Seawater ingression vulnerability Study in the coastal aquifers of Cuddalore district
Résumé
This research paper explores the situation of seawater ingression in coastal aquifers of the Cuddalore
district. Totally 58 subsurface water samples collected from open and bore wells were analyzed for
significant physical and chemical parameters for the pre and post-monsoon periods of 2019. The average
water level, Average water quality, Average Rainfall for the past 30 years, Aquifer characters, existing
lithology data of tube wells, and Ghyben and Herzberg methodology are adopted to know the height of
interface between seawater and freshwater in coastal aquifers. The experimental results show that the
chloride (Cl-) value limits within the Brackish type with a value of 300 -103. The range of Chlorine–
Bicarbonate ratio (Cl/CO3=HCO3) is shown within the moderately contaminated water specification and
few due to industrial pollutants and anthropogenic effects. The permissible limit of Nitrate is increased in
24% of the total samples. By analyzing water level data by Ghyben-Herzberg methodology, the interface
point shows within the safe limit of freshwater - seawater interface zone. In addition, analyzing the lithology data of tube wells, clay thickness ranges from 35.0m to 60.0m in the unconfined aquifers along
the coast reduces the possibility of seawater intrusion.