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Time of India
04-08-2025
- Climate
- Time of India
‘Land sinking by 35mm/yr in Ahmedabad's Bopal'
Ahmedabad: What if the very ground you're walking on is slowly and silently giving way? A new satellite-based study has revealed that parts of Ahmedabad, particularly Bopal in the southwest and Vatva in the southeast, are experiencing gradual but steady land subsidence — a phenomenon where the Earth's surface sinks due to underground changes. The study focused on the period between 2020 and 2023, spanning approximately 3.5 years. Researchers say, "distinct pattern of average line-of-sight (LOS) land subsidence" in two primary zones: the southwest and southeast regions of the city. In the southwest, the average sinking rate ranged from -1.5 cm/year to -3 cm/year, while in the southeast, it ranged from -2.0 cm/year to -3.5 cm/year. Alarmingly, the study recorded a maximum subsidence of up to 35 mm/year (3.5 cm/year) in Bopal and Vatva during this period. You Can Also Check: Ahmedabad AQI | Weather in Ahmedabad | Bank Holidays in Ahmedabad | Public Holidays in Ahmedabad Titled 'Mapping land subsidence in Ahmedabad city, India', the study was conducted by researchers from Tata Consultancy Services' research and innovation team, in collaboration with the Dhirubhai Ambani Institute of Information and Communication Technology (DAIICT), Gandhinagar. Using satellite radar technology (InSAR), the team monitored ground movement and identified the worst-hit areas. The primary cause of the subsidence, the study found, is localised groundwater depletion. by Taboola by Taboola Sponsored Links Sponsored Links Promoted Links Promoted Links You May Like Global Indices Are on the Move — Time to Trade! IC Markets Learn More Undo By correlating Interferometric Synthetic Aperture Radar (InSAR) data with Central Ground Water Board (CGWB) records, the researchers observed a sharp decline in groundwater levels. In Bopal, levels dropped from around 11 metres in mid-2005 to less than 2 metres by 2019. In Vatva, they fell from approximately 42 metres in 2005 to about 28 metres in 2019. This is significant because, as the study explains, "when groundwater is excessively withdrawn, the resulting decrease in pore-fluid pressure increases stress on the soil structure". This added stress can compress the soil, leading to irreversible compaction of the aquifer and eventual land subsidence. In essence, as water is pumped out, the soil loses its support, causing the ground above to sink. The study utilised data from Sentinel-1, a radar imaging satellite mission operated by the European Space Agency (ESA) The research team included Ankur Pandit, Suryakant Sawant, Jayantrao Mohite and Srinivasu Pappula from TCS Research and Innovation, based in Indore, Pune, Thane West and Hyderabad respectively. Nishtha Ahuja represented DAIICT, Gandhinagar.
Time of India
30-07-2025
- Science
- Time of India
Explainer: How synthetic aperture radar (SAR), at the heart of Nisar, works
Unlike optical sensors, the synthetic aperture radar (SAR) at the heart of the Nisar mission expected to launch at 5.40pm today (July 30), doesn't rely on visible light. SAR uses microwaves, allowing satellites to 'see' through clouds and operate day or night. Tired of too many ads? go ad free now This capability makes SAR a powerful tool for monitoring everything from Antarctic ice to earthquakes and deforestation. From conventional radar to SAR Conventional radar systems send out microwave pulses that bounce off the Earth's surface. The radar then captures the returning echoes, measuring how long the signal took to return, its strength, and frequency shifts. These data reveal information about the object's distance, movement, and texture — but not with high visual clarity. SAR takes this concept further by adding movement and computation into the equation. As a satellite like Nisar orbits Earth, its radar antenna continues to emit and receive microwave pulses. Since the satellite is moving, each return signal comes from a slightly different angle. These slight differences create changes in the frequency of the returned signal — a phenomenon known as the Doppler shift, familiar from how a siren sounds different when approaching and then receding. Synthesising an antenna Ordinarily, to get a radar image with high resolution, one would need a physically enormous antenna — too big to launch or operate in space. For example, Nisar's L-band radar would need a 19-km-wide antenna to produce 10-metre resolution images using traditional radar techniques. Instead, SAR 'synthesises' a large antenna using the movement of a smaller one over time. Nisar's actual radar antenna spans 12 metres when deployed — about the length of a city bus — but through SAR processing, it achieves resolution comparable to that of a much larger antenna. Tired of too many ads? go ad free now In effect, SAR uses the satellite's forward motion to simulate a larger antenna. It stitches together multiple radar returns, aligning them through complex onboard data processing. The spacecraft's flight path becomes like a camera lens sweeping across a landscape, focusing the echoes into a sharp, high-resolution image. Visualising with SAR Once the raw SAR data are collected, they can be processed into different types of images for scientific analysis. ■ Interfero metry (InSAR): By comparing two SAR images of the same location taken at different times, scientists can produce an interferogram. These look like colourful contour maps and highlight subtle shifts in land elevation — crucial for monitoring earthquakes, landslides, and glacier movement. The closer the bands in the image, the greater the surface displacement. ■ Polarimetry : This involves analysing how radar waves are oriented when they return. For example, vertical structures like buildings often reflect waves in the same orientation they were sent, while complex, irregular surfaces like tree canopies alter that orientation. This helps researchers distinguish between different types of land cover and assess damage after floods or storms. Why SAR matters SAR's ability to observe surface change in any weather, at any time, makes it essential for studying Earth's dynamic systems. It supports disaster response, environmental monitoring, and climate science . For example, SAR can measure how much a glacier has retreated, track soil moisture changes during droughts, or detect whether land near a fault line has subtly shifted. As Charles Elachi, former director of Nasa's Jet Propulsion Laboratory, puts it: SAR 'allows us to refine things very accurately.' By capturing frequent and detailed images of the same locations, missions like Nisar can monitor change over time, turning raw radar echoes into critical knowledge about Earth's evolving surface.
India Today
27-07-2025
- Science
- India Today
Nisar: The billion-dollar radar that can see through clouds and darkness
When Nisar, a.k.a the Nasa-Isro Synthetic Aperture Radar, takes flight aboard India's GSLV Mk-II rocket from the Satish Dhawan Space Centre, Sriharikota, on July 30, 2025, it won't just be another Earth observation satellite in orbit, it will be a technological marvel, the likes of which the world has never seen satellite will be placed in a sun-synchronous polar orbit, 747 km above Earth, completing 14 orbits every just 97 minutes, Nisar will circle the planet once, and in 12 days, it will have mapped nearly every inch of Earth's landmass and ice sheets. For scientists, climate researchers, and disaster managers, this is a dream come true. The mission's open-source data will be freely available to researchers. (Photo: Isro) WHAT MAKES NISAR A GAME-CHANGER? At its heart, Nisar carries a world-first technology – a dual-frequency Synthetic Aperture Radar (SAR). Most radar imaging satellites work with a single frequency, but Nisar carries two powerful radar systems: L-band radar (24 cm wavelength) built by Nasa and S-band radar (12 cm wavelength) developed by unique combination allows Nisar to 'see' through clouds, thick forest canopies, smoke, and even in complete importantly, it can detect tiny changes in the Earth's surface, as small as a few millimeters. That means scientists can track how much a glacier has shifted, how much a fault line has moved after an earthquake, or even how much a city is sinking due to groundwater depletion. Nisar is set to become something more – a guardian that can sense Earth's heartbeat. (Photo: Nasa) Nisar achieves this precision through a special technique called Interferometric Synthetic Aperture Radar (InSAR). Think of it like taking two radar 'photos' of the same place a few days apart and comparing them to spot tiny sends out invisible radar waves to Earth's surface and listens for the waves that bounce back. By carefully analysing the timing (or 'phase') of these returning waves, InSAR can detect changes as small as a centimeter, like the ground shifting slightly after an earthquake or a glacier moving over creates detailed maps showing how Earth's surface is changing, helping scientists predict disasters or monitor climate shifts with incredible accuracy, no matter the weather or time of this data is made possible thanks to its massive 12-meter gold-plated deployable mesh antenna – the largest radar imaging antenna ever launched into space. For comparison, it's almost as wide as a badminton court when fully unfolded. WHY THE WORLD NEEDS NISAREarth's rapid changes are outpacing the capabilities of traditional satellites, which often lack the precision needed to capture critical details. Nisar bridges this gap with its high-resolution, all-weather, day-and-night imaging, delivering a near real-time view of our planet's dynamic will revolutionise our understanding by:advertisementTracking climate change: Observing polar ice loss, glacier shifts, and permafrost thawing with unprecedented management: Identifying subtle signs of land subsidence, landslide risks, and fault-line movements to predict earthquakes & water security: Forecasting crop yields, monitoring soil moisture, and mapping groundwater depletion to ensure resource & ecosystems: Measuring deforestation, forest biomass, and the carbon storage potential of vegetation to support conservation simple terms, Nisar will give us a near-real-time 'health check-up' of the Earth every few days. It has the largest radar imaging antenna ever launched into space. (Photo: Nasa) A BILLION-DOLLAR PARTNERSHIPNisar is one of the most expensive Earth observation missions ever undertaken, with a total cost estimated at $1.5 billion (Rs 12,500 crore).Nasa's contribution, covering the L-band radar, radar electronics, GPS receivers, and engineering support, is approximately $1.2 billion (Rs 10,000 crore).Isro's contribution, which includes the S-band radar, satellite bus, launch vehicle, and ground systems, is around Rs 788 crore (approximately $93 million).Despite the significant investment, the mission's open-source data will be freely available to researchers and governments worldwide, offering immense value for global scientific and climate research efforts. THE ROAD AHEADFor decades, satellites have been our eyes in the sky, but Nisar is set to become something more – a guardian that can sense Earth's tracking movements invisible to the naked eye, it promises to help humanity understand natural hazards, prepare for disasters, and fight climate it finally unfurls its giant golden antenna in orbit, Nisar will mark not just a triumph of space technology but also a symbol of international cooperation for the planet's future.(This is an authored article by Manish Purohit. Manish is a solar energy and spacecraft solar panel expert with extensive experience in managing critical space missions, including Chandrayaan-2 and Mangalyaan)- EndsMust Watch
Associated Press
12-06-2025
- Business
- Associated Press
Advancements and prospect of safety monitoring, inspection and assessment technologies for oil and gas pipeline networks
GA, UNITED STATES, June 12, 2025 / / -- A comprehensive review highlights cutting-edge advancements in inspection, environmental monitoring, and safety assessment technologies for oil and gas pipelines. These innovations address growing challenges posed by aging infrastructure, geohazards, and complex operational demands, paving the way for smarter, safer energy networks. As global energy demands rise and pipeline networks expand, ensuring the safety and reliability of oil and gas infrastructure has become a priority. A new review(doi: ) published by Chen Pengchao from the PipeChina Institute of Science and Technology outlines the current developments of pipeline safety technologies around the world, offering suggestions to future development of defect detection, environmental risks monitoring, and structural integrity assessment with unprecedented precision. 'The integration of high-grade steel, large-diameter pipelines, and unconventional energy sources has introduced new complexities to pipeline safety,' explains Chen. 'The research focuses on bridging technological gaps in inspection, monitoring, and fitness-for-service (FFS) assessments to mitigate risks and prevent catastrophic failures.' Chen highlights significant progress in both in-line and external inspection methods. Advanced in-line tools such as magnetic flux leakage (MFL) and ultrasonic testing devices in Germany, America and China now detect micro-defects in millimeter-scale in high-grade steel pipelines. 'PipeChina's magnetoelectric integrated inspection tool combines ultra-high-resolution sensors to identify weld defects with 90% accuracy for 0.3 mm defects, shares Chen. 'It's a milestone for China's domestically developed technologies.' Meanwhile, pipeline leaks and geohazards like landslides pose severe threats to infrastructure and ecosystems. 'Real-time data fusion algorithms, integrated with supervisory control systems, allow China to achieve leak detection sensitivity as low as 1% of flow rate, minimizing false alarms,' says Chen. The review also emphasizes innovations in distributed fiber-optic sensing (DFOS). For geohazard management, advanced tools like satellite-based interferometric synthetic aperture radar (InSAR) and unmanned aerial vehicles (UAVs) provide early warnings of ground displacement near pipelines. 'Combining space-air-ground monitoring with AI-driven risk models allows us to predict geologic hazards and prioritize interventions,' says Chen. 'The future lies in transforming conventional pipelines into intelligent networks by leveraging AI and emerging sensing technologies.' DOI 10.1016/ Original Source URL Lucy Wang BioDesign Research email us here Legal Disclaimer: EIN Presswire provides this news content 'as is' without warranty of any kind. We do not accept any responsibility or liability for the accuracy, content, images, videos, licenses, completeness, legality, or reliability of the information contained in this article. If you have any complaints or copyright issues related to this article, kindly contact the author above.
Scientific American
08-05-2025
- Science
- Scientific American
The 28 Most Populous Cities in the U.S. Are All Sinking
All 28 of the most populous cities in the U.S. are sinking, worsening risks of flooding and damage to urban infrastructure, a new study finds. One of the main culprits is the extraction of groundwater to quench the thirst of growing populations and commerce. The research, published Thursday in Nature Cities, shows this subsidence is 'ubiquitous—people should be looking everywhere' for it, says Cornell University geophysicist Matt Pritchard, who was not involved with the study. People have long known that certain cities around the world are sinking, particularly coastal ones. In the U.S., New Orleans has been perhaps the most famous example. This subsidence can have both natural and humanmade causes, such as ground that continues to respond to the retreat of the ice sheets, dams that prevent sediment from replenishing river deltas and buildings that weigh a city down. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. A few detailed studies have been conducted on some particular cities, such as Miami, but otherwise data have come from sparse, on-the-ground measurements that don't reveal the nuance needed to properly gauge risks to infrastructure. To get granular data, the researchers behind the new study turned to interferometric synthetic aperture radar (InSAR) measurements taken from satellites. Study co-author Leonard Ohenhen, a postdoctoral researcher at Columbia University's Lamont-Doherty Earth Observatory, explains that InSAR is akin to bouncing a ball at a steady rate against a wall. If the wall moves away from you, the ball takes longer to bounce back. If the wall moves closer, the ball returns more quickly. Similarly, in the new research, the pulses sent out by the InSAR device were able to detect upward and downward deformations of Earth's surface down to the millimeter scale in grids made up of 28-meter squares. The team found that in all 28 cities examined in the study—which each have populations of more than 600,000—at least 20 percent of their area was sinking. In 25 of them, at least 65 percent was subsiding. Nine cities—New York City, Chicago, Houston, Dallas, Fort Worth, Columbus, Seattle, Denver and Detroit—had an area-weighted average rate of subsidence of more than two millimeters per year. Houston, Fort Worth and Dallas had the highest rates of any of the cities, with an average of more than 4 mm per year. In fact, more than 42 percent of Houston is sinking faster than 5 mm per year, and 12 percent is sinking by more than 10 mm per year. Those numbers may sound small, but measurements began around 2015, meaning 'it's been 10 years at that rate—and that starts to add up,' Pritchard says. Also, damage can occur even with small displacements. 'The value here is in detecting things before they get worse or at smaller more subtle scales,' he adds. This is particularly true when there are different rates of sinking across a city, or even areas where some ground is sinking and some is rising. The study showed how ground deformation varied across the cities—for example, the area around LaGuardia Airport is sinking much faster than most of the rest of New York City. These different rates can cause buildings to tilt and can lead to other infrastructure damage. 'We have buildings that collapse from this type of ground deformation,' Pritchard says, citing conditions that might have played a role in the 2021 collapse of a condominium in the Miami suburb of Surfside, Fla. Of the 5.6 million buildings in the cities examined in the study, about 29,000 are in areas of concern. That doesn't mean those buildings will necessarily be damaged; factors such as soil type, construction methods and building age can come into play. But it does show where a more detailed analysis should be done, Pritchard and Ohenhen say. Another subsidence-related concern is flooding. When you have areas of sinking in a city, it can create a 'subsidence bowl,' Ohenhen says. 'Where the land was flat, [water] could easily flow from one place to the other,' but now it gets trapped in that bowl instead. The reasons for the subsidence vary from city to city, and even within a city, but the team found that 80 percent of the sinking was associated with groundwater extraction. That points to the need to balance demand for water with maintaining aquifers to avoid collapse. Cities in drought-prone regions, such as Texas, should be particularly concerned because when drought sets in, 'you a have a really, really high probability' of further subsidence as aquifers become more depleted, Ohenhen says. Pritchard says the study shows that subsidence is a problem outside of previous poster cities such as New Orleans—and that 'we really we should be looking at this everywhere, not even just in large cities.'
