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Correlation between overexploitation of groundwater and land subsidence

Context:

This article discusses the impact of excessive groundwater extraction on and subsidence.

Introduction:

5. Several independent studies have found out that the excessive groundwater extraction is causing land subsidence in north-west India, including Punjab, Haryana, Delhi, and Faridabad.
5. The Central Ground Water Board (CGWB), a subsidiary body of the Jal Shakti Ministry, is tasked with assessing the state of India’s groundwater resources.
5. It has a system of groundwater observation-wells and monitors water levels four times a year. It, however, does not analyse the consequences of ‘over exploitation.’

Over exploitation:

5. Agricultural practices in north-west India are heavily dependent on groundwater withdrawal. With limited monsoon rain, the groundwater table is precariously low.
5. The CGWB has reported that many groundwater blocks are over-exploited, leading to the depletion of underlying aquifers.
5. In Punjab, for instance, 76% of the groundwater blocks are ‘over exploited’. In Chandigarh, it is 64% and about 50% in Delhi.  This means that more groundwater than can be recharged is extracted.
5. Land subsidence is caused when these aquifers run dry and the layers of soil and rock above them start to sink.
5. GRACE (Gravity Recovery and Climate Experiment) satellites based analysis has shown a correlation between building deformities and groundwater withdrawals, and unplanned growth and urbanisation have exacerbated the issue in some parts of Delhi-NCR.
5. Land subsidence can lead to increased flooding, as the land sinks and reduces the capacity of water bodies to hold water. In the Ganga basin, over-extraction of groundwater has caused the land to sink, leading to flooding in the area.

Groundwater depletion

5. Groundwater depletion in India is a major concern because it is the primary source of drinking water. Some of the main causes of groundwater depletion in India include over-extraction of groundwater for irrigation, urbanisation, and climate change.
5. According to the Central Ground Water Board (CGWB) of India, approximately 70% of the total water used in India is from groundwater sources. However, the CGWB also estimates that around 25% of the country's total groundwater extraction is unsustainable, meaning that it is being extracted at a faster rate than it can be replenished.
5. Overall, groundwater depletion in India is a serious problem that needs to be addressed through sustainable water management practices, such as improved irrigation techniques and conservation efforts.

What are the Major Causes of Groundwater Depletion in India?

5. Over-extraction of Groundwater for Irrigation: Irrigation accounts for around 80% of total water use in India, and much of this water is sourced from groundwater.
5. As demand for food continues to grow, more and more groundwater is being extracted for irrigation, leading to depletion.
5. Climate change: Rising temperatures and changing precipitation patterns can alter the recharge rates of groundwater aquifers, making them more vulnerable to depletion.
5. Draughts, flash floods, and disrupted monsoon events are recent examples of climate change events that are placing pressure on India's groundwater resources.
5. Poor Water Management: Inefficient use of water, leaky pipes, and inadequate infrastructure for capturing and storing rainwater can all contribute to groundwater depletion.
5. Decrease in Natural Recharge: The natural recharge of groundwater aquifers can be decreased by factors such as deforestation, which can lead to soil erosion and reduce the amount of water that is able to seep into the ground and replenish the aquifers.

What are the Issues Associated with Depleting Ground Water?

5. Water Scarcity: As groundwater levels drop, there may not be enough water available for domestic, agricultural, and industrial use. This can lead to water shortages and conflicts over water resources.
5. Land Subsidence: When groundwater is extracted, the soil can become compacted, leading to land subsidence (the sinking or settling of the land). This can cause damage to infrastructure, such as roads and buildings, and can also increase the risk of flooding.
5. Environmental Degradation: Depleting groundwater can also have negative impacts on the environment. For example, when groundwater levels drop, it can cause saltwater intrusion in coastal areas, leading to the contamination of freshwater resources.
5. Economic Impacts: Groundwater depletion can also have economic impacts, as it can lead to reduced agricultural production and increased costs for water treatment and pumping.
5. Lack of Depletion Data: Indian government regulates groundwater exploitation by "notifying" highly overexploited blocks in water-stressed states.
5. However, only about 14% of overexploited blocks are currently notified.

What are the Government Initiatives Related to Groundwater Conservation?

5. Pradhan Mantri Krishi Sinchayee Yojana
5. Jal Shakti Abhiyan- Catch the Rain Campaign
5. Atal Bhujal Yojana
5. Aquifer Mapping and Management Programme
5. Atal Mission for Rejuvenation and Urban Transformation (AMRUT)

What Should be the Way Forward?

5. Water Conservation: In the urban areas (where groundwater is five-six metres below the surface), it is possible to reduce groundwater depletion by creating green corridors, mapping channels for potential recharge zones to store floodwater, and creating artificial groundwater recharge structures.
5. The use of dysfunctional bore wells for recharging groundwater with clean rainwater will also be a good option.
5. Regulation of Ground Water Extraction: Implementing regulations to control the extraction of groundwater can help to ensure that it is not being over-exploited.
5. The requirement for a Water Impact Assessment should be made mandatory for all industries, in addition to introducing a "Blue Certification" program which rates industries according to the amount of water they recharge and reuse.
5. Promoting the Use of Alternative Sources of Water: Encouraging the use of alternative sources of water, such as treated wastewater, can help to reduce the demand for groundwater.
5. Developing a dual sewage system for grey water and black water, as well as promoting the reuse of recycled water in agriculture and horticulture, should be promoted.
5. Water Education and Awareness: Raising awareness about the importance of conserving water and the need to prevent groundwater depletion can help to encourage individuals and communities to adopt sustainable water use practices.