Typhoon Doksuri made landfall in Fujian Province, China, on the morning of Friday 28 July 2023, after claiming at least 39 lives as it passed across the Philippines earlier this week. The dead in the Philippines include a mother, her child, and two other children that were in the same house when it was buried by a landslide at Baguis in Benguet Province, on Wednesday 26 July. 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. These combined often lead to catastrophic flooding in areas hit by tropical storms.. Also in Benguit Province a 17-year-old was killed in a lamdslip triggered by heavy rains. In Isabela Province, a woman selling bread from a bicycle cart was killed by a falling tree. The majority of those who lost their lives, however, were on a ferry travelling town of Binangonan on Luzon Island and the smaller island of Talim, which capsized about 50 m after setting sail. Thirty people have now been confirmed dead following this incident, with many more still missing.
After passing over the Philippines Typhoon Doksuri swept to the south of Taiwan, brining with it winds gusting at up to 191 km per hour, and rains of up to 70 mm. Around 4000 people were evacuated from vulnerable areas as a precaution, and all internal and most international flights were grounded as a precaution. In the event there have been no major damage or casualties reported, although about 15 700 houssholds temporarily lost their power. In Fujian Province around 400 000 people were evacuated from areas deemed at risk, all boats were required to return to port as a precaution, and almost all transport services were suspended. No casualties have been reported in Fujian, and the only significant damage was to a sports stadium, which lost part of its roof.
Tropical storms are caused by the warming effect of the Sun over tropical seas. As the air warms it expands, causing a drop in air pressure, and rises, causing air from outside the area to rush in to replace it. If this happens over a sufficiently wide area then the inrushing winds will be affected by centrifugal forces caused by the Earth's rotation (the Coriolis effect). This means that winds will be deflected clockwise in the northern hemisphere and anti-clockwise in the southern hemisphere, eventually creating a large, rotating Tropical Storm. They have different names in different parts of the world, with those in the northwest Pacific being referred to as typhoons.
Despite the obvious danger of winds of this speed, which can physically blow people, and other large objects, away as well as damaging buildings and uprooting trees, the real danger from these storms comes from the flooding they bring. Each drop millibar drop in air-pressure leads to an approximate 1 cm rise in sea level, with big tropical storms capable of causing a storm surge of several meters. This is always accompanied by heavy rainfall, since warm air over the ocean leads to evaporation of sea water, which is then carried with the storm. These combined often lead to catastrophic flooding in areas hit by tropical storms.
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