# The Impact Assessment of Water Supply DMA Formation on the Monitoring System Sensitivity
## 3 Results and Discussion
### Case Study  
The research began with the preparation of a contour map that shows the areas of pressure drop in the analysed DMA zone after each of the selected hydrants has been opened (Figure 14). The marked isolines are described by the values of the pressure drop in m H\({}_{2}\)O. Only the opening of hydrants 69669 (located mostly to the west) and 69984 (centre) caused the pressure to drop above the assumed alarm threshold of 5.0 m H\({}_{2}\)O. As at the first stage of the research on model networks, this means that it is necessary to use more pressure gauges to correctly locate leaks in the entire zone. As indicated in the description of the case study network (Section 2.2), the analysed DMA zone covers a relatively large area and serves a large number of customers. Due to the significant reserve of water transmission capacity that characterises this zone, the increase in water demand, corresponding to the opening of the fire hydrant, did not result in a significant increase in the flow velocity in the network pipelines. This was the reason for the slight differences in the pressure head in the network caused by these openings. The detailed measurement indications of the monitoring system in the analysed DMA zone are presented in Table 3. The monitoring system indications are divided into three groups: (1) existing monitoring points (KP1 and KP2), (2) additional portable hydrant loggers J1-J5, and (3) additional portable flowmeters (Q1 and Q2). The existing monitoring system triggered an alarm only in the case of the opening of the H01 (ID: 69669) and H03 (ID: 69984) hydrants due to the recorded pressure drop above 5 m H\({}_{2}\)O in the KP2 monitoring point (marked grey in Table 3). The KP1 pressure monitoring sensor, located and the entrance of the analysed DMA zone, proved not to be sensitive to opening fire hydrants in the zone. Therefore, the alarm at the KP1 monitoring station was triggered only by the increase in the metered flow (marked yellow in Table 3). Adding additional pressure loggers in five different locations in the DMA zone proved to be of little improvement in terms of triggering alarms; in only 3 out of 25 cases, the pressure drop recorded by the  
Figure 12: The average length of the error relative to the number of loops and the number of monitoring sensors applied. Figure 13: The average length of the error in relation to the fractal dimension and the number of monitoring sensors applied. portable loggers was above 5 m H\({}_{2}\)O. On the contrary, the additional flowmeters turned out to be very effective in terms of triggering alarms in the analysed DMA zone. In 8 out of 10 cases, the increase in flow caused by the hydrant opening was noticed (an increase above 10% of flow compared to normal conditions) in portable flowmeters (marked green in Table 3). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Open Hydrant** & **H01** & **H02** & **H03** & **H04** & **H05** & **Normal** \\
**Hydrant ID:** & **69669** & **69714** & **69984** & **351864** & **69717** & **Conditions** \\ \hline
**Monitoring** & **Unit** & \multicolumn{5}{c}{**Measurement Indication**} \\ \hline KP1 & (m\({}^{3}\)/h) & 58,45 & 58,45 & 58,45 & 58,45 & 58,45 & \\ KP1 & (m H\({}_{2}\)O) & 40,28 & 40,28 & 40,28 & 40,28 & 22,45 \\ KP2 & (m H\({}_{2}\)O) & 58,45 & 46,70 & 12,58 & 48,03 & 48,03 & 41,69 \\  & & & & & & 50,40 \\ \hline J1 & (m H\({}_{2}\)O) & 11,11 & 43,77 & 39.68 & 45,10 & 44,47 & \\ J2 & (m H\({}_{2}\)O) & 43,79 & 43,36 & 44,18 & 44,74 & 44,03 & \\ J3 & (m H\({}_{2}\)O) & 43,82 & 43,71 & 43,92 & 44,09 & 43,68 & 47,47 \\ J4 & (m H\({}_{2}\)O) & 43,92 & 44,17 & 43,41 & 44,24 & 44,19 & 47,11 \\ J5 & (m H\({}_{2}\)O) & 40,68 & 40,68 & 40,68 & 33,83 & 40,68 & 46,45 \\  & & & & & & & 46,61 \\  & & & & & & & 43,05 \\ \hline Q1 & (m\({}^{3}\)/h) & \multicolumn{5}{c}{} & & & 1,29 & 1,29 & 1,29 \\ Q2 & (m\({}^{3}\)/h) & \multicolumn{5}{c}{} & & & 7,21 & 1,29 & 7,20 \\ \hline \hline \end{tabular}
\end{table}