In the northern-western parts of the Indian subcontinent, an acute shortage of water is being witnessed and the issue is that these states are heavily dependent on groundwater for agricultural work.

Actually, India has a greater groundwater extraction rate than it's recharge. Hydrological cycle is continuously being affected by a rise in pollution levels, global warming, and other events of climate change.

This problem is coupled with the issue of land subsidence.

What is Land Subsidence?

It is the progressive or abrupt sinking of the earth's surface by the elimination of dislocation of sub-surface earth components (aquifers) triggered by natural/human activity.

When the underlying aquifers - deep water channels that are capable of storing water aren't recharged, they run dry. Hence the layers of soil and rock above them start to sink.

Satellite data reveals that the NCR region sank 15mm per year between the years 2011-2017. Urbanisation and unprecedented population growth are responsible for this.

Impact:

• Land sinking over a large area will imply that the region will become flood-prone.
• It can also affect civic facilities such as roads, buildings, and residences.
• It may cause fundamentals to either develop cracks or deteriorate.

Link between Groundwater and Land Subsidence:

• The Central Ground Water Board - a subsidiary body of the Jal Shakti Ministry doesn't analyse the consequences of 'over-exploitation'.
• The link only started to highlighten when GRACE (Gravity Recovery and Climate Experiment) revealed that there are minute changes in gravity on different parts of Earth's surface.
• It is also difficult to detect as unlike landslides which are clearly visible, it is not so clearly seen.
• It is even harder to correlate with structural damage.

Way Forward:

• There needs to be greater recognition that groundwater exploration also has serious consequences.
• Geographers and Government both should have a fair idea of the geophysical properties of the areas undergoing subsidence.
• Increasing rainwater harvesting to establish equilibrium in the hydrological cycle.
• Various campaigns such as 'Groundwater: Making the Invisible Visible', 'Aquifer Mapping and Management Scheme', and 'Jal Shakti Abhiyan of 2019' have been launched.

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Reference:

• thehindu.com