Zhouqu County Mudslides

On the 8th August 2010, a mudslide occured in Zhouqu county, in southern Gansu province (Gannan Tibetan Autonomous Prefecture) in the PRC. The mudslide was 5km long and 300m wide, and up to 5m thick in places.

Causes

The mudslide was caused by a variety of factors, human and physical.

Forests around Zhouqu had been cut down for mining and agriculture which lead to soil erosion and destabilisation of the slopes, as roots were no longer holding the soil together and trees could no longer absorb water from the soil, leading to faster soil water saturation.  Despite the logging ban in 1998, trees continued to be felled. In the PRC, there had been 53 hydroelectric construction projects in recent years, with 12 just within Gansu province, where Zhouqu county is located. The dams have caused 750,000 tonnes of water and soil erosion and over 3 million cubic tonnes of bulldozed material, throughout the country. This has left the slopes weak and exposed to rainfall, allowing slides to occur more readily.

Oscillations between the patterns of El Nino and La Nina (climatic events where air currents across the Pacific Ocean change, effecting the local weather systems among dozens of countries) caused unusually intense monsoon rains in 2010.  Regions were receiving an extra 24 mm of rain above the normal daily rainfall. In ‘the largest downpour for a century’ 96 mm of rain fell in just one hour in the area.  The earthquake in Sichuan two years previously created cracks in the rock face and destabilised the ground; Zhouqu county is very close to Sichaun province, so instabilities within Sichaun can very easily effect towns within Gansu, directly to the North. The 9-month drought which preceded the heavy rain had added to the weakness and instability of the soil, especially when followed by the heavy rainfall.

Impacts

Social Impacts:

  • 1,471 people died due to the slide.
  • 1,200 people had to be rescued from the debris.
  • 300 people were never found, and are presumed dead.
  • 1,700 people who were evacuated from the immediate area were forced to live in schools. In total 45,000 people in Zhouqu county were evacuated.
  • Medical care in the region was disrupted as 10 doctors from the Zhouqu People’s Hospital were among the missing.

Economic Impacts:

  • 66% of the county went without power, disrupting local businesses and transport.
  • More than $40 billion worth of damage was caused in Gansu.
  • Power lines were down in 2/3 of the county which had to be repaired. Wider infrastructure was destroyed at great cost.
  • Mudslides throughout China in 2010 destroyed 8.76 million hectares of crops to be destroyed.
  •  The livelihoods of millions of people were entirely destroyed or otherwise decimated and China’s capacity to export was massively reduced.

Environmental Impacts:

  • 300 buildings were buried under mud.
  • A 3km temporary lake formed behind a blockage when the mudslide reached the local river at the base of the city of Zhouqu where the slide occured. This dam later burst causing further damage.
  • The river was clogged with debris, damaging habitats and reducing biodiversity.

Management 

  • 7,000 soldiers, firefighters and medical staff were deployed by the government. 20 speed boats and 4 helicopters were also mobilised.
  • Gansu province received 120 million yuan ($17.7 million) by August 13th 2010.
  • The PRC government promised local families $1,182 worth of financial aid for each victim lost.
  • Tents, food and medical supplies were rushed to the stricken area but the remote mountainous location made access difficult.
  • The governmentpromised to help rebuild homes and buildings in the affected area.
  • A National Day of mourning was observed to help with the emotional trauma.
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Sri Lanka Mudslides, 2016

Image result for sri lanka mudslide 2016

Mudslides hit Sri Lanka in May this year. Mudslides hit three villages in central Kegalle district. The landslide started near the town of Aranayake on the 17th May, 2016, but events leading up to it should have made the outcome predictable from the 15th onward.

Many cities were flooded with more than 100mm of rain on the 15th of May. International airports had to be closed just from the weather, and 35 families had been displaced. Airports would remain closed over the next few days.

Causes

3 days of torrential rain destabilised slope areas, in the heaviest rainfall in 25 years. The rain started on the 14th May.

Before the extreme weather, Sri Lanka had been experiencing a drought, and power cuts as hydroelectric power stations could not function. A rare benefit of the extreme weather which triggered the event was that the dams filled up to 75% capacity, allowing a supply of electricity to rescue workers to help them work effectively.

The main landslide area was very sparsely populated by only a few minor villages. No major work had been undergone on the slopes, as evidenced by footage of the event. Instead it was caused by a sudden huge increase in slope water content combined with susceptible rock type.

Impacts

On the 18th, 134 people remained unaccounted for, and 14 bodies had been recovered, with 37 deaths total. 350,000 people were displaced. 92 deaths have now been confirmed. 220 famlies were reported missing according to the Sri Lankan Red Cross. As of May 25th, the death toll was deemed to be 101 with 100 missing people.

The slide crashed into 3 separate villages; Elangapitiya, Pallebage and Siripura, all of which were obliterated.

60 houses were buried in dirt.

The mud level was up to 30ft deep in some areas.

Many sectors of infrastructure were effected, such as planes. Many major roads were entirely flooded, including the Southern Expressway. There were heavy power failures in some towns. The government warned members of industries such as fishing to not go to work until the situation was sorted- this was of course an attempt to save lives, but there was an economic impact because of this upon fishermen.

Response

The Meteorology Department of the government issued a severe weather warning on the 14th, for 12 hours. 100mm of rainfall was expected, with wind speeds of up to 80kmh in exposed areas.

One of the initial responses to the initial weather, was closing down air traffic.  Closed airports included: Bandaranaike International Airport (flights diverted to Cochin International Airport or Mattala Rajapaksa International Airport), and Ratmalana Airport. The Sri Lanka Airforce had to be called in to rescue stranded fishermen. The Navy had to save 200 people trapped in floods on the 17th, and the mud slides started, killing 21 in just one slide. The Airforce continued rescue work throughout using military grade helicopters. 81 Navy flood relief teams were dispatched.

Rescue teams were sent out to the area specifically, so that 156 people had been rescued by the 18th May, along with 1,550 people already sheltered in seven different evacuation sites. Soldiers were active in rescue efforts for weeks afterwards. Military spokesman Brigadier Jayanath Jayaweera said that the situation was being constantly assesed and that more troops would be deployed as needed, but that he doubted they would find many survivors.

More than 185,000 people who lost their homes were housed in temporary emergency shelters. The rain hindered the effectiveness of rescue efforts, in addition to causing the initial event. Many roads were underwater, and impassible, and national parks were completely closed off, and rescuers struggled to bring in their equipment. The Ceylon Electricity Board imposed emergency power cuts as a precautionary measure. In one night, the Army and Navy evacuated 26,000 people from Colombo (the capital). 1,500 armed personal were rallied,  including 71 officers.

All schools were closed on the 20th.

International efforts from other countries included:

  • Australia contributing $500,000 to UNICEF for humanitarian assistance
  • India pledging to provide assistance, and then bringing in Navy ships full of supplies.
  • Japan sent planes carrying emergency items, such as generators, blankets, and water purifiers.
  • Nepal offered $100,000
  • Pakistan gave a 30-bed field hospital
  • Singapore Red Cross donated $150,000 in relief items
  • United Nations- in collaboration with other NGOs- offered people to help administer aid
  • USofA provided $50,000 in immediate aid and a further $1 million in providing water for populations vulnerable to floods.

(Image Source: http://www.bbc.co.uk/news/world-asia-36328863)