Nonlinear proximity effects of linear cultural heritage as reflected in traditional village morphology along the Grand Canal

Linear cultural heritage is associated with the morphology of adjacent rural settlements, but its spatial effects remain insufficiently quantified. Using China’s Grand Canal as a case study, this study examined the non-linear relationship between Canal proximity and the morphology of adjacent traditional villages. We quantified the morphology of 42 villages using five landscape-pattern indices and applied a Continuous Piecewise Linear model to identify distance thresholds. Six robustness checks were used to evaluate the results. FRACT, AI, and DIVISION showed a consistent breakpoint at approximately 3.5 km. Within this zone, villages closer to the Canal had more regular boundaries, higher aggregation, and lower fragmentation. COHESION and LSI showed less distinct breakpoints at 6.5 and 15.5 km, respectively, indicating multi-scale spatial responses. Village morphology was also associated with the latitudinal gradient. These findings support the delineation of heritage influence zones and spatially differentiated conservation strategies for linear cultural heritage.