Objectives As an important part of cultural heritage, immovable cultural relics are facing increasing risks of rainstorm and flood disaster. In order to improve the capabilities of prevention on rainstorm and flood disaster for immovable cultural relics, we proposed a risk assessment method based on the theory of natural disaster risk assessment considering the seasonal variation of rainstorm and flood disaster, and took 24 national ancient sites in 18 counties in Fujian Province as an example.

Methods The regional L-moments method was used to acquire the rainfall values of various return periods in different season, and analyze the characteristics of seasonal rainstorm and flood risk.We estimated the risk from three aspects: Hazard factors, disaster formative environment and hazard bearing body of cultural heritages. The coefficient of variation method, entropy weight method and Delphi method were adopted to calculate the weight of those three aspects.

Results The results show that the seasonal difference of risk assessment results is obvious, which indicates that the assessment method is feasible. The risk of rainstorm and flood was the highest in the second quarter, followed by the first and the third quarters, and the spatial distribution of risk in different seasons was significantly different. In the first and the second quarters, the risk of rainstorm and flood was high in coastal and northern counties, and low in central counties. The risks in the third and the fourth quarters were high in the coastal areas and low in the inland areas.

Conclusions The proposed model for immovable cultural relics can well reflect the seasonal difference of rainstorm and flood risk, and is suitable for regions with large seasonal difference of rainstorm and flood disaster. The results of seasonal differences can provide scientific reference for disaster prevention and mitigation planning for immovable cultural relics.