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Korea Herald
24-06-2025
- Climate
- Korea Herald
Forests, parks and ponds can help cool Kathmandu by up to 1.6 degrees Celsius, study finds
KATHMANDU, Nepal (Kathmandu Post/ANN) -- Urban forests, parks and ponds could reduce temperatures in the Kathmandu valley by as much as 1.6 degrees Celsius if they are strategically managed, according to a new study published in the journal Urban Climate. This is the first study to examine how different types of blue-green infrastructure contribute to cooling effects across the Valley's urban areas. An international team from seven institutions used satellite-based data and machine learning algorithms to analyze 301 parks, 130 forest patches, and 26 ponds within densely populated parts of the Valley. The study finds that temperatures rise notably as one moves away from blue-green spaces such as forests, parks and ponds. For instance, the Swoyambhu forest recorded a temperature of 31.9 degrees Celsius, compared to 36.0 degrees in adjacent built-up areas -- a difference of 4.1 degrees Celsius. UN Park remained at 34.3 degrees Celsius while nearby areas climbed to 38.2 degrees, showing a 3.9-degree difference. A traditional pond, Na Pukhu in Bhaktapur, registered 39.6 degrees Celsius, while the surrounding urban zone hit 42.5 degrees. These figures -- captured from satellite data over five summers -- represent the highest recorded cooling impacts, demonstrating the crucial role these natural features play during peak heat periods. Although the temperature estimates need to be confirmed with on-ground measurements, relative differences point to clear patterns of urban heat mitigation. At Ranipokhari, for example, the central water body measured 37.1 degrees Celsius, while the surrounding streets were at 39.8 degrees, hotter by 2.7 degrees. The study found that the cooling effect of ponds generally extends up to 150 meters from the edge, with the most noticeable impact within the first 100 meters. In Bhaktapur, Siddha Pokhari recorded a temperature of 36.0 degrees Celsius, compared to 38.5 degrees in nearby urban areas. Pimbahal pond in Lalitpur showed a cooling effect of 2.1 degrees, with its surroundings at 40.4 degrees, while the pond stayed at 38.3 degrees. The effect extended up to 300 meters from the water's edge. On average, urban forests delivered the strongest cooling, reducing temperatures by up to 1.2 degrees Celsius. Parks followed with a cooling impact of 0.9 degrees, while ponds lowered temperatures by up to 0.85 degrees. However, the cooling capacity depends heavily on the surrounding landscape. In vegetation-dominated areas, blue-green spaces can reduce heat by as much as 1.6 degrees Celsius. However, in densely built zones, the cooling effect falls between 0.3 and 0.6 degrees. Lead researcher Saurav Bhattarai, a PhD candidate at the Jackson State University, Mississippi and an ORISE (Oak Ridge Institute for Science and Education) fellow, said the findings show that simply adding green spaces is insufficient. "Cooling strategies must be adapted to the local context. Green spaces need to be well integrated into the urban fabric to be effective," he said. The study comes amid a steady warming of Kathmandu. Since 1976, average temperatures in the Valley have risen by 0.38 degrees Celsius decade on decade. Today, core city areas are typically 2–3 degrees hotter than surrounding regions. Adding to the concern, the researchers found that soil moisture levels across the Valley have declined by an average of 2.1 percent in the past 10 years. In some central areas, the reduction has been as high as 35 percent. Dr. Rocky Talchabhadel of Jackson State University stressed the urgency of urban climate planning. "Our study shows that Kathmandu's densely built areas are especially vulnerable to extreme heat. Without immediate intervention, these heat islands will grow," he said. Urban forests showed the strongest correlation between size and cooling impact: when forest area doubles, the cooling effect increases by roughly 30 percent. Parks, on the other hand, showed that cooling effectiveness depends more on internal design than size. Tree canopy coverage was the single most important factor. In small parks, a 1 percent increase in high canopy coverage led to almost a 1-degree increase in cooling. In large parks, the same increase brought a 1.76-degree drop in temperature. "This isn't just about planting more trees," said Professor Vishnu Prasad Pandey at the Tribhuvan University Institute of Engineering. "The ratio of tree canopy, grass and paved areas within a park influences cooling more than size alone. Well-designed parks can be powerful tools against heat, even in space-constrained cities." The study offers tailored recommendations for different urban contexts. In transitional areas -- those between urban cores and vegetation-dominated zones -- the focus should be on expanding forest patches and designing parks with large, continuous tree canopies for maximum shade. In greener zones, protecting existing forests and establishing buffer areas can help prevent the future emergence of heat islands. Dr. Prajal Pradhan of the University of Groningen, Netherlands, said the methodology and results have global implications. "Cities around the world can learn from our Kathmandu-based study. We offer a practical framework that can be replicated to evaluate and improve urban climate resilience anywhere," he said. Dr. Nawa Raj Pradhan from the US Army Engineer Research and Development Centre warned that the health impacts of unchecked urban warming could be severe. "If no action is taken, rising temperatures will strain public health systems, drive up electricity demand for cooling, and disproportionately impact the most vulnerable communities," he said. The study estimates that integrated cooling strategies could reduce energy demand for cooling by 15–25 percent in urban areas, potentially saving significant electricity costs while improving public health outcomes. The researchers encouraged residents to get involved in heat tracking and climate adaptation. Comparing temperatures in city parks and nearby roads during mornings and evenings using simple thermometers can help people understand local heat patterns. The team recommends avoiding outdoor activities between 12 p.m. and 3 p.m., choosing shaded or tree-lined routes, and recognizing symptoms of heat stress such as excessive sweating, dizziness and fatigue. Practical personal strategies include wearing light-colored, breathable clothing, carrying water, and using hats or umbrellas for shade. Residents are also urged to join municipal tree-planting campaigns focusing on native species such as peepal, banyan, and nim, participate in pond-cleaning drives, and report illegal pond filling to authorities. koreadherald@
Time of India
19-06-2025
- General
- Time of India
Study warns loss of water bodies in Chennai significantly increases flood risk
Chennai: Ten years ago, a relentless downpour of 50 cm of rainfall in Chennai on December 1, 2015, followed by the release of water from the Chembarambakkam reservoir, flooded most areas and brought the city to a standstill. Tired of too many ads? go ad free now A new study now warns that if the city loses its existing upstream water bodies, which currently have a capacity of 174.7 million cubic metres, to future urbanisation, flood damages could increase by 44%, deaths by 60%, and risk to the population by 40.5% if a 2015-like flood repeats. Researchers said the 2015 flood could have caused less damage if the city retained its traditional tanks, man-made water bodies designed to store rainwater. The study found flood losses could have dropped by 17% and fatalities by 12% if the lost urban tanks were still functional, with flood levels dropping by up to 0.8 m in areas like T Nagar, Ashok Nagar, Virugambakkam, and Saidapet. The population at risk would have decreased by 25.3% compared to the 2015 flood. Since the early 1900s, urbanisation has led to the loss of 13.6 million cubic metres of tank storage within the city. The remaining 174.7 million cubic metres of tank storage outside the city are also at risk. Though the urban tanks held a smaller volume than the upstream ones, their proximity to densely populated areas meant they could have intercepted rainwater before it flooded streets and homes. "The 2015 flood was primarily due to excessive rainfall. The water release from Chembarambakkam reservoir played some role, but it was only 25% of the total flow from upstream," said researcher Abinesh Ganapathy. Tired of too many ads? go ad free now "The water bodies provide extra cushion to store water and reduce inflow into the Adyar River. The lakes that disappeared should have provided even more storage and moderated the flood in the city." Researchers simulated three scenarios: the actual 2015 flood (baseline), a version where lost urban tanks still existed (with tanks), and one where even upstream tanks are lost (no tanks). Compared to the 2015 scenario, if the traditional tanks were present, flooding in the lower flood hazard zones in parts of Vadapalani, Mylapore, Alwarpet, Adyar, Ashok Nagar, Ekkattuthangal, and Guindy could have dropped by 23% to 37%. When encroached tank areas are included, this reduction rose to over 60% in parts of Vadapalani, Mylapore, and Alwarpet. In contrast, if upstream tanks are also lost, flooding in the high-risk flood zones like parts of Koyambedu, Adyar, Porur, T Nagar, Nandanam, St Thomas Mount, parts of Mylapore, RA Puram, and Nungambakkam would expand by 45% to 54%. About 80,000 people and 15,000 buildings were spared from flooding in the 'with tanks' scenario, while over 1.7 lakh people and 30,000 buildings were newly affected in the 'no tanks' scenario. The study, conducted by institutions including GFZ Potsdam, IIT Roorkee, and IIT Madras, was published in Urban Climate. An earlier study led by corresponding author Nithila Devi Nallasamy projected that urban areas in the Adyar Basin will expand from 20% to 46% by 2050, putting the upstream tanks at high risk. Nivedita Sairam, a researcher from GFZ Potsdam, said, "The study shows that in addition to flood defences, we need to give room for the river and controlled urban development. Protecting water bodies plays a role in controlling weather extremes." The study supports using nature-based solutions for flood control in cities like Chennai, which face both flood risks and water scarcity. T Kanthimathinathan, coordinator, Tamil Nadu State Disaster Management Authority, said the only way to reduce flooding in the city is for urban planners to ensure the clearing and protection of the flow paths of existing water bodies to downstream systems from the impact of urbanisation. He said that between 1975 and 2008, many water bodies were lost to city expansion, including those in Nungambakkam, Mambalam, and Mogappair. Only 49, now significantly shrunk, remained. "We must give room for the water to flow," he said. "The water bodies in the upstream may shrink in size, but not disappear. The Thiruppugazh committee recommended restoration of these upstream water bodies to their original condition. If possible, they can be deepened to increase holding capacity, without affecting groundwater or the environment," he added.
Yahoo
31-03-2025
- Health
- Yahoo
Researchers make shocking discovery about health factors for pregnant women and babies: 'Little attention has been given'
New research suggests that pollution and extreme temperatures could be making pregnancy even more challenging, according to the Hindustan Times. A study published in Urban Climate linked these environmental effects to longer pregnancies, which carry risks for women and babies. Researchers from Curtin University in Australia created the first study exploring the relationship between environmental stressors and prolonged pregnancy. To clarify, this study defines prolonged pregnancy as one lasting more than 41 weeks. "We know that being 'born too soon' — preterm birth — has well-documented health risks, but little attention has been given to the risks associated with being 'born too late,'" lead author Dr. Sylvester Dodzi Nyadanu said. To determine how environmental changes influenced pregnancy length, the researchers looked at data from 393,384 births. They determined that high exposure to air pollution was associated with prolonged pregnancy. Another contributor was biothermal stress, which measures temperature, humidity, and wind. Similar to pre-term pregnancy, prolonged pregnancy can be risky for women and their babies. It's associated with larger babies that can be difficult to birth, stillbirth, and injury to the birth canal, according to UpToDate. The Curtin University study suggests that air pollution and extreme weather may make pregnancies longer by disrupting natural labor triggers. Environmental stressors can influence maternal stress levels, hormones, and endocrine and inflammatory responses, all of which play a role in pregnancy and labor. As the planet continues to heat up, its side effects could lead to more pregnancy complications. Several initiatives are addressing the impact of pollution-related stressors on human health. One policy from the Pan American Health Organization focuses on vulnerable groups, like pregnant women and the elderly. It aims to reduce pollution created by healthcare facilities and processes and increase healthcare industry financing to support climate-friendly policies. Grassroots efforts are also working to improve access to more affordable energy. For example, Native Renewables is making it easier for Native American families to access off-grid solar power. And some cities are offering free public transport to encourage travelers to cut down on vehicle pollution. To reduce your personal impact on the environment and make the planet healthier for all, there are many small and larger actions you can take. For example, consider walking or biking around town when possible to reduce vehicle pollution; limit energy use at home by switching to LED lightbulbs, adding energy-efficient window coverings, and lowering your water heater temperature; and support anti-pollution action and policies in your town and state. Do you worry about air pollution in and around your home? Yes — always Yes — often Yes — sometimes No — never Click your choice to see results and speak your mind. Join our free newsletter for weekly updates on the latest innovations improving our lives and shaping our future, and don't miss this cool list of easy ways to help yourself while helping the planet.
