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Article

Spatial and Temporal Variations of the Hydrochemical Parameters in the Gravelly Aquifer of the Lower Course of Vjosa River, Albania

by
Elsa Dindi
1,* and
Ardian Shehu
2
1
Department of Applied Geology and Geoinformatics, Faculty of Geology and Mining, Polytechnic University of Tirana, 1019 Tirana, Albania
2
Department of Earth Sciences, Faculty of Geology and Mining, Polytechnic University of Tirana, 1019 Tirana, Albania
*
Author to whom correspondence should be addressed.
Hydrology 2023, 10(12), 234; https://doi.org/10.3390/hydrology10120234
Submission received: 30 October 2023 / Revised: 26 November 2023 / Accepted: 1 December 2023 / Published: 7 December 2023
(This article belongs to the Section Surface Waters and Groundwaters)
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Versions Notes

Abstract

:
Vjosa is the main river of South Albania. Currently, the confined Quaternary gravelly aquifer in its lower course supplies drinking water for roughly 300,000 local residents. In the past years, extracted groundwater quantity has increased, whereas the groundwater quality has been affected by seawater intrusion. This paper aims to assess the groundwater quality and to discuss the dominant hydrochemical processes in the aquifer. To fulfil this goal, the study discusses the groundwater quality’s spatial and temporal variations on the basis of the hydrochemical parameters and ratios for 2010–2021 period, during which data are collected from three monitoring wells, located 6, 14 and 17 km, from the sea. While for 1961–2009 period, hydro-chemical water types and TDS maps are prepared using roughly 100 chemical analyses. The hydro-chemical parameters are discussed related to the factors controlling the groundwater’s chemical constituents and the groundwater extraction. Heavy metals and nitrates’ contents indicate that the aquifer is not affected by anthropogenic pollution. The main conclusion is that the groundwater quality is affected by seawater intrusion due to overexploitation. The study reveals its gaps, mentions its possible usefulness, and underlines the discrepancy between the policy makers and the hydrogeologists approaches concerning groundwater extraction.

1. Introduction

This paper discusses the spatial and temporal variations of the ground water quality in the confined Quaternary gravelly aquifer of the lower course of Vjosa River, Albania. Currently, this aquifer provides drinking water for roughly 300,000 residents of Fier and Vlore Counties, which population has increased during the last 30 years due to demographic changes from rural to urban areas of the western lowland of the country. The study area is split into two sub-areas: Vjosa River valley and Vjosa River plain [1] (Figure 1). The groundwater quality in the study area has been monitored continuously from 2010 to 2021. Vjosa River valley aquifer’s groundwater that supplies drinking water to roughly 50,000 local residents, is within the drinking water quality standards. Roughly 250,000 inhabitants are supplied in drinking water from Vjosa River plain aquifer, where are located three wellfields, namely Pishe Poro, Novosela and Kafaraj. Amid them, Pishe Poro is no longer in use due to significant seawater intrusion. The total groundwater amount extracted in Novosela and Kafaraj, was roughly 1420 L/s in 2011 [2] and 1560 L/s in 2021 [3]. The distribution of the extracted groundwater amount in 2021 was; up to 900 L/s in Kafaraj, 300 L/s in Novosela, 300 L/s from private wells, and 60 L/s from local public wells [3]. Thus, from 2011 to 2021, there is an increase in the extracted groundwater amount in the confined aquifer of Vjosa River plain, especially in Kafaraj wellfield. It should be noted that the statistics for the private wells are not accurate due to the increasing number of informal wells used mainly for irrigation purposes [4].
The increasing water demand increases the need for more groundwater extraction that could lead to the deterioration of the groundwater quality. The groundwater chemical composition is controlled by various natural and human factors, including the initial composition of surface waters, geological environment, time of interaction water-rock, well’s geographical location, groundwater exploitation, and anthropogenic pollution [5,6,7].
The main objective of this paper is to assess the groundwater quality for drinking purposes and to characterize the hydrochemical processes that are dominant in the study area. The groundwater quality and the hydrochemical processes are discussed in space and time.
Efforts are made to indicate the possible sources of groundwater’s chemical constituents, such as the river catchment geology, the sedimentation conditions of the aquifer, the interaction water-rocks, the seawater intrusion, etc. A particular attention has been paid to the rCa/rMg ratio, which is seemingly “abnormal” compared to the other analyzed hydrochemical ratios. The possibility of occurrence of any anthropogenic pollution has been studied through concentrations of the heavy metals and nitrates. The study ends by mentioning the difference between the policy makers approach to development needs in increasing the extracted groundwater’s amount and the opinion of the hydrogeologists who call for sustainable water extraction practices that respect aquifer characteristics with regard to optimal groundwater management.
The present article is the first scientific paper that discusses the chemical composition of groundwater of Vjosa River Quaternary gravelly aquifer and the processes that control it. Previous hydrogeological studies on this aquifer include hydrogeological reports, two PhD thesis, and occasional and short scientific articles. The hydrogeological reports have been prepared by ASG, for the purposes of local projects for drinking water supply. These reports describe the state of groundwater, but none of them analyses the groundwater chemistry in function of the processes that could control it [8,9]. In his PhD thesis, Eftimi deals with the hydraulic properties of the porous aquifers of the whole Albanian Western Lowland, including Vjosa River aquifer, and the location of the wellfields in this aquifer [8]. While Dindi’s PhD thesis studies the vulnerability of the Vjosa River aquifer during 1961–2008 period, in function of the sustainable management of the groundwater sources [9]. Vjosa River Quaternary gravelly aquifer is also shortly described in a scientific article, the aim of which is the hydraulic properties of the aquifer in function of the optimal groundwater’s extraction [10]. None of the above-mentioned papers has taken into consideration the relationships between the groundwater chemical composition and the processes that control or influence it. The only scientific paper that discusses groundwater chemical composition in the Vjosa River aquifer is based on data up to 2008, and briefly describes the hydrochemical situation of the aquifer, without any explanation of the processes that control or influence it [11].
It should be noted that the monitoring wells from which data for the period 2010–2011 were collected, serve also as exploitation wells as there is no any proper monitoring network in this aquifer. The monitoring wells do not cover the whole aquifer because of their limited number. In addition, there is no water level measurements in these wells. Thus, there is no accurate data on the private wells and on the groundwater amount extracted by them.
This article could serve as an impulse for further in-depth studies on this aquifer. Above all, it could serve as an initial general guideline for exploiting the aquifer in accordance with its natural characteristics, which should be respected as a key and indispensable step of a scientific-based management of the aquifer by decision-makers.

2. Study Area

2.1. Vjosa River Basen and the Study Area

Vjosa River is 272 km long, from which roughly 80 km in Greece and 192 km in Albania [12]. It traverses the Southern Albania from East to West. The study area includes the lower course of the river that extends from Poçem Village to Adriatic Sea. It is split into two sub-areas: Vjosa River valley and Vjosa River plain (Figure 1). The latter is part of the confined aquifer of the western Albania lowland, which is rich in groundwater due to natural factors such as the large presence of geological formations with good water-bearing properties (sandstones, conglomerates, gravels and sands), the favorable climatic conditions (average rainfall 1000–1200 mm/year and average annual air temperature 15 °C–16 °C), the dense hydrographic network that constitute the main rechargers of the gravelly aquifer, as well as the flat terrain with a westward low slope [9].

2.2. Hydrogeological Settings

The gravelly deposits that are spread throughout the lower course of Vjosa River underlie the cover deposits, with the exception of the river bed from Poçem to Adbunace villages (Figure 1) that constitutes the recharge area.
The cover layer is composed of sub-clays, sub-sands and lentils of clays of the montmorillonite type. Its thickness varies from 5–20 m in the southeast of the study area (Poçem to Mifol), to over 60 m in the northwest, near Vjosa River mouth. The average thickness of the water-bearing gravels is about 30–40 m. The maximum thickness is 115 m in the central part of the study area, at the location called Mifol Bridge. Towards the southwest the thickness decreases up to 15 m, until the gravelly aquifer is pinched-out at the border of Narta Lagoon [13].
From Poçem to Adbunace, the thickness of the cover layer varies from 0.0 m to 4.0–5.0 m on both sides of the river bed, the water table lies from 2.0 to 5.5 m underneath the surface, and the aquifer is unconfined with the exception of a relatively small area in Cakran, Varibop, Vreshtas and Adbunace villages territories, on the right of the river bed (Figure 2). Whereas from Adbunace to the coastline, the aquifer is confined [4,9,14]. Figure 2 provides the piezometric lines map or the hydroisohypses map of the study area. A piezometric line or a hydroisohypse is a line on a map connecting points of equal level on the piezometric surface.
In the whole study area, the hydraulic parameters and water-bearing capacity of the gravelly aquifer are generally high, with the exception of the coastal area, where their values decrease [15]. Table 1 provides the hydraulic properties and water-bearing capacity in the central part of the study area where the thickness of the gravelly aquifer is high.
From Poçem to Adbunace, the main recharging factors of the aquifer include Vjosa River, through infiltration into the gravels of the river bed, as well as the drainage of the ground waters originating from Vlore River aquifer. The recharge from the sides of the Vjosa River valley is insignificant. The groundwater flow direction in this sector is that of the river valley (SE-NW).
From Adbunace towards the northwest, the ground waters are under pressure due to the subclayey—subsandy cover layer, the thickness of which increases towards the river mouth. The main groundwater flow direction is SE-NW, which corresponds to the river flow direction. Whereas the secondary directions are northwards in Ferras, and southwards in Novosela (Figure 2).
In the section Poçem—Adbunace, limited amounts of groundwater are extracted from hydrogeological wells that supply in drinking water the villages of the area and Patos town [16], as well as from private wells owned by families and private companies [9]. Three wells located in Varibop area, with a total discharge of 60 L/s, provide drinking water of good quality for Patos town.
The Kafaraj and Novosela pumping stations, as well as numerous informal private wells, all collect roughly 1480 L/s of groundwater in the Vjosa River plain [3], with the exception of Pishe Poro, which groundwater is not suitable for drinking purpose.

2.3. Groundwater Extraction in the Study Area

Currently, the Quaternary gravelly aquifer of Vjosa River in the study area provides drinking water for roughly 300,000 residents of Fier and Vlore Counties. The demographic profile of this area has undergone significant change due to population movements, from rural areas towards the main urban areas of the Albanian western lowland, during the last 30 years.
There are four wellfields in the Vjosa River confined Quaternary aquifer. Three of them, namely Novosela, Kafaraj and Pishe Poro are located in Vjosa River plain, while Varibop is located in Vjosa River valley (Figure 1). Currently, Novosela wellfield supplies drinking water to roughly 46,000 inhabitants of Vlore County [17]. Formerly, Vlore city (143,000 inhabitants [17]) was partially supplied by this wellfield. According to the annual State of Environment Reports (SoER), the groundwater amounts extracted in Novosela in 2011 and 2021 were about 700 L/s and 300 L/s, respectively [2,3]. This change is due to supply of drinking water to Vlore city by other sources, in carbonate rocks. Kafaraj wellfield supplies drinking water to Fier city and six rural administrative units of Fier County [18]. The total population supplied by Kafaraj wellfield has increased from 107,600 inhabitants in 2011 to 186,350 in 2018 [19]. In particular, Fier city population increased from 43,800 inhabitants in 1989, to 58,500 in 2011 and 92,550 in 2018 [19].
Varibop wellfield supplies partly (60 L/s) with drinking water Patos town and two rural administrative units [18]. Patos population increased from 21,800 in 2001 [20] to 31,050 in 2017 [17]. Pishe Poro wellfield is no longer used for drinking water supply as its groundwater is heavily affected from seawater intrusion.
The total groundwater amount extracted in the Vjosa River plain aquifer was roughly 1420 L/s in 2011 [2] and 1560 L/s in 2021 [3]. Out of the 1560 L/s, up to 900 L/s were extracted in Kafaraj, 300 L/s in Novosela, 300 L/s from private wells, and 60 L/s from local public wells [3]. Thus, from 2011 to 2021, there is an increase in the extracted groundwater amount in the confined aquifer of Vjosa River plain. It should be noted that the statistics for the private wells are not accurate because of the increasing number of informal private wells [4], which are used mainly for irrigation purposes in the rural areas. Before the 1990s, groundwater was not used for irrigation purpose, as agricultural lands were irrigated only by surface water through a complex system of irrigation and drainage channels. In the post 1990s, due to lack of maintenance of the irrigation system, many formal and informal private wells were installed for drinking and irrigation purposes.

3. Materials and Methods

3.1. Data and Information Sources

This study is based on the data collected during two time periods; 1961–2009 and 2010–2021. There was no groundwater monitoring network in Albania between 1961 and 1999. Because the monitoring wells were not the same from 1999 to 2009 and the water analyses were not constant, the monitoring network was not fixed during that time. The AGS’s hydrogeological laboratory conducted more than 100 comprehensive and representative groundwater chemical analyses between 1961 and 2009. Water samples were taken mainly during the pumping period of the water wells, in the framework of AGS’s drinking water supply projects, in the whole study area [9].
For the period 2010–2021, the data for Vjosa River plain were obtained from AGS. Given that AGS does not monitor any well in Vjosa River valley, data on the chemical composition of the ground waters in this valley, for the period 2010–2021, were obtained from the monitoring of three wells by the Regional Health Directorate (RHD) of Fier County [21]. The Varibop area where are installed the wells monitored by RDH Fier, is located in the northeastern part of Vjosa River valley aquifer. This part of this aquifer is confined. The water bearing gravelly layer that underlies and overlies clays deposits, is found at an average depth of 31 m. In Varibop 1, 2 and 3 wells the gravelly layer is found in 31.0–43.5 m, 50.5–60.5 m and 29.0–50 m, respectively [4,9].
Regarding Vjosa River plain, the data for the period 2010–2021 were secured from the State of Environment Report (SoER), published annually by the National Environmental Agency (NEA) [22]. NEA uses the data provided by AGS. In total, 86 water chemical analyses were carried out during this period in Vjosa River plain. All the selected monitoring wells are exploitation wells that are located in the confined aquifer. Three wells (Novosela 2N, Kafaraj 4E and Pishe Poro) have been monitored continuously from 2010 to 2021. The gravelly layer in these wells is found in 28–60 m, 26–55 m and 50–64 m, respectively. The gravelly layer overlies clay deposits [4,8,9]. Figure 1 shows the location of the monitoring wells, while Table 2 provides the number of the analyzed water samples and the monitoring period for each well.
The demographic data were secured from formal and publicly available sources, such as the websites of Fier and Vlore Counties and municipalities, National Agency on Territory Planning (NATP), etc.

3.2. Methodology

The values and trends of the hydrochemical parameters for the period 2010–2021 were analyzed and compared to the related results obtained for the period 1961–2009. The latter have been grouped, analyzed and mapped on the basis of water types [23].
The hydrochemical maps of the groundwater for the 1961–2009 period, are prepared based on the physic-chemical parameters, for the whole study area. The Total Dissolved Solids (TDS) is calculated as TDS—(HCO3)/2 in meq/L [14]. The hydrochemical water types are grouped and mapped on the basis of ions in amounts over 25% meq [9,14]. In addition, some characteristic hydrochemical ratios such as r(Mg2+/Ca2+), r(Na+/Cl−) and r(HCO3−/(SO42− + Cl−)) in meq/L are analyzed based on the water types classification [9].
Concerning Vjosa River valley during 2010–2021 period, 66 chemical analyses were conducted in the RHD laboratory of Fier County. The water samples were collected four time per year (spring, summer, autumn and winter), during three consecutive years (2013, 2014 and 2015), in three hydrogeological wells located in Varibop wellfield (wells located in Cakran, Varibop and Vreshtas villages). 15 samples were taken in spring, 24 in summer, 9 in autumn, and 18 in winter. The analyzed chemical parameters include pH, NO2−, NH4+ and Cl− [21].
Groundwater analyses for Vjosa River plain were conducted twice a year in the period 2010–2021, during the minimum and maximum water table levels (nearly between March and June and September and November, respectively). The physical parameters pH and EC were measured on site, while the chemical analyses were carried out in the hydrogeological laboratory of AGS. The analyses were conducted in compliance with the Albanian regulations on the drinking water quality standards. The government decree 145/1998 regulated the previous national standards, whereas the decree 379/2016 [24] provides the current ones, which fully comply with the provisions of the EU Council Directive 98/83/EC on the quality of water intended for human consumption [25]. It should be noted that the requirements of the decree 145/1998 were more stringent than those set forth by the decree 379/2016.
The graphs on hydrochemical parameters related to Vjosa River plain for 2010–2021 years, were prepared based on the major ions content. Given that the temporal changes of the ions‘ content may not be sufficient to determine their origin in groundwater, the temporal trends of TDS (mg/L), Total Hardness (TH) (in German Degree) and hydrochemical ratios for each monitoring well were analyzed, too [14]. The characteristic hydrochemical ratios taken into account include r(Mg2+/Ca2+), r(Na+/Cl−) and r(HCO3−/(SO42− + Cl−), calculated in meq/L [26], as well as Simpson’s coefficients in mg/L.
Various indicators can be used for evaluating the effect of the seawater intrusion on the groundwater [27]. In this study, in addition to other hydrochemical ratios, the Simpson coefficient Cl−/(HCO3− + CO32+) was used, too. Five classes of groundwater are distinguished in function of this coefficient; good quality (<0.5), slightly contaminated (0.5–1.3), moderately contaminated (1.3–2.8), injuriously contaminated (2.6–6.6) and highly contaminated (6.6–15.5) [28,29,30].
The r (Na+/Cl−) ratio combined with the other considered hydrochemical parameters, may indicate the origin of the ions in groundwater, even when the Cl− ion content is rather low. The ratio r(Na+/Cl−) < 1 is an indicator of the seawater intrusion, while r(Na+/Cl−) > 1 indicates an anthropogenic pollution [30,31,32]. When r(Ca2+/Mg2+) < 1, the predominance of Mg2+ over the Ca2+ ion content can be attributed to the seawater’s intrusion [32]. The decrease of the fresh water ratio r(HCO3−/(SO42− + Cl−)) <1 indicates difficult conditions of fresh water circulation in the aquifer [23].
The effect of the anthropogenic activity on the groundwater quality is rather complex and difficult to be determined. Nitrate ion content that originates mainly from different anthropogenic sources, is generally used to indicate this effect [14,30,31]. Heavy metals concentration has been used as another indicator of the groundwater pollution from the human activity [14,33].

4. Results and Discussion

4.1. Spatial Variations of the Groundwater Chemical Composition

The physic-chemical composition of the groundwater is based on the data collected during the 1961–2009 period [9]. Groundwater generally has good physical properties. The temperature varies between 14 and 17 °C. The pH varies from 7.25 to 7.75 in Vjosa River valley and from 7.7 to 8.9 in Vjosa River plain, where the highest values are reached near the coastline. The Spatial variations of the groundwater’s chemical composition have been studied on the basis of the hydrochemical water types. There are six hydrochemical water types within the study area (Table 3 and Figure 3). Table 3 provides the average content of the major ions and the hydrochemical ratios for each water type.
Figure 3 provides the spatial variations’ map of the groundwater hydrochemical types (called also water types) within the study area. The shades of blue and green colors show the spatial extent of each water type. The main ions and hydrochemical ratios for each of them are provided in Table 3. The waters’ types are mapped using GIS on the basis of the main ions in amounts over 25% meq [9,14]. The groundwater analyses are conducted by AGS during 1961–2009 period [9].
Table 3 indicates that the anions content in the river waters is rHCO3− > rSO4−2 > rCl−, whereas that of the cations is rCa+2 > rMg+2 > rNa+.
The initial chemical composition of the groundwater is related to the chemical composition of Vjosa River waters, combined with the sedimentation’s conditions of the gravelly deposits, the hydrodynamic conditions of the river basin, etc.
The chemical composition of water type I (Ca-Mg-HCO3) is influenced by the infiltration of the sub-clayey cover layer waters. Ca2+ and SO42+ ions contents decrease compared to those of the river waters. The ranking of rHCO3− > rSO42+ > rCl− and rCa2+ > Mg2+ > Na+ ions contents is preserved (Table 3). The TDS map shows that in the major part of the area of water type I, TDS < 0.3 g/L (Figure 4). The ratio r(Na+/Cl−) > 1, suggests any possible effect on groundwater by any human activity and/or from the interaction between the groundwater and the crossed geological formations. The water refreshing ratio r(HCO3−/(Cl− + SO4+2)) > 1 indicates a good relationship between the surface and groundwater (Table 3).
Figure 4 provides the TDS map prepared through GIS [9]. The used data were collected by AGS during 1961–2009 period [9]. The TDS is calculated as TDS—(HCO3)/2 in meq/L [14].
During the water movement in the aquifer, it is observed a faster increase in the amount of Cl− compared to Na+. The Ca2++ ion content decreases due to its precipitation that occurs when the groundwater is oversaturated with calcium, while the Mg2+ content increases significantly. The waters are of type II (Mg-Na-HCO3-Cl). TDS varies from 0.5 to 0.7 g/L. The groundwater refreshing coefficient is greater than 1, indicating a good circulation of the infiltration’s waters in the aquifer. The quantity and velocity of the groundwater flow play an important role in the chemical composition of water type II. This type spreads in the shape of a belt in the northwest of the waters of type I (Figure 3).
The waters of type III (HCO3-Cl-Na-Mg) spread in the west of type II waters (Figure 3). TDS varies from 0.5 to 0.8 g/L, while the ranking in ions content is rHCO3− > rCl− > rSO42+ and rNa+ > rMg2+ > rCa2+. The groundwater refreshing coefficient remains greater than 1, indicating a good circulation of the fresh water in the aquifer.
According to the hydrogeological map of Albania [1], in addition to the main groundwater flow, which direction is from Southeast to Northwest, there are some secondary flow directions. One of them flows northwards, from the recharge area to Ferras and further on to Levan (Figure 3), where waters of type IV (Cl-HCO3-Mg-Na) are formed. The ranking of the ions contents is rCl− > rHCO3− > rSO42+ and rMg2+ > rNa+ > rCa2+. The refreshing coefficient is lower than 1, indicating a difficult circulation of the fresh water in the aquifer. Waters of type IV spread in the NE of Vjosa River plain and are bordered by type II waters.
The waters of type V (Cl-HCO3-Na-Mg) spread in the west of type III waters, while the waters of type VI (Cl-Na) lie on the westernmost part of Vjosa River plain, in the shape of a belt 3–6 km wide that spreads in the west of type V waters (Figure 3). The refreshing coefficients of both water types V and VI are significantly lower than 1, indicating a very difficult circulation of the fresh water in the aquifer. Types V and VI are characterized by a significant increase of the Na+ and Cl− ions contents compared to type III. The content of Na+ and Cl− ions increases the closer the waters are to the coast. TDS values follow the same trend. In the westernmost part of the study area, TDS exceeds 4 g/L. For both water types V and VI, the ranking of the ions content rCl− > rHCO3− > rSO42− and rNa+ > rMg2+ > rCa2+ is preserved. Hereinabove mentioned indicate that the compositions of water types V and VI are influenced by the seawater.

4.2. Temporal Variations of the Ions Contents and Hydrochemical Coefficients

The temporal variations of the of ions and hydrochemical coefficients in Vjosa River valley and Vjosa River plain have been studied separately, in function of the available data/information.
Given that AGS has not monitored any well in the Vjosa River valley during 2010–2021 years, the water analyses of three wells in Cakran, Varibop and Vreshtaz that were monitored by the RHD of Fier County during 2013, 2014 and 2015 years [21], were taken into account. The average values of the analyzed chemical parameters in these wells were; pH = 7.66, NO2− = 0.0 mg/L, NH4+ = 0.0 mg/L and Cl− = 35.9 (maximum 70.9). Thus, all the ions contents taken into consideration are within the required standards, during the whole monitoring period. Besides, chemical analyses show that there is no any significant temporal change in the values of any of the above parameters.
The groundwater temporal chemical variations in the Vjosa River plain for the period 2010–2021, were based mainly on the chemical analyses of three wells monitored by AGS. These wells are located in Novosela, Kafaraj and Pishe Poro villages’ territories. Their distance from the coastline is roughly 14, 16 and 6 km, respectively. Hereinafter are examined the temporal variations of the main ions contents and hydrochemical coefficients related to these wells.

4.2.1. Novosela Wells

There are two monitoring wells in the area of Novosela village, named 2N and 3N that are located roughly 400 m from each-other. In total, only 6 water analyses have been conducted in the 3N well (August 2017 to August 2019). For the purposes of this study, only the data from the 2N well have been taken into account since this well has a complete series of analyses during the whole 2010–2021 period.
Graphs in Figure 5 show the temporal variations of the hydrochemical parameters for 2N well.
Table 4 provides the correlation coefficients of the hydrochemical parameters for 2N well. The correlation coefficient quantify the relationships between two parameters. When it is positive, both parameters increase in the same direction. Negative values indicate that when a parameter increases, the other decreases. The significance levels of the correlation coefficients are low (0 < 0.4), moderate/good (0.4 < 0.7), or strong/very good (0.7 < 1) [34].
The following describes the temporal variations of the hydro-chemical parameters for the 2N well as shown in Figure 5 and Table 4. The highest variations affect the Na+ ion, in November 2012 and in the four analyses of 2020 and 2021 years, when its content exceeds the permitted maximum limit for the drinking water standards. The increase in Na+ is associated by the increase in Mg2+ ion and the decrease in Ca2+ ion content. The HCO3− content reaches the highest value in March 2011, while in all the other analyses, it varies around the average value of 264 mg/L. The lowest value of Cl− ion content belongs to March 2011, while in November 2012 and three analyses of 2020 and 2021 years it is above the permitted limits for drinking water. The SO42− ion content shows small changes, but it still remains close to the lower permitted limit value. The NO3− ion content varies between 0.02 and 2.17 mg/L that is very low compared to the permitted maximal value of the drinking water standard (50 mg/L).
The variations in the TDS curve are fully in compliance with the Na+ and Cl− ions increase, as well as with EC (>1000 µS/cm) measured in 2020 and 2021 years. Table 4 shows that there is a very good correlation between the contents of Na+, Mg2+ and Cl− ions, and a negative correlation of Ca2+ ion with Na+ and Mg2+ ions. EC has a good correlation with the Na+, Mg2+ and Cl− ions and TDS, while with the Ca2+ ion it has a negative correlation. TH varies from 14 to 20 German degrees, with the exception of 2020 and 2021 years, when its values are very close to the permitted upper limit of 20 German degrees.
Graphs in Figure 6 show the temporal variations of the hydrochemical ratios for 2N well.
The temporal variations of the hydrochemical ratios for 2N well, are described hereinbelow.
The trend of the r(Na+/Cl−) ratio shows that the Cl− increases at a higher rate than the Na+ content, with the exception of June 2010, 2013 and 2015 years, and April 2016, when r(Na+/Cl−) > 1. The ratio r(Ca2+/Mg2+) is lower than 1, indicating that the Mg2+ increases faster than the Ca2+ content, with the exception of June 2013, when r(Ca2+/Mg2+) = 1. The water refreshing coefficient r(HCO3−/(SO42− + Cl−)) is greater than 1, showing a good circulation of the fresh water in the aquifer, with exceptions observed in June 2010, November 2012, and in years 2020 and 2021, when it varies from 0.60 to 0.76, indicating a reduction of the fresh water circulation. The variations of the Simpson coefficients show that in June 2010, November 2012 and in years 2020 and 2021, the groundwater is of second class [29,32], which means it is slightly affected by the seawater intrusion. All the other analyses indicate fresh waters, unaffected by seawater intrusion.
According to the map of water types (Figure 3), during 1961–2009 period, the water of 2N well is of Ca-Mg-HCO3 type (type I). During 2010–2019 period, it is of Mg-Ca-HCO3-Cl type, which is in between types I and II. While in the four analyses conducted in years 2020 and 2021, the Ca2+ ion is replaced by the Na+ ion, and the water type changes to Mg-Na-HCO3-Cl (type II).
Based on the above, the temporal variations of the hydrochemical parameters and ratios for 2N well indicate a deterioration of the groundwater quality in the years 2020 and 2021. The following provide evidence of this deterioration:
  • TDS values increase slightly, but still within the drinking water quality standards.
  • The values of Mg2+ and Cl− ions contents and EC do not satisfy the drinking water quality standards.
  • Simpson’s coefficients give evidence to the advance of the seawater intrusion in the aquifer. This is also confirmed by the variations of the hydrochemical ratios r(Na+/Cl−), r(Ca2+/Mg2+) and r(HCO3−/(SO42− + Cl−)).

4.2.2. Kafaraj Wells

In the area of Kafaraj Village there are two monitoring wells, named 3E and 4E. Only two water analyses were conducted during 2020 year in 3E well, which is located roughly 550 m from the recharging area, and 1900 m from the 4E well. Because 4E well has a complete series of analyses for 2010–2021 period, only the data of this well were taken into account for the purposes of this study. It should be emphasized that 3E well’s water meets all standards for drinking water quality.
Graphs in Figure 7 show the temporal variations of the hydrochemical parameters for 4E well.
Table 5 provides the values of the correlation coefficients of the hydrochemical parameters for 4E well. The coefficients’ significance levels are low (0 < 0.4), moderate/good (0.4 < 0.7), or strong/very good (0.7 < 1) [34].
Figure 7 and Table 5 provide the temporal variations of the hydrochemical parameters for the 4E well; these variations are explained herein below. Starting from June 2012, the Na+ content is above the permitted drinking water standards, with the exception of two analyses (March 2018 and March 2021), when it is 28.4 and 18.8 mg/L, respectively, which is close to the permitted lower limit value. From March 2010 to November 2011, the Cl− content is within the drinking water standards. Whereas from June 2012 to September 2021, it is above the permitted maximum limit, with the exception of the values of March 2018 and March 2021 that are close to the permitted minimum limit, respectively 35.5 and 21.3 mg/L. Thus, in general, from June 2012 to September 2021, the Cl− and Na+ ions contents values follow the same trend. The minimum and maximum values of the Mg2+ ion content are 36.5 and 109.6 mg/L, respectively. The Mg2+ content exceeds the permitted maximum limit in over 95% of the water samples. The trend of Mg2+ ion content values has a very good compliance with those of Na+ and Cl− ions. Thus, there is a good correlation between the values of Na+, Cl− and Mg2+ ions. The Ca2+ content (average 77 mg/L), varies around the lower limit for drinking water quality standard (75 mg/L). HCO3− content increase gradually from 347 to 460 mg/L. A middling correlation between HCO3− and Na+ and Mg2+ ions contents is observed. The average of SO42− content is 65.6 mg/L, which is within the drinking water standards (25–250 mg/L). The NO3− content vary from 0.58 to 8.53 mg/L, which is very low compared to the permitted maximal limit for drinking water standard (50 mg/L).
TDS varies between 477 and 883 mg/L, which is within the drinking water quality standards. The values of TDS and Cl−, Na+ and Mg2+ ions contents show the same trend. TH is constantly higher than the permitted drinking water quality standards (20 German Degree), with the exception of five analyses (March, June and December 2010, March 2011 and March 2021), when it fulfils the required standards. The high TH can be explained by the increase of Mg2+ ion content above the permitted maximum limit (Figure 7).
Graphs in Figure 8 show the temporal variations of the hydrochemical ratios for 4E well.
From Figure 8 it results that the r(Na+/Cl−) ratio varies around the average value of 0.79, with the exception of three analyses (June 2010, March 2018 and March 2021) when this ratio is >1. The value 0.79 may result from the effect of the seawater intrusion. The r(Ca2+/Mg2+) ratio varies around the average value of 0.69, with the exception of four analyses (March 2010, March 2011, March 2018 and March 2021), when it is >1. From March 2010 to November 2011, the ratio r(HCO3−/(Cl− + SO42−)) is greater than 1, indicating a good water circulation in the aquifer. Simpson’s coefficients, are lower than 0.5 (water class 1), indicating that the groundwater is not affected by the seawater intrusion. While from June 2012 to November 2021, the ratio r(HCO3−/(Cl− + SO42−)) is <1, showing a reduction of the fresh water circulation. During this last period, the Simpson’s coefficients are higher than 0.5, classifying the ground waters as slightly affected by seawater intrusion (class 2). Exception is made in two analyses (March 2018 and March 2021), when the ratio r(HCO3−/(Cl− + SO42−)) > 1 and the Simpson’s coefficients are lower than 0.5.
Water from the 4E well is type I (Ca-Mg-HCO3), according to the map of water types for the years 1961 to 2009 (Figure 3). The type II (Mg-Ca-HCO3-Cl) period spans from March 2010 to November 2011 and May 2017 to May 2018. Ca2+ replaces the ion Na+. The water is of type IV (Mg-Na-Cl-HCO3) between June 2012 and April 2017, and July 2018 and June 2019, whereas from August 2019 to September 2021 (the last five analyses), it changes to type II with a high Ca2+ content.
Here-below, the findings of the monitoring results for Kafaraj-4E well, are given. The hydrochemical parameters showed an upward trend from March 2010 to November 2011. However, the water is still of good quality and meets the drinking water standards. Nevertheless, these standards are not met from June 2012 to September 2021. TH and the ions Na+, Cl− and Mg2+ contents are above the permitted limits for drinking water quality standards. The Ca2+ content varies around the permitted lower limit value. The hydrochemical ratios indicate that the groundwater is slightly affected by the seawater intrusion. r(Na+/Cl−) < 1, r(Ca2+/Mg2+) < 1, the water refreshing coefficient r(HCO3−/(SO42− + Cl−)) < 1, and Simpson’s coefficients belong to the second water class (slightly contaminated).
During 2012–2021 years, the water parameters are within the drinking water quality standards only for two analyses (March 2018 and March 2021). It is thought that this might be due to the prolonged heavy rainfalls, as a result of which the infiltration and the water table level increased. This opinion is also reinforced by the high value (>3) of the water refreshing coefficient. It should be added that Kafaraj 4E well is located roughly 2 km downstream of the recharge area.
In summary, since year 2012, the water quality in Kafaraj 4E well is slightly deteriorated as a result of the seawater intrusion.

4.2.3. Pishe Poro Well

Pishe Poro area is situated in the main groundwater flow path. Pishe Poro well, located roughly 6 km from the coastline, has a complete series of analyses during the whole monitoring period 2010–2021.
Graphs in Figure 9 show the temporal variations of the hydrochemical parameters for Pishe Poro well for the period 2010–2021.
Table 6 provides the values of the correlation coefficients of the hydrochemical parameters for Pishe Poro well. The significance levels are low (0 < 0.4), moderate/good (0.4 < 0.7), or strong/very good (0.7 < 1) [34].
The temporal variations of the hydrochemical parameters for Pishe Poro well that result from Figure 9 and Table 6 are described herein below. The contents of the Na+, Mg2+ and Cl− ions have very high values that exceed the permitted maximum limit for drinking water quality standards. The increase rate of the Na+ and Cl− contents is higher than that of the Mg2+, which increases progressively in the range of 89–139.8 mg/L. The trend of Ca2+ content is stable, in the range of 15–38 mg/L that is lower than the permitted minimum limit for drinking water standards. The values of Na+ and Cl− contents and TDS follow the same trend with a correlation coefficient of 0.88. The TDS increase is mainly due to the increase of the Na+ and Cl− contents. The NO3− ion content varies from 0.07 to 7.46 mg/L that is very low compared to the permitted maximal value for drinking water standard values that is 50 mg/L. A very strong correlation between the couples Cl−–Na+, Cl−–Mg2+ and Na+–Mg2+ ions is observed. While between the couples SO42−–Mg2+, SO42−–Na+ and SO42−–Cl− ions, the correlation is moderate. The analyses of the first six water samples (March 2011–November 2013), indicate that TH varies slightly around the permitted maximum limit value. Whereas from March 2014 to September 2021, TH increases progressively above this limit, because of the Mg2+ ion content increase. It should be noted that from April 2019 to September 2021, TH values exceed 30 German degrees.
Graphs in Figure 10 show the temporal variations of the hydrochemical ratios for Pishe Poro well.
Figure 10 shows that the ratio r(Na+/Cl−) varies from 0.71 to 0.83, with a slight downward trend, which is an indicator of seawater intrusion. The maximum value of r(Ca2+/Mg2+) ratio is 0.24, indicating a high Mg2+ ion content that is roughly 2.5 times higher than the permitted maximum value for drinking waters. The water refreshing coefficient r(HCO3−/(Cl− + SO42−)) has low values, indicating a difficult water circulation in the aquifer. According to Simpson’s coefficient Cl−/(HCO3− + CO32+), from March 2011 to April 2016 the water is of third class (moderate pollution), from September 2016 to April 2019, the coefficient values vary around 2.8, classifying the water between the third and fourth class (high pollution), while from June 2020 to September 2021, the water is of fourth class (injuriously contaminated). The Groundwater is of hydrochemical type V (Na-Mg-Cl-HCO3) for the 1961–2009 period, and of type VI (Na-Mg-Cl) for the period 2010–2021.
In short, during the whole monitoring period 2010–2021, the hydrochemical parameters indicate that the water of Pishe Poro well does not satisfy the drinking water quality standards because of the seawater intrusion effect, which increases as the time passes.

4.3. The Calcium and Mgnesium Contents

4.3.1. The Calcium—Magnesium Ratio in the Vjosa River Aquifer

The values of the ratios rHCO3/(r(Cl + SO4) < 1, rNa/rCl < 1 and Simson’s coefficients are indicators of seawater intrusion. They converge in the three monitoring wells. In Novosela 2N, Kafaraj 4E and Pishe Poro wells, the seawater intrusion was observed in the periods 2020–2021, 2012–2021, and 2010–2021, respectively. Likewise, the hydrochemical parameters EC, Cl, Na and Mg, which have a very good correlation between them, have increased over the permitted values for the drinking water standards for each monitoring well, in the respective periods cited above. The TDS in 2N and 4E wells is within the permitted standard, but shows a continuous increase during the whole monitoring period.
In this study, rCa/rMg < 1 cannot be considered as a reliable indicator of the seawater intrusion. The interaction of seawater with groundwater can be due to other factors, which are attributed to the geological environment. The ratio rCa/rMg in Novosela 2N well fluctuates around the average value of 0.66. While in Kafaraj 4E well, it fluctuates around 0.69. The alkalinity/Ca2+ ratio is 2:1 for both these wells. Both these ratios indicate that the dolomite dissolution might prevail compared to the dissolution of calcite [35,36,37]. The ratio rCa/rMg in Pishe Poro fluctuates around 0.10, which is lower than the reference value of 0.2 of the Mediterranean seawater [7]. This low value cannot be explained only by the seawater intrusion. The alkalinity/Ca2+ ratio of 4:1 indicates that the dissolution of dolomites could be the main source of Mg content in groundwater [35,36,37,38].
Although the rCa/rMg ratio cannot be considered as a reliable indicator of the seawater intrusion, it indicates that this intrusion does not consist of a simple mixture of seawater with groundwater. The Mg ion increase may occur from the interaction of the modern groundwater with the old remaining waters in the overlaid and under laid clayey layers. These layers may also contain minerals rich in Mg, such as dolomites, which dissolution contributes to the low values of rCa/rMg ratio [35,36,37,38,39]. Based on the available data, it can be said that the seawater intrusion dominates the formation of the groundwater chemistry. Whereas the seemingly abnormal values of rCa/rMg may result from the dissolution of the dolomites.

4.3.2. Potential Sources of Magnesium in the Vjosa River Aquifer

Vjosa River waters are considered as a typical freshwater’s model, where the order of ions is Ca-Mg-Na for cations and HCO3-SO4-Cl for anions. In the three monitoring wells, rCa/rMg < 1 is observed, so there is an increase in Mg versus Ca, accompanied by a faster increase in Cl versus Na.
The chemical composition of the groundwater might be conditioned by various factors, including the water-rock contact, the decomposition of the organic matter contained in the clayey layers, and the geology of the river basin catchment.
The mixing of seawater with freshwater does not consist of a simple physical mixture because of the diagenesis of the clayey minerals which compose the clayey layers that underlay and overlay the gravelly aquifer [6,7]. The loose coastal deposits are formed in alluvial-marine-marshy environment, where coarse grain sediments are intercalated with fine grain ones, as a result of the coastline displacement due to transgression and regression phenomena [40,41]. Regarding Vjosa River plain, it can be said that the clayey deposits under the aquifer body correspond to an undisturbed environment dominated by the sea influence, as a result of which fine grain sediments are deposited. Whereas the gravelly layer corresponds to an abrupt regression phase as a result of which coarse grain sediments brought by the river are deposited over the previous fine grain sediments. While clays of the cover layer correspond to another transgression phase, which is followed by a slow regression as a result of which subs and sands are deposited [40,41,42,43,44]. According to Ciavola et al., 15,000 years ago the coastline on both sides of Vjosa River mouth was roughly 10 km from the current one, in the direction of the mainland [43]. Both the bottom and the cover clayey layers have a low filtration coefficient. Their pore water is different from the modern day groundwater because they are formed in different environments. Such changes, conditioned by the long time water-rock contact, are reflected in the groundwater chemical composition in the groundwater flow paths [6,45]. In general, the thicker is a clayey layer, the longer is the water-rock contact period.
The decomposition of the organic matter included in the clayey deposits can cause a ‘hidden’ exchange of Ca for Mg or Na [7,26]. The richest clays in organic matter are the marshy ones. According to Simeoni et al., the paleoenvironment of Vjosa River plain was characterized by a mixed fluvial-marine-marshy environment [44].
Mayo and Loucks suggest that the groundwater chemical composition is strongly affected by the geology of the river basin [35]. According to them, if rCa/rMg ratio is equal or less than 1, the dissolution of the dolomite will prevail versus the calcite one. The ratio value 4:1 of the alkalinity/Ca2+, indicates a contribution of the dolomite dissolution in the groundwater chemical composition [38]. The Vjosa River catchment consists mainly of carbonate formations. A limited surface of dolomitic rocks outcrop in Tragjas Mountain area [46], which is included in the Vlora River catchment that is the second important effluent of Vjosa River. However, the influence of the dolomite dissolution on the chemical composition in the study area requires further studies.

4.4. Temporary Variations of the Heavy Metals in the Vjosa River Aquifer

The monitoring of heavy metals in the study area is conducted only in Novosela 2N well. The Albanian standards on the heavy metals content in drinking water [24] are identical to the EU Directive 98/83/EC standards [25], which have been updated by the EU Directive 2020/2184 [47] that entered in force in January 2023. Table 7 provides the annual monitoring results [22]. No heavy metal analyses were conducted in the monitoring well in the years 2015, 2016, 2020 and 2021.
Heavy metals enters into water sources when the water dissolves minerals that contain such metals, or through human activity, such as; mining activities, industrial discharge, leaching from waste disposal, etc. [14,33,48,49,50,51].
Table 7 shows that the measured heavy metals contents in Novosela 2N well are within the required standards. During the monitoring period 2011–2019, a continuous decrease in the concentration of heavy metals in the well water was observed. We think that the cause of this decrease is the Vjosa River water quality improvement as a result of the closure of Memaliaj lignite mine, which is located roughly 38 km upstream of the study area. Coal waste is a source of heavy metal pollution and can be transported over long distances by surface waters [52,53]. The mining activity in Memaliaj ceased in 1995, while the mine was officially closed in 2001 [54]. However, the lignite stocks left outside the mine were a source of heavy metal pollution due to the erosion of coal stockpiles by atmospheric factors and to their passage into the Vjosa River waters [55]. As time passes, the impact of heavy metal pollution is being reduced. In 2005, Miho et al. [56,57,58] observed that the quantity of heavy metals in waters or sediments was unexpectedly low, compared to previous mining impact [59], as a consequence of the closure of the mining industry in Albania after year 1991 [54]. However, it should be added that the MnO content in the ash composition of the Memaliaj lignite is rather low compared to other coal mines in Albania [60]. In addition, coverage of the Memaliaj coal waste stockpiles by natural vegetation, has decreased the erosion and the quantity of pollutants that pass into the surface waters [61]. The improvement of the Albanian rivers’ waters quality due to the partial cessation of the mining activity is reflected in the seawater quality. As a result, the concentration of the heavy metals in the Adriatic seawater and the costal sediments of Albania is rather low [62,63]. Accornero et al. [64] showed that the concentration of heavy metals in Adriatic seawater close to Vjosa River mouth is low.
Heavy metals contained in the geological formations may dissolve in certain conditions, such as the reductive conditions, which are responsible for the dissolution of the Fe and Mn and the increase of their content in water [65,66]. The water refreshing coefficient in Novosela well during the monitoring period is higher than 1 (Figure 6), indicating a good circulation of the fresh water in the aquifer, and therefore a groundwater rich in dissolved oxygen.

4.5. Groundwater Extraction and Groundwater Quality

Ten water wells were installed in Kafaraj during 1962–1973 period. Because of their poor efficiency due to ageing, the old wells have been replaced by new wells installed next to each of the old ones. Four of these replacing wells, with a total discharge of 640 L/s, were installed in 2006–2008, and four others in 2014–2019. Besides, an additional new well of discharge 90 L/s was installed in 2014 [18], and the water distribution network was improved in 2015–2017 years [16]. As a result of these actions, Fier Municipality increased the drinking water supply to Fier city [67], whose population has increased by more than twice between 1989 [68] and 2018 [19]. In addition, from 2014 to 2021, the amount of water extracted from formal private wells for industrial and irrigation purposes in Vjosa River plain increased from 100 to 300 L/s [3,69].
It should be noted that the decision to increase the extracted groundwater quantity from the Kafaraj wellfield was made ignoring the advice of hydrogeologists, who have often warned about the deterioration of groundwater quality from overexploitation [4,69,70]. The speed of the seawater intrusion progress depends on the well’s geographical location in relation to the main or secondary groundwater flow paths, well distance from the coastline, and the amount of extracted groundwater [6,7]. Pishe Poro and Kafaraj wellfields are located in the main groundwater flow path. Eftimi thinks that currently the groundwater extraction coefficient in the Vjosa River plain aquifer could be around 0.95 [10], which is alarming to aquifer’s future and the supply of drinking water to the residents of this area. Pishe Poro wellfield is no longer in operation because of the significant seawater intrusion effect on the water quality (Figure 10). This wellfield is located roughly 6 km from the sea and very close to the seawater intrusion front. Although Kafaraj 4E well is situated 17 km from the sea, its water quality is slightly affected from seawater intrusion since the year 2012. We think this intrusion is due to the groundwater overexploitation in this wellfield. Whereas, water of the wells in Novosela wellfield has been affected slightly by seawater intrusion only in 2020 year (Figure 6). Novosela was affected so late because in this wellfield the aquifer is no longer under stress, because the amount of water extracted in recent years is only 300 L/s, compared to about 700 L/s that was extracted before 2014 [69].
As a conclusion, we think that intrusion of the seawater into the aquifer occurs due to overexploitation in Kafaraj wellfield coupled this with the increase in the amount of water extracted from private wells. It should be added that hydrogeologists have also studied large springs in carbonate rocks [71,72], which could be a sustainable and optimal alternative for the partial (at least half) replacement of extracted water quantity in the Vjosa River plain aquifer.

5. Conclusions

The analysis of the hydrochemical conditions in the study area during 1961–2021 period is summarized as follows:
  • In Vjosa River valley, the predominant water type is Ca-Mg-HCO3. The groundwater quality is within the drinking water standards during the whole period taken into consideration (1961–2021). There is no indication of any significant geochemical evolution of the groundwater.
  • The hydrochemical parameters for the period 2020–2021 indicate that the water in Novosela 2N well is affected by the seawater intrusion. In the period 2010 to 2019, however, it fulfils the drinking water quality standards.
  • From June 2012 to December 2021, the water of Kafaraj 4E well does not meet the drinking water quality standards. Simpsons’ coefficients indicate a second water class due to a slight effect of the seawater intrusion. Whereas the water of Kafaraj 3E well, which is located roughly 550 m from the recharging area and 1900 m from the 4E well, fulfils the required standards. However, it should be underlined that 3E well has been monitored only twice (March and November 2020).
  • Pishe Poro well, located roughly 6 km from the coastline, is affected by a higher rate of seawater intrusion compared to the other monitored wells. That might be due to the location of this well in the front of the seawater intrusion. The water quality of Pishe Poro well does not comply with the required drinking water standards during the whole monitoring period 2010–2021.
  • The low values of heavy metals contents and NO3− ion in the whole study area indicate that the groundwater chemical composition is not affected by any anthropogenic pollution.
In conclusion, the spatial and temporal variations of the groundwater hydrochemical parameters in Vjosa River plain indicate that in the last years, the groundwater quality is affected by the seawater intrusion. This phenomenon occurs in the area from Kafaraj (during 2012–2021 period) and Novosela (2020–2021 period) to the coastline. The maximum length of the affected area is roughly 17 km. The impact of seawater intrusion increases with the proximity to the coast. The groundwater quality upstream of Kafaraj 3E well, however, has not changed and continues to meet drinking water criteria. The intrusion of the seawater into the aquifer occurs due to groundwater overexploitation.

Author Contributions

Conceptualization, E.D.; methodology, E.D. and A.S.; data collecting, E.D. and A.S.; data analyses, E.D.; writing—original draft preparation, E.D. and A.S.; writing—review and editing, A.S.; supervision, E.D. and A.S. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

Readers can contact the authors for the available data and materials.

Conflicts of Interest

The authors declare no conflict of interest.

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Hydrology 10 00234 g001
Figure 1. Study area.
Figure 1. Study area.
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Figure 2. Map of Piezometric Lines in the Quaternary gravelly aquifer of Vjosa River.
Figure 2. Map of Piezometric Lines in the Quaternary gravelly aquifer of Vjosa River.
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Hydrology 10 00234 g003
Figure 3. Map of groundwater’s hydrochemical types in the Quaternary gravelly aquifer of Vjosa River.
Figure 3. Map of groundwater’s hydrochemical types in the Quaternary gravelly aquifer of Vjosa River.
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Hydrology 10 00234 g004
Figure 4. Map of Total Dissolved Solids in the Quaternary gravelly aquifer of Vjosa River.
Figure 4. Map of Total Dissolved Solids in the Quaternary gravelly aquifer of Vjosa River.
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Hydrology 10 00234 g005
Figure 5. Temporal variations of hydrochemical parameters for 2N well. (a) cations, (b) anions, (c) TH, (d) TDS and EC.
Figure 5. Temporal variations of hydrochemical parameters for 2N well. (a) cations, (b) anions, (c) TH, (d) TDS and EC.
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Hydrology 10 00234 g006
Figure 6. Temporal variations of the hydrochemical ratios for 2N well. (a) hydrochemical ratios (b) Simpson coefficient.
Figure 6. Temporal variations of the hydrochemical ratios for 2N well. (a) hydrochemical ratios (b) Simpson coefficient.
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Hydrology 10 00234 g007
Figure 7. Temporal variations of the hydrochemical parameters for 4E well. (a) cations, (b) anions, (c) TH, (d) TDS and EC.
Figure 7. Temporal variations of the hydrochemical parameters for 4E well. (a) cations, (b) anions, (c) TH, (d) TDS and EC.
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Hydrology 10 00234 g008
Figure 8. Temporal variations of the hydrochemical ratios for 4E well. (a) hydrochemical ratios, (b) Simpson coefficient.
Figure 8. Temporal variations of the hydrochemical ratios for 4E well. (a) hydrochemical ratios, (b) Simpson coefficient.
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Hydrology 10 00234 g009
Figure 9. Temporal variations of the hydrochemical parameters for Pishe Poro well. (a) cations, (b) anions, (c) TH, (d) TDS and EC.
Figure 9. Temporal variations of the hydrochemical parameters for Pishe Poro well. (a) cations, (b) anions, (c) TH, (d) TDS and EC.
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Hydrology 10 00234 g010
Figure 10. Temporal variations of the hydrochemical ratios for Pishe Poro well. (a) hydrochemical ratios, (b) Simpson coefficient.
Figure 10. Temporal variations of the hydrochemical ratios for Pishe Poro well. (a) hydrochemical ratios, (b) Simpson coefficient.
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Table 1. Hydraulic parameters and water-bearing capacity of the gravelly aquifer in the study area.
Table 1. Hydraulic parameters and water-bearing capacity of the gravelly aquifer in the study area.
LocationK (m/Day)T (m2/Day)qs (L/s/m)
K minK avK maxT min T avT maxqs minqs avqs max
Adbunace95225320220057009900224678
Çerven100245390420075009400307192
Novosela145215270490055507700485581
Ferras150260450610075009100627389
Bishan-300--9000--95-
Table 2. Monitoring wells in Vjosa River plain during 2010–2021 period.
Table 2. Monitoring wells in Vjosa River plain during 2010–2021 period.
Geographical Location
and Well Name 		Monitoring YearsNo of Samples
Novosela Village area; 2N2010–202125
Novosela Village area; 3N2017–20196
Kafaraj Village area; 4E2010–202129
Kafaraj Village area; 3E20202
Pishe Poro Village area; PP2011–202124
Table 3. Average content of the major ions and the hydrochemical ratios for each water type.
Table 3. Average content of the major ions and the hydrochemical ratios for each water type.
Water TypeNo of SamplesMajor ion Average Content (meq/L)Hydrochemical Ratio
Na+Mg+2Ca+2HCO3−SO4−2Cl−r Na+/rCl−rCa+2/rMg+2rHCO3−/r(Cl−+ SO4−2)
Ca-Mg-HCO3I101.502.502.944.810.981.131.331.182.28
Mg-Na-HCO3-ClII122.494.651.865.120.653.180.780.401.34
Na-Mg-HCO3-ClIII86.502.830.745.700.653.690.760.261.31
Mg-Na-Cl-HCO3IV85.007.492.586.510.727.830.640.340.76
Na-Mg-ClHCO3V914.543.631.336.340.8612.371.180.370.48
Na-ClVI534.644.411.216.41.3432.021.080.270.19
Vjosa River150.151.053.243.041.230.67---
Table 4. Correlation coefficients of the hydrochemical parameters for 2N well.
Table 4. Correlation coefficients of the hydrochemical parameters for 2N well.
pHNa+Ca2+Mg2+HCO3−Cl−SO42−TDSEC
pH1
Na+0.151
Ca2+−0.42−0.811
Mg2+0.360.77−0.721
HCO3−−0.16−0.190.380.131
Cl−0.160.96−0.780.85−0.081
SO42−−0.36−0.210.37−0.39−0.05−0.321
TDS0.180.98−0.770.86−0.090.97−0.251
EC0.050.92−0.650.850.020.96−0.240.961
Table 5. Correlation coefficients of the hydrochemical parameters for 4E well.
Table 5. Correlation coefficients of the hydrochemical parameters for 4E well.
pHNa+Ca2+Mg2+HCO3−Cl− SO42−TDSEC
pH1
Na+0.151
Ca2+−0.42−0.811
Mg2+0.360.77−0.721
HCO3−−0.16−0.190.380.131
Cl− 0.160.96−0.780.85−0.081
SO42−−0.36−0.210.37−0.39−0.05−0.321
TDS0.180.98−0.770.86−0.090.97−0.251
EC0.050.92−0.650.850.020.96−0.240.961
Table 6. Correlation coefficients of the hydrochemical parameters for Pishe Poro well.
Table 6. Correlation coefficients of the hydrochemical parameters for Pishe Poro well.
pHNa+Ca2+Mg2+HCO3−Cl− SO42−TDSEC
pH1
Na+−0.131.00
Ca2+0.060.061.00
Mg2+−0.210.930.151.00
HCO3−−0.370.24−0.270.321.00
Cl− −0.150.970.290.960.211.00
SO42−−0.140.650.110.610.190.581
TDS−0.160.980.280.970.270.990.641
EC−0.280.750.270.790.060.790.470.801
Table 7. Temporal variations of the heavy metals contents in groundwater—Novosela 2N well.
Table 7. Temporal variations of the heavy metals contents in groundwater—Novosela 2N well.
Standard
& Year		Heavy Metal Content (mg/L)
NiMnZnPbCuCrCd
98/83/EC0.02 0.05 3.00.05 2.0 0.05 0.005
2020/2184/EC0.020.05** n/a0.012.00.0250.005
20110.022–0.019 0.002–0.0070.035–0.028 0.04–0.050.007–0.008 0.025–0.026 * n.d.
20120.011–0.0080.006–0.0060.022–0.0160.04–0.030.002–0.0020.020–0.018n.d.-0.002
20130.008–0.005n.d.-0.0040.009–0.0070.008–0.040.008–0.0020.024–0.004n.d.-0.002
20140.008–0.010.01–0.0240.003–0.0070.014–0.0180.002–0.0030.005–0.0070.002
20170.001–0.0020.004–0.0070.002–0.0090.007–0.0180.002–0.0030.001–0.003n.d.
20180.0010.015–0.0060.001–0.0070.0010.001–0.002n.d.n.d.
20190.008 0.0060.067n.d.0.0010.001n.d.
* n.d.: no detectable; ** n/a: not applicable.
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Dindi, E.; Shehu, A. Spatial and Temporal Variations of the Hydrochemical Parameters in the Gravelly Aquifer of the Lower Course of Vjosa River, Albania. Hydrology 2023, 10, 234. https://doi.org/10.3390/hydrology10120234

AMA Style

Dindi E, Shehu A. Spatial and Temporal Variations of the Hydrochemical Parameters in the Gravelly Aquifer of the Lower Course of Vjosa River, Albania. Hydrology. 2023; 10(12):234. https://doi.org/10.3390/hydrology10120234

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Dindi, Elsa, and Ardian Shehu. 2023. "Spatial and Temporal Variations of the Hydrochemical Parameters in the Gravelly Aquifer of the Lower Course of Vjosa River, Albania" Hydrology 10, no. 12: 234. https://doi.org/10.3390/hydrology10120234

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