# The Impact Assessment of Water Supply DMA Formation on the Monitoring System Sensitivity
## 2 Materials and Methods
### Case Study Network  
In the second stage of the research, a selected zone of the real water supply network was used. The analysed water distribution system (WDS) has a very complex geometric structure and consists of 24 pressure zones, with several pumping stations and tanks (Figure 3). The WDS delivers water to approx. 30,000 inhabitants. Among the typical household customers in the analysed WDS, there are several industrial customers, demanding water in significant amounts at random times of the day. The prevalent pipe material is PVC and PE, but the oldest parts of the network consist of asbestos cement, ductile iron, and steel pipes, mainly in the old-town district. The total pipe length equals approx. 260 km and the total daily water demand is approx. 3850 m\({}^{3}\)/day (128.3 dm\({}^{3}\)/(d-person)). However, the demand for water can periodically increase to 7120 m\({}^{3}\)/day (237.3 dm\({}^{3}\)/(d-person)). The analysed WDS is characterised by great water losses, varying from 7% up to 43% of the total input volume between zones. In the majority of the 24 pressure zones, the population density can be described as low or medium, which usually results in a long leakage detection time--the water outflow to the surface is noticed in a couple to several days. Figure 3: Geometric structure of the water supply network along with the location of the water intake, pumping station, and water tanks. The blue line designates the analysed zone. The research studies were conducted for the zone marked in blue in Figure 3. In this area, three DMA zones were separated (Figure 4). The DMA zones were equipped with flow meters (one at the entrance to each zone) and additional network manometers. The sensor readings were transferred to the existing GIS database through the online SCADA system. A calibrated numerical model of the network, developed in the Bentley WaterGEMS software, was integrated with the GIS database, equipped with the Darwin Calibrator module that enables searching for water leak locations. The DMA 02 zone, which covers approx. 6500 m of water pipes and 443 junctions, was selected for experimental research. There are two monitoring points in this zone: KP1 (flow rate and pressure measurement) and KP2 (pressure measurement). The location of the measurement points is shown in Figure 5. The considered zone is characterised by a significant capacity reserve, resulting in a stable spatial distribution of the pressure head. The difference between its minimum and maximum values during normal operation ranges from 7.49 to 7.87 m H\({}_{2}\)O.  
Figure 4: The division of the selected zone of the network into DMAs. Figure 5: Location of monitoring points and open fire hydrants in the analysed DMA 02 zone. In the first phase of the case study, the size of the pressure head drop in the network, caused by the successive opening of the five fire hydrants indicated in Figure 5, was checked using a calibrated numerical model, analogically to Section 2.1. The hydrants were opened at the hour of maximum water demand in the analysed DMA 02 zone. The abnormal situation alarm threshold was assumed to be a pressure drop of 5.0 m H\({}_{2}\)O. This value resulted from both the measurement uncertainty of the installed manometers (\(\pm\)2.0%) and the existence of continuous, up to 4 m H\({}_{2}\)O, pressure fluctuations in the analysed zone. The observed amount of pressure head drop due to the opening of the hydrant is presented in the form of a contour plot graph. The subsequent phase of the experiment consisted of the physical opening of the fire hydrants indicated in Figure 5. Then, the pressure drops recorded by the SCADA system at the measurement points existing in the zone were used as input data to the numerical model of the network. As in the case of model grid networks, these data were the basis for carrying out simulation calculations aimed at searching for the location of water leakage. The calculations were carried out in a manner analogous to that presented in Section 2.1.