Hardness analysis
Hardness in groundwater samples is varied from 97 to 961 mg/l. The permissible limit for hardness is 500 mg/l (WHO 2011). The GIS analysis of hardness shown in Fig. 2a indicates that the most of the area has hardness value within the permissible limit. Yellow, Green, and Pink colors indicate that the value of hardness is within the limit. The high concentration of hardness is found in the village 197 R.B. Baghian Wala, 130 J.B. Sidhupur, and 55 J.B. Khurdpur that are indicated by purple color on a map. The areas are near to these villages, also having a high hardness value between 530 and 666 mg/l (Sawyer et al. 2003) and indicated by blue color on a map.
The probability density function (pdf) of hardness in different years is shown in Fig. 2c. The peak of each curve represented the mean value of the particular year. From the graph, it is quite clear that the mean value of hardness for the year 2015 is more than 2010. The R square value of the mean of these pdf is 0.7 which indicates that the biasness is 30 %. The long-term trend of the hardness of groundwater is shown in Fig. 2b. The straight line tells that there is increasing trend up to 2030.
Alkalinity analysis
Alkalinity is the capacity of some of the components of the compound to accept a proton. The principal anions for producing alkalinity of fresh water are sulphate, bicarbonates, and chloride. The alkalinity of groundwater samples of the study area is varied from 1.34 to 13.20 mmol/l. Most of the samples have the alkalinity more than the permissible limit that is 2.77 mmol/l (CPCB). The GIS analysis of the spatial variability of alkalinity indicates that alkalinity value is more than the permissible limit. Figure 3a shows the spatial variability in alkalinity. Purple color indicates the highest value of alkalinity in water samples of 55 J.B. Khurdpur 11.2 mmol/l. The green color in the map indicates that the samples in this area have alkalinity value from 3.57 to 5.79 mmol/l.
Figure 3c shows the probability density function of alkalinity in different years. It can be clearly seen that the mean value of alkalinity is increasing every year. The R square value of the mean of these pdf is 0.6 which shows that the biasness is 40 %. Figure 3b represented long-term trend of alkalinity from 2008 to 2030 on the basis of pdf.
Cadmium analysis
Cadmium in groundwater samples of industrial zone is varied between 0.001 and 0.012 mg/l. Most of the samples have the cadmium value within the permissible limit that is 0.01 mg/l (WHO 2011). Figure 4a shows the spatial variability in cadmium. The green color in the map indicates that the samples in this area have cadmium within the permissible limit. The area of high concentration of cadmium is located in Chak # 105 JB and 110 JB having cadmium value 0.012 mg/l that is indicated by purple color.
The value of cadmium in an industrial zone is almost negligible in the year 2010–11, as shown in Fig. 4c. There is a significant change during the year 2012–15. The predicted value for next 20 years can be seen from Fig. 4b that there is an increasing trend.
Lead analysis
The main sources of lead in water are paints, batteries waste, pipes, gasoline, and manufacturing industries. It is a serious body poison. Guideline value for lead is 0.01 mg/l (WHO 2011). Lead in groundwater samples in the study area is varied between 0.01 and 0.270 mg/l; Fig. 5a indicates the value of lead at different areas. The area having a high concentration of lead is indicated by purple color on a map. The blue color in a map shows that the value of cadmium is more than the guideline value. Most of the industries lie in this area. Industrial drainage is also passed by from this area, so there is more effect.
Figure 5c shows the probability density function of lead in different years. The peak of each curve is showing the mean value of the particular year. From the graph, it is quite clear that the mean value of a lead for the year 2015 is more than the previous years. The R square value of the mean of these pdfs is 0.9 which shows that the biasness is only 10 %. Figure 5b represented long-term trend of lead from 2008 to 2030 on the basis of probability distribution function.
Nickel analysis
Nickel in groundwater samples of study area varied between 0.001 and 0.019 mg/l. It shows that all the samples have the nickel value within the permissible limit that is 0.20 mg/l (WHO 2011). Figure 6a shows the spatial variability in nickel. The green color in the map indicates that the samples in this area have nickel within the permissible limit. The maximum concentration of nickel in the area is indicated by purple color in a map having nickel value 0.015–0.018 mg/l.
The peak of each curve in Fig. 6c shows the mean value of nickel in the respective year. From the graph, it is quite clear that the value of nickel for the year 2015 is more than 2010. After the statistical analysis, it is clear that there is only 10 % biasness form the original value shown in Fig. 6b that is represented long-term trend of nickel from 2008 to 2030 on the basis of probability distribution function.
Arsenic analysis
Arsenic in groundwater samples varied from 0 to 25 ppb. The permissible limit of arsenic by WHO is 10 ppb. In most of the samples, arsenic is absent. GIS analysis of the spatial variability in arsenic indicates groundwater having no arsenic.
Figure 7a shows the spatial variability in arsenic. Yellow color in the map indicates that the samples in this area have no arsenic. The area covering green color indicates that arsenic value is between 4 and 10 ppb. The area of high concentration of arsenic is located at Chak # 196 RB Ghona having arsenic value 25 ppb and indicated by purple color. The area nearer to this point having arsenic value is more than the permissible limit.
Figure 7c shows the probability density function of arsenic for the year 2010–15. There are only two peak curves for the year 2014–15, because in rest of the year, its value is almost negligible. The number of industries in this zone is increasing, so the arsenic value is becoming more dangerous and it is a serious threat for future, as shown in Fig. 7b.
Fluoride analysis
Drinking water is the main source of fluoride intake. Favorable concentration in water is 1 mg/l; however, greater than 1.5 mg/l is linked to dental fluorosis and also to cancer. Fluoride in groundwater samples varied from 0 to 2.0 mg/l. Most of the samples have the fluoride value within the permissible limit. The GIS analysis of the spatial variability in fluoride indicates that major area has the groundwater which has fluoride near to permissible limit.
Figure 8a shows the spatial variability in fluoride. Green and pink colors in the map indicate that the samples in this area have fluoride within the permissible limits. The area of high concentration of fluoride is indicated by purple color having fluoride value that is more than the permissible limit.
The long-term trend of fluoride, as shown in Fig. 8b, represents that the concentration of fluoride is increasing gradually and it is very harmful to the human health specially for dental problems, such as mottling of teeth and bending of the spinal cord (Singh et al. 2014).