Guan et al. (2025) Characterization of spatial and temporal distribution of flood impacts in China

Identification

• Journal: Natural Hazards
• Year: 2025
• Date: 2025-09-13
• Authors: Xinjian Guan, Tao Xu, Yu Meng, Hong Lv
• DOI: 10.1007/s11069-025-07663-9

Research Groups

• School of Water Conservancy and Transportation, Zhengzhou University, Zhengzhou, Henan, China
• Yellow River Laboratory, Zhengzhou University, Zhengzhou, Henan, China
• Yellow River Engineering Consulting Co. Ltd., Zhengzhou, China

Short Summary

This study develops a novel dynamic clustering framework and a Flood Impact Index (FII) to characterize the spatiotemporal distribution of flood impacts in China from 1993 to 2023. It reveals an overall declining trend in flood impacts, with concentrations in central and southern regions, providing a quantitative basis for disaster mitigation.

Objective

• To introduce a Flood Impact Index (FII) derived from direct economic losses and affected population, and employ a dynamic clustering framework to investigate its spatiotemporal characteristics across China.

Study Configuration

• Spatial Scale: China, encompassing 34 provincial administrative divisions (excluding Hong Kong, Macao, and Taiwan), covering an area of approximately 9.6 million square kilometers.
• Temporal Scale: Annual data from 1993 to 2023 for FII calculation and analysis. Some contextual data (e.g., reservoir capacity) from 1981 to 2020.

Methodology and Data

• Models used:
  • Flood Impact Index (FII) calculation: Entropy Weight TOPSIS method.
  • Clustering: Dynamic clustering framework combining spectral clustering (for initial optimal cluster number determination using Calinski–Harabasz index) and hierarchical clustering (for temporal consistency via variance-based splitting and merging).
  • Temporal trend analysis: Mann-Kendall (MK) test.
  • National FII aggregation: Hierarchical weighting strategy considering cluster size, gross regional product, and resident population.
• Data sources:
  • Annual flood data (direct economic loss and affected population): Ministry of Water Resources of China (http://www.mwr.gov.cn) for provincial-level administrative areas.
  • Socioeconomic data (gross regional product, resident population): National Bureau of Statistics (https://www.stats.gov.cn/).

Main Results

• From 1993 to 2023, the overall impact of floods in China exhibited a declining trend.
• Spatially, flood impacts are primarily concentrated in the central and southern regions of China (e.g., Hunan, Guangdong, Sichuan, Zhejiang, Jiangxi), while northern regions (e.g., Tianjin, Shanghai, Beijing, Tibet, Ningxia) experience comparatively minor effects.
• Regions with either severe or minimal flood impacts show relative stability, whereas regions with moderate flood impacts exhibit greater fluctuations over time.
• A significant downward trend in FII was observed from 2015 to 2023 (p < 0.05).
• Provincial analysis showed decreasing flood impacts in East China, Northeast China, and Central and South China, but increasing trends in northern regions. Specifically, Jiangsu, Zhejiang, Shanghai, and Xinjiang showed statistically significant downward trends (p < 0.05), while Gansu and Tibet showed statistically significant upward trends (p < 0.05).

Contributions

• Introduces a novel Flood Impact Index (FII) that objectively combines direct economic losses and affected population to visualize and comprehensively assess actual flood impacts.
• Develops an innovative dynamic clustering framework that automatically determines the optimal number of clusters for each year and ensures temporal consistency through hierarchical clustering with variance-based splitting and merging.
• Incorporates a hierarchical weighting strategy for aggregating provincial FII into a national index, considering cluster centers, size, regional economic output, and population.
• Provides a robust quantitative foundation for policymakers and planners to improve flood prevention and mitigation strategies in China.

Funding

• National Key Research and Development Program of China (Item No. 2024YFC3211300)
• National Natural Science Foundation of China (Grant No. 52509038)
• National Key Research and Development Program of China (Item No. 2023YFC3206800)
• Young Elite Scientists Sponsorship Program by Henan Association for Science and Technology (Item No. 2025HYTP048)

Citation

@article{Guan2025Characterization,
  author = {Guan, Xinjian and Xu, Tao and Meng, Yu and Lv, Hong},
  title = {Characterization of spatial and temporal distribution of flood impacts in China},
  journal = {Natural Hazards},
  year = {2025},
  doi = {10.1007/s11069-025-07663-9},
  url = {https://doi.org/10.1007/s11069-025-07663-9}
}