A Review of Causes and Consequences of Groundwater Depletion in Varanasi Urban Area

Groundwater is the main water source for people, industries, and commerce in Varanasi, which is among the oldest cities in the world still inhabited. For the last several decades, the city has faced a drastic decline in the water table, which makes the problem even more serious for the hydrological balance and the city's economy. The present study is concerned with the diverse reasons and the major impacts of groundwater dropping in the Varanasi urban region. The researchers made use of a mix of continuous hydrogeological data, satellite images, and urban growth evaluation to point out unregulated urbanisation and high population density as the main depletion factors. The spread of impermeable surfaces has greatly limited the areas that naturally recharge, while the extraction rate is several times higher compared to the annual replenishment capacity of the underlying Gangetic alluvial aquifers. Plus, the change to water-intensive lifestyles and the absence of a centralised regulatory framework for private tube-well installations have increased the problem. The impacts of this depletion are very serious and show their face in water scarcity all over the place since shallow borewells fail, and it leads to deeper and more expensive drilling. The study also indicates a simultaneous problem of water quality deterioration, as the inward spread of contaminants and the increase of geogenic contaminants, namely arsenic and fluoride, frequently occur along with the decline of water levels. Land subsidence is also a potential consequence that would endanger the city’s ancient buildings because of the changes in the subsurface pore pressure. The article recommends an integrated water resource management (IWRM) plan as the way to conduct further research, and suggests that the enforced use of rainwater harvesting, the restoration of traditional urban ponds (kunds), and the development of a digital groundwater monitoring network be used to ensure the long-term sustainability of Varanasi’s water security.