries like Iran, so this need to minimize the amount of waste so that resources can be used optimally. In recent years, various solutions have been considered to reduce leakage by researchers and managers of the water industry; This includes hardware methods (acoustic procedures, flow measurements, etc.) and software methods (neural network, genetic algorithm, WATERGEMS, etc.). In this paper, a software method is developed to facilitate leakage detection and eliminate uncertainty of hardware methods such as human and device errors. In other words, to reduce the cost and time of hardware methods, a simulation-modeling method is developed here based on harmonic search algorithm. For this purpose, EPANET hydraulic model and MATLAB environment have been used. Different scenarios for locating leaks and finding leakage sizes were investigated in two water supply networks. Scenarios include one leak and three simultaneous leaks in different parts of the networks. Also, the variability of nodal demands during the day and night was considered as an uncertainty parameter, and thus the coefficients of the consumption pattern during 24 hours were allocated to the nodes of both networks in EPANET software. After that, the main body of the Harmony Search Algorithm was written in MATLAB environment, and in accordance with each of the location and leakage scenarios, the Harmony Search Algorithm was developed. Algorithm parameters were also adjusted according to the type of scenario, the size of the studied network (number of nodes) and the number of variables to produce acceptable responses. The algorithm in MATLAB environment was linked to EPANET software. The developed model examined 14 different scenarios. The results show that the developed model has been successful in locating one leak, finding the size of the leak, and locating three leaks, respectively. In general, the model has had an acceptable performance in locating and finding the size of leakage during the day and night.