In the summer of 2021, floods occurred frequently globally. In Zhengzhou, the hourly rainfall reached 201.9 mm, breaking the record of the largest hourly rainfall in mainland China; floods in western Germany caused more than 100 deaths due to continuous heavy rain. Flood is often triggered by extreme events such as rainfall, hurricanes, typhoons, tides, low-pressure surges, etc., leading to the loss of lives and property and other disasters, such as landslides, mudslides, and epidemics. As warned in the international climate assessment report issued by IPCC on 9th, August, the water cycle has been strengthening and will continue to strengthen with global warming. To deal with the increasingly frequent floods, the world should work together to strengthen academic communication on flood control.
In January 2017, President Xi Jinping visited Switzerland and gave a speech entitled "Build the Community of Shared Future for Mankind" at the United Nations Headquarters in Geneva. Consensus about building platforms to promote innovative corporations between enterprises, universities, and research institutions between China and Switzerland has been achieved.
In April 2019, the China Ministry of Emergency Management and the Swiss Ministry of Foreign Affairs signed the "Memorandum of Understanding on Cooperation in Disaster Prevention and Emergency Planning and Response", to promote cooperation between the two countries.
In this context, in order to jointly cope with the risk and challenge of flood-related disasters to mankind, ETH Zurich and the Southern University of Science and Technology jointly held the China-Swiss Flood and Public Security International Symposium. Internationally renowned experts and scholars from China, Switzerland, and other countries were invited to discuss together to improve the knowledge about the changes and impacts of flood, and to provide solutions for decision-makers concerning urban safety. The symposium concerned the following four directions:
1) Quantify the risk of suffering flood: reviewed trends of historical flood and statistical characteristics in the frequency, severity, social security, and economic losses of flood disasters.
2) Cascading and coupling effects of secondary disasters caused by floods: discussed the cascading effects of different secondary disasters caused by flood and the interaction between different disasters, including but not limited to the water pollution, epidemics, short-term effects on health; damage to energy, water, waste, and transportation networks; losses of industry, economy, and agriculture.
3) The impact of the flood on coastal regions: assess the risk of flood caused by heavy rains, urban floods, ocean tides, surges, typhoons and their combinations; assess various engineering and non-engineering facilities (green and gray infrastructures) to cope with coastal flood losses ); assess the erosion of strong waves on coast; explore the monitoring and forecasting of the coastal flood; evaluate the impact of the flood on the coastal environment and ecological security.
4) Public safety plan: For other disasters caused by flood, safety plans of long-term, medium-term and short-term were discussed, as well as disaster prevention and mitigation strategies based on natural ecological restoration. The safety plan includes the risk management of flood, urban resilience establishment, and enhancement of anti-vulnerability of cities. "