Research by our members

Rapid urbanization has significantly intensified the impact of natural disasters, particularly floods, posing a severe threat to urban safety. To enhance urban flood risk management, a quantitative assessment of urban flood vulnerability is essential. This study integrates multi-source data to develop the urban Development Index (DI) and the Normalized Difference Frequency Index (NDFI). By applying area-weighted aggregation, spatial overlay analysis and K-Means clustering, this research explores the spatiotemporal dynamics of urban expansion and its relationship with flood vulnerability in the Chengdu-Chongqing urban agglomeration. The results indicate that between 1995 and 2020, the region experienced significant urban expansion, with urban land increasing by 4,232 km2. Moreover, the newly developed urban areas were found to be more vulnerable to flooding, with 42.26 % affected by floods in 2020. However, the flood vulnerability did not show a simple linear relationship with development level. In more developed cities, such as Chongqing, showed decreasing vulnerability (from level C to A) due to high-elevation terrain and sustained investment in flood mitigation. In contrast, Chengdu experienced increasing vulnerability (from level A to C) due to rapid expansion over flat agricultural land with dense construction. Furthermore, Ziyang showed high flood vulnerability despite slow development, with over 80 % of its newly developed urban areas were affected by floods. The proposed flood vulnerability assessment framework provides a scientific basis for flood risk management in Chengdu-Chongqing urban agglomeration and other similar inland city clusters. Additionally, it serves as a valuable reference for future urban expansion planning and disaster prevention strategies.

China’s monsoon climate, characterized by hot summers and substantial rainfall, leads to significant seasonal water accumulation in river basins. This often results in short-term heavy rainfall events, causing rapid water flow into river basins and subsequent flooding. River embankments, which narrow channels, exacerbate downstream flooding and pose severe safety threats. This study explores integrated urban and riverine flood risk management strategies within the Fujiang River Basin, focusing on Mianyang City. The research addresses the growing challenges of global climate change and rapid urbanization, which have intensified flood risks. Utilizing the one-dimensional Storm Water Management Model (SWMM) and two-dimensional hydrodynamic Rainfall-Runoff-Inundation (RRI) model, the study simulates flood events and urban flooding in Mianyang City and the Fujiang River Basin. These models were validated with data from hydrological stations and satellite imagery. The study evaluates extreme flood events in Mianyang City between 2015 and 2021. The findings highlight the significant role of sponge city initiatives and low-impact development (LID) facilities in mitigating flood impacts. Despite their benefits, these measures have limitations under extreme flood conditions. This study contributes to understanding the interactions between urban and riverine systems and provides a basis for improving flood risk management and resilience in rapidly urbanizing river basins. It supports ongoing efforts to implement sponge city concepts in China, offering crucial insights into effective strategies for managing flood risks in similar geographic and climatic contexts.