Sunday 18 August 2013

Over a million rail passengers trapped by landslides in China.

Over a million rail passengers were still trapped at Guangzhou Railway Station by a series of landslides in China in the wake of Typhoon Utor on Saturday 17 August 2013. The station serves as a major hub for railways in south China, but has been cut off from Beijing and the north of the country by a series of landslides in the mountainous north of Guangdong Province. Passengers trying to get to Guangzhou are now being diverted to Shenzhen and placed in temporary accommodation while authorities try to clear some of the backlog of passengers at Guangzhou, and sales of tickets via the station have been suspended. Many people have been stranded for over 24 hours, and while trains are now reportedly getting through to Beijing, they are traveling at much reduced speeds due to ongoing work on railway lines, and it is feared that around 80 000 will not be able to begin their journey today (Sunday 18 August).

Passengers queuing for refunds in the ticket hall at Guangzhou Railway Station on Saturday 17 August 2013. Nandu.

One train was hit by a landslide between Lechang and Chenzhou in the north of Guangdong Province, smashing windows and requiring four passenger to be taken to hospital for treatment. Sections of the line between Pingshi and Lechang are said to have been flooded, as well as being hit by multiple landslides. 

Typhoon Utor hit south China on Wednesday 14 August, brining with it torrential rains and flooding. The low pressure above tropical storms causes water to rise there by ~1 cm for every millibar drop in pressure, leading to a storm surge that can overwhelm low-lying coastal areas, while at the same time the heat leads to high levels of evaporation from the sea - and subsequently high levels of rainfall. This can cause additional flooding on land, as well as landslides, which are are a common problem after severe weather events, as excess pore water pressure can overcome cohesion in soil and sediments, allowing them to flow like liquids. Approximately 90% of all landslides are caused by heavy rainfall.

The approximate location of the Guangzhou Railway Station. Google Maps.

Tropical storms are caused by solar energy heating the air above the oceans, which causes the air to rise leading to an inrush of air. If this happens over a large enough area the inrushing air will start to circulate, as the rotation of the Earth causes the winds closer to the equator to move eastwards compared to those further away (the Coriolis Effect). This leads to tropical storms rotating clockwise in the southern hemisphere and anticlockwise in the northern hemisphere.These storms tend to grow in strength as they move across the ocean and lose it as they pass over land (this is not completely true: many tropical storms peter out without reaching land due to wider atmospheric patterns), since the land tends to absorb solar energy while the sea reflects it.

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