Tracking ground water quality changes in Wadi El-Assiuti, Assiut, Egypt

Symbol

Na%

sodium percentage

Abbreviations

EC

electric conductivity

IWQI

Irrigation Water Quality Index

KR

Kelly ratio

MAR

magnesium adsorption ratio

PS

potential salinity

r

correlation coefficient

SAR

sodium adsorption ratio

SSP

soluble sodium percentage

TH

total hardness

TDS

total dissolved solids

U

uncertainty

WQI

Water Quality Index

In Assiut, groundwater was abundant, especially with the increasing reclaim of new lands adjacent to villages in the Assiut eastern desert plateau and western desert plateau. In Wadi El-Assiuty, there is one of the most promising new reclaimed land in the east of the desert. Groundwater has been used for different purposes, especially agriculture, for over 25 years. However, heavy exploitation may lead to declining groundwater table and quality. As a result of the increasing demand for water and shortage of supply, it is essential to ensure that the water is used more efficiently (Manaa et al. 2021). The following processes affect groundwater quality (Todd 1980; Appelo & Postma 1993; Winter et al. 1998; Bear et al. 1999; Apodaca et al. 2002; Martinez & Bocanegra 2002; Subramani et al. 2005; Karanth 2008; Nwankwoala & Udom 2011; Sakram et al. 2013; Ravikumar et al. 2015): water's reactions with geological materials; gas dissolution, biochemical reactions, biodegradation, and dissolution of gases from various biological processes; and anthropogenic pollution sources. All these reactions depend on the bedrock's nature and geology, soils, topography, the aquifer's chemical characteristics, length of water contact time, and recharged water quality. Groundwater chemistry alters due to different groundwater mixing along the flow paths in the subsurface and interaction with the aquifer's matrix; appraisal of groundwater's chemistries will give information on the changes in water phases and quality (Saravanan et al. 2015).

Water quality is of the same importance as its quantity, as water quality is essential to water's suitability for various purposes attached to human welfare. Thus, it is necessary to analyze groundwater's physiochemical, chemical, and hydro-chemical features that indicate water's characteristics and variables. Measured values must be compared to standards to determine the quality and suitability for different proposes, and any deviation from these standards for one or more of the quality parameters of water is considered pollution and needs treatment before water is used.

Physical parameters such as pH are of paramount quality controlling parameters. The groundwater's pH values are controlled by the chemical composition of the adjacent aquifer rocks, the materials' solubility, recharge zones, and anthropogenic activities (Islam et al. 2017). The total dissolved solids (TDS), also known as salinity, is the total amount of solids that includes both inorganic and organic materials dissolved and remain when water evaporates to dryness and are commonly used as a water quality indicator (Drever 1997; Bates & Jackson 1984). The electrical conductivity (EC) parameter measures dissolved ions' concentration in water and depends on their percentage and water temperature (Srinivas et al. 2000; Boyd 2000). In addition, the total hardness (TH) parameter reflects the water content of Ca, Mg ions, and alkalinity, which is due to HCO₃ content, dissolved CO₃, and hydroxide content, where CO₂ gas is the principal source of bicarbonate, and the dissolution of carbonate rocks and organic matter decomposition in the soil (Todd 1980; Bates & Jackson 1984; Appelo & Postma 1993; Drever 1997; Winter et al. 1998; Boyd 2000; Srinivas et al. 2000; Apodaca et al. 2002; Martinez & Bocanegra 2002; Cathy & Jacques 2006; Nwankwoala & Udom 2011; Sakram et al. 2013; Ravikumar et al. 2015; Saravanan et al. 2015; Islam et al. 2017). For the chemical composition of groundwater, the content of major ‘ions in the form of anions and cations' is mainly due to primary and secondary minerals' weathering from rocks (Saravanan et al. 2015). Eight ions form more than 90% of the dissolved solids, which are sorted into main cations (Ca, Mg, Na, and K) and main anions (Cl, HCO₃, NO_x, and SO₄) (Gill 1997).

Water quality and pollution indices are important indicators and the best way to explain water quality, and they are easily determined. Its importance is due to the crucial role of water resources nowadays (Kumar et al. 2021; Chatterjee & Raziuddin 2002; Iticescu et al. 2013), as it converts the original data from many quality parameters into a single number to understand water quality (Brown 1970; Akhtar et al. 2021). It is used to assist in planning water quality management programs through numerical index values (Asadollah et al. 2021) and is calculated using a mathematical process based on different water quality criteria (Xu et al. 2022).

The Water Quality Index (WQI) is used for calculating water's contamination amount, as it transforms a large number of quality state parameters' data, such as pH, HCO₃, TDS, Cl, SO₄, Ca, Mg, Na, and K, to a single number which reflects the quality parameters' composite influence on the overall water quality (Chatterjee & Raziuddin 2002; Iticescu et al. 2013; Horton 1965; Brown et al. 1970).

The suitability of water for irrigation relies on the types of salts, their effect on crop growth and development, and the amount present in irrigation water. Na and EC play the controlling role in irrigation water. Salinity content is a water quality problem influencing the soil solution's osmotic pressure. Plants can absorb water with a suitable amount at low osmotic pressure, but with pressure increases, absorption becomes more complex (Negm 2019; Al-Manmi 2008; Glover 1996). The magnesium adsorption ratio (MAR) (Ayers & Westcot 1985; Kavurmac & Karakus 2020), sodium adsorption ratio (SAR) (Todd 2007; Ayers & Westcot 1989; Wilcox 1955), sodium percentage (Na%) (Todd 2007), soluble sodium percentage (SSP) (Todd 2007; Nagaraju et al. 2014), Kelly ratio (KR) (Nagaraju et al. 2014; Kelly 1940; Kelly 1963), and potential salinity (PS) (Doneen 1964), the Irrigation Water Quality Index (IWQI), a single dimensionless value of a mathematical method based on various hydro-chemical properties, are employed (Pesce & Wunderlin 2000; Shil et al. 2019; Al-Kubaisi et al. 2022). Table 1, which will be presented later, summarizes the equations of these parameters and the quality classification based on suitability parameters.

Table 1

Groundwater quality classification based on suitability parameters

Parameter .	Formula .	Range .						Ref. .
Sodium percentage (Na%)		Water quality class	Excellent	Good	Permissible	Doubtful	Unsuitable	(Todd (2007), Srinivasamoorthy et al. (2014), Pradhan & Pirasteh (2011))
		Range	<20	20–40	40–60	60–80	>80
			< 60 Suitable			> 60 Unsuitable
SSP		Water quality class	Excellent	Good	Permissible	Doubtful	Unsuitable	(Todd (2007), Nagaraju et al. (2014))
		Range	<20	20–40	40–60	60–80	80–100
Sodium adsorption ratio (SAR)		Water quality class	Excellent	Good	Doubtful		Unsuit	(Negm (2019), Don (1995))
			Low Na	Medium Na	High Na		Very high Na
			Used for all soils	Preferably for coarse texture, soils of good permeability	produce harmful effects and good soil management is essential		Not satisfactory for irrigation purposes
		Range	0–10	10–18	18–26		26–100
Mg absorption ratio (MAR)		Water quality class	Suitable		Unsuitable			(Ayers & Westcot (1985), (Kavurmac & Karakus (2020))
		Range	< 50		> 50
Kelly ratio (KR)		Water quality class	Suitable		Unsuitable			(Nagaraju et al. (2014), Kelly (1963))
		Range	< 1		> 1
		NB	Good		Not good
Potential salinity (PS)		Water quality class	Suitable		Unsuitable			(Doneen (1964)
		Range	<3		>3
Water Quality Index		Water quality class	Excellent	Good	Poor	Very poor	Unsuitable	(Chatterjee & Raziuddin (2002), Iticescu et al. 2013, Horton (1965), Brown et al. (1970))
		Range	0.0–25	26–50	51–75	76–100	>100
Irrigation Water Quality Index		Water quality class	Excellent	Good	Poor	Very poor	Unsuitable	(Pesce & Wunderlin (2000), Shil et al. (2019))
		Range	0–25	26–50	51–75	76–100	>100

Parameter .	Formula .	Range .						Ref. .
Sodium percentage (Na%)		Water quality class	Excellent	Good	Permissible	Doubtful	Unsuitable	(Todd (2007), Srinivasamoorthy et al. (2014), Pradhan & Pirasteh (2011))
		Range	<20	20–40	40–60	60–80	>80
			< 60 Suitable			> 60 Unsuitable
SSP		Water quality class	Excellent	Good	Permissible	Doubtful	Unsuitable	(Todd (2007), Nagaraju et al. (2014))
		Range	<20	20–40	40–60	60–80	80–100
Sodium adsorption ratio (SAR)		Water quality class	Excellent	Good	Doubtful		Unsuit	(Negm (2019), Don (1995))
			Low Na	Medium Na	High Na		Very high Na
			Used for all soils	Preferably for coarse texture, soils of good permeability	produce harmful effects and good soil management is essential		Not satisfactory for irrigation purposes
		Range	0–10	10–18	18–26		26–100
Mg absorption ratio (MAR)		Water quality class	Suitable		Unsuitable			(Ayers & Westcot (1985), (Kavurmac & Karakus (2020))
		Range	< 50		> 50
Kelly ratio (KR)		Water quality class	Suitable		Unsuitable			(Nagaraju et al. (2014), Kelly (1963))
		Range	< 1		> 1
		NB	Good		Not good
Potential salinity (PS)		Water quality class	Suitable		Unsuitable			(Doneen (1964)
		Range	<3		>3
Water Quality Index		Water quality class	Excellent	Good	Poor	Very poor	Unsuitable	(Chatterjee & Raziuddin (2002), Iticescu et al. 2013, Horton (1965), Brown et al. (1970))
		Range	0.0–25	26–50	51–75	76–100	>100
Irrigation Water Quality Index		Water quality class	Excellent	Good	Poor	Very poor	Unsuitable	(Pesce & Wunderlin (2000), Shil et al. (2019))
		Range	0–25	26–50	51–75	76–100	>100

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The well's water quality deterioration may be due to human activities, contamination, behavior, and other factors. There are two types of deterioration: quality and quantity. Quality deterioration is due to water interaction with the surrounding geological layer's materials. The land constituents control time, flow directions, and water quality. The dominant processes that affect water quality are dissolution, explosion of gases, reactions with geological materials, biodegradation, geochemical reactions, and anthropogenic pollution. Most effective of these are the chlorides' dissolution and sulfate salts (gypsum, halite, and anhydrite) and the cations transformation between water and rocks, which leads to increasing salinity in the water flow direction and consequently the deterioration of water types (Bear et al. 1999; Subramani et al. 2005; Ayers & Westcot 1976; Fattah 2017).

The intensive exploitation of water for different applications leads to a highly downward gradient, which accelerates the migration of contaminants to aquifers, causing intensive contamination, especially in rapidly urbanized areas (Saravanan et al. 2015; Masoud & El-Osta 2016; Negm et al. 2019). Due to urbanization, population increase, agricultural activities, deficiency of proper sewage and irrigation drainage systems, and land reclamation (Chen & Feng 2013; Obeidat et al. 2013), human activities, as an extensive and unplanned abstraction (over-pumping), are causing depletion and deterioration of the resources. Furthermore, discharge of raw wastewater or inadequately treated agricultural runoff from farms and untreated sewage discharge can release substances such as domestic sewage, industrial wastes, inorganic and organic fertilizers, and pesticides, which include a range of harmful substances that affect quality both directly and indirectly leading to the deterioration and contamination of aquifers' groundwater (Masoud & El-Osta 2016; Negm et al. 2019; Shaheeda 2007). Conceptually, groundwater quality and quantity may have been subjected to erosion and internal and external pollution (anthropogenic activity).

Many studies have been introduced for checking the quality of wells' water in the region of Wadi El-Assiuti in Assiut – Governorate Egypt. Bakheit (Bakheit et al. 1993) studied the characteristics of groundwater in aquifers and revealed that the first aquifer's depth ranges between 13 and 47 m, while thickness ranges between 20 and 70 m. Its feeding is from the River Nile. The second one is in the area's eastern part, with depth ranging between 110.0 and 130.0 m and from 60.0 to 80.0 m in thickness. Farrag (Farrag 2007) investigated the characteristics of aquifers' water and revealed that the aquifers in the area have heterogenetic characteristics, and the groundwater composition and qualities vary locally with time and can be safely used for irrigation purposes in some parts. The over-exploitation of the groundwater caused a lowering in the water levels and deterioration in its quality, especially in the intermediate and northern areas, which are expected to increase and may lead to groundwater resource depletion in some localities. It is recommended that the present pumping rates be decreased and the productive well numbers in the area be controlled; surface water resources be used conjointly with the groundwater resource; recent irrigation tools be used; and plants and crops of low water consumption be selected. (Elewa 2008) studied the expected future situation's probabilities of the Pleistocene Aquifer in the study area and highlighted the need for an arrangement scheme to stop future drilling of new wells near the wells already present in the area. Korany et al. (Korany et al. 2013) revealed mutual relationships among the existing aquifers in the Assiut area. Between some of them and the surface water system, the hydraulic connections between aquifers occurred vertically through the deep-seated faults and horizontally via the lateral seepage. The Pleistocene aquifer in the Nile Valley is hydraulically connected with the surface water canals. Also, there was mixing (physiochemical processes) between waters contained in the Eocene aquifer and both the Pleistocene and Nubian aquifers due to the hydraulic connection between them. This may affect the wells' water quality due to mixing different water types and evaporation before infiltration, which changes the chemical constituents and composition of the aquifer's groundwater content. Abu El Ella and Sellim (Abu El Ella & Sellim 2014) revealed that the groundwater in the area suffers from high salinity. Hence, it is unsuitable for drinking or irrigation but can be treated using reverse osmosis membranes. El-Tahlawi et al. (El.Tahlawi et al. 2014) studied the 335 wells data from 2006 to 2009, classified them according to Egyptian standards (1995), whether for irrigation or drinking, and showed that they are suitable for drinking and irrigation. Also, Abdel-Hameed et al. (2016) used the DRASTIC index model of the EPA to address the vulnerability of shallow groundwater to contamination potential from surface contamination. The Generic and Agricultural DRASTIC aquifer vulnerability map shows that Assiut is under low moderate, moderate vulnerable, and mild to moderately high vulnerable aquifer areas, respectively. From this study, an area with high vulnerability could be prioritized for restricting some land uses, while future development may be directed to the areas with low vulnerability. El Tahlawi et al. (2016) concluded that the wells' water in that area is unsuitable for drinking water but can hardly be used for irrigation purposes. This conclusion is based on determining its suitability for drinking and irrigation purposes and calculating the Unweighted Arithmetic Water Quality Index ‘WQIUA’ for 2006–2013. Sharaky et al. (Sharaky et al. 2017) studied the quality along the Nile River banks from Aswan to Assiut. They revealed that the significant sources of Nile water and groundwater contamination are industry, agriculture, and household waste, and agriculture is the most harmful source of groundwater quality. Farrag et al. (Farrag et al. 2018) investigated the groundwater conditions in Wadi El-Assiuti. They concluded that large values of TDS in the middle of the area are related to the increase in agriculture activities and pumping rates. This necessitates an urgent need for a management scheme or a policy to decrease these problems in this area. They recommended controlling the distance between wells and the pumping rate, which must be managed to permit the aquifer equilibrium. Saleem et al. (Saleem et al. 2019) revealed that data taken in 2015 from the Nile aquifer along the Assiut governorate are highly contaminated with iron, manganese, and HCO³⁻. They attributed this to the solution of those elements in water from surrounding rocks and soil, and high levels of carbonates in nearly all wells result from the calcareous structural plateau. Megahed (Megahed 2020) said that the large TDS values in the middle of the study area may be related to the increase in the pumping rates in these areas, so an urgent need to apply strategies in this area is required to reduce these problems. The present situation indicates that water in the study area will worsen unless urgent measures are taken to protect the groundwater and mitigate contamination. They recommended that the wells' depth in the area be more than 120m to avoid the percolation of polluted water, control agrochemicals on agricultural lands, and manage hazardous pesticides and fertilizers. The removal of iron by physical treatment method is also recommended.

This study aims to present a historical overview of the quality and deterioration of groundwater in Wadi El-Assiuty, an extension of the Assiut governorate. The water in that area has been the primary source of irrigating crops since groundwater was used in the nineteenth century. The historical tracking of the water quality in such an important area has not been addressed so far. So, this paper appears to be the first in this regard.

Wells water samples were withdrawn, prepared, and analyzed using standard procedures to determine their physical and chemical constituents. Bottles of samples were prepared according to ASTM standards steps, and the water samples were taken under careful conditions. In addition, previous measurements' results for Wadi El-Assiuti were collected since 1997 up to 2023 from the earlier studies in the literature.

The analyses determined and showed the water pH, hardness, alkalinity, and TDS. The measurements were conducted according to the standard specification, where pH and EC were measured directly in the field by the HANA (HI9811-5) instrument. Cations, including calcium, magnesium, and TH, were analyzed using the volumetric method (APHA 2017), and Na and K were measured using a flame photometer instrument (APHA 1998). Anions such as HCO₃ were analyzed by chemical titration with H₂SO₄ using phenolphthalein + methanol 60% (APHA 2005), and SO₄ was calculated by UV spectra photometer (UV). Finally, chloride was analyzed by chemical titration with AgNO₃ using a potassium chromate indicator.

The water sample's physical analysis results, such as pH, TDS, EC, and TH, were analyzed and determined; also, the average of all samples was calculated. Water samples were chemically analyzed for the major cations and major anions. The descriptive statistics of physicochemical parameters include groundwater samples' minimum, maximum, mean, and standard deviation values, as in Table 2.

At U ≤ 5, the result could be accepted, but if 5 <U ≤ 10, it will be accepted but with risk (Al-Hamadani 2009). The ionic balance results showed that nearly all samples are <5%. This indicates an electro-neutrality, i.e., the concentration of –Ve and +Ve ions is almost 100% certainty (Hem 1985; Batista-Garcia et al. 2015). Thus, the accuracy of the results could be used and dependent on it in hydro-chemical interpretation (Al-Hamadani 2009).

The TDSm-to-EC ratio could determine the analyses' correctness and instruments' accuracy, and the standard ratio ranges from 0.55 to 0.7. TDS or conductivity is suspect if it is out and must be re-analyzed (APHA 2017). The resulting ratios reveal that all samples are within the limit, which is accurate and accepted.

The data used to build the interrelationships between water quality parameters, which were recognized by Pearson correlation between analysis (PCMA) and the correlation coefficient (r). The data were statistically computed using the correlation coefficient to indicate the sufficiency of one variable to predict the other (Davis 1986). In a study area, correlation coefficient analysis and scatter matrix plots are presented in Table 3.

The groundwater quality parameters are major ions, TDS, pH, EC, TH, and SAR. The results of the correlation matrix revealed that significantly positively correlated values were found between TDS and EC (r= 0.99), and TH (r= 0.99), between Na and SAR (r= 0.93), between Mg and Cl (r= 0.94), and between TH and EC (r= 0.94).

Furthermore, strong positively correlated values which range between (r= 0.65 to 0.9) were found between K and Mg (r= 0.68), and Cl (r= 0.69); between Ca and SO₄ (r= 0.68), Cl (r= 0.68), pH (r= 0.7), EC (r= 0.7), and TH (r= 0.68); between HCO₃ and SO₄ (r= 0.75), EC (r= 0.75), and TH (r= 0.78). The extremely negative correlated values appeared between Mg and SO₄ (r= − 0.98), Cl and TDS (−0.98), EC (r= − 0.97), and TH (r= − 0.98). In addition, some strong negative correlations were observed between K and HCO₃ (r= − 0.7), SO₄ (r= − 0.57), TDS (r= − 0.57), EC (r= − 0.55), and TH (r= − 0.55); Mg and HCO₃ (r= − 0.67); HCO₃ and Cl (r= − 0.84). As TH has a strong +Ve correlation with Ca²⁺(r= 0.69), Mg²⁺ (r= 0.90), and (r= 0.99). It indicates a reverse exchange of ions and a weathering process dominating the nature of groundwater. The SO₄ has a robust positive correlation with Mg (r= 0.93), indicating anthropogenic influence.

The average physical parameters results for the years 1997 (Farrag 2007), 2006 (El Tahlawi et al. 2016), 2007 (Farrag 2007; El Tahlawi et al. 2016), 2008–2012 (El Tahlawi et al. 2016; Dawoud & Ewea 2011), 2013 (Korany et al. 2013; El Tahlawi et al. 2016), 2014 (Abu El Ella & Sellim 2014; El.Tahlawi et al. 2014), 2015, 2016 (Abdel-Hameed et al. 2016; Farrag & Abdel Moghny 2017), 2019 (Megahed 2020), 2020 (Megahed 2020; Abdelmoneim et al. 2020), 2021 (Abdelmoneim et al. 2020), and for 2023 pH, TDS, EC and HT were tabulated as in Table 4. In addition, chemical specifications were tabulated for the significant cations, anions, iron, and manganese from 1997 to 2016 and 2019 to 2023, as in Table 5.

As shown above, historical results and samples analyzed during 2023 are close and also accepted as descriptive statistics, and the interrelationships and the correlation coefficient (r) between water quality parameters (Pearson correlation matrix) were statistically computed as stated in Table 3, so the following is discussed.

The physical water quality parameters in Table 2 showed that groundwater in Wadi El-Assiuti during 2023 had pH values ranging from 6.9 to 7.8 with an average value of 7.3, indicating that water has good quality in terms of pH (GEMS/Water Programme 2006). The EC for water samples varied in the range 2,560–9,896 μS/cm with a mean value of 5,260 μS/cm, exceeding permissible limit values of the quality for agriculture and irrigation guidelines (Ayers & Westcot 1994). TDS values range from 1,629 to 5,902 μS/cm, with a mean value of 3,119.7 mg/L, exceeding the guideline value of TDS, 2,000 mg/L (Ayers & Westcot 1994), indicating that the obtained groundwater samples are highly salinized. Finally, TH shows that the Wadi's water is problematic, ranging between 564 and 2,400 ppm of CaCO₃.

The chemical water quality parameters in Table 2 show that the order of abundance of the major cations (in mg/L) was according to the following decreasing order: Ca²⁺ > Na⁺ > Mg²⁺ > K⁺. They range from 800 to 1,200; 276.1 to 414.4; 39 to 107.3; and 9.3 to 17.8 mg/L with mean values of 919.4, 320.8, 74.6, and 14.9 mg/L, respectively. The Ca is the dominating cation, along with Na⁺ and Mg²⁺, which contributes considerably to the mineralogical composition of the samples.

The order of concentration of the major anions (in mg/L) showed the following decreasing order: > Cl⁻ >HCO₃. They vary from 675 to 2,465 mg/L; 532.5 to 1,775 mg/L; and 200 to 366 mg/L, with the mean concentrations of 1,314.7; 1,304.8; and 267.9 mg/L, respectively. Sulfate is the dominating anion.

Regarding the suitability of the significant cations, only Na and K satisfy the standard water-quality guidelines for agriculture, while Ca exceeds the allowable limit for irrigation (Ayers & Westcot 1994). For anions, while HCO₃ satisfies the standard, Cl does not meet the standard water-quality agricultural guidelines (Ayers & Westcot 1994). The increase in ions' concentration may be due to the rocks and soil dissolution increasing groundwater ions' concentration. In addition, the water flows through the area's geology, consisting of gypsum and anhydrite rocks, which may dissolve the salts in the groundwater (Sataa et al. 2016). Infiltrating surface water affects the quality and quantity of groundwater and the absence of restrictions on inefficient irrigation methods, fertilizer use, and human activities. These reasons increase the concentration of ions and affect the groundwater quality (Alikhan et al. 2020), which authors thought that all these reasons might apply to this area.

Table 4 shows that the pH values rose during 2012–2014 and 2016–2020 from 8.1 to 8.4 and 8.2 to 8.4, respectively. The EC and TDS values showed the same behavior in that periods, with values of 2,648–6,117.2 μS/cm and 1,695–3,915 ppm, respectively, and raised in the second period from 1,383 to 4,367.3 μS/cm and 798.6 to 2,769.7 ppm for EC and TDS, respectively. Finally, TH followed the same way, rising from 351.9 to 2,089.8 ppm during the first period and 1,885.3 ppm in 2019.

Significant ions in the area started with high concentrations of cations and anions, but their concentration decreased after using groundwater for years. Then, it behaved as other parameters increased in the first period and the year 2019 for nearly all ions, as in Table 5.

The WQI reveals the degree of groundwater contamination and reflects the composite influence of quality parameters on the overall groundwater quality. WQI values behave like other hydro-chemical parameters in the study area in the two periods. They rose more than 100 in both periods, meaning groundwater quality became unsuitable for drinking, as shown in Table 7.

For evaluating the suitability for irrigation uses, the hydro-chemical quality parameters are determined in the following.

SAR values behave the same in the two periods but do not exceed 15.92, which indicates that water is suitable for irrigating coarse-textured soils of good permeability, as in Table 7.

Sodium percentage (Na%): excess sodium causes deflocculation, which leads to damage to the soil structure, soil aeration, soil infiltration, and soil permeability, which finally leads to a reduction in the plant's growth (Balamurugan et al. 2020). The Na% values have the same as other hydro-chemical parameters behavior in the two periods as it ranges from 51.85 to 54.74% (with a maximum value of 65.46% in 2013) and from 54.74 to 80.52% in the period 2012–2014 and 2016–2020, respectively, i.e., the groundwater quality reached to become unsuitable in both periods as in Table 7.

Magnesium hazards (MAR): as raised magnesium concentration has adverse effects on the soil structure and reduces the yield of crops (Kavurmac & Karakus 2020), MAR values have the same as other hydro-chemical parameters behavior in the two periods as it raised more than 50% in both periods, i.e., the groundwater quality reached to become unsuitable in both periods as in Table 7.

KR or Kelly index (KI): if it is greater than one, it means unsuitable water for irrigation, as there is excessive sodium ion in groundwater. The KR values are the same as other hydro-chemical parameters in the two periods, as they rose more than 1 in both periods but reached 4 in 2020. For example, the groundwater quality reached unsuitable in both periods, as shown in Table 7.

SSP: SSP values behaved like other hydro-chemical parameters in the two periods. They rose more than 60% in both periods but reached 80.02% in 2020, indicating that the groundwater quality reached doubtful to unsuitable, as in Table 7.

PS is the sum of Cl and half of the SO₄ ion concentration in groundwater (Ahmed et al. 2020). In the study area, PS (epm) values have the same behavior as other hydro-chemical parameters in the two periods as it raised more than 3 meq/L in both periods but also reached 50.45 meq/L in 2020, i.e., the groundwater quality reached to become unsuitable for irrigation as in Table 7.

The IWQI is a single unitless value that reveals the degree of water contamination. In the study area, IWQI values behaved the same as WQI values in the two periods, rising more than 100, meaning the groundwater quality became unsuitable for irrigation purposes, as in Table 7.

From the above results, groundwater in the Wadi El-Assiuti area was normal, as its quality parameters showed high values in 1997 and decreased from 2007 to 2012. Then, they started rising unusually in 2012–2014 because they began constructing a new Assiut barrage in the El-Fatah district. This barrage is in the western entrance of Wadi El-Assiuti (Abdelmoneim et al. 2020; Mohamed & Abu El Ella 2021), whereas a lot of infiltration water, about 360,000,000 m³ (https://www.arabcont.com/English/project-568), was withdrawn using underground pumps. This water should seep naturally into the Wadi, and this withdrawal and water shortage led to the deterioration of groundwater quality parameters. At the end of the construction and after stopping the groundwater withdrawal, Nile surface water starts seeping into the groundwater, improving quality parameters and water quality. Then, these parameters deteriorated again due to decreased water infiltration from irrigation canals, which were recently lined with concrete in the area near EL-Wadi. These results clearly showed the relationship between surface human activities and groundwater quality through the impacts of these activities on the infiltration of surface water to aquifers and its water quality accordingly. Depending on our results, future studies should be conducted on the treatment method for EL-Wadi water.

The present study reviewed groundwater quality in the Wadi El-Assiuty area from 1997 to 2023. According to the study findings, the following points arise:

• The groundwater was generally highly saline. Each encountered physical and chemical parameter started with high values, but due to continuing groundwater use for years, they decreased and then increased again from 2014 to 2019.

• Calcium was the dominating cation in groundwater samples, while sulfate was the dominating anion, and both were beyond the allowable values.

• The behavior of quality parameters such as SAR, MAR, Na%, SSP, KR, and PS increase the study's importance since it considers the effect of the surface's anthropogenic behavior on the groundwater.

• The WQI and IWQI were employed to emphasize the results. The values of these indices follow the same trend as all of the other parameters, which supports the previous postulate that human activities, including the construction of the new Assiut Barrage and the canals' concrete lining, may be considered the cause of water quality deterioration and pollution, as they limited surface water infiltration into groundwater.

Based on the findings of the study, here are some following recommendations for future research:

• Investigate the specific effects of different agricultural practices on groundwater quality. This includes the use of fertilizers, pesticides, and irrigation methods. Research can focus on developing sustainable farming practices that minimize groundwater contamination.

• Assess the impact of urbanization and industrial activities on groundwater quality. This can involve studying the discharge of industrial effluents and urban runoff into groundwater sources.

• Explore and evaluate various remediation techniques to improve groundwater quality. This can include physical, chemical, and biological methods to remove contaminants from groundwater.

• Utilize advanced technologies such as remote sensing, GIS, and machine learning to enhance the monitoring and analysis of groundwater quality. These technologies can provide more accurate and comprehensive data for decision-making.

The authors would like to express their appreciation for the support of the Islamic University of Madinah, Saudi Arabia.

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.