A study by IIT Kharagpur researchers published in Scientific Reports has shown that powerful cyclones can alter groundwater quality even 100 metres below the surface in deep coastal aquifers, posing a challenge to drinking water security in the Sundarbans. The findings indicate that extreme weather can disturb the balance between freshwater and seawater, facilitating the mixing of the two.
The research examined 11 extreme climatic events between May 2017 and May 2020, including seven atmospheric depressions and four tropical cyclones—Titli, Fani, Bulbul and Amphan. Using groundwater‑level measurements at multiple depths, hydrogeochemical analysis, stable‑isotope analysis and numerical modelling, the team assessed changes before, during and after the events.
Results showed that cyclones and depressions can rapidly change groundwater levels and hydraulic gradients, with shallow aquifers experiencing larger, immediate fluctuations while deeper aquifers exhibited longer‑lasting changes. Stable‑isotope evidence confirmed water movement and mixing that level data alone could miss, underscoring the complexity of groundwater responses.
The study highlights the need for depth‑specific groundwater‑management strategies. Authors recommend continuous monitoring at multiple depths, integration of extreme‑weather forecasts into extraction plans, and careful well placement to protect deeper aquifers.
The implications extend beyond the Sundarbans, emphasizing that groundwater security must be integral to climate‑adaptation efforts in vulnerable coastal regions worldwide.
