The provinces of Guangxi and Hunan in southern China have been hit by extensive flooding over the last week, displacing many people from their homes and resulting in at least nineteen deaths. In Guangxi more than 230 000 people have been forced to flee their homes, with over a thousand homes confirmed to have been destroyed, after the Lijiang River burst its banks, flooding a wide area, including parts of the city of Guilin, and resulting in at least six deaths, with several more people still missing. A series of rainfall associated floods and landslides have killed at least thirteen people in Hunan Province, with several more people missing, and Guizhou has also reported at least eight people missing after similar incidents.
Flooding in Rong'an County, to the east of Guilin in Guangxi Province, China. AFP/Getty Images.
South China has a monsoonal tropical climate, with peak rainfall falling in May and June, when Guangxi can expect to see more than 250 mm of rain per month in a typical year. 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.
Flooding in Yangshuo County, to the south of Guilin, on 7 June 2020. AFP.
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.
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