# The Impact Assessment of Water Supply DMA Formation on the Monitoring System Sensitivity
## 3 Results and Discussion
### Case Study

Table 3: Measurement indications of the monitoring system (existing and additional) in the analysed DMA zone. Figure 14: Contour map of pressure drop areas caused by open hydrants in the DMA 02 zone. In the second phase of the case study experiment, the Darwin Calibrator leak detection module was applied, using the indications of the pressure and flow sensors installed in the analysed zone. The obtained location indications turned out to be unsatisfactory. The so-called length of the error ranged from 178 to almost 1300 m. Increasing the number of pressure gauges by five additional portable loggers resulted in a decrease in this length in three cases and an increase in two (hydrants 69984 and 351864). However, the average value of error length decreased by almost 60%. Interestingly, adding two additional flowmeters to the monitoring system in the third stage of the experiment did not improve and even slightly worsened the effectiveness of leak location indications. The full list of calculated error lengths is presented in Table 4.  
As the referenced example, the case of the open hydrant H05 (ID: 69717) with three groups of monitoring points is presented in Figure 15a-c. At first, while using only the existing KP1 and KP2 monitoring points, the length of error equalled 762 m. Adding five additional pressure loggers enabled the Darwin Calibrator module to limit this distance (error length) to 234 m. Data from two additional flowmeters resulted in very precise leakage detection: the length of the error was 13 m. Similarly, in cases H01 and H02 the additional pressure loggers resulted in reducing the length of the error. Paradoxically, in cases H03 and H05 additional monitoring sensors resulted in increasing the length of the error. Interestingly, although the increase in the number of network manometers improved the effectiveness of leak detection, the subsequent introduction of additional network flow meters did not translate into a further improvement in the effectiveness of the diagnostic system. The solution to this problem may be the division of the analysed zone into smaller \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Open Hydrant** & **H01** & **H02** & **H03** & **H04** & **H05** & **Average** \\
**Hydrant ID:** & **69669** & **69714** & **69984** & **351864** & **69717** & **Average** \\ \hline
**Monitoring Points** & & & & **Length Error (m)** & & \\ \hline KP1, KP2 & 178 & 1299 & 381 & 155 & 762 & 555 \\ \hline KP1, KP2 & 32 & 1 & 635 & 192 & 234 & 219 \\ J1-J5 & 32 & 301 & 635 & 207 & 13 & 238 \\ Q1, Q2 & & & & & & \\ \hline \end{tabular}
\end{table} 
Table 4: Calculated length of the error of leakage indications in the analysed DMA zone. Figure 15: Length of the error for open hydrant H05: (**a**) length of the error equal to 762 m, (**b**): 234 m, and (**c**): 13 m.  
subzones in terms of territory and number of recipients, as recommended by [PERSON] et al. [20]. It is also worth considering the possibility of equipping such subzones with additional acoustic sensors, which is recommended by [PERSON] and [PERSON] [32].