ABSTRACT
In some of the tropical hard rock areas dependability on groundwater is high and also increasing continuously. Earlier groundwater was abstracted in these areas from weathered zone aquifer through hand dug wells. The growing demand prompted for the sinking of public as well as private shallow bore wells. These wells were at the most affected by seasonal water level decline and some of them running dry in summer months indicating a temporal variation in saturated weathered zone thickness and consequent alteration in aquifer dimension and storage. The excessive withdrawal of groundwater more than its annual natural replenishment resulted in a wide-spread common phenomenon of declining groundwater level. The shallow weathered zone aquifers, distributed discontinuously as pockets with limited storage capacity got dewatered or dried-up at many places rendering a large number of wells dry throughout. It triggered drilling of deeper wells and also successive deepening of wells to exploit the saturated fractured zones for a better yield. With increased depth to groundwater level and reduced availability the stress on physical as well as economic access to groundwater also increased heavily. Overall, it resulted in a huge draft of groundwater inconsistent with its annual natural recharge. Consequentially the water level continued to decline, eventually forcing the most important resource to the present near-irreversible precarious situation in some of the tropical hard rock areas. Besides, in urban areas while draft has increased enormously, the decrease in permeable surface area has increased the surface runoff and reduced the natural recharge, causing localized lowering of groundwater levels. In coastal tracts, depleting the level of groundwater has caused sea water intrusion, resulting in a deterioration in groundwater quality.
