Water table declined in pockets of 6 major cities by more than 4 metres over the years
The groundwater level in 33 per cent of the wells monitored by the Central Ground Water Board (CGWB) declined by 0-2 metres in November 2020 as compared to the decadal water level average (2010-2019).
The observations also showed a decline of more than 4 m of the water table in a few pockets of Delhi, Chennai, Indore, Coimbatore, Madurai, Vijayawada, Dehradun, Jaipur, Allahabad, Ghaziabad, Kanpur, and Lucknow over the years.
Metro cities with declining water tables
Decline in water table (in meter)
7 to 20
India is the largest user of groundwater with a fourth of the total global withdrawal. Indian cities cater to about 48 per cent of its water supply from groundwater.
The unmanaged groundwater and increasing population may result in seasonal water shortages by 2050 for an estimated 3.1 billion people and perpetual water shortage for almost a billion.
Further, water and food security will also be compromised and lead to poverty in the cities despite having good infrastructure development.
The theme for this year's World Water Day (March 22) was also Groundwater: Making the invisible visible to bring attention to the invisible yet impactful resource.
Water supply, sanitation and drainage are key requirements of the urbanisation process. Furthermore, the subsurface plays an important role in the infrastructure development for these three as well for the disposal of effluents and wastes.
Groundwater is of better quality than surface water and easily available near the water-demand sites. This reduces the capital and operational costs and makes it vulnerable.
Climate Change impacts the spatial and temporal distribution of water. Rainfall variability, urban floods and higher temperature leading to drought will potentially hinder the achievement of the United Nations-mandated Sustainable Development Goals (SDG), especially SDG11 (sustainable cities and communities) and SDG 6 (clean water and sanitation).
Accelerated population growth: The burgeoning urban population increases demand for water as well as the management of waste and polluted water.
Unplanned urbanisation: Increase in the built-up and paved area eliminates infiltration, reduces evapotranspiration, and thereby increases surface runoff and urban flooding. A study in the United States indicated that for every 1 per cent increase in the impervious surface area, there is a 3.3 per cent increase in the urban flood magnitude.
Over-exploitation of groundwater and increased number of private bore / tube wells to fulfill the demand and supply of water leads to deepening of the water table, land subsidence, saline water intrusion and aquifer contamination.
Transformation of the natural landscape, watershed and flow direction by urban sprawl often modifies the groundwater cycle and may result in a sharp decline or rise of groundwater levels, reduced well yields and deteriorating quality.
The modification of groundwater flow paths due to underground infrastructures like tunnels, metros, basements as well as disturbed natural drainage systems and watershed areas also result in the loss of habitat and frequent urban flooding.
The groundwater recharge rate tends to increase through leakage of water supply pipelines, on-site sanitation systems, sewage lines and industrial effluents.
The subsoil strata are not capable of transmitting the excessive groundwater. This may result in hydraulic and corrosion effects on the building foundations and tunnel linings, flooded tunnels and basements.
Urban groundwater pollution: Infiltration and seepage from roads, gardens, industrial sites, waste dump sites, effluent drains with heavy metals and micro-pollutants; microbiological contamination through the sewage system and on-site sanitation are playing a major role in it. Nitrate, arsenic, fluoride are some of the major elements responsible for groundwater pollution.
The various organisations that manage India’s groundwater lack accountability and responsibility. They also have limited knowledge and capacity on groundwater and its behaviour. Some of the major groundwater management stressors are:
For planning and management of groundwater, there is a need to focus on the Integrated Water Resource Management framework. It promotes the coordinated development and management of water, land and related resources.
The guidelines also include other components of the urban water system, such as surface water, wastewater, stormwater and their relationships.
To begin with, adopting water-sensitive urban design and planning can help maintain the water cycle by managing groundwater, surface water and rainwater for water demand and supply.
Provision for wastewater recycle and its reuse to promote the circular economy of one water cycle will also help in source sustainability and groundwater pollution mitigation.
Interventions like rainwater harvesting, stormwater harvesting, rain-garden and bio-retention ponds that intercept rainfall with vegetated land are low-maintenance alternatives to conventional systems. These help in groundwater recharge and urban flood mitigation.
Another pertinent point in addressing these challenges in the city is the potential role of the green (trees, parks, gardens, playgrounds and forests) and the blue (seas, rivers, lakes, wetlands and water utilities) spaces. This is known as the blue-green infrastructure approach.
Finally, the strengthening of regulatory frameworks and stakeholder participation need to be formulated and imposed. Aquifer characterisation and robust monitoring of urban groundwater quality as well as quantity are imperative. Data collection, formulation of effective regulatory legal policies, laws and acts for better management will go a long way.
Public awareness and participation as well as trust-building between formal water sector institutions and communities will further fill the void in urban groundwater management.
Some of the Indian cities that started working on these are Bhopal’s green-blue smart city plan, Delhi’s Masterplan 2041, Chennai’s water as leverage initiative and Bengaluru through its recharge wells.
We are a voice to you; you have been a support to us. Together we build journalism that is independent, credible and fearless. You can further help us by making a donation. This will mean a lot for our ability to bring you news, perspectives and analysis from the ground so that we can make change together.
Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.