The Central Post Office in the Hankou District of Wuhan, August 1931
(source: YANGTZE WATER RESOURCES COMMISSION 2001: 143). Hankou district was passable by boats only and the population had to be evacuated. The flood claimed 36,000 casualties in the city solely.
What is a Flood?
'The water level of a river is naturally subject to considerable variations. It is part of the seasonal course within the hydrological cycle. Natural factors can influence the runoff and water level of a river and cause floods. The extent of floods is characterised by floodwaves that exceed the main channel and cover the natural floodplain temporarily for a given cross-section. The processes for the origins of a flood can vary. The spatial-temporal distribution of rainfall, the size and structure of the catchment as well as its discharge capabilities are the primary factors that are interdependent with floods. Flood is a natural hazard if the flood extent endangers human live or property assets. It can exceed catastrophic dimensions if the designed flood extents are exceeded and technical flood protection measures threaten to fail.' (from Gemmer, 2004)
The Central Post Office in the Hankou District of Wuhan, August 1954
(source: YANGTZE WATER RESOURCES COMMISSION 2001: 143). The dykes were improved by emergency operations. The flood set the historical highest flood peak of 29.73 m. The important north-south railway connection Beijing-Guangzhou was blocked for 100 days.
Floods in China
'Floods as natural hazards and catastrophes are omnipresent in China. Floods at the Yangtze River are natural events and historically documented incidents. They are no phenomena of modern age and have been recorded for a long time even before man interfered with the hydrological cycle. Flooding, waterlogging and drought are the most severe natural disasters in China based on terms of economic losses, damaged farmlands and casualties. Yangtze river floods are the results of natural processes (precipitation and runoff) as well as human activities in the catchment and the floodplain. The main source of floods in the Yangtze river catchment is heavy, long-lasting precipitation during summer time. This is influenced by the East Asian Monsoon and often results in events with heavy rainfalls. Therefore, floods at the Yangtze river are natural events and historically documented incidents. They have been recorded a long time before man interfered with the hydrological cycle. There were 178 extreme flood events recorded in the Yangtze river catchment between the 2nd and 20th century. Merely six regional or basin-wide heavy floods occurred in the Yangtze river catchment in the 1990s. The latest flood that attained publicity occurred in 2002. With regard to the affected population (240 million) and the monetary losses (20 billion US$), the 1998 flood event at the Yangtze river was the most disastrous flood in China. Nevertheless, it was not the probable maximum flood and the consequences of future floods could be more far-reaching....
Floods can never be entirely prevented by natural and technical measures, but flood risks can better be dealt with if the consequences of floods are better known. This enhances the ability of decision makers to optimise flood risk management and to find adapted non-structural flood measures such as emergency planning to cope with the current flood risks.' (from Gemmer, 2004)
The Central Post Office in the Hankou District of Wuhan, November 2001
(sorce: M. Gemmer, Nov 3, 2001). It is protected by costly dykes and the area is highly developed. The dykes have been reinforced in the 1970s and 1990s.
www.yangtzefloods.net is the most comprehensive website for Climate Change Impacts on Floods and Water Resources Science in China