Flood Risk in Asia's Urban Mega-deltas Drivers, Impacts and Response

Asia's urbanized mega-deltas are experiencing increased incidences of flooding. Flood risk is increasing due to urban growth, which makes people more vulnerable and threatens economic assets, and due to factors that increase flood hazard, including reduced delta aggradation, subsidence though natural resource extraction, and climate change, including extreme weather events, such as typhoons, and sea level rise. The recent history of flooding in Asia's deltaic cities and the drivers of that risk have been examined in this article. We give particular attention to the Pearl River Delta, and its cities of Guangzhou, Hong Kong and Shenzhen, important economic centres of Asia. The flood risk is substantial, but flood risk management appear to suffer through a lack of sufficient strategic planning, and the difficulty of defending deltaic cities through traditional engineering approaches alone. Drawing on lessons from flood risk management internationally, we suggest that there are ways forward in developing flood mitigation strategies for deltaic cities in the region, which deserve further exploration.