Give a brief account of the ground-water resource potential of the Ganga, Narmada and Krishna basin after describing the sources of their recharge and drift.

Groundwater Resource Potential: Ganga, Narmada, and Krishna Basins:

Groundwater potential is dynamically governed by Recharge (monsoonal infiltration, canal seepage, surface irrigation return flow) and Draft (agricultural tube-well extraction, industrial and domestic pumping):

• 1. Ganga River Basin (Highest Potential in India):
  • Potential: Vast, multi-layered, deep alluvial unconfined/confined aquifers ($>170 ext{ Billion Cubic Metres - BCM}$ replenishable groundwater).
  • Recharge vs. Draft: Heavy monsoonal recharge ($>1,000 ext{ mm}$) and perennial Himalayan river recharge maintain high water tables, though Western UP/Haryana suffer over-exploitation.
• 2. Narmada River Basin (Moderate to High Potential):
  • Potential: Deep alluvial fill in the central trough (Jabalpur, Narsinghpur, Hoshangabad) holding ~10.8 BCM groundwater.
  • Status: Well-managed recharge; high potential in alluvial river terraces.
• 3. Krishna River Basin (Moderate to Low Potential):
  • Potential: Hard crystalline Archean granites and Deccan basalts with low secondary porosity (~26.4 BCM).
  • Status: Low monsoonal rain in interior Rayalaseema/Karnataka creates severe drought vulnerability and seasonal overdraft.