Objective River defence plays a vital role in the development of the Ming Great Wall’s military defence system. The spatial arrangement of river defence, represented by the Yellow River defence, embodies the ancient practice of adapting to local conditions, optimizing resource utilization, and transforming challenges into the guide of construction. This research takes river as a focal point to investigate the intricate relationship between the water system and military defence system. The analysis of the spatial pattern of river defense can improve the theoretical framework of the Great Wall defense system, thus fully integrating the multiple resource values of the Great Wall and the Yellow River.

Methods The quantitative analysis is conducted using the ArcGIS geographic information platform, involving the review of historical documents, the field investigation of existing sites, the utilization of drones for low-altitude image data collection for purpose of generating 3D real scene model, and the integration of historical aerial films and other multi-source data.The specific methodology comprises two key components: Firstly, analyzing the constituent elements of the defense system of river defence space and summarizing their functional attributes based on the theoretical framework of the Ming Great Wall’s military defence; secondly, summarizing the spatial distribution characteristics of river defence elements by incorporating changes in geographic location, hydrology, environment, and other natural factors. Indicators such as elevation, slope, and distribution distance are extracted to analyze the spatial characteristics of river defense under varying conditions. Then, the spatial distribution characteristics of the defense system in different modes were quantified. Ultimately, historical aerial films and real 3D point cloud data are utilized to reproduce the original appearance of defence facilities at river defence nodes.

Results Research results are summarized as follows. 1) In terms of the composition of element systems, the military river defense space focuses on strengthening the construction of the border wall system, military settlement, and beacon transmission system within each subsystem of the Ming Great Wall defense system. These systems are combined through points and lines to form a tight defense network of “waterfront warning−border defense−information transmission−reinforcement and response−military command−logistics support” to jointly realize the construction of a military defense pattern in the river defense space. 2) In terms of spatial distribution and site selection, military defense facilities have formed three geographical spatial distribution patterns under the influence of river morphology and specific natural factors. Starting from Laoniuwan, the Yellow River in the research area runs from north to south through Louziying to Hequ, with its southernmost end reaching Shiti Pass. During this process, the Yellow River experiences changes in elevation from high to low and water velocity from fast to slow, forming a geographical spatial change pattern from a curved river valley to an accumulation of shoals. 3) In the development of node facilities, city defense facilities and border wall nodes are tailored to cater to the requirements of river defense. This includes expanding corner ramparts for frontal enemy protection and incorporating passes and water gates on border walls to manage water flow. Using data extracted from historical aerial photos and 3D Real Scene point cloud, the original historical original appearance of Hequying City (a river defense node) and its border walls is restored.

Conclusion Driven by the intricate river water environment and military defense demands, a layered military defense network has emerged within the spatial pattern of river defense, and a comprehensive defense layout has been established by fully leveraging the natural terrain. Research results underscore the intrinsic relationship between the Great Wall’s military defense system and the natural river elements, which can promote the value research and comprehensive preservation of the military river defense space in Ming Dynasty. This research is envisioned to interconnect the Yellow River and the Great Wall National Cultural Park networks through river systems, thus contributing to the establishment of a comprehensive national cultural park system and the creation of significant symbols of Chinese culture.