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In the last month, two incidents of land subsidence took place in Rajasthan, alarming both geologists and the general public. Both incidents took place in desert districts, raising suspicions of a possible connection between them.
On April 16, 2024, one and a half bigha of land collapsed around 3:30 am in Sahajrasar village of Lunkaransar tehsil of Bikaner district. At the time, a train full of passengers was passing by, narrowly escaping the sinking ground with the assistance of a tractor. The subsidence formed a pit about 70 feet deep, which, according to villagers, has since expanded to about 80-90 feet.
The second incident occurred on May 6, 2024, in Nagana village of Barmer district, where two parallel cracks appeared in the ground over an area of about one and a half kilometres. A geological team has submitted its preliminary report to the administration on these incidents occurring in the two districts of the Thar Desert.
However, the question remains: What are the reasons behind these geological phenomena in the desert areas?
The preliminary reports suggest that water is a common factor in both districts. Down to Earth (DTE) spoke with residents of Sahajrasar and Nagana and investigated the area’s history. Alongside the Geological Survey of India’s (GSI) claims, a different perspective emerged. Villagers are questioning the two main reasons for land subsidence cited in GSI’s preliminary report.
GSI attributed excessive groundwater exploitation and reduced rainfall as the primary reasons for the pit in Sahajrasar. DTE spoke with GSI officials who visited Bikaner and prepared the report, but they declined to comment officially, stating the preliminary report had been submitted to the administration. A detailed report is forthcoming, based on satellite imagery, water data, and other technical information.
Lunkaransar SDM Rajendra Singh told DTE:
Analysis of groundwater, rainfall and other relevant data along with geological field observations showed that the area is experiencing a high degree of groundwater depletion over the years. It may lead to drying up the water bearing aquifer rocks / sediments at the contact zone of the sub-surface hard rocks and aeolian deposits which may induce compaction of dried up pore spaces / voids, consequently reduction of volume of sub-surface strata and resultant loose sand bearing land subsidence
According to a groundwater status report by Bikaner district, the area primarily consists of light-textured, weakly structured sand and sandy loam soil. The preliminary GSI report also mentions reduced rainfall in the region. However, data from the state government’s water resources department’s annual monsoon report suggests an increase in average rainfall over the past 30 years.
Despite the increase in average rainfall, there is a water shortage in the area, indicating that rainwater is not penetrating the ground effectively. SDM Singh explained that the area’s groundwater is shallow, with only sand up to 150 metres underground. He also mentioned the excessive exploitation of groundwater highlighted in the GSI report.
However, residents of Sahajrasar dispute claims of groundwater exploitation and leakage.
Rameshwar, a social worker, stated that only four borewells are present in Sahajrasar, with only two functioning due to the salty water. He emphasised that water scarcity forces reliance on external sources for agriculture, which mostly occurs during the monsoon season.
The area’s only permanent pond remains due to historical deepening during famine relief efforts, indicating water recharge into the ground.
Former Sarpanch Natthilal Singhor also questioned the administration and GSI’s claims of excessive groundwater exploitation. Shyam Sundar Jyani, an environmental activist, noted the absence of flowing water in the area, even during rainfall, with water primarily absorbed into the sand.
The sinking land in Sahajrasar has historical precedence, with elders recounting a crater formed by a lightning strike many years ago. Over time, the pit filled, leaving a void that impacts the road’s construction and maintenance.
Omkarmal, aged 40, shared that the crater is over 50 years old, with surrounding sand dunes directing monsoon water into the ground through the pit. He noted continuous sinking since 2018-19, with recent incidents occurring over two days.
“Water seepage into the pit during the rainy season, forming whirlpools before groundwater absorption,” said Singhor.
DTE looked at old photos of the incident site from Google Earth. It came to light that since 2018, there has been a pothole on the side of the road that is gradually getting bigger. We extracted images of 2018, 2020, 2023 and May 2024 through Google Earth.
Google Earth screengrab from 2018 shows a a small pothole visible on the curve of the road.
Another screengrab from 2022 also shows a crater, slightly bigger compared to 4 years ago
2023 screengrab shows the crater has become much larger and the surrounding sand is also getting absorbed into it.
In Barmer, about 20 days after the Bikaner incident, two parallel cracks appeared in the ground 1.5 kilometres apart in Nagana village. The incident occurred between wells 6-7 of the Mangala Processing Terminal, which extracts crude oil. The width between the cracks is 6-7 metres.
According to Barmer GSI officer Bhakar Ram, preliminary investigations suggest water as the cause. He explained that abundant multani mitti (Fuller’s earth) in the soil dissolved floodwater in 2005, creating a cave-like space underground. Subsequent water shifts created a vacuum, resulting in the emergence of cracks as the soil burst due to decreasing groundwater levels. GSI is monitoring the situation, with plans for geophysical surveys if cracks escalate.
Local residents alleges groundwater overexploitation by Mangla, the crude oil company. Bhakar Ram stated that, while not highlighted in the preliminary report, investigations will consider this aspect if cracks worsen.