In early June 2020, heavy rains caused by the regional rainy season led to floods severely affecting large areas of southern China including the Yangtze basin and its tributaries. Rains and floods extended to central and eastern China during July and were described as the worst since at least 1998.
According to the Ministry of Emergency Management, by the end of June flooding had displaced 744,000 people across 26 provinces with 81 people missing or dead. As of 13 August, the floods have affected 63.46 million people and caused a direct economic loss of 178.96 billion CNY, which are 12.7% and 15.5% higher than the 2015-2019 average, respectively. 219 people were found dead or are missing, and 54,000 houses collapsed, which is 54.8% and 65.3% lower than the 2015-2019 average, respectively. The Ministry of Water Resources said that a total of 443 rivers nationwide have been flooded, with 33 of them swelling to the highest levels ever recorded. According to statistics from the National Cultural Heritage Administration (NCHA), 76 key national cultural relics and 187 provincial cultural heritage sites have suffered damage of varying degrees.
Affected regions include Guangxi, Guizhou, Sichuan, Hubei, and Chongqing. The regions include the upper and middle river basin of the Yangtze and its tributaries. With more rain, floods started to extend to lower regions of the Yangtze basin such as Anhui, Jiangxi, and Zhejiang. Hunan, Fujian, and Yunnan were also affected.
Causes of floods
Natural causes
Hu Xiao from the China Meteorological Administration (CMA) indicated that the rains were caused by increased vapors arising from the Indian and Pacific oceans.
Many experts believe that climate change due to human activity contributed to the severity of the flooding, and such events may become more frequent in the future.
Artificial causes
The local governments in recent years had made steps to implement nature-based flood mitigation strategies like tree planting, sponge cities and floodplain restoration. Experts have noted these measures did have some positive effect as the intensity of precipitation in 2020 is much higher than the rains that caused the 1998 floods, yet the flooding has been less serious and damaging. However, huge challenges in flood management and resilience remain. The Yangtze flows through some of the most productive agricultural, economic and industrial centers in China. With the rapid increase of population in China and breakneck economic growth, a large number of lakes and other wetlands had been reclaimed into farmland or urban development. The serious shrinkage and disappearance of lakes in the middle and lower reaches of the Yangtze River is an important reason for the aggravation of flood disasters.
In 1915, Dongting Lake was 5,000-square-kilometre (1,900 sq mi). In 2000, it was only 2,625-square-kilometre (1,014 sq mi). In the 1950s, Poyang Lake was 4,350-square-kilometre (1,680 sq mi). In 2000, it was only 3,750-square-kilometre (1,450 sq mi). Hubei was once known as "The Province of a thousand of Lakes". In the late 1950s, there were 1,066 lakes in Hubei. By the early 1980s, only 309 were left.
Three Gorges Dam
Multiple dams in the Yangtze river basin control floodwaters; the biggest and most important of these is the Three Gorges Dam with its catchment area of about 1,000,000-square-kilometre (390,000 sq mi). It was constructed not only for power generation but also for flood control. By the end of June, the dam had started to release floodwaters. While the CMA indicated flood discharge started on 29 June, satellite images suggest that floodgates were opened already five days earlier. Yichang, a city below the dam, experienced extensive flooding, raising questions about the effectiveness of the flood control by the dam. According to the company that manages the dam, the dam had been "effectively reducing the speed and extent of water level rises on the middle and lower reaches of the Yangtze". Critics, however, suggest that the dam is "not doing what it is designed for" and unable to deal with severe events. Other experts have pointed out that studies do show that the dam does help alleviate typical flooding during normal years and that the problem is not the design of the dam, but the public's expectation that the dam alone can solve all the problems of flooding on the Yangtze. Significant amounts of rainfall occurred downstream of the Three Gorges Dam in the middle and lower reaches of the Yangtze which will never pass through the dam. During July, three flood waves from rains in the upper Yangtze basin arrived at the dam, necessitating the opening of sluice gates multiple times to create space in the reservoir. In Chinese social media it was claimed that this exacerbated downstream flooding, while the dam operators maintained that the action helped to delay floodwaters going downstream. On 15 August, "Flood #4" passed through the Three Gorges reservoir with a maximum inflow of 62,000 cubic meters per second, the highest reached at that time during this flood season. "Flood #5" passed the dam by 22 August when the reservoir's water level reached 167.85 metres, the highest level ever recorded.
According to a member of the expert committee of the state-sanctioned National Disaster Reduction Centre, the restrictions in human flow during the COVID-19 pandemic in mainland China halted regular dam maintenance, dam inspection, training of officials and the construction of hydraulic projects, which were scheduled in the winter and spring of 2020.
Flooding by province
Anhui
On 27 June, a 3-hour total of 118 millimetres (4.6 in) of rain was recorded in Hefei Economic and Technological Development Zone, of which 94 millimetres (3.7 in) was recorded during 1.5 h from 17:30 p.m. to 19:00 p.m. Some road sections and communities were submerged.
On 6 July, Lecheng Bridge, a Qing dynasty stone arch bridge and provincial cultural relics protection unit in Sanxi Town of Jingde County, was destroyed. On 7 July, some houses along the Shuiyang River in Xuanzhou District of Xuancheng were submerged.
On 7 July, several reservoirs in She County filled over capacity and reached record levels, requiring large releases of water to alleviate the dangerously high storage of water. Homes in She County were inundated. The first day of the National College Entrance Examination (Gaokao) was postponed due to hard rain. On 7 July 2020, Zhenhai Bridge, a large stone arch bridge in Tunxi District of Huangshan City and a "Major Historical and Cultural Site Protected at the National Level in Anhui", was destroyed by mountain torrents.
On 9 July, the Yaodu and Longquan rivers in Dongzhi County exceeded their highest recorded water levels.
All residents in Laozhou Township and Xuba Township of Tongling along the Yangtze River were ordered to evacuate on 11 July.
On 14 July, an emergency was issued by the Office of Anhui Provincial Flood Control and Drought Relief, which ordered all residents living in the central island of the Yangtze River or along the Yangtze River in Anqing, Chizhou, Tongling, Wuhu and Maanshan to evacuate.
On 16 July, in Tietong Township of Zongyang County, all the remaining 2,272 people were evacuated except 176 left behind.
On 18 July, the Huai River Commission of the Ministry of Water Resources raised the flood-control response from Level III to Level II.
On 19 July, the Government of Quanjiao County blasted several gaps in Chu River Levee to release floods.
At 8:32 am on 20 July, the Government of Nan County opened sluice gates at Wangjia Dam on the Huai River because water there was building up to too high a level. The last flood discharge was 13 years ago.
At 10:24 a.m. on 21 July, the water level at Zhongmiao Station of Chaohu reached 13.36-metre (43.8 ft), which is the once-in-a-century water level of Chaohu.
On 22 July, five excavators were washed away by the flood in Shida Levee, Lujiang County. That same day, firefighter Chen Lu was swept away by the flood while searching for trapped people in Lujiang County.
On 23 July, in Chaohu, affected by the continuous heavy rainfall, the water level of the Zhegao River rose and streets of Zhegao Town were submerged.
Chongqing
At 20:00 p.m. on 22 June, the Qijiang Wucha Hydrological Station in Jiasi Town recorded a water level of 205.85 metres (675.4 ft), which was 5.34 metres (17.5 ft) higher than the safe water level (200.51 metres (657.8 ft)). The Qijiang Wucha Hydrological Station reached 205.85 metres (675.4 ft), topping the previous record of 205.55 metres (674.4 ft) in 1998 China floods. On 22 June, parts of Qijiang District's Wenlong Subdistrict were submerged, with some roads underwater. 13,874 residents in Qijiang District along the Qi River were ordered to evacuate on 22 June.
On 15 July, hundreds of homes in Miaoba Town of Chengkou County were evacuated due to catastrophic rain and floods.
At 15:00 p.m. on 17 July, floods burst a bridge in Baojia Town of Pengshui Miao and Tujia Autonomous County, a man fell into the river and disappeared.
On 27 July, affected by persistent heavy rainfall, the first floor of the shops in the town of Ciqikou alongside the Yangtze River were inundated. Parts of Yuzhong District and the entire Caiyuanba Building Materials Market and Fruit Market near the swollen river were inundated.
As of August 16, 2020 the center of the city of Chongqing was flooded under 1 to 2 metres (3 ft 3 in to 6 ft 7 in) of water after the Jialing River overflowed due to heavy rainfall.
On 20 August, the Cuntan Hydrological Station in Chongqing rose over the high of 191.41 metres (628.0 ft), which was set in 1981. Downtown streets, houses, parks, and wharves, were inundated.
Gansu
China National Highway 212 was partially washed away, effectively cutting off Wen County from the outside world for three days.
Fujian
From 11 to 14 June, a torrential rainfall hit Youyang Tujia and Miao Autonomous County and Shizhu Tujia Autonomous County. On 14 June, Huaxia Minzu School was inundated. On 22 June, homes in Youyang Tujia and Miao Autonomous County were also inundated.
On 9 July, a rainstorm occurred in Nanping, causing floods, landslides and other disasters, many roads were destroyed and crops were flooded. Wuyishan City had serious waterlogging, and the local government issued a rainstorm red warning signal, and Wuyishan Scenic Spot had been closed.
Guangdong
On 22 May, the largest one hour rainfall in 2020 in China is Huangpu Bridge of Guangzhou, 168-millimetre (6.6 in). Line 13 of Guangzhou Metro was shut down due to floodwater flowing into the subway tunnel.
At 11:00 a.m. on 8 June, roads and farmland in Lianxin Village of Linjiang Town in Heyuan were engulfed by floods. The Yonghan Levee on the Dong River collapsed, releasing an 3-metre (9.8 ft) to 5-metre (16 ft) wall of water. Flood surrounded Hekou Village of Yonghan Town in Longmen County, making it an island. Roads and highways were severely damaged or destroyed in Longmen County.
Guangxi
On 7 June, the daily rainfall in Yangshuo County of Guilin was 327.7-millimetre (12.90 in), breaking the local record of daily precipitation. Waterlogging occurred in several towns and townships, including Putao, Baisha and Jinbao. The county seat was underwater when the torrential rainfall hit. The dam of Shazixi Reservoir in Gaotian Town collapsed, 510 residents were forced to evacuate. Luojin Town and Baoli Township of Yongfu County were waterlogged. Maling Town and Hualong Town of Lipu alongside Maling River, Lipu River and Hualong River were besieged by flooding.
On 8 June, the Pingle Hydrological Station of Gui River rose to an all-time high of 105.87-metre (347.3 ft) and crossed the danger mark 6.37-metre (20.9 ft), surpassing the previous record set in 1936. National Highway G321 and G323, G65 Baotou–Maoming Expressway, and G59 Hohhot–Beihai Expressway were closed due to landslides. In Luorong Town of Yufeng District, Liuzhou, homes, streets and businesses was underwater when the torrential rainfall hit.
Guizhou
From 7:00 a.m. on 11 June to 7:00 a.m. on 12 June, a torrential rain of 264.6 millimetres (10.42 in) fell in Bifeng Town of Zheng'an County, with the maximum hourly rainfall of 163.3 millimetres (6.43 in), breaking the historical record of Guizhou in one hour. It is also China's largest one hour rainfall, after Guangzhou of 168 millimetres (6.6 in) on 22 May. Throughout the county, 8 people were killed and 5 were missing.
At 7:00 a.m. on 14 June, a total of 438,000 people in 51 counties of 8 cities in Guizhou were affected, 10 people died, 14 people were missing, 21,000 people were forced to evacuate; nearly 100 houses collapsed and more than 8,000 houses were badly damaged; 175,000 hectares (1,750 km2) of crops were affected, including 28,000 hectares (280 km2) will have no harvest; and the direct economic loss was 880 million yuan.
In 26 June, the torrential rainfall hit Rongjiang County, resulting in a direct economic loss of 4.8 million yuan due to rural roads in the county sustained major damage.
At 7:05 a.m. on 8 July, at least six people were killed when a landslide occurred in Shiban village of Songtao Miao Autonomous County.
On 12 July, portions of National Highway G212 in Meijiuhe Town of Renhuai was closed due to mountain flood. Loushanguan Scenic Spot was also closed.
Hubei
As of 13 July in Hubei province, at least 14 people were dead, and five others were missing. Over nine million people were affected.