A geochemical investigation and control management of saline water intrusion in the coastal aquifer of Purba Midnapur district in West Bengal, India

摘要

The coastal groundwater storage of Purba Midnapur district in West Bengal, India is deteriorated as regards to quality and quantity as a severe risk to excessive overdraft due to ingression of saline water into fresh water aquifers. Here it is found that the upper soil horizon is of quaternary origin and consists of alternating deposits of clay and sand of marine origin. As with all marine deposits, rounded grains and high porosity are dominant characteristics. The mixture of alluvial and marine deposits soil characteristics has been found in the northern part of district. Also there is a great spatial heterogeneity in the aquifer. The coastal line up to 5 to 40 km wide tract has been contaminated due to the movement of saline water in the fresh water aquifers, as result groundwater becomes unused for irrigation and drinking for domestic purposes. The groundwater samples from the northern side of Purba Midnapur near the Rupnarayan River have been collected and analyzed at the chemical laboratory of State Water Investigation Directorate, Government of West Bengal. From the chemical analysis, it is clear that the values of concentration of dissolved solids, chloride and iron exist above or more than permissible limits. The contour lines for chloride concentration are drawn based on the chemical analysis. The above properties are compared with the drinking water standards set by World Health Organization. Based on the results, it is concluded that various prevention and control techniques would be implemented into the study area. This paper also suggests methodology for controlling saline water intrusion in the area concern.