Lakshadweep atolls shaped and reshaped by natural phenomena, biological and human activity: IITGN study
The researchers, through fieldwork and analysis, found that more than 95 per cent of the lagoon sediments in Agatti and Kavaratti consist of biogenic material, composed mainly of coral, mollusc, and foraminiferal fragments, which are less than 2 mm in size. These sediments, known as biodetrital grainstone, reflect a system primarily driven by biological productivity rather than inorganic processes. Interestingly, unlike these atolls, the ones in the Maldives show a greater contribution from calcareous algae such as Halimeda, marking a distinct difference in sediment sources across the atolls.
The study, published in Marine Geology, further revealed how local hydrodynamics — waves, currents, and tides — interact with biological zones to shape the patterns of sediment transport and deposition. Lighter particles, like mollusc fragments, tend to travel farther, while finer materials settle in calmer parts of the lagoon. These patterns, combined with the lagoon's physical structure, create zones of sediment accumulation and erosion. The shallow lagoons of Agatti and Kavaratti, with depths averaging just 2 to 4 metres, are particularly sensitive to these processes.
'We observed that coral clasts were less abundant in areas influenced by dredging,' said Shradha Menon, a PhD student and first author of the study. 'This suggests that anthropogenic disturbances, such as dredging and pollution, are altering the sediment-producing ecosystem, potentially affecting the island's ability to sustain itself.'
Focusing on spatial patterns, sediment grain sizes, and dominant biological contributors, the study paints a detailed picture of how these islands are being shaped and reshaped by natural phenomena and biological as well as human activity.
'Our goal is to map spatial variability in sediment type produced by different organisms and how the natural forcings and anthropogenic activity influences the sediment production, accumulation, and their redistribution across the length and breadth of the atoll lagoons and islands,' said Prof Pankaj Khanna, Associate Professor in the department of Earth Sciences at IITGN and lead investigator of the study. 'This helps us understand not only how islands are built, but how stable they are over time.'
From corals, molluscs and algae to tiny shell-forming creatures like foraminifera, the ocean constantly produces and deposits calcium carbonate, the material that forms their skeletons and shells. As these organisms die, their remains accumulate and gradually break down into sand-sized particles. Over time, these sediments build up to create the very landmass of atoll islands like those in Lakshadweep. This continuous process of biological calcium carbonate production is referred to by geologists as a carbonate factory, a term that captures how marine life effectively drives the production of island-building material.
The study investigated the spatial variation in the functioning of these carbonate factories across different geomorphic zones within the lagoons, such as patch reefs, seagrass meadows, and reef flats. Each of these zones supports distinct biological communities and plays a different role in sediment production and accumulation. 'These zones not only influence the types of organisms that thrive there but also determine the nature and quantity of sediment that enters the lagoon system,' explained Shradha Menon, a PhD student and first author of the study.
By placing their findings within a broader regional context, the team compared Lakshadweep's sediment dynamics with those observed in other Indian Ocean atolls, particularly the Maldives. While the basic biological processes of carbonate sediment production are shared, local ecological and geomorphological differences lead to distinct patterns in sediment composition and distribution. 'Our work highlights the importance of understanding site-specific factors,' said Saikat Kumar Misra, a PhD student and co-author of the study. 'Even subtle variations in lagoon structure or water movement can significantly impact sediment production and transport.'
As sea-level rise, coral bleaching, and expanding coastal development continue to pressure these ecosystems, the study underscores the need for locally informed conservation strategies. Safeguarding sediment-producing habitats such as coral reefs, patch reefs, and seagrass meadows is essential not only for marine biodiversity but also for the long-term physical stability of the islands. Sustaining these natural processes will help ensure that Lakshadweep's islands remain resilient in the face of change.
Lakshadweep, India's only chain of coral atolls, is more than a stretch of tranquil beaches and turquoise waters. These low-lying islands are living geological records, built over millennia by the remnants of marine life. As climate change accelerates and sea levels continue to rise, it becomes increasingly important to understand what sustains these fragile landforms and how their natural balance may be shifting, Prof Khanna added.
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Indian Express
5 hours ago
- Indian Express
Study reveals how partial flood defences in Surat shifted risk toward vulnerable communities
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'By simulating floods under both 'no levee' and 'partial levee' conditions using a fully coupled 1D – 2D hydrodynamic model, we observed a sharp redistribution of risk,' stated Ashish S Kumar, the lead author of the study and a Ph D scholar in IITGN's Department of Civil Engineering. When the team analysed flood impacts across Surat's 284 neighbourhoods, they found that 134 areas experienced reduced flooding, while 119 saw deeper water. The maximum flood depth reduction reached an impressive 10.13 meters in protected areas, but some unprotected neighbourhoods faced increases of up to 2.38 meters. 'While core areas remained dry longer, downstream and peripheral wards, which are often less affluent and less protected, flooded earlier and more severely,' added Kumar, who is also the recipient of the central government's prestigious Prime Minister Research Fellowship. 'We observed that flooding was delayed by up to 12 hours in protected wards near the river, a valuable lead time for evacuation or emergency response,' said Dr Bhatia in a statement issued by IITGN. In contrast, the team noted that in some downstream regions, the onset of flooding happened up to seven hours earlier than in the baseline scenario. 'This temporal resolution in flood modelling is vital for preparedness planning. Delaying a flood by even a few hours can make the difference between controlled evacuation and disaster,' he added. To better understand the social impact, the IITGN team collaborated with Prof Rajarshi Majumder, a development economist from the University of Burdwan, and Prof Vivek Kapadia, a water policy expert who served as Secretary to the Government of Gujarat and Director of the Sardar Sarovar Narmada Nigam Limited between 2020 and 2023. Relying on Prof Majumdar's economics expertise, the researchers analysed how flood damage and exposure were distributed across neighbourhoods. They used the Gini index, a standard measure of inequality, where 0 means perfect equality and 1 indicates extreme disparity. The results were striking. The Gini index for flood damage rose from 0.55 to 0.66, and for population exposure, it rose from 0.31 to 0.39. More starkly, 91% of post-levee flood damage was concentrated in just 50% of the city's neighbourhoods, many of them poorer, with a higher proportion of marginal workers, a proxy for economic vulnerability. 'The data suggest that the residual flood risk disproportionately shifted toward communities that were already disadvantaged,' observed co-author Majumder. In Surat, as in many cities of the Global South, peripheral areas house informal settlements, agricultural workers, and artisanal communities with limited access to infrastructure or disaster support. 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Hindustan Times
12 hours ago
- Hindustan Times
Partial flood defence shifts risks toward vulnerable people in cities: IIT study
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Cities worldwide use partial embankment systems and levees against flooding, from Spain to India, the study stated while noting that these structures hold back water and shield urban cores but redirect waters to city edges and informal settlements. 'In many cities of the Global South, peripheral areas house informal settlements, agricultural workers, and artisanal communities with limited access to infrastructure or disaster support,' said Bhatia. The study uses Surat as a case study to generate what-if scenarios, a city on Gujarat's Tapi River that has suffered repeated floods, including a major one in 2006. The researchers used a hydrodynamic model built with river records, city data, and 49 years of Ukai Reservoir discharges to simulate a 100-year flood with and without partial levees. They combined this with land-use damage estimates updated to 2022 replacement costs and ward-level demographic data to assess how losses change. 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13 hours ago
- India.com
Meet India's youngest IITian, cracked IIT-JEE at 13, had no formal schooling till Class 8, his name is..., he is now...
Meet India's youngest IITian, cracked IIT-JEE at 13, had no formal schooling till Class 8, his name is..., he is now... IIT-JEE is one of the most competitive exams in India. Several students start preparing for the exam after their Class 10 examination. Their sole aim is to get admission into the prestigious IITs in the country. But what if we tell you that there is one boy who cracked the JEE exam at just 12 years old? It is not a myth or a fiction. Well, Satyam Kumar of Bakhorapur village in Bhojpur district in Bihar cracked the JEE examination and became the youngest IITian in the country. Who is India's youngest IITian? Where did he grow up, and what was his family background? In 2012, when children his age were learning primary mathematics in middle school, Satyam made history by achieving an All India Rank(AIR) of 8137 on his first attempt at the IIT-JEE. However, his ambitions were even bigger. In 2013, he sat for the exam again and topped the examination. He scored 292 marks out of 360 in the JEE Mains exam. He secured an AIR of 679 in JEE Advanced at the very young age of 13. Before him, the record was held by Sahal Kaushik, who achieved this milestone at the age of 14. However, it is reported that Satyam appeared for the JEE exam twice. What made his journey unique? Satyam was born on July 20 to Sidhnath Singh, a poor farmer. According to his LinkedIn profile, he took admission at the Indian Institute of Technology, Kanpur, where he pursued a BTech-MTech dual degree in Electrical Engineering. In 2019, he pursued a Doctor of Philosophy PhD, ECE at the University of Texas at Austin. What was Satyam Kumar's IIT JEE rank? After finishing his studies, Satyam worked as a research intern at Telecom Bretagne. Additionally, he worked as a teaching assistant at the Indian Institute of Technology, Kanpur. In October 2017, he worked as a research assistant at ETH Zurich. As per his LinkedIn profile, he worked as a machine learning intern at Apple in 2023, graduate research assistant at the University of Texas at Austin from 2019 to 2024. At present, he works as a machine learning systems research engineer. 'Research Interests: Deep Learning, Brain-Computer Interface, Speech Recognition, Time-Series Analysis, Human-Robot Interaction, Neuroengineering,' reads his LinkedIn bio. It is to be noted that Kumar appeared for the JEE exam twice. At first, his rank was 8137. Not satisfied with his result, he once again appeared for the exam, thus obtaining an AIR of 679. As per the PTI report (2013), Satyam's uncle, Pashupati Singh, a clerk at Veer Kuer Singh College, stated that Satyam had no formal schooling till Class 8th owing to the family's financial struggles and the lack of adequate educational resources at the local government school. Satyam started his academic journey in 2007, when he enrolled the Class 8. After passing the Rajasthan board, he took admission at Modern School in Kota. According to his uncle, Pashupati Singh, the principal of the school, R.K. Verma took full responsibility to pay for all of Satyam's educational and coaching fees in preparation for the IIT entrance exam, as per the report.
