Sciency Thoughts: Chiang Rai Province

Showing posts with label Chiang Rai Province. Show all posts

Friday, 29 June 2018

International rescue teams join efforts to rescue Thai teens from flooded cave system.

Rescuers from Britain and the United States have joined efforts to rescue a group of Thai teenagers from a cave system in Chiang Rai Province in northern Thailand. The group, comprising twelve members of a school football team, aged between eleven and sixteen, plus their coach, were trapped in the Tham Leung Cave System by rising floodwaters during a visit on Saturday 23 June 2018 and have not been contacted since, despite the best efforts of local rescue teams. These have now been joined by international cave rescue specialists, including cave divers from the UK, and a team of US military engineers who hope to lower floodwaters in the caves by drilling drainage holes.

A Thai rescue team carrying oxygen tanks in the Tham Leung Cave System in Chiang Rai Province earlier this week. Getty Images.

Most cave systems are the product of erosion, caused by water flowing through soft, porous, limestone systems and slowly eating away at the rock. This means that even cave systems which are not permanently flooded tend to be prone to flooding during wet weather, as is currently the case in Thailand, where, as in other parts of Southeast Asia, an exceptionally heavy Southwest Monsoon, caused by high temperatures over the Bay of Bengal, has lead to widespread flooding this year.

A member of a Thai military rescue team in the Tham Leung Cave System on Wednesday 27 June 2018. Soe Zeya Tun/Reuters.

Monsoons are tropical sea breezes triggered by heating of the land during the warmer part of the year (summer). Both the land and sea are warmed by the Sun, but the land has a lower ability to absorb heat, radiating it back so that the air above landmasses becomes significantly warmer than that over the sea, causing the air above the land to rise and drawing in water from over the sea; since this has also been warmed it carries a high evaporated water content, and brings with it heavy rainfall. In the tropical dry season the situation is reversed, as the air over the land cools more rapidly with the seasons, leading to warmer air over the sea, and thus breezes moving from the shore to the sea (where air is rising more rapidly) and a drying of the climate.

Diagrammatic representation of wind and rainfall patterns in a tropical monsoon climate. Geosciences/University of Arizona.

Much of Southeast Asia has two distinct Monsoon Seasons, with a Northeast Monsoon driven by winds from the South China Sea that lasts from November to February and a Southwest Monsoon driven by winds from the southern Indian Ocean from March to October. Such a double Monsoon Season is common close to the equator, where the Sun is highest overhead around the equinoxes and lowest on the horizons around the solstices, making the solstices the coolest part of the year and the equinoxes the hottest. However northern Thailand is largely protected from the Northeast Monsoon by the mountains separating the country from Myanmar.

The winds that drive the Northeast and Southwest Monsoons in Southeast Asia. Mynewshub.

Thursday, 26 February 2015

The diet of breeding Grass Owls in Thailand.

Grass Owls are members of the Barn Owl family, Tytonidae, distinguished by their habit of roosting and nesting in tall grasses or other ground-cover plants, rather than trees. Until fairly recently all Grass Owls were thought to belong to a single species, but there are now two species recognised, the African Grass Owl, Tyto capensis, which is found across much of Africa, and the Eastern Grass Owl, Tyto longimembris, which is found in south China, Nepal, India, Myanmar, Southeast Asia, Indonesia, the Philippines, New Guinea, New Caledonia and Australia. The Eastern Grass Owl was first discovered in Thailand as recently as 2006, where a small colony was found nesting in a small area of marsh grassland called Nong Lom in Mae Jan District in Chiang Rai Province in the north of the country.

In a paper published in the Raffles Bulletin of Zoology on 17 February 2015, Akalak Kunsorn of the Department of Biology at Chiang Mai University and the Environmental Ornithology Research Unit at Mahidol University, Siriwadee Chomdej of the Department of Biology and the Materials Science Research Center at Chiang Mai University, Narit Sitasuwan, Prasit Wangpakapattawong and Chatmongkon Suwannapoom, also of the Department of Biology at Chiang Mai University and Brett Sandercock of the Division of Biology at Kansas State University, describe the results of a study of the diet of the Grass Owls of Nom Long carried out by examining Owl pellets from the site during the breeding season.

Eastern Grass Owl, Tyto longimembris, in flight. Rob Hutchinson/The Owl Pages.

Birds lack teeth with which to process food like mammals, instead grinding it up in a muscular gizzard before it is passed to the stomach. As flying animals they are obliged to keep their weight to a minimum, and therefore need to dispose of inedible parts of their prey as quickly as possible, and so both Owls and Raptors regurgitate pellets comprising indigestible items such as fur and bone without passing them through the stomach and gut.

As well as Grass Owls the Nom Long site is also home to four species of Harriers; the Eastern Marsh Harrier, Circus spilonotus, the Pied Harrier, Circus melanoleucos, the Hen Harrier, Circus cyaneus and the Western Marsh Harrier, Circus aeruginosus. Grass Owl pellets tend to be larger and more elongate than Harrier pellets, but to avoid confusion Kunsorn et al. collected pellets only from the nests of Owls.

Kunsorn et al. carried out DNA tests on bones recovered from Owl pellets at Nom Long, in order to determine identify animals being consumed by the Owls. They were able to identify three species of Rodent by this method, the Black Rat, Rattus rattus, the Asian House Mouse, Mus musculus, and the Ricefield Mouse, Mus caroli. In addition wings and tails of Barn Swallows, Hirundo rustica, were also found in the Owl nests, suggesting that these Birds were also being consumed.

Pellets of the Eastern Grass Owl, Tyto longimembris, collected from nests at Nom Long. Kunsorn et al. (2015).

The diet of Eastern Grass Owls has previously been studied in southern Taiwan, where they were found to be consuming Lesser Rice-field Rats, Rattus losea, Ricefield Mice, Mus caroli, Formosan Blind Moles, Mogera insularis, House Shrews, Suncus murimus, Shrews Crocidura spp. and juvenile Formosan Hares, Lepus sinensis, as well as small Birds. This is a far larger range of prey than consumed at the Thai site, which Kunsorn et al. attribute to the more varied hunting grounds available to the Taiwan Owls. Nom Long is largely surrounded by grasslands and wetlands, with some Orange orchard about a kilometre away to the northwest, while the Taiwan site was within easy reach of shrubland, Rice paddies, Bamboo forest, Sugarcane fields, Mango orchards and Human settlements.

Monday, 5 May 2014

Magnitude 6.0 Earthquake in Chiang Rai Province, northern Thailand.

The United States Geological Survey recorded a Magnitude 6.0 Earthquake at a depth of 7.4 km in southern Chiang Rai Province in northern Thailand slightly before 6.10 pm local time (slightly before 11.10 am GMT) on Monday 5 May 2014. The quake was felt across much of northern Thailand and southern Myanmar, and there are reports of minor damage to buildings and roads in several areas, though no reports of any injuries.

Damage to a house following the 5 May 2014 Chiang Rai Province Earthquake. AP.

Northern Thailand is not greatly prone to Earthquakes, but does suffer the occasional event. It lies close to the margin between the Indian and Eurasian Plates, and suffers tectonic stresses due to the northward movement of the Indian Plate, which is driving into the Eurasian Plate at a rate of about 30 mm per year, causing uplift in the Himalayan Mountains, the Tibetan Plateaux, the mountains of Central Asia, and the bordering hills that separate Myanmar from India and China.

The approximate location of the 5 May 2014 Chiang Rai Earthquake. Google Maps.