4.1.2. Results for Scenario 2: Water Consumption Increase

Figure 5 and Table 5 show the correlation between reliability indices and hydraulic measures according to the application of Scenario 2. In Scenario 2, system-wide increased water consumption causes an increment of flow and head loss in all pipes; that is, a system-wide stress is produced under this scenario. This mainly affects the branch-type networks (P-25–P-33) and significantly reduces the measures of Red2 and Rob2 that are related to the minimum nodal pressure as seen in Figure 5 (see scatter plots in second and fourth rows).

**Figure 5.** Scatter plots of Scenario 2 (*x*-axis—Reliability index; *y*-axis—Hydraulic measures). The plots highlighted in yellow show high correlation coefficient of 0.95 or higher.

**Table 5.** Correlation coefficients for Scenario 2.


Note: The values highlighted in yellow indicate high correlation coefficient of 0.95 or higher.

The hydraulic indices (RI, MRI, and API) show great correlations with the measures overall (in range of 0.94–0.99) under Scenario 2. The higher value of the hydraulic indices implies that the networks have excessive pressure, thus providing redundancy, guaranteeing maintenance of pressure, and allowing better serviceability.

In contrast, the topological indices (AD and NE) and entropic index (FE) show relatively low correlation with the performance measures under Scenario 2 in which overall flows increase without changes in network connectivity/layout and flow paths.

For the mixed indices, PHRI quantifies the serviceability well, while RRI represents the redundancy and robustness measures well. It is noteworthy that RRI has a strong correlation with Red2 and Rob2 (*R* values are 0.97 and 0.96, respectively), which cannot be seen in other indices under Scenario 2.
