Ever wondered what would happen if cities expanded faster than the ground they stand on could handle? As Indian cities like Mumbai, Delhi, Kolkata, and Chennai are growing at a fast pace, the land beneath them is sinking.
This problem comes from something called land subsidence, which is a gradual lowering of the land below due to increased human activities that tend to harm it. In the megacities of India, this issue arises from the over-extraction of groundwater, which leads to the compaction of the aquifers, thus leading to the sinking of the land underneath.
The Problem Of Land Subsidence
As defined by the National Oceanic and Atmospheric Administration (NOAA), “Land subsidence refers to the gradual sinking, lowering, or collapse of the Earth’s surface due to the removal or loss of subsurface materials, such as soil, groundwater, or mine.”
This simply means that when the subsurface materials, that is, the materials under the earth’s surface that help to hold the land firm and in place, are exploited, it results in the land sinking downwards.
Adding to this, Nitheshnirmal Sadhasivam, the co-author from Virginia Tech, U.S., explains, “Across all five megacities, groundwater dependence and overexploitation emerge as the dominant local drivers of subsidence.”
Sadhasivam elaborates, “As groundwater is withdrawn, the resulting loss of pore pressure in compressible aquifer layers causes gradual compaction, leading to measurable land surface sinking over time.”
As per a study titled Building Damage Risk in Sinking Indian Megacities, published in Nature, “Surface water supply and groundwater demand in India critically depend on monsoon precipitation for replenishment.
However, observed shifts in the monsoon dynamics, characterised by a delayed onset and earlier offset, coupled with variable precipitation intensities, have exerted considerable stress on aquifers in recent decades.”
These changing monsoon patterns, combined with extensive extraction of groundwater and no recharge, drive the land towards pressure, causing it to sink gradually. This study further highlights the crisis faced by Delhi. It reads, “The Capital currently has 2,264 buildings categorised as being at high risk from the ongoing land subsidence”.
Moreover, it emphasises that the capital experiences a 51 millimetre rate of subsidence every year. This means that there’s a serious threat that this sinking is causing to urban life. As the land beneath loses its support and starts to loosen, buildings too become vulnerable to cracks, tilts, and ultimately, the complete failure of structures.
Read More: Citizens Not Government Is Responsible For Pollution, Traffic And Garbage
Megacities That Are Affected
Delhi is among the fastest-sinking megacities in India. As highlighted by the study, Delhi has almost 1.7 million people prone to land subsidence, becoming the third largest area exposed to this problem at 196.27 km². The capital has subsidence rates of 28.5 mm, 20.7 mm, and 38.2 mm per year in Bijwasan, Ghaziabad, and Faridabad, respectively.
Additionally, the study reveals that 2,264, 110, and 32 buildings in Delhi, Mumbai, and Chennai, respectively, are vulnerable to land subsidence. The report analysed that in the next 30 years, approximately 3,169, 95,8, and 255 buildings in Delhi, Chennai, and Mumbai will be on the verge of acute damage.
Moreover, in the coming 50 years, about 11,457, 3,477, 112, 8,284, and 199 buildings in Delhi, Mumbai, Bengaluru, Chennai, and Kolkata, respectively, will be exposed to damage.
A Gradual Crisis
The problem of land subsidence is a slow, gradual crisis that the country is facing. Unlike any other calamity, like an earthquake, this sinking isn’t noticeable all at once, but it is slowly taking place. Such a crisis poses a threat not only to the buildings and monuments, but it will also lead to a weak subsurface.
This will also increase the effects of floods due to the lowering of the land, particularly in cities that lie in the coastal regions. This means that cities like Chennai and Mumbai are prone to adverse results if affected by floods.
Not only does this phenomenon amplify the effects of floods and earthquakes, but it also adds to the economic cost that the country will have to bear. Due to the failure of the infrastructure in the years to come, the government will have to bear a heavy maintenance cost.
What Comes Next
The first step towards overcoming a problem is addressing it. To tackle this crisis, proper infrastructural planning with adequate research and technology use is a must. A properly planned approach towards infrastructural development, keeping in mind the needs of each city, community, and other socioeconomic factors, is much needed.
Further, regular soil testing, implementation of InSAR (Satellite Radar Interferometry), and other advanced technologies will help overcome this threat. Ultimately, it is about how we manage our demands on nature, keeping in mind the sustainable growth of the people today, as well as tomorrow.
Images: Google Images
Sources: The Times of India, The Indian Express, Deccan Herald
Find the blogger: @shubhangichoudhary_29
This post is tagged under: land subsidence india, sinking indian cities, delhi sinking, mumbai land subsidence, groundwater depletion india, indian megacities risk, climate impact india, urban infrastructure failure, monsoon pattern changes, environmental crisis india, building damage india, groundwater overextraction
Disclaimer: We do not hold any right or copyright over any of the images used; these have been taken from Google. In case of credits or removal, the owner may kindly email us.
Other Recommendations:
Why Are ‘South’ Mumbai, Delhi, Kolkata Posher Than Its Other Parts?
