Consider the hydrogeological dynamics of the coastal alluvial and sandy aquifers of Kerala: Statement I: Excessive groundwater extraction in densely populated coastal tracts often induces saline water intrusion from adjacent backwaters and the sea. Statement II: The freshwater-saltwater interface in coastal aquifers is governed by Ghyben-Herzberg relation, where the depth of the freshwater lens below sea level is proportional to the height of the water table above sea level. Which of the following is correct?

💡 Solution & Explanation

Coastal aquifers maintain a delicate hydrostatic equilibrium where freshwater floats on denser saline water. Lowering the water table through heavy pumping disrupts this balance, causing saltwater to upwell or migrate inland in accordance with the Ghyben-Herzberg principle, which states that every meter of freshwater head above sea level supports about forty meters of freshwater depth below sea level. This phenomenon threatens drinking water wells across coastal districts like Alappuzha and Ernakulam. Sustainable watershed management requires careful regulation of borewell depths in these fragile zones.