Sciency Thoughts: Sindhupalchowk District

Showing posts with label Sindhupalchowk District. Show all posts

Thursday, 16 July 2020

Landslide kills at least two in Sindhupalchok District, Nepal.

Two people have died and another three are missing following a landslide in the Sindhupalchok District of Nepal on Wednesday 15 July 2020. Landslides are a common problem in rural Nepal at this time of year, associated with the annual monsoon season. Landslides 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. All of the casualties are reported to be members of the same family, with the dead identified as Nimasyangbo Sherpa, 34, and Anji Sherpa, 16, while those missing are Somsang Sherpa, 84, Chhiring Sherpa, 12, and an as yet unidentified woman of 42. A further six households were forced to evacuate their homes following the incident, with another eighteen warned that they may need to evacuate if the area cannot be stabilised.

The site of the 15 July 2020 Sindhupalchok landslide. eAdarsha.

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. This situation is particularly intense in South Asia, due to the presence of the Himalayas. High mountain ranges tend to force winds hitting them upwards, which amplifies the South Asian Summer Monsoon, with higher winds leading to more upward air movement, thus drawing in further air from the sea.

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

Monday, 25 August 2014

At least eight dead after two landslides in Nepal.

Eight people are known to have died and at least three more are missing after two landslides in Nepal on Monday 25 August 2014. The first incident happened at Baramchi in Sindhupalchowk District, where three houses were destroyed and five people are known to have died. These have been named as Ganesh Kumari Thapa, Nir Bahadur Thapa, Dambar Bahadur Thapa and Bhagawat Thapa, who all perished at the scene of the event, and Chandrawati Thapa, who died later while being treated at Jalbire Hospital. Two further people are still missing following this event. The second landslide occurred at Pokhara on Lake Phewa, where three people died and a further one is missing after a landslide struck a restaurant popular with tourists. All four are described as staff at the restaurant.

The aftermath of the 25 August 2014 Pokhara landslide. Setopati.

The landslides have been linked to heavy rains associated with the Nepali monsoon, which lasts from June till September, with the heaviest rainfall usually occurring in July when many areas typically experience over 400 mm of rain; the Pokhara area is particularly wet, typically receiving over 800 mm of rainfall in July and over 600 in August. Landslides 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, and Nepal frequently suffers many landslip-related fatalities during the monsoon season.

The approximate locations of the two 25 August 2014 Nepal landslides. Google Maps.

Saturday, 2 August 2014

At least eight dead following Nepal landslide.

Eight people are known to have died and many more are missing following a massive landslide near Jure in the Sindhupalchowk District of Nepal on Saturday 2 August 2014. At least forty people were also injured in the incident, one of whom has been identified as a Belgian national by local authorities. The landslip has also blocked the path of the Sunkoshi (or Kosi) River, provoking fears of flash flooding, and teams of engineers and geologists are trying to clear the dam safely. Potentially water can build up behind a mud dam until the weight of the water overcomes the resistance of the blockage, leading to flash flooding as a giant wave passes down the length of the river. It is feared that is not cleared safely this dam could lead to flooding as far downriver as Bihar in India.

The scene of the 2 August 2014 Jure landslide. The New Indian Express.

The landslide has been linked to heavy rains associated with the Nepali monsoon, which lasts from June till September, with the heaviest rainfall usually occurring in July when many areas typically experience over 400 mm of rain. Landslides 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, and Nepal frequently suffers many landslip-related fatalities during the monsoon season.