In April 2024, severe flooding affected large parts of Guangdong province in southern China, including the city of Guangzhou. Over the course of the month, Guangzhou recorded 609 mm of rainfall — its highest April total in more than 60 years (Al Jazeera, 2024), — disrupting a metropolitan area of around 14 million people.
Guangdong is China’s most highly populated province, home to around 127 million people and a major manufacturing centre contributing over 10% of national GDP (Faranda et al., 2024). Flood impacts in this region therefore extend far beyond local damage, with implications for global supply chains and insured losses.
Flooding outside the expected season
Southern China is accustomed to seasonal flooding associated with the monsoon period from late May to October. What made the April 2024 event notable was its timing and magnitude, occurring earlier than the traditional flood season.
Predictions suggest that shifts in rainfall seasonality and prolonged wet periods are increasingly likely across parts of Asia (Faranda et al., 2024), alongside a long-term upward trend in precipitation (Han et al., 2024) across China and other neighbouring countries. This introduces greater uncertainty around when and where damaging floods may occur.
For the re/insurance sector, this reinforces the importance of understanding flood risk beyond historical seasonality assumptions.
Using flood maps to interpret observed impacts
Following the Guangdong floods, JBA compared observed flood extents, photographic evidence and estimated flood depths with outputs from its China Flood Map. This allowed return periods to be assessed spatially across affected locations.
In the town of Yingde, north of Guangzhou, observed flood depths of around four metres were consistent with a 50-year flood event in several areas. Figure 1 shows JBA’s China Flood Map for this area. Mapping shows river flooding extending into transport corridors and adjacent infrastructure, highlighting clear concentrations of risk within and to the south of the town.
A similar approach was applied in Hanhuang, where estimated flood depths of approximately 1.5 metres aligned with a 200-year river flood combined with a 100-year surface water event. (See the relevant JBA China Flood Map shown in Figure 2). In this case, much of the town centre and its key transport links were inundated, illustrating how compound flood mechanisms can significantly increase impact severity over short distances.
Clarity through high‑resolution mapping
These examples demonstrate how high-resolution flood mapping:
- Offers clear differentiation between river and surface water flooding and the associated impacts
- Highlights changes in hazard over small areas
- Supports post-event analysis by linking observed impacts to probable flood scenarios
For insurers and reinsurers managing exposure in China, this level of detail is critical for understanding and predicting accumulation, stress-testing portfolios and interpreting flood events.
As rainfall behaviour continues to evolve, high quality flood hazard information will play an increasingly important role in assessing and managing flood risk across highly urbanised and economically significant regions such as Guangdong.
For more information about JBA’s Global Flood Map, please contact help@jbarisk.com.
References
Al Jazeera. (2024). China evacuates over 100,000 as heavy rain continues to lash south. https://www.aljazeera.com/news/2024/4/23/deadly-record-rainfall-evacuates-110000-in-chinas-guangdong
Han, J., Zhang, R., Guo, B., Han, B., Xu, T., Guo, Q. (2024). Long-Term Variation Patterns of Precipitations Driven by Climate Change in China from 1901 to 2022. Sustainability. https://www.mdpi.com/2071-1050/16/17/7283
Faranda, D., Alberti, T., Pons, F., Mengaldo, G. (2024). April 2024 China floods exacerbated by both human-driven climate change and natural variability. Climameter. https://www.climameter.org/20240420-23-china-floods