Water Quality of Assessment of Angacha –Doyo Area, Central Ethiopia Region, Ethiopia

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Tselot Denekew Getachew
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Abstract

Rock-water interaction has an impact on the chemistry of groundwater, which in turn affects groundwater quality. The study area is found in the Kembata Tembaro zone in Angacha Woreda Bedena kebele, central Ethiopia, where the surface water is unsafe for drinking. So, the area mainly depends on groundwater for drinking purposes. The study’s main objective is to assess the water quality of the study area. Five water sample chemistry data sets were collected from the central Ethiopia region. The data was analyzed using IBM SPSS Statistics version 29, Excel, ArcGIS 10.3, and Grapher software. The dominant cations with mean value of are Ca+ 2 (18.89Mg/L)>Na+1(17.76Mg/L) > K+ (7.99Mg/L)>Mg+2 (5.20Mg/L) and the dominant ion is HCO3–(129.1 Mg/L)   > Cl–(5.33Mg/L)   > SO42-. (4.33 Mg/L).  From the piper and drive diagram, the water type of the area is Ca-Na-HCO3 and Ca-Na-Mg-HCO3, which results from rock-water interaction. Based on Pearson’s correlation result, TDS is highly correlated withNa+1, Cl–, and SO42-, which contributes to the salinity of the groundwater. According to WHO standards and the water quality index, the water type is suitable for drinking purposes with excellent water quality. The water quality index is a very important tool for assessing the water quality of groundwater for different purposes.

Keywords: Groundwater, groundwater quality, groundwater facies, statistical analysis, Water quality index

Introduction

Background of the study

Water is one of the most essential substances needed to sustain human life, animals, plants, and other living things. There are different water bodies, among the different water bodies groundwater is found underground in the earth at different depths. Fresh water is essential in many spheres of human life in which groundwater accounts for 90 % of all liquid freshwater1 Groundwater is one of the reliable and vital sources of drinking water because of its widespread availability, occurring in natural conditions and less susceptible to water contamination as compared to freshwater

Due to increasing population growth, human water demand for domestic, industrial, and agricultural purposes to supply adequate food for the nation is increasing2

  Ethiopia has always been characterized by high hydrological variability, compounded by the almost total absence of water storage and highly vulnerable watershed because of its geography and climate3

The groundwater quality of Ethiopia shows large variation, ranging from fresh waters in many of the springs issuing from the crystalline basement rocks to more saline waters in parts of the Rift and the sedimentary formations of the plains.4

Groundwater quality includes the physical, chemical, and biological properties of groundwater. Temperature, turbidity, color, taste, and odor make up the list of physical water quality parameters5

.The chemical parameters include major ions(calcium, magnesium, sodium, potassium chloride, sulfate, and bicarbonate) whereas the biological includes microorganisms such as bacteria and viruses   The chemical water quality of groundwater is the result of a hydrogeochemical process of solution and minerals6. The hydrogeochemical process is affected by precipitation, rock-water interaction, the structure of the geology, the minerals in the aquifer, and human activities7.

Water quality is the major concern for people because it has a direct impact on their health. It is impacted by both natural and man-made elements, such as runoff from homes, industrial, and farms.  Thus, water Quality evaluation of the groundwater is evaluated based on physical and chemical parameters Water Quality Index (WQI), a well-known method for assessing water quality offers a simple, stable, and reproducible unit of measurement and communicates information of water quality to the concerned body8

The water quality of groundwater can be assessed by using the water quality index (WQI).

The application of WQI helps the decision-makers in the possibility of successful management of WQ and supplies more details about the WQ for various uses by public people9

Problems Statement and rationale

In the study area, most of the perennial rivers are randomly used by the surrounding community without any rules with activities such as washing, bathing, irrigation, and cattle feeding, therefore the water quality of these rivers cannot be considered as potable water.  Water such as rivers was not considered as a potential water source. It is due to not meeting hygienic standards and not being permanent resources due to seasonal fluctuations.  So, Groundwater is essential to secure the safety of the water supply in the Angacha–Doyo area but little information is documented or studied about the chemistry and the Quality of the groundwater.  The area practices a mixed-crop livestock farming system. The crop farming uses fertilizer that may pollute the groundwater and the livestock and human waste has also impacted on the quality in which the area has no specified waste management area. Water quality is a major concern for people because it is directly associated with human well-being. Thus, this study aimed to assess water quality spectra and the current status of the groundwater based on hydrochemistry. This study was to fill the gap related to groundwater chemistry and quality, which other researchers used as a benchmark.

Significance and purpose

The output of this study work is very important to see the full picture of the current water quality status of the groundwater that was not determined previously by including all basic water quality parameters (physical and chemicals) for sustainable management of water regarding water quality. It is also used as a benchmark to study the water quality of the groundwater by other researchers.

Objectives

Specific Objectives

  • To assess the physical water quality status of the groundwater
  • To assess chemical water quality status of the groundwater
  • To identify the water type of the groundwater

Scope and Limitations

This study is devoted to assessing and analyzing the current water Quality status of the Angacha–Doyo area based on the physicochemical parameters not based on biological ones. The analysis was done by using five water samples due to unavailability of data.

Theoretical framework

Groundwater is defined as water contained in the aquifer matrix below the surface of the saturated zone, which naturally contains dissolved minerals.10. Different hydrogeochemical process determines different physicochemical characteristics of groundwater, particularly in the zone of saturation11. For viability, the administration and evaluation of groundwater assets need a comprehension of the hydrogeochemical and hydrogeological highlights of the groundwater aquifer12. As groundwater quality is affected by several factors, an appropriate study of groundwater aquifer characteristics is an essential step to state a supportable utilization of groundwater resources for future development and requirements13. When groundwater moves through the rocks and subsurface soil, it has the opportunity to dissolve various sources of substances and contaminants14. The total dissolved solid describes small amounts of inorganic salts and organic matter present in the water. The knowledge about the hydrochemistry of the water is essential to evaluating groundwater quality in any place15. The groundwater quality deterioration is critical due to geogenic and human-induced activities16. The water quality index is considered to be the most effective method to evaluate water quality.17 Groundwater chemistry depends on several factors, such as general geology, degree of chemical weathering of the various rock types, quality of recharge water, and inputs from sources other than water-rock interaction. The groundwater quality parameters used for the assessment of groundwater quality are categorized into two levels. The Level 1 parameters (core parameters) – pH, electrical conductivity (EC), and nitrate (NO3), provide essential information on acidification, salinization, and nutrient enrichment due to pollution by human activities, including agriculture and waste disposal, respectively. The Level Two parameters compromise Major cations.

Materials and Methods

Study Area Description

The study area is found in the central Ethiopia region Kembata Tembaro zone in Angacha Woreda Bedena kebele 2351m above sea level. The main water-bearing formation in the area is moderately to highly fractured and weathered Ignimbrite. The mean annual rainfall is 1656 mm with a bimodal pattern that extends from February to September. The rainy seasons are April, July, August, and September. The mean annual maximum temperature is an average 24 °C and the monthly temperature is 23 to 24 °C. The mean annual minimum temperature is 14 0C and monthly values range between 13 and 14 0C. The geology of the area under investigation consists of three- to four-dimensional and quaternary Rhyolite and basalt volcanic rocks covered by quaternary alluvial deposits and pre-Cambrian underground gneiss and granite. Quaternary volcanic rocks such as Pitchstone, Pumice and Obsidian outcrops are among the most important quaternary volcanic rocks.

Figure 1 Location Map of the study area

Data Collection

A total of five groundwater samples were collected from the central Ethiopia water office. The data contain water chemistry parameters like PH, EC, TDS Na +, K +, Ca +2, Mg+2, Cl, HCO3−, SO42−, NO3 −, total hardness and total alkalinity, A total of five water samples were chosen because the area had five functional boreholes for providing community water. Before the water was collected, groundwater was pumped to get rid of any stagnant water. Rinsing the sampling bottle with the water sampled to prevent sample contamination and acidifying it with sulfuric acid to preserve the chemical reaction.

Accuracy of laboratory analysis

Before doing the analysis, it should be checking the charge balance error. The standard threshold limit for the charge balance error (CBE) % is ±1018. The Charge balance error is used to judge the validity and quality of water analyses and is a critical assessment that verifies the electrical neutrality of a water sample assuring that the analytical processes have been accurately executed.  The CBE of the sample is below 10 which is acceptable

(1)   \begin{equation*}\small\text{Charge Balance Error (CBE)} = \frac{\sum \text{Cations} - \sum \text{Anions}}{\sum \text{Cations} + \sum \text{Anions}} \times 100\end{equation*}

Statistical Analysis

Pearson’s correlation of physicochemical parameters and the levels of metals in groundwater water were assessed using   IBM SPSS Statistics version 29, and graphs were plotted using Grapher software and Excel, and ArcGIS version 10.3 was used to prepare a location map of the study area.

Water Quality Index (WQI)

This research objective is to assess the water quality of the Kembata Tembaro zone in Angacha Woreda Bedena kebele, central Ethiopia by employing which has not been extensively explored in previous studies. .The study integrates a wide range of physicochemical parameters to develop a robust WQI tailored for groundwater analysis and comparison of the results with WHO standards, providing a global benchmark for groundwater quality that has been largely overlooked in the current literature. By doing so, we identify critical discrepancies and potential health risks associated with groundwater consumption in the study area. 

The water quality index is a quantitative measure used to determine the suitability of water for different purposes19. WQI is a simple expression to represent the general quality of water as there are a variety of physical, chemical, and biological water quality parameters20

The Methods to calculate the water quality index are as follows21

1. identify the parameters: The parameters that were used to calculate the water quality index are pH, TDS, Na, K, Ca, Mg, Cl, SO4, NO3, total hardness and total alkalinity
2. Determination of the weightage
3. Determination sub-indices
4. Integration of sub-indices in mathematical

Results and Discussion

Physicochemical parameters of water

Sample IDpHECTDSNaKCaMgClSO4HCO3PO4NO3Total HardinessAlkalinity
GW016.54182.4100.311.46.410.826.4931.5105.60.2154.0886.5
GW026.4222.412315.28.5155.283.91.78122.60.40.262100.5
GW036.47198.8109.315.27.521.442.54.83113.10.40.16492.7
GW046.84390215268.7624.487.348.9512.73156.00.41.1491.8127.9
GW056.57247135.7218.821.724.4162.64148.60.160.6271.4121.8
Table 1 Physicochemical parameters of water

Total Hardness

Total hardness is the sum of calcium and magnesium concentration, both expressed as calcium carbonate, in milligrams per liter. The hardness of water can be determined based on these concentrations of calcium carbonate: Below 75 mg/L – is generally considered soft. 76 to 150 mg/L – moderately hardness out of the six samples one sample is moderate hardness with the value of 91. The others are soft water with values below 75.

Electrical Conductivity

Conductivity is the ability of water to conduct current. It is sensitive to variations in dissolved solids, mainly mineral salts. Conductivity is expressed as micro Siemens per centimeter (μS cm-1) and, for a given water body, is related to the concentrations of total dissolved solids and major ions. One of the essential indicators for evaluating the quality of water is electrical conductivity. Since the composition of mineral salts affects the electrical conductivity of groundwater, it is important to understand the relationships between mineral salt composition and electrical conductivity22

PH, Acidity and Alkalinity

The pH is an important variable in water quality assessment23 and It affects a variety of chemical and biological activities that occur in a body of water. pH, also known as hydrogen ion activity, is determined by the dissolved chemical and shows how acidic or basic a solution is at a particular temperature.

A pH of 6.57 is slightly acidic, but it is still within the range considered safe for drinking water. However, it is important to note that the pH of groundwater can vary depending on the geological formations and the presence of dissolved minerals and alkalinity with a minimum value of 86.5 and a maximum value of 127.9.

TDS

Total dissolved solids (TDS) are the amount of organic and inorganic materials, such as metals, minerals, salts, and ions, dissolved in a particular volume of water24. The TDS ranges from 100-215, below the maximum Value of 1000.

Major ions Concentration

Major ions (Ca2+, Mg2+, Na+, K+, Cl–, SO42-, HCO3–) are naturally variable in surface and ground waters due to local geological, climatic, and geographical conditions. The major ion concentration of each sample is plotted using a pip diagram.

Figure 2. Pie chart of major ions of samples

The most dominant dissolve cations in the study area are Ca and Na and the most common anion is bicarbonate.

Descriptive Statistics of the Groundwater

Parameters     
    RangeMinMaxMeanStd. ErrorWHO standards in mg/L
PH.426.426.846.5680.072906.5-8
EC207.6182.4390.0248.44037.0567 
TDS114.7100.3215.0136.66020.48821000
Na14.611.426.017.7602.5686200
K2.406.408.807.9920.46245 
Ca13.6610.8224.4818.89202.4416875
Mg4.842.507.345.2040.8415550
Cl5.953.008.955.33001.03218250
HCO350.48105.55156.03129.17609.89568 
PO4.24.16.40.3120.05426 
NO31.04.101.14.6120.2075250
Total Hardness37.7254.0891.8068.65606.40943 
Alkalinity41.486.5127.9105.8808.1135 
SO411.231.5012.734.33002.11774250
                 Table 2.  Descriptive Statistics of the Groundwater

     From the descriptive statistics data all the parameters fulfill the WHO standards

The pH levels of the groundwater samples range from 6.42 to 6.84, which is generally considered suitable for drinking water. Total dissolved solids (TDS) and electrical conductivity (EC) range from low to moderate, with GW04 having relatively highest TDS recorded. The amounts of potassium and sodium are within normal levels. Nitrate levels are low, which indicates acceptable water quality and little agricultural runoff, whereas anions like chloride and sulfate are still quite low, indicating little pollution. Total hardness and alkalinity show fluctuation, altering flavor and buffering capacity, which are vital for both human consumption and ecological health. Overall, the quality of the groundwater seems appropriate for agricultural and drinking purposes, but ongoing monitoring is required to handle any new issues that may arise.

Pearson’s Correlation

The quality of water was characterized by various physicochemical parameters. These parameters change widely due to many factors like source of water, type of pollution, and seasonal fluctuations. The correlation analysis of the physicochemical properties of groundwater gives a fairly good amount of information like their correlation of each water quality parameter. The most widely used measures of monotone connection are Pearson’s, Spearman’s, and Kendall’s correlation coefficients; the latter two are typically recommended for data that is not normally distributed.

 The more commonly used Pearson’s r is a measure of linear correlation, which is one specific type of monotonic correlation25

If the data lie exactly along a straight line with a positive slope, then r = 1. The correlation coefficient (Pearson ‘r’) has been calculated between each pair of water quality parameters by using an IBM SPSS spreadsheet for the collected data.

 PHECTDSNaCaMgClSO4PO4NO3HCO3Total HardnessAlkalinity
PH1            
EC0.9041           
TDS0.9050.999991          
Na0.8160.930550.92981         
K0.3380.655590.65330.801         
Ca0.5420.698620.6980.85641        
Mg0.650.56270.56340.314-0.18981       
Cl0.8740.949840.94980.97760.867290.3181      
SO40.9230.994470.99470.89030.631780.630.9221     
PO40.0650.337050.33740.17740.35313-0.0730.2720.3391    
NO30.8060.550030.55140.401-0.02680.8510.4370.608-0.3531   
HCO30.7310.858020.85670.96870.773320.3280.8970.810.0060.391  
Total Hardness0.8720.974410.97430.97570.837490.3760.9940.950.3240.440.91 
Alkalinity0.7310.858090.85680.96880.773530.3270.8970.810.0060.3910.89704371
Table 3. Pearson’s Correlation

The correlation coefficient ‘r’ has a value from -1 to 1. A negative sign represents that the two variables do not have a similar trend of variation whereas a positive value represents a similar trend. More will be the accuracy of fitness if r is closer to unity. A zero value indicates that “X” and “Y” have no relationship and are independent of one another.

Correlation between different pairs of water quality parameters for different water samples collected at different places of groundwater provides an idea about the hydrochemistry of the water resources. Statistical approaches were carried out in this study, to assess the water quality trends in the study area.  Value with r > 0.75 is highly correlated like TDS, with EC, Na, Cl, SO4, that the salinity of groundwater is mainly dependent on Na, Cl and SO4and value between 0.5-0.75 medium correlates like TDS with K, Ca, and Mg. The one with a value below 0.5 is less correlated.

Hydrochemical facies

Hydrochemical facies (Water Type) are a term used in this paper to denote the diagnostic chemical aspects of groundwater solution occurring in the hydrologic system26 The water’s flow pattern and the reaction of chemical processes taking place inside the lithologic framework are both reflected in the facies. Hydrochemical facies were constructed using Grapher software by plotting piper and Drove diagrams. The Piper diagram is a graphical representation of the chemical composition of water samples. It is used to classify water types based on the relative proportions of major cations (calcium, magnesium, sodium, and potassium) and anions (chloride, sulfate, and bicarbonate). The diagram is divided into three sections: a diamond for cations, a triangle for anions, and a connecting line that represents the overall water type. From the Piper and drove diagram, the water type of the area is mixed water type Ca-Na-HCO3 and Ca-Na-Mg-HCO3 which is the result of rock water interaction.

Figure 3. Piper diagram of the samples
Figure 4. Drove diagram of the samples

Water quality index

Bascaron water quality index results were influenced by the weightage as well as the sensitivity of the parameters. The parameters that have values far above and far below the WHO standards influenced the index value27

Sample IDparametersSi1/siKWiWi(Mi)Mi/SiQiWQI
GW01PH8.50.1176470.7716050.090777050.0907776.540.76941276.941186.984493
 TDS5000.0020.7716050.001543210.001543100.30.200620.060.030957
 NA2000.0050.7716050.003858020.00385811.40.0575.70.021991
 K120.0833330.7716050.064300410.06436.40.53333353.333333.429355
 Ca750.0133330.7716050.010288070.01028810.820.14426714.426670.148422
 Mg300.0333330.7716050.025720160.025726.490.21633321.633330.556413
 Cl2500.0040.7716050.003086420.00308630.0121.20.003704
 SO42000.0050.7716050.003858020.0038581.50.00750.750.002894
 NO3450.0222220.7716050.017146780.01714710.0222222.2222220.038104
 Total hardness2000.0050.7716050.003858020.00385854.080.270427.040.104321
 Total Alkalinity2000.0050.7716050.003858020.00385886.50.432543.250.16686
         Total11.48751
Table 4.The water quality index of sample number one
Sample IDparametersSi1/siKwiWi(Mi)Mi/SiQiWQI
GW02PH8.50.1176470.7716050.0907770.0907776.540.75529475.529416.856337
 TDS5000.0020.7716050.0015430.0015431230.24624.60.037963
 NA2000.0050.7716050.0038580.00385815.20.0767.60.029321
 K120.0833330.7716050.06430.06438.50.70833370.833334.554612
 Ca750.0133330.7716050.0102880.010288160.21333321.333330.219479
 Mg300.0333330.7716050.025720.025725.250.17517.50.450103
 Cl2500.0040.7716050.0030860.0030863.90.01561.560.004815
 SO42000.0050.7716050.0038580.0038581.780.00890.890.003434
 NO3450.0222220.7716050.0171470.0171470.20.0044440.4444440.007621
 Total hardness2000.0050.7716050.0038580.00385854.080.270427.040.104321
 Total Alkalinity2000.0050.7716050.0038580.00385886.50.432543.250.16686
         Total12.43487
Table 5. Water quality index of sample number two
Sample IDparametersSi1/siKwiWi(Mi)Mi/SiQiWQI
GW03PH8.50.1176470.7716050.0907770.0907776.470.76117676.117656.909736
 TDS5000.0020.7716050.0015430.001543109.30.218621.860.033735
 NA2000.0050.7716050.0038580.00385815.20.0767.60.029321
 K120.0833330.7716050.06430.06437.50.62562.54.018776
 Ca750.0133330.7716050.0102880.01028821.440.28586728.586670.294102
 Mg300.0333330.7716050.025720.025722.50.0833338.3333330.214335
 Cl2500.0040.7716050.0030860.0030864.80.01921.920.005926
 SO42000.0050.7716050.0038580.00385830.0151.50.005787
 NO3450.0222220.7716050.0171470.0171470.10.0022220.2222220.00381
 Total hardness2000.0050.7716050.0038580.003858640.32320.123457
 Total Alkalinity2000.0050.7716050.0038580.00385892.70.463546.350.178819
         Total12.43487
Table 6. The water quality index of sample number three
Sample IDparametersSi1/siKwiWi(Mi)Mi/SiQiWQI
GW04PH8.50.1176470.7716050.0907770.0907776.840.80470680.470597.304883
 TDS5000.0020.7716050.0015430.0015432150.43430.066358
 NA2000.0050.7716050.0038580.003858260.13130.050154
 K120.0833330.7716050.06430.06438.760.73734.69393
 Ca750.0133330.7716050.0102880.01028824.480.326432.640.335802
 Mg300.0333330.7716050.025720.025727.340.24466724.466670.629287
 Cl2500.0040.7716050.0030860.0030868.950.03583.580.011049
 SO42000.0050.7716050.0038580.00385812.730.063656.3650.024556
 NO3450.0222220.7716050.0171470.0171471.140.0253332.5333330.043439
 Total hardness2000.0050.7716050.0038580.00385891.80.45945.90.177083
 Total Alkalinity2000.0050.7716050.0038580.003858127.90.639563.950.246721
         Total13.58326
Table 7. The water quality index of sample number three
Sample IDparametersSi1/siKwiWi(Mi)Mi/SiQiWQI
GW05PH8.50.1176470.7716050.0907770.0907776.570.77294177.294127.016532
 TDS5000.0020.7716050.0015430.001543135.70.271427.140.041883
 NA2000.0050.7716050.0038580.003858210.10510.50.040509
 K120.0833330.7716050.06430.06438.80.73333373.333334.715364
 Ca750.0133330.7716050.0102880.01028821.720.289628.960.297942
 Mg300.0333330.7716050.025720.025724.410.14714.70.378086
 Cl2500.0040.7716050.0030860.00308660.0242.40.007407
 SO42000.0050.7716050.0038580.0038582.640.01321.320.005093
 NO3450.0222220.7716050.0171470.0171470.620.0137781.3777780.023624
 Total hardness2000.0050.7716050.0038580.00385871.40.35735.70.137731
 Total Alkalinity2000.0050.7716050.0038580.003858121.80.60960.90.234954
         Total12.89913
Table 8. The water quality index of sample number three

Where S_i is a standard value,
M_i is the measured value,
k = \frac{1}{\sum \frac{1}{S_i}},
W_i = \frac{w_i}{\sum w_i},
Q_i = 100 \left(\frac{M_i}{S_i}\right),
WQI = \sum W_i Q_i.

 According to (Bascaron, 1979) water quality can be categorized based on the index as follows below

WQI rating      classification
0-25                  Excellent
25-50slightly polluted  (Good)
50-75          moderately polluted (poor)
75-100            polluted (very poor)
>100           Excessively polluted (unsuitable)
Table 9. Categorization of water quality
Sample IDWater quality index
GW0111.49
GW0212.43
GW0312.43
GW0413.58
GW0512.89
Table 10 water quality index of samples

A single value or index can be created from large amounts of water quality data using the water quality index28.  The results of the water quality index can be utilized to assist planners and decision-makers in choosing the best GW management strategies29. A water quality index (WQI) summarizes large amounts of water quality data into simple terms (e.g., excellent, good, bad, etc.) for reporting to managers and the public consistently. According to the results, every sample has exceptional groundwater quality, which is crucial for managing groundwater.

Ionic ratio

It is possible to determine calcite, dolomite dissolution, and silicate weathering using the Ca+2/Mg2+ molar ratio. Ca+2/Mg2+ = 1 denotes the dissolution of dolomite, Ca2+/Mg2+ > 2 denotes the dissolution of silicate, and between 1 and 2 denotes the dissolution of calcite30.The Ca+2/Mg2+ ratio in the study’s Ca+2/Mg2+ values are between 1 and 2 and > 2, indicating that silicate weathering and, to small extent, calcite dissolution are the primary processes.

The chloride–alkaline index (CAI) is an important tool for explaining the chemical processes of ion exchange between groundwater and its geological environment. A negative CAI value suggests an exchange of alkaline earth metals (Ca2+ and Mg2+) from rock minerals with the presence of alkali metal ions (Na+ and K+) in groundwater, causing the influx of Ca2+ and Mg2+ ions into the groundwater system and a subsequent rise in their concentrations31

(2)   \begin{equation*}\text{CAI-1} = \frac{\text{Cl}^- - (\text{Na}^+ + \text{K}^+)}{\text{Cl}^-}\end{equation*}

(3)   \begin{equation*}\text{CAI-2} = \frac{\text{Cl}^- - (\text{Na}^+ + \text{K}^+)}{\text{SO}_4^{2-} + \text{HCO}_3^- + \text{NO}_3^-}\end{equation*}

In the area, CAI -1 and CAI-2 are negative which shows Na+ and K+ in the surrounding rock have been exchanged by Ca2+ and Mg2+ of water.

Figure5. Na versus Cl

The plot for Na versus Cl shows that many samples fall below the line of Na: Cl ratio equal to 1 indicating chloride source is other than the halite dissolution.

Conclusion

From the analysis, the PH of the groundwater samples is slightly acidic, with a mean of 6.57 within the acceptable range. The electrical conductivity (EC) and total; dissolved solids (TDS) are relatively low, with means of 248.44 and 136.66, respectively. This suggests that the groundwater is not saline. The concentrations of various ions such as Sodium (Na), Potassium (K), Calcium (Ca), Magnesium (Mg), Chloride (Cl), Sulfate (SO4), Bicarbonate (HCO3), Phosphate (PO4), Nitrate (NO3), and fluoride (F), are also relatively low. This suggests that the groundwater is not contaminated with various dissolved salts. The total hardness and alkalinity of the water samples are also relatively low, which suggests that the water is soft and has low buffering capacity. Overall, the chemical composition of the groundwater samples suggests that the water quality is good. Based on the water quality index and WHO standards all samples have excellent water quality. The findings have significant implications for policymakers and stakeholders, enabling more informed decision-making and the development of targeted strategies to ensure safe and sustainable groundwater resources. It is recommended to do further research by including other methodologies and data. 

Declarations: I declare that this work is not published or submitted in any other journal
Competing interest: The authors declare that there are no competing interests.
Author contributions: All parts of this work are done by Teselot Denkew

Reference

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