A 2000-year spatiotemporal pattern and relationship between cities and floods in the Yangtze River Basin,China

The Yangtze River is one of the most important rivers in China, and its basin is the most populous urban area in China. The relationship between cities and floods in the Yangtze River Basin is of significance. In our analysis of 4,511 historical county-level cities and 37,512 historical flood disasters, we used ARCGIS to conduct spatial analyses, including kernel density analysis, coldspot and hotspot analysis, and center of gravity analysis, to reveal the relationship between cities, population, and floods in the Yangtze River Basin in the past 2000 years. The results indicate that three relatively stable, dense urban areas are the Chengdu Plain; the border of the Anhui, Zhejiang, Jiangsu Provinces and surrounding areas; and the central Guizhou Province and southwestern part of Hubei Province. The hotspot areas of floods were the main tributaries and lakes of the Yangtze River, whereas the coldspot areas were the Chengdu Plain and the surrounding areas. More importantly, cities are not far from flood regions, and this will cause serious flooding. Due to location advantages, cities tend to be close to rivers, lakes, and other water systems. This research provides historical details of urban development and ecological environment protection in the Yangtze River Basin in China.