Groundwater exploitation is silently sinking the Land

Geography Water - Issues, Challenges and Solutions

Context: Cracks in buildings and ‘sinking’ land in Joshimath, Uttarakhand a hill town in Uttarakhand, made the headlines earlier in 2023.

A similar phenomenon has been playing out for years in the plains of Punjab, Haryana, Delhi and Faridabad. According to the data gathered for years by the Central Ground Water Board (CGWB), excessive groundwater extraction is identified as the underlying cause of these alarming incidents.

Land subsidence refers to the gradual sinking or settling of the Earth's surface, usually due to the compaction of underground layers of soil, rock, or other materials.
It occurs when the support structures beneath the land, such as aquifers, underground mines, or natural gas extraction, are depleted or when certain geological processes take place.

In urban areas, it can damage infrastructure, including roads, buildings, and underground utilities.
It can also increase the risk of flooding in coastal regions by reducing the elevation of the land relative to sea level.
In agricultural areas, subsidence can affect irrigation systems, disrupt the flow of water in rivers and canals, and cause permanent damage to farmland.

Groundwater is the water found underground in the cracks and spaces in soil, sand and rock.
It is stored in and moves slowly through geologic formations of soil, sand and rocks called aquifers.
Aquifers are typically made up of gravel, sand, sandstone, or fractured rock, like limestone.
Water can move through these materials because they have large connected spaces that make them permeable.
Aquifers, hand-dug wells, and artesian wells are different types of sources of groundwater.

Increased demand for water for domestic, industrial and agricultural needs and limited surface water resources lead to the over-exploitation of groundwater resources.
Limited storage facilities owing to the hard rock terrain, along with the added disadvantage of lack of rainfall, especially in central Indian states.
Green Revolution enabled water-intensive crops to be grown in drought-prone/ water deficit regions, leading to over-extraction of groundwater.
Frequent pumping of water from the ground without waiting for its replenishment leads to quick depletion.
Subsidies on electricity and high MSP for water-intensive crops is also leading reasons for depletion.
Inadequate regulation of groundwater laws encourages the exhaustion of groundwater resources without any penalty.
Deforestation, unscientific methods of agriculture, chemical effluents from industries, and lack of sanitation also lead to pollution of groundwater, making it unusable.
Natural causes include uneven rainfall and climate change that are hindering the process of groundwater recharge.

Lowering of the water table: Groundwater depletion may lower the water table leading to difficulty in extracting groundwater for usage.
Reduction of water in streams and lakes: A substantial amount of the water flowing in rivers comes from seepage of groundwater into the streambed. Depletion of groundwater levels may reduce water flow in such streams.
Subsidence of land: Groundwater often provides support to the soil. When this balance is altered by taking out the water, the soil collapses, compacts, and drops leading to subsidence of land.
Increased cost for water extraction: As the depleting groundwater levels lower the water table, the user has to delve deep to extract water. This will increase the cost of water extraction.

The relationship between excessive groundwater extraction and land subsidence became evident through the analysis of data from Gravity Recovery and Climate Experiment (GRACE) satellites.
Excessive groundwater withdrawal, coupled with limited monsoon rain, has resulted in critically low groundwater levels in the region.
Land subsidence occurs when underlying aquifers, which are deep water channels storing percolated water, are not adequately recharged.
The depletion of aquifers causes the layers of soil and rock above them to sink gradually.
This sinking of soil is similar to “soil settlement” observed in mining operations.

It has the mandate of regulating groundwater development and management in the country.
It is constituted under the Environment (Protection) Act of 1986.
CGWA issues advisories, public notices and grant No Objection Certificates (NOC) for ground water withdrawal.

The NAQUIM is an initiative of the Ministry of Jal Shakti for mapping and managing the entire aquifer systems in the country.
It maintains the Hydrological Map of India.

It is a Central Sector Scheme, for sustainable management of groundwater resources with community participation in water-stressed blocks.

Routine survey: There should be regular assessment of groundwater levels to ensure that adequate data is available for formulating policies and devising new techniques.
Assessment of land use pattern: Studies should be carried out to assess land use and the proportion of agricultural land falling under overt-exploited units.
Changes in farming methods: To improve the water table in those areas where it is being overused, on-farm water management techniques and improved irrigation methods should be adopted.
Reforms in power supply subsidies: The agricultural power-pricing structure needs to be revamped as the flat rate of electricity adversely affects the use of groundwater.
Monitoring extraction: There should be a policy in place to monitor the excessive exploitation of groundwater resources to ensure long-term sustainability.
Wastewater Recycling and Reuse: There is a need to encourage the use of treated wastewater for non-potable purposes like industrial processes to reduce the reliance on freshwater sources and alleviate the pressure on groundwater extraction.
Crop Diversification and Efficient Irrigation: There is a need to promote crop diversification and shift to more water-efficient irrigation techniques like drip irrigation and sprinkler systems.