Improving the response to urban flooding with early warnings

Critical infrastructure in our cities such as roads, bridges, powerlines and subways are vulnerable to extreme weather events, such as flooding.

Failure of vital infrastructure during a severe flood is experienced by around 400 million people annually and many people lose their lives in such events.

Flooding also takes a severe toll on the economy. In the UK the economic losses from flooding between November 2019 and March 2020 are estimated to be about £333 million. In China alone, urban river flooding has affected 60% of mega cities.

A UK-China project team conducted a pilot study in Guangzhou, China’s third largest city. Guangzhou is a critical part of the Pearl River Delta cluster, an area of global importance for manufacturing and shipping.

By integrating cutting-edge radar with the city’s urban flood warning system, the team could provide rainfall monitoring and storm warning information to government decision makers. This gave accurate and timely weather forecasts and weather warnings for cities on a large scale. It was the first time a system like this has been used at such a large scale.

The methodology was successfully tested in June 2020 in Guangdong province. Early warning of sudden weather such as rainstorms, thunderstorms gave decision making support to the city government to reduce the effect of catastrophic floods.

The system, which is called Active Phase Array Radar, worked alongside advanced modelling to help extend the advanced warning time by 10 minutes. This proved to be valuable time for people to prepare and adapt to the coming floods.

The early warning allows for increased economic development because businesses can plan and even continue during the flood. More business and services mean enhanced social welfare and benefits to the industrial sectors.

Outcomes of the project will help improve development of next generation radars and their integration into atmospheric modelling. This will help protect cities against urban flooding, not only in China but in many other countries globally. UK project lead, Prof. Xuan, has gone on to research prediction of extreme storms and floods in Wales.

Early warning system for urban flooding in Chinese mega cities using advanced active phased array radar (APAR)

Project Leads: Dr Yunqing Xuan, Swansea University, UK, Prof Dehua Zhu, Nanjing University of Information Science and Technology, China

Project Partners: Royal Academy of Engineering and HR Wallingford, UK, and Zhuhai Naruida Technology Ltd, China