*3.2.1 Descriptive statistic of results*

A summarized statistic descriptive of results of fluoride's concentration (mg/L) in groundwater of the study area is shown in **Table 1**, and the minimum, maximum, means and standard deviation of results based on each sub-basin are illustrated in **Table 2**.

We used boxplot tool in order to provide a simplified presentation of how the values of fluoride's concentration are distributed, the boxplot (**Figure 15**) illustrated, the values' distributions are dissimilarities in their distribution in three sub-basins.


**Table 1.**

*Descriptive statistics of F- mg/L for all samples.*


#### **Table 2.**

*Descriptive statistics of fluoride values mg/L in groundwater samples of the study area by sub-basin.*

#### **Figure 15.**

*Box plot to provide a simplified presentation of how the values of fluoride's concentration are distributed in groundwater of three sub-basins.*

#### *3.2.2 The correlation analysis*

The correlation analysis between the fluoride concentration and the different physicochemical parameters showed that the fluoride concentration is positively correlated with the Cl, EC, TDS, K, Na, Mg and T. H at the significance level of 0.01 and with the parameters Ca and HCO3 at the significance level of 0.05 (**Table 3**).

## *3.2.3 The relationship between the concentration of fluoride and the water type*

**Figure 16** illustrated how the values of fluoride's concentration are distributed according to water type, and **Figure 17** show the comparison of the mean of F-mg/L according to water type with 95% confidence interval.

From the results of fluoride contain in the 93 samples, we found that the very high fluoride's concentration (4.501–6 mg/L) was associated with the water type both of Na-Cl (5 samples), Na-HCO3 (1 sample) and Mg-Cl (1 sample), the high fluoride's concentration (3.01–4.5 mg/L) was associated with the water type both of Na-Cl (8), Na-SO4 (3), Mg-Cl (1), Na-HCO3 (2) and Ca-HCO3 (1), the moderately abundant of fluoride's concentrations (1.5–3.0 mg/L) was associated with the water type both of Ca-Cl (4), Ca-HCO3 (2), Ca-SO4 (2), Mg-Cl (2), Mg-SO4 (1), Na-Cl (13), Na-HCO3 (16) and Na-SO4 (4), the optimal fluoride's concentration (0.5– 1.5 mg/L) was associated with the water type both of Ca-HCO3 (5), Mg-HCO3 (5), Na-Cl (8), Na-HCO3 (7) and Na-SO4 (1) and one sample with water type of Na-SO4 has fluoride's concentration lower than 0.5 mg/L as shown in **Table 4** and **Figure 19**. The distribution of water type according to sub-basins of the study area is illustrated in **Figure 18**, and the spatial distribution of both of water type and fluoride concentrations is illustrated in **Figure 19**.

There are variations for the fluoride concentration in the same of water type as shown in **Table 4**. Normal concentration of fluoride in Al-Dhabab sub-basin was associated with Ca-HCO3 and Mg-HCO3 water type; however, the sources of samples (wells No. 32 and 43, and spring No. 44) in Al-Hawban with the Ca-HCO3 water type showed high values of fluoride concentration 3.66, 2.36 and 1.96 mg/L containing fluoride concentration that exceeds the WHO drinking water, respectively. These sources are located in the southwest of Al-Hawban sub-basin, likely the sources of fluoride results of geology formation of the Sabir's mountain granits, **C°**

**135**

Fmg/L

P C Sig. (2-tailed)

No *PC, Pearson Correlation.*

*\*Correlation*

 *is significant at the 0.05 level (two-tailed).*

*\*\*Correlation*

**Table 3.** *Correlation*

 *between fluoride and different* 

*physico-chemical*

 *parameters.*

 *is significant at the 0.01 level (two-tailed).*

93

 93

 93

 93

 92

 93

 93

 93

 93

 93

 93

 93

 93

 92

 93

 93

*GIS and Statistical Evaluation of Fluoride Content in Southern Part of Upper Rasyan Aquifer…*

 0.414 0.602

 0.000

 0.000

 0.000

 0.897

 0.043

 0.000

 0.000

 0.000

 0.490

 0.000

 0.107

 0.012

 0.895

 0.086

0.055

 0.491

\*\*

0.491

0.394

0.014

 0.211\*

0.427\*\*

0.453\*\*

0.489\*\*

0.072

 0.536\*\*

0.168

 0.262\*

0.014

 1

\*\*

\*\*

 **pH EC (μs/**

**cm)**

**(mg/L)**

**(mg/L)**

**(mg/L)**

**(mg/L)**

**(mg/L)**

**(mg/L)**

**(mg/L)**

**(mg/L)**

**(mg/L)**

**(mg/L)**

**(mg/L)**

**(mg/L)**

**(mg/**

**L)**

**TDS**

**T.H**

**T.A**

**Ca**

**Mg**

**Na**

**K**

**Fe**

**Cl**

**SO4**

**HCO3**

**NO3**

**F-**

*DOI: http://dx.doi.org/10.5772/intechopen.91329*

*GIS and Statistical Evaluation of Fluoride Content in Southern Part of Upper Rasyan Aquifer… DOI: http://dx.doi.org/10.5772/intechopen.91329*


*\*\*Correlationissignificant at the0.01level(two-tailed).*

**Table** 

**3.** *Correlation between fluoride and different physico-chemical parameters.*

*3.2.2 The correlation analysis*

*groundwater of three sub-basins.*

**Figure 15.**

*Resources of Water*

**134**

The correlation analysis between the fluoride concentration and the different physicochemical parameters showed that the fluoride concentration is positively correlated with the Cl, EC, TDS, K, Na, Mg and T. H at the significance level of 0.01 and with the parameters Ca and HCO3 at the significance level of 0.05 (**Table 3**).

*Box plot to provide a simplified presentation of how the values of fluoride's concentration are distributed in*

**Figure 16** illustrated how the values of fluoride's concentration are distributed according to water type, and **Figure 17** show the comparison of the mean of F-mg/L

From the results of fluoride contain in the 93 samples, we found that the very high fluoride's concentration (4.501–6 mg/L) was associated with the water type both of Na-Cl (5 samples), Na-HCO3 (1 sample) and Mg-Cl (1 sample), the high fluoride's concentration (3.01–4.5 mg/L) was associated with the water type both of Na-Cl (8), Na-SO4 (3), Mg-Cl (1), Na-HCO3 (2) and Ca-HCO3 (1), the moderately abundant of fluoride's concentrations (1.5–3.0 mg/L) was associated with the water type both of Ca-Cl (4), Ca-HCO3 (2), Ca-SO4 (2), Mg-Cl (2), Mg-SO4 (1), Na-Cl (13), Na-HCO3 (16) and Na-SO4 (4), the optimal fluoride's concentration (0.5– 1.5 mg/L) was associated with the water type both of Ca-HCO3 (5), Mg-HCO3 (5), Na-Cl (8), Na-HCO3 (7) and Na-SO4 (1) and one sample with water type of Na-SO4 has fluoride's concentration lower than 0.5 mg/L as shown in **Table 4** and **Figure 19**. The distribution of water type according to sub-basins of the study area is illustrated in **Figure 18**, and the spatial distribution of both of water type and

There are variations for the fluoride concentration in the same of water type as shown in **Table 4**. Normal concentration of fluoride in Al-Dhabab sub-basin was associated with Ca-HCO3 and Mg-HCO3 water type; however, the sources of samples (wells No. 32 and 43, and spring No. 44) in Al-Hawban with the Ca-HCO3 water type showed high values of fluoride concentration 3.66, 2.36 and 1.96 mg/L containing fluoride concentration that exceeds the WHO drinking water, respectively. These sources are located in the southwest of Al-Hawban sub-basin, likely the sources of fluoride results of geology formation of the Sabir's mountain granits,

*3.2.3 The relationship between the concentration of fluoride and the water type*

according to water type with 95% confidence interval.

fluoride concentrations is illustrated in **Figure 19**.

#### **Figure 16.**

*The distribution's values of fluoride according to water type.*

#### **Figure 17.**

*Comparison of the mean of F- mg/L according to water type with 95% confidence interval.*


lower than 1.5 mg/L [(7 wells located in the Al-Hawban sub-basin (wells No. 54, 37, 49, 53, 51, 40 and 5) and one well (No. 72) located in the Al-Burayhi and Hedran sub-basin)]. The wells with the Na-HCO3 water type have 19 groundwater samples out of 26 samples (wells and one spring) with a high fluoride's concentration [(11 wells and one spring in Al-Hawban (dug wells No. 9, 22, 27, 18, 15, 47, 17, 19, 20, 23 and 52, spring No. 16) and 7 wells in Al-Burayhi and Hedran sub-basin (No. 67, 85, 70, 89, 69, 84 and 86)]. There are 7 samples out of 9 groundwater samples with water type of Na-SO4 have a high values of fluoride's concentration, 6 wells located in the Al-Hawban [(wells No. 39, 33, 4, 46, 3 and 35) and one located in Al-Burayhi and Hedran sub-basin (well No. 66)]. All samples with water type both of Ca-SO4, Mg-Cl, Ca-Cl and Mg-SO4 have abnormal fluoride's concentration as shown in **Table 5**. Abnormal concentration of fluoride was more prevalent with groundwater

*GIS and Statistical Evaluation of Fluoride Content in Southern Part of Upper Rasyan Aquifer…*

*The spatial distribution both of water type and the F- mg/L in the study area.*

*The distribution of water type according to sub-basins of the study area.*

*DOI: http://dx.doi.org/10.5772/intechopen.91329*

**Figure 19.**

**137**

**Figure 18.**

samples with Mg-Cl water type in Al-Hawban sub-basin (well No. 41 with

#### **Table 4.**

*Classification of F- mg/L and their relation to the water type.*

according to [21]. The groundwater with high concentration of fluoride is associated with the granits rocks.

For the Na-Cl water type, we found that 26 samples out of 34 samples have high concentration of fluoride, 12 samples located in the Al-Burayhi and Hedran subbasin [(wells No. 83, 80, 78, 77, 68, 65, 88, 82, 87, 79, 75 and 92), where 4 samples of them (wells No. 83, 80, 78 and 77) have 4 of highest values of fluoride's concentration of out of 5 the highest values)] and 14 samples located in the Al-Hawban subbasin (wells No. 6, 12, 2, 11, 1, 36, 30, 25, 42, 29,24, 28, 55 and 34); however, there are 8 wells with water type of Na-Cl that have fluoride's concentration equalizer or

*GIS and Statistical Evaluation of Fluoride Content in Southern Part of Upper Rasyan Aquifer… DOI: http://dx.doi.org/10.5772/intechopen.91329*

#### **Figure 18.**

*The distribution of water type according to sub-basins of the study area.*

#### **Figure 19.**

*The spatial distribution both of water type and the F- mg/L in the study area.*

lower than 1.5 mg/L [(7 wells located in the Al-Hawban sub-basin (wells No. 54, 37, 49, 53, 51, 40 and 5) and one well (No. 72) located in the Al-Burayhi and Hedran sub-basin)]. The wells with the Na-HCO3 water type have 19 groundwater samples out of 26 samples (wells and one spring) with a high fluoride's concentration [(11 wells and one spring in Al-Hawban (dug wells No. 9, 22, 27, 18, 15, 47, 17, 19, 20, 23 and 52, spring No. 16) and 7 wells in Al-Burayhi and Hedran sub-basin (No. 67, 85, 70, 89, 69, 84 and 86)]. There are 7 samples out of 9 groundwater samples with water type of Na-SO4 have a high values of fluoride's concentration, 6 wells located in the Al-Hawban [(wells No. 39, 33, 4, 46, 3 and 35) and one located in Al-Burayhi and Hedran sub-basin (well No. 66)]. All samples with water type both of Ca-SO4, Mg-Cl, Ca-Cl and Mg-SO4 have abnormal fluoride's concentration as shown in **Table 5**. Abnormal concentration of fluoride was more prevalent with groundwater samples with Mg-Cl water type in Al-Hawban sub-basin (well No. 41 with

according to [21]. The groundwater with high concentration of fluoride is associated

*Comparison of the mean of F- mg/L according to water type with 95% confidence interval.*

Na-HCO3 (16) and Na-SO4 (4)

4.501–10.0 Na-Cl (5), Na-HCO3 (1) and Mg-Cl (1)

*Classification of F- mg/L and their relation to the water type.*

**Type of water and number of samples**

3.01–4.5 Na-Cl (8), Na-SO4 (3), Mg-Cl (1), Na-HCO3 (2) and Ca-HCO3 (1)

0.5–1.5 Ca-HCO3 (5), Mg-HCO3 (5), Na-Cl (8), Na-HCO3 (7) and Na-SO4 (2) 1.5–3.0 Ca-Cl (4), Ca-HCO3 (2), Ca-SO4 (2), Mg-Cl (2), Mg-SO4 (1), Na-Cl (13),

For the Na-Cl water type, we found that 26 samples out of 34 samples have high concentration of fluoride, 12 samples located in the Al-Burayhi and Hedran subbasin [(wells No. 83, 80, 78, 77, 68, 65, 88, 82, 87, 79, 75 and 92), where 4 samples of them (wells No. 83, 80, 78 and 77) have 4 of highest values of fluoride's concentration of out of 5 the highest values)] and 14 samples located in the Al-Hawban subbasin (wells No. 6, 12, 2, 11, 1, 36, 30, 25, 42, 29,24, 28, 55 and 34); however, there are 8 wells with water type of Na-Cl that have fluoride's concentration equalizer or

with the granits rocks.

**Figure 16.**

*Resources of Water*

**Figure 17.**

**Table 4.**

**136**

**Concentration of fluoride (mg/L)**

*The distribution's values of fluoride according to water type.*


#### **Table 5.**

*Water type, normal and abnormal of F- mg/L and number of wells.*

ultimately Ca-Cl when the pH range between 7.3 and 8 was more lower than pH 6¼ [7.3–8] (**Figure 21**) and the comparison of the groups "pH [7.3–8]" and "pH ¼6 [7.3–8]" showed a significant difference in fluoride concentration (p < 0.05). Results of the multivariate analysis are shown in **Table 6**. In the two logistic regression model, after adjusting for pH, water type and sub-basin (ORa = 0.366; CI: 1.76–0.76), the water type (ORa = 1.71; CI: 1.261–2.32) remained dependently

pH [7.3–8] 0.417 0.164–1.062 0.067 0.373 0.139–0.99 0.050 Water type 1.755 1.295–2.378 0.000 1.711 1.261–2.322 0.001 Sub-basin 0.389 0.194–0.778 0.008 0.366 0.176–0.760 0.007 *ORa: odds ratio adjusted. pH* 6¼ *[7.3–8]: reference. Mg-HCO3 water type: reference. Al-Hawban sub-basin: reference.*

*GIS and Statistical Evaluation of Fluoride Content in Southern Part of Upper Rasyan Aquifer…*

**ORcrude CI for 95% p-value ORa CI for 95% p-value**

The results statistic analysis show that the different of the fluoride concentration between the different sources of water samples (dug well, bore well and spring) in the study area is not significantly different. Fluoride concentration decreases not

Fluoride concentration is positively and not significantly related to depth of the

The comparison of the abnormal and normal fluoride concentration according to TDS (total dissolved solids) in the three sub-basins showed a significant differences between the three sub-basins (p < 0.0001) and positive relationship between the fluoride concentration and TDS (r = 0.5; p < 0.0001). A multiple comparison of median concentration among these sub-basins in fluoride shows that Al-Hawban and Al-Burayhi and Hedran sub-basins reach higher fluoride content which is more

*3.2.6 The comparison of the abnormal and normal fluoride concentration according*

associated with abnormal fluoride concentration (**Table 6**).

*Logistic regression univariate and multivariate model for fluoride variation.*

significantly according to well's type F (2) =2.19, p = 0.121.

*of sources of samples*

groundwater (r = 0.046, p > 0.05).

*to TDS*

**139**

**Figure 21.**

**Table 6.**

*Distribution of water type according to pH.*

*DOI: http://dx.doi.org/10.5772/intechopen.91329*

*3.2.5 The relationship between the concentration of fluoride and type*

#### **Figure 20.**

*The difference of means for F- mg/L with 95% Cl.*

4.87 mg/L, No. 26 with 1.58 mg/L and well No. 10 with 3.33 mg/L) and Al-Burayhi and Hedran (source No. 81 with 2.66 mg/L); and with water type both of Ca-SO4 (wells No. 38 and 8 in Al-Hawban sub-basin), Ca-Cl (wells No. 71, 73 and 91 in the Al-Burayhi and Hedran sub-basin and well No. 31 in Al-Hawban sub-basin) and Mg-SO4 (well No. 7 in Al-Hawban sub-basin). **Figure 20** illustrated that there are no significant different in the fluoride concentration between the sources of groundwater samples according to the water type.
