Risk assessment and validation of flood disaster based on fuzzy mathematics

Floods often take place around rivers and plains, which indicates a higher risk of flooding in these areas. This paper adopts fuzzy comprehensive assessment (FCA), simple fuzzy classification (SFC), and the fuzzy similarity method (FSM) to assess flood disaster risk in Kelantan, Malaysia. Validation data, such as the flooded area, paddy area, urban area, residential area, and refuges, were overlaid to validate and analyze the accuracy of flood disaster risk. The results show that (1) 70–75% of flooded areas lie within the higher and highest risk zones, which shows an effective assessment accuracy; (2) paddy, built-up, and residential areas concentrated in the higher and highest risk zones are more likely to be destroyed by flood disasters; (3) 200–225 refuges in the higher and highest risk zones account for around 50% of all refuges, which means that more refuges should be built in the higher and highest risk zones to meet the accommodation requirement; (4) three methods proved to be feasible and effective in evaluating flood disaster risk, among which FCA is more suitable for the study area than the two other methods.