Objective In the long-term historical process, social, economic and cultural exchanges between traditional settlements in China are frequent, and in this dynamic process, the overall regional development is shaped. The relationship between settlements and the environment, as well as between settlements, is a comprehensive logic and meaning system underlying spatial representation that can reflect the regional human context and regional characteristics. Therefore, exploring the correlated and similar morphological characteristics and mechanisms of traditional settlements is an important foundation for establishing a regional protection framework for urban and rural historical and cultural heritage.

Methods Based on historical data and literature including ancient maps, modern image maps, and local chronicles, this research conducts field surveys, visits, and interviews to corroborate the research results. Starting from the regional evolution process of the coastal invasion area, the historical correlation logic of traditional settlements is sorted out, and based on this, the types and patterns of correlation morphology are summarized.

Results The marine ingressive regions, represented by the Ningshao Plain, have been affected by seawater intrusion in history and generally face problems such as dense lakes and swamps, frequent saline tides, and severe soil salinization. Therefore, the primary task of regional development is to comprehensively manage and utilize the water environment, which has gradually made water conservancy construction the core condition for the regional development of marine ingressive regions. The primary water conservancy task is to divert and store fresh water, block saline tides for the development of agriculture, and improve water transportation conditions to enhance navigation functions for trade transportation, administrative management, and military strategy. Under the support of agricultural development based on water conservancy project and urban economic development based on canal waterways, a unique regional cultural block is formed in the Ningshao Plain as a result of the close linkage and interaction between various sectors within the plain. On the one hand, by adapting to nature and moderately transforming and utilizing land resources, an agricultural system centered on water conservancy facilities is formed. On the other hand, a hierarchical urban-rural system is formed by connecting some originally unrelated towns and villages through linear corridors such as canals and roads. Finally, the correlation morphologies of landscape units and cultural corridors are summarized and extracted at two scales. One is the correlation of natural bases in regional landscape units, manifested as human settlement environments featuring the coupling of landscape, farmlands and settlements in different geographic units such as lakes, plains, and coastlines. The other is the point-axis structural correlation of urban-rural settlement clusters, manifested as the integrated urban-rural settlement model of “town − village − city” linked by transportation channels such as canals and seawalls.

Conclusion Studying the traditional settlement morphology from the regional correlation perspective can shift the research focus from the physical space of ontology elements to the relational space and link the “correlation morphology” with the “ontology morphology”, thus revealing the overall logic and meaning system underlying fragmented spatial representations. This research attempts to provide a foundation for identifying and protecting regional settlement characteristics at a larger scale and further guiding the protection and construction of regional historical and cultural spaces within the framework of territorial spatial planning.