Introduction
The Sundarban Biosphere Reserve (SBR) of India lies in the southwestern part of the Ganges delta. The SBR, suffers from the scarcity of fresh water as the rivers in SBR are saline and shallow groundwater is brackish in nature. Fresh ground water is only available from the deep confined aquifers and not easily accessible.
Objective
The 4.43 million strong population in the SBR depend fully on deep groundwater to meet their drinking water demand. It is, therefore, necessary to assess the quality of this groundwater to fulfill the sustainable development goal.
Methodology
The water quality index (WQI) has been estimated for shallow and deep aquifers based on water quality parameters like pH, TDS, EC, Cl, SO4, HCO3, TH, Ca, Mg and Na. Hydrological facies of the shallow and deep water samples have been identified using the Piper trilinear diagram. The Cl/HCO3 ratio has been calculated to study saline water intrusion in the coastal aquifer of the SBR.
Result
The groundwater in the SBR region belongs to NaHCO3, MgHCO3, NaCl and mixed type hydro-geochemical facies. The dominant cations are found in the order Na>Mg>Ca, and dominant anions in the order HCO3>Cl>SO4. The Cl/HCO3 ratio indicates that the shallow aquifers in the SBR are affected by the saline water intrusion. Following the limit set by the Bureau of Indian Standards, the shallow groundwater in the SBR is found to be unsuitable for drinking. Although the deep groundwater is within the permissible limit of safe drinking water, its quality is poor.
Conclusion
To meet the goal of sustainable development and safe drinking water for all in future, extensive rainwater harvesting and supply of treated surface water through pipeline and desalination of subsurface brackish water are some of the feasible options in the region.