JNTU B.Tech IV GROUND WATER HYDROLOGY Previous Question Paper (February/March - 2022 - R18)

Groundwater in India is a critical resource, with the country being the largest user of groundwater globally. The potential is unevenly distributed due to diverse geological and climatic conditions. The Indo-Gangetic-Brahmaputra plains, underlain by thick alluvial deposits, possess the highest groundwater potential, offering high-yielding aquifers. In contrast, the hard rock terrains of the Peninsular shield, covering about two-thirds of the country, have limited potential, restricted to weathered and fractured zones.

Development is primarily driven by agricultural needs, with over 85% of groundwater extraction used for irrigation. While this has facilitated the Green Revolution, it has led to critical challenges including:

1. Over-exploitation in states like Punjab, Haryana, and Rajasthan, leading to a significant decline in water tables.
2. Quality issues such as fluoride, arsenic, and salinity contamination in various regions.
3. Saltwater intrusion in coastal aquifers due to excessive pumping.

Current development strategies emphasize artificial recharge, rainwater harvesting, and the implementation of the Atal Bhujal Yojana to shift from groundwater extraction to sustainable management and community-led conservation.

The origin of groundwater is primarily attributed to the Hydrologic Cycle. Groundwater is essentially water that has infiltrated the earth's surface and percolated through the soil and rock layers to reach the zone of saturation.

The primary sources are:

1. Meteoric Water: This is the most significant source, derived from precipitation (rain, snow, hail). It infiltrates the ground and moves downward under gravity until it reaches an impermeable layer, forming aquifers.
2. Connate Water: This is water trapped in the interstices of sedimentary rocks at the time of their deposition. It is often saline and found in deep geological formations.
3. Juvenile (Magmatic) Water: This is water released from deep-seated magma during volcanic activity. It is considered 'new' water reaching the surface for the first time.
4. Metamorphic Water: Water released from minerals during the process of metamorphism when rocks are subjected to high heat and pressure.

Among these, meteoric water accounts for the vast majority of usable groundwater resources globally.