Water-related cultural heritage architecture (WRCHA) represents a globally significant and potentially hybrid heritage found across river basins worldwide. Its spatial and temporal evolution characteristics offer insight into the development trends of river basin environments, yet their value within water-related cultural and environmental systems remain incompletely assessed. This study undertakes qualitative and quantitative analyses of the historical spatial and temporal distributions, influencing factors, and environmental changes affecting the water-related culture, climate, population, and urban areas of 295 WRCHA sites in the Li River Basin of China, employing drought–flood indices, GIS analyses, random forest algorithms, and other methodologies. The results reveal that (1) the Lishui Basin contains a significant distribution pattern of agglomeration for WRCHA within the river basin, concentrated along the river, at low altitudes, with minimal terrain variation, and radiating around ancient governance centers, with varying increases observed across different periods and aggregation zones and with significant spatial and temporal heterogeneities; (2) the distribution pattern is influenced by joint natural and human factors, closely tied to variables such as the river network density, DEM, population changes, and distance to ancient government sites; (3) the combination of the architecture’s location and elevation, along with drought–flood curves, reflects the position of the ancient riverbed of the Lishui River and its historical maximum water level. The quantity of new constructions, in conjunction with the distance from ancient government centers and the trends in population change, thus indicates the urban scale and the frequency and severity of disasters. This study provides a research paradigm and historical reference model for investigating environmental changes in watershed systems, aiding in clarifying the historical human–water symbiosis pattern in the middle reaches of the Yangtze River. Such insights will furnish a scientific basis for future regional ecological planning and watershed environmental management.

The middle reaches of the Minjiang River, shaped by the Dujiangyan irrigation system, provide a typical setting for studying long-term human–water interactions. During the Little Ice Age, the water management system as a whole experienced a full cycle of recovery, expansion, and decline from 1644 to 1949 (Qing to Republican period), although subregions exhibited marked spatial heterogeneity. This heterogeneity makes the area an ideal case for comparative analysis; however, previous studies have neither quantitatively reconstructed river–canal changes nor systematically disentangled the composite natural and anthropogenic drivers across different subregions. Using archival documents, historical maps, remote sensing imagery, and water cultural heritage sites, this study reconstructs the evolution and quantifies two change types: anthropogenic construction, including new construction, reconstruction, and modification, and environmentally driven changes such as rerouting, damage, and maintenance. Correlations were analyzed among the four subregions: Inner River, Outer River, Nanhe River, and the Lower Basin to identify driving mechanisms. Results indicate that anthropogenic construction is constrained by natural conditions and driven by population growth, whereas environmentally driven changes are primarily caused by floods and worsened by canal head maintenance failure. The four spatially differentiated driving patterns are: Inner River—human-dominated intervention type; Outer River—flood stress type; Nanhe River—low-disturbance stable type; and Lower Basin—natural–human composite type. This study offers new insights into long-term human–water interactions in large irrigation districts under climate change.