Objective Regional water environment is an important factor influencing the development of regional settlements. During Ming and Qing dynasties, the towns along the Grand Canal in Southern Shandong were greatly influenced by the construction of the Grand Canal and the interference of the Yellow River intruding into the Huaihe River, consequently being endowed with the typical water adaptive spatial characteristics. These spatial characteristics are the result of not only the long-term exploration by local people on the law of water environment, but also the interaction between the aforesaid towns and the Grand Canal for hundreds of years, which will have a positive effect on the development of these towns and the inheritance of canal culture. This research analyzes the ecological wisdom and canal culture contained in these characteristics.

Methods Using the research methods of field investigation and literature review, this research, in combination with the connection and typicality of the relationship between towns and water, selects 8 ones from the 13 towns along the Grand Canal in Southern Shandong as the research object. After that, by virtue of GIS platform and image analysis software, the research explores the water adaptive spatial expression of the eight towns from the perspective of the universality of multiple towns and the typicality of a single town by the method of spatial graphical analysis.

Results Through the dual-perspective analysis of the eight towns as a whole and each single town therein, the research has the water adaptation expression of towns classified into two systems: flood control adaptability based on flood control demand, and water utilization adaptability based on water demand. The flood control adaptability is manifested in three aspects. 1) Avoid flood by virtue of terrain. All the eight towns were initially sited in places with relatively high terrain and built on artificially raised foundations. 2) Stop flood relying on dykes. The governments of Ming and Qing dynasties built large-scale dykes to protect the Grand Canal, which essentially protected the towns along the Grand Canal in Southern Shandong. Town managers also organized the construction of small flood banks or big dykes around the towns, city walls and other flood protection facilities to protect their homes. 3) Discharge flood using ponds. Each of the towns is adjacent to pond or lake that can quickly distribute flood water. Through the implementation of a series of flood control measures, the eight towns have formed a unique town-water pattern, and distinctive dyke and pond landscape. The water utilization adaptability is manifested in two aspects. 1) At the level of the towns as a whole, the eight towns are all distributed on both sides of the Grand Canal, and closely connected with the canal. In addition, they are all located at the intersection between the canal and adjacent land/water transportation corridors. 2) At the level of individual town, the town boundary presents the trend of longitudinal extension along the canal, the location relationship between towns and the canal presents the characteristic of being adjacent to and crossing the canal, the distribution of streets and the orientation of residential buildings both present a parallel or vertical relationship with the canal, and the functional layout of town commerce and the handicraft industry and the distribution of town public space both present the spatial texture of distributing along the canal. The water adaptive spatial characteristics of the eight towns can be summarized into three points based on the analysis of the formation mechanism and spatial expression of the flood control adaptability and the water utilization adaptability. 1) Adapt to the water environment foundation. The flood control measures adopted in the eight towns contain the ecological wisdom of low intervention and localization, which well fits local water environment. 2) Cater to the dividends brought by water transportation. Based on the common foundation of water transportation, the eight towns have established some common characteristics in terms of spatial layout and spatial morphology, and formed a kind for canal town paradigm with strong canal characteristic. 3) Conform to the demand of water transportation. Four types of spaces, namely water conservancy facility sites, water transportation switch sites, water god's sacrificial sites and governmental water conservancy and water transportation sites, have gradually taken shape in the eight towns under the influence of the canal, which are not only functional spaces serving the canal, but also important public activity spaces or cultural spaces to the towns.

Conclusion Water environment is the dominant driving force for the spatial evolution of traditional towns along the Grand Canal in Southern Shandong, and the towns have gradually developed typical water adaptability characteristics under the dual influence of the Yellow River and the Grand Canal. These characteristics are the result of the long-term adaptation of the towns to local water environment, the characterization of the canal landscape in Southern Shandong, and an important part of the world cultural heritage of the Grand Canal.