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Exceptional floods in Southeast Asia


Following directly after the health crisis caused by the coronavirus, China was faced with another disaster, during the rainy season. Repeated and exceptionally heavy rains caused floods in the basins of the Yangtse (the Blue River) and the Yellow River. Other Asian countries were also hit.


As early as June, torrential rain fell over southwest China, before shifting eastwards. The country’s Ministry of Water Resources declared in mid-July that 433 rivers had reached dangerous levels and 53 their highest historic levels, causing many floods.

By mid-August, it was the turn of Peking to sound the alarm and close its airports, parks and public transport lines. Other major cities were also affected, such as Tianjin and the regions of Hebei and Sichuan.

By the end of August, the hydrological situation in the Yellow River basin gave rise for concern and the Yellow River Conservation Commission announced the sixth flood of the year. The Chinese authorities declared the heaviest rainy season since that of 1998, which led to 15 million people losing their homes and 3,500 deaths.

According to the first estimation, 55 million people were affected in 27 provinces and nearly 4 million people were displaced or evacuated. Thanks to the monitoring system and the speedy evacuation of the inhabitants, the number of lives lost did not reach previous levels, although there were more than 200 deaths and disappearances. The economic cost (material damage, lost agricultural production, etc.) was huge, estimated at €22 billion.


Dams put to the test

Hydropower plants were severely tested by the rise in water levels and strong discharges. At the Three Gorges Dam (the largest dam in the world in terms of installed capacity), the flood protection gates were opened to allow the water to pass with a discharge of 75,000 m3/s! The level of the water in the reservoir rose to 165 metres on the morning of 21 August (its maximum height is 175 metres). 40,000 people downstream of the dam had to be evacuated. A greater number of inspections had to be carried out, due to the appearance of infiltrations and slight deformations. Elsewhere, in the province of Anhui, a dam on the River Chu was dynamited at the end of July to ensure the safety of the adjacent population. According to the Ministry of Emergency Situations, 30 billion cubic metres were held back by the different dams and reservoirs on the Yangtse (the longest river in China, with 6,300 km) from June to the beginning of August, which allowed mitigating the floods downstream, especially in the megacity of Shanghai, in eastern China.


A warning signal of climate change 


China is not the only country to face severe weather conditions this year. They have also affected most of the countries of Southeast Asia, like every year, with the monsoon as well as tropical storms.

South Korea was also struck by an exceptional situation, with more than 50 consecutive days of rain. In India, the monsoon rains were lethal: nearly 800 people were killed, at least according to official figures. Nepal and Bangladesh also recorded very high levels of rain.

Environmental organisations consider these extreme phenomena as an alarm signal of the impacts of climate change. The damage incurred was certainly exacerbated by the impermeabilization of soil by urban development, which prevents the normal runoff of precipitations. The Chinese government has already tackled this problem, by developing a new form of urban planning since 1994, based on the concept of sponge city. By making the city permeable, the aim is to improve urban resilience against torrential rain and secure the water supply of cities. The Chinese government plans to make 80% of China’s urban areas capable of absorbing and reusing 70% of the rain falling on them by 2030. $12 billion dollars of public subsidies and private investments have been made available to this end.


As for the Mekong River Commission, it has announced a partnership with Facebook to launch a fast warning system to alert the populations living close to the river in case of flooding, and to monitor droughts for the Lower Mekong, which covers Cambodia, Laos, Thailand and Vietnam.

This region is increasingly vulnerable to droughts and floods, due to the effects of climatic changes (+0.8°C increase in the average temperature from now to 2030). 22 hydrological stations have been installed to monitor and collect data on the river’s water levels and the rainfall in view to supplying them to the forecasting system. Developed for the public, this forecasting and warning system is also intended for governments so that they can better manage risks.


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