The rural water—adaptive model and hydrological performance in response to short-duration rainfall in coastal irrigation area: experience and evidence from China

Climate change has intensified global water security challenges. Coastal hilly regions are early human settlement areas and highly sensitive to hydrological disasters. This has led to the development of irrigation district systems with strong water adaptation features. However, degraded water networks, urban-rural disparities in flood management, and labor migration have increased rural flood vulnerability. There is a pressing need to systematically analyze flood adaptation strategies in these areas while identifying traditional villages’ limitations in handling extreme rainfall. Taking the Putian Mulanbei Irrigation District as an example, this study aims to establish a localized water adaptation model based on the hydrological and settlement evolution data across 1500 years. Through the integration of hydrological records, subsurface data, and drainage network characteristics from three representative villages, the Storm Water Management Model (SWMM) and surface diffuse flow analysis are employed to assess traditional settlements’ performance during short-duration extreme rainfall events. The key findings include: (1) The human settlement system in the Mulanbei Irrigation District evolved through mutual adaptation among land-sea changes, water conservancy infrastructure, and settlement development. The establishment of the Mulanbei project system shifted water resource management from decentralized to centralized, providing a critical foundation for flood prevention. This transformation significantly influenced the spatial distribution and organization of traditional villages. (2) When subjected to rainfall events with a return period of 1-10 years, the proportion of average flooded nodes was observed to increase from 44.39% to 79.24%. However, most flooding events persisted for less than 0.2 h, with floods being rapidly discharged into adjacent river systems. (3) Rural streets and lanes were found to function as temporary flood drainage pipes, while flooded nodes were primarily located in building-enclosed paved areas and adjacent low-lying agricultural land. This research provides a basis for integrating traditional water-adaptation strategies with modern flood resilience planning, supporting localized water resilience solutions.