**1. Introduction**

Water is one of the substantial requirements in planning, developing, protecting, and controlling water resources. Improper and inefficient assessment and managemen<sup>t</sup> of surface and groundwater could provide essential risks in the fields of human health and well-being, food security, industrial development, and the life of ecosystems [1–4]. Groundwater is considered one of the most important resources worldwide in the drinking and agriculture sectors. During the last few years, urbanization and population growth have led to an increase in the use of groundwater resources. Therefore, water quality evaluation is one of the significant problems in groundwater studies [5]. Variation in the quality of water resources is a grea<sup>t</sup> danger in usage by the agricultural, urban, and industrial sectors [6,7]. Several methods have been developed for water quality determination. Among these key methods to evaluate and manage groundwater resources for drinking purposes, the Schoeller diagram and the Water Quality Index (WQI) methods are the most common. In this study, to assess the water quality of groundwater, the Schoeller

**Citation:** Noori, A.; Ranjbari, F.; Bonakdari, H. Investigation of Groundwater Resources Quality for Drinking Purposes Using GWQI and GIS: A Case Study of Ottawa City, Ontario, Canada. *Environ. Sci. Proc.* **2023**, *25*, 74. https://doi.org/ 10.3390/ECWS-7-14314

Academic Editor: Athanasios Loukas

Published: 3 April 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/).

diagram, Canadian Groundwater Quality Index (GWQI), and Geographic Information System (GIS) were combined. Schoeller's semi-logarithmic diagram is widely used to compare groundwater quality. This graph shows the concentration differences between water samples. It is classified based on several physio-chemical parameters to evaluate the quality of groundwater [8]. The GWQI method has high capability for groundwater quality assessment across the world. In the GWQI index based on GIS, several chemical parameters affecting the quality of groundwater are integrated. GIS is used for the interpolation and classification of water quality parameters. For this purpose, the kriging method was applied to interpolate each data layer of water quality parameters. Further, to reduce the uncertainties of the obtained results, interpolation map layers were converted to fuzzy set in GIS environment.

During recent years, multiple studies have been presented to evaluate water quality for drinking uses with the Schoeller diagram, water quality indices, and GIS software in different parts of the world [9,10]. In another study, NickPeyman and Mohammadzadeh, 2013, studied groundwater quality in the Mashhad plain aquifer by estimating the GQI index [11]. Soleimani et al., 2013, conducted a study entitled "Investigation of qualitative changes in water resources of east Koohsorkh using the GQI quality index in the GIS environment" [12]. Sadat-Noori et al., 2014, used a combination of the Water Quality Index (WQI) and GIS to determine the groundwater quality of the Saveh-Nobaran aquifer in Arak province, Iran. They used the kriging method in GIS for creating spatial distribution maps of pH, TDS, EC, TH, Cl, HCO, SO4, Ca, Mg, Na, and K [13]. In another study, Alavi et al., 2016, assessed the water quality of Dez eastern in Iran for drinking and agricultural uses with Schoeller and Wilcox diagrams, and the zoning water quality in a GIS environment considering physical and chemical parameters. They used the kriging interpolation method in GIS [14]. Farhan et al., 2020, investigated the Canadian Water Quality Index (CCME WQI) for drinking and domestic use in Mosul, Iraq. This research examined ten sampling sites along the river to collect samples from 2008 to 2014. The results showed that the water quality of the Tigris River was between 3.66 and 7.93, which is in the good and moderately good category [15]. Pourkhosravani et al., 2021, tried to evaluate groundwater resources' chemical quality for drinking and agricultural purposes using Schoeller and Wilcox diagrams in the Sirjan Plain of Iran. Their classification map of each effective parameter was prepared using IDW-based GIS [16]. Given the fact that a comprehensive study on chemical parameter variations of groundwater quality has not been carried out in the study area, this study aimed to investigate the variation in groundwater quality parameters for drinking purposes in Ottawa city using the interpolation of GWQI and the Schoeller diagram in a GIS environment.

### **2. Materials and Methods**

### *2.1. Study Area*

Ottawa city, with the area of 2790 km2, is located in in the east of southern Ontario. This city is located at latitude 45◦2529 N and longitude 75◦4142 W, with an elevation of 70 m above sea level. The climate is semi-continental, with a warm, humid summer and a very cold winter. The temperature typically varies from −14 ◦C to 27 ◦C, while the mean precipitation is 920 mm. Rain falls throughout the year in Ottawa. The highest mean monthly rainfall in Ottawa is in July, with an average rainfall of 76 mm, while the lowest rainfall month is February, with an average rainfall of 12.7 mm. The study area involved different residential and industrial regions which supply the needed water from groundwater resources. Groundwater is one of the main sources of water in this area. There are lots of wells in the study area's aquifers that have high potential as a source of drinking water. The location of the study area is illustrated in Figure 1.

**Figure 1.** Location of the study area and the sampling wells.
