**1. Introduction**

Today, the problem of the continuing decrease in available freshwater reserves is widely recognized, which is significantly magnified if one considers the effects of climate change on the spatial and temporal distribution of water resources [1–5]. Consequently, there is an urgen<sup>t</sup> environmental and societal need to implement efficient managemen<sup>t</sup> practices to water distribution networks (WDNs), which constitute the core infrastructure for drinking water supply to users.

The first step towards developing efficient managemen<sup>t</sup> strategies is the accurate hydraulic modeling of WDNs using a dedicated software package (e.g., EPANET) in order to identify their weaknesses and evaluate their overall operational condition. To do so, one needs to develop a detailed representation (i.e., a model) of the pipeline grid using appropriate hydraulic objects (e.g., pipes, pumps, valves, junctions, reservoirs, tanks, etc.). The effectiveness of the modeling procedure is mainly determined by the modeling accuracy, which is significantly affected by the density of the computational nodes (i.e., junctions). Although a high nodal density model produces more accurate results, it also dramatically increases the computational requirements, leading to time-consuming solutions. Under this setting, the current work focuses on developing a practical methodology for the optimal allocation of computational nodes, in terms of modeling accuracy and computational cost.

### **2. Area of Application**

We have applied the analysis that follows to the four largest and most highly populated pressure managemen<sup>t</sup> areas (PMAs) of the water distribution network of the city of Patras, in western Greece (namely Boud, Kentro, Panachaiki, and Prosfygika; see Figure 1). The corresponding PMAs, which share similar characteristics regarding their population density as well as land uses and topography, consist of over 200 km of HDPE and PVC

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**Citation:** Serafeim, A.V.; Perdios, A.; Fourniotis, N.T.; Langousis, A. Towards More Efficient Hydraulic Modeling of Water Distribution Networks Using the EPANET Software Engine. *Environ. Sci. Proc.* **2023**, *25*, 46. https://doi.org/ 10.3390/ECWS-7-14166

Academic Editor: Lampros Vasiliades

Published: 14 March 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

pipes, and cover most of Patras's city center (about 4 km2), providing water to more than 58,000 customers, as reported by the associated public authorities (see Table 1).

**Figure 1.** Map showing the position of the four largest pressure managemen<sup>t</sup> areas located in the central region of Patras. Numbers are linked to the entries listed in Table 1.

**Table 1.** Name, total area, length of the pipeline grid, and population of the four largest pressure managemen<sup>t</sup> areas (PMAs) of the city of Patras. Numbers reflect the encompassed areas in Figure 1.

