Quantitative risk assessment for the compound drought-wildfire disaster

Compound drought-wildfire (CDW) disasters, driven by the interaction of drought and wildfire, are increasing worldwide. Despite this trend, there is still a lack of methodologies for quantitatively assessing CDW disaster risk, which makes it difficult to develop response plans. Therefore, this study proposes a quantifiable methodology for CDW risk assessment by applying a drought scenario to simulate drought induced weather conditions and the Fire Weather Index (FWI) to quantify potential wildfire spread and severity. The drought scenarios represent a 12-month drought with a 30-year return period, whereas the normal scenarios are based on typical regional climate conditions. Based on each scenario, DFWI and NFWI were calculated to quantify the risks of CDW disasters and single wildfire disasters. The estimated DFWIs showed the quantitative risk of CDW disasters in each region and monthly risk maps were developed to highlight high risk areas. By comparing DFWI and NFWI, the impact of drought on wildfire risk was analyzed and presented quantitatively. These results provide essential information for disaster response strategies for CDW disasters and emphasize the need for integrated drought and wildfire response management by clearly demonstrating the impact of drought on wildfire risk.