**3. Status of water sources in the present study location**

Groundwater used for domestic water consumption in South 24 Parganas is sixty-eight (68) Million cubic meters (MCM) which is very much significant, as a result, groundwater is depleting very fast. According to Census India 2011 report, the population of Gosaba block was five thousand three hundred and sixty-nine (5369) that has increased substantially in the current year 2021, the increment being around 7% p.a. The population in Gosaba is around 10,000 as of the year 2020. The density of population in South 24 Parganas is more than that of West Bengal as a consequence

of which groundwater is extracted more resulting in saline water intrusion as per Ghyben Herzberg Principle that states one scale decline of groundwater results in forty scale intrusion of seawater into the mainland. From the information provided by Public Health Engineering Department (PHED), South 24 Pargana, it has been confirmed that groundwater is contaminated with arsenic, arsenic contamination in Jayanagar was 0.05 mg/l, salinity in groundwater in the year 2011 was ranged from 0 ppm at Budge Budge to 4624 ppm in Mathurapur-II and in Jayanagar-I was 2195 ppm. Iron content in groundwater is also a big problem in South 24 Pargana. The concentration of iron in groundwater is ranged from 0 at few places to 6.15 ppm at Magrahat II and in Jayanagar is 3.96 ppm which is beyond the acceptable limit according to IS 10500:2012. The contour map of chloride, iron content and salinity in groundwater of that location is shown in **Figure 2**.

#### **Figure 2.**

*Groundwater quality parameter's contour map in South 24 Parganas of West Bengal.*

Similarly, arsenic contamination in Jayanagar was 0.05 mg/l. Water samples were taken from twenty-nine locations of South 24 Pargana. According to IS 10500:2012, the permissible value of salinity in drinking water should be within 1000 ppm and similarly, the permissible value of arsenic in drinking water should be less than 0.01 mg/l. By inspection of the above value, it is found Gosaba block in Jayanagar was both saline and arsenic affected. Surface water is also saline due to the geographical location of South 24 Pargana. So, Gosaba block in Jayanagar is water scarce area. Water samples were taken from twenty-nine locations of South 24 Pargana. According to IS 10500:2012, the permissible value of salinity and arsenic in drinking water should be within 1000 ppm and less than 0.01 mg/l respectively. After thorough investigation, it has been found that the Gosaba block in Jayanagar is water scarce area as the groundwater is both saline and arsenic affected and surface water is also saline due to the geographical location of South 24 Parganas. Moreover, according to Central Water Management Index, 2018 by NITI AAYOG, South 24 Parganas have been found as water scarce area with the ratio of total water to total population available less than 1000 per cubic meter per capita per year.
