The spatiotemporal distribution and influencing mechanism of China's hydraulic heritage sites

Hydraulic heritage is important carriers of human civilization. Furthermore, hydraulic heritage in China is a typical representative of world hydroculture. Based on cultural heritage lists of different grades, 1733 China's hydraulic heritage sites (CHHS) were screened out and divided into 4 categories, and spatial analysis methods were used to study the spatial-temporal distribution of CHHS since the Neolithic Age. The results are as follows: (1) CHHS show a weak centralization trend and fluctuating growth over time. Most of these sites developed during three unification periods (Qin and Han Dynasties, Sui and Tang Dynasties, Song, Yuan, Ming and Qing Dynasties) in terms of quantity and type; 76.80 % of CHHS is associated with these periods. (2) CHHS are spatially distributed in a quadrilateral pattern, with 85.75 % located in the core area and buffer of the quadrilateral, for which Beijing, Hangzhou, Chengdu, and Guangzhou are the vertices; the distribution of various types and periods of CHHS also conform to this pattern. (3) The quadrilateral pattern has significant natural, political and economic characteristics, as it is located on the second and third steps of the terrain; situated in the middle and lower reaches of the Yangtze River Basin (YZB) and the Yellow River Basin (YWB), and other eastern basins; concentrated in warm and humid agricultural areas; corresponded to the layout of basic economic zones and political centers in ancient China. The distribution of hydraulic heritage sites is directly related to the construction and preservation of hydraulic projects and is affected by the combined action of political, economic, natural, and technological factors. Exploring the distribution law of CHHS can provide a reference for protecting world hydraulic heritage.