Hazard assessment of rainstorm-geohazard disaster chain based on multiple scenarios

Hazard assessment is an important task in addressing disaster chain risk. According to the formation process of the three rainstorm-geohazard disaster chains, the disaster chain hazard values were transformed into the sum of the hazard values of the rainstorm and secondary geohazards. Multiple rainstorm scenarios were expressed using return periods and durations, and rainstorm intensity is obtained by fitting based on historical rainfall data. Combining DE-LightGBM and SMOTE-Tomek, the hazard values of secondary geohazards were calculated step by step by integrating rainstorm intensity, environmental factors and the formation process of secondary geohazards as input variables. Most of the study areas were classified as low hazard and very low hazard. The areas of medium hazard and high hazard have spatial agglomeration characteristics and were closely related to the distribution of the river system. The hazard distribution of disaster chains and secondary geohazards is basically positively correlated with rainstorm intensity. The hazard value characteristics of multi-level secondary geohazards can reflect the effect of amplifying damage by the disaster chain. The model shows good performance on the basis of RSME, accuracy and area under the curve.