Calculation of the return period for shallow landslides triggered by extreme rainfall

To quantitatively assess the dynamic risk of rainfall-induced shallow landslides over extended periods and provide references for geological disaster risk prevention and mitigation in southeast China , this study proposes a method for calculating the return period of shallow landslides considering rainfall uncertainty. The specific calculation framework includes: (1) Constructing the joint distribution of extreme rainfall intensity-duration (I-D) based on the Copula function; (2) Determining the I-D threshold for landslides based on geological conditions and hydrological factors; (3) Using the Monte Carlo method to simulate the probability that the joint I-D distribution of extreme rainfall events exceeds the I-D threshold, representing the probability of slope failure, and further calculating the landslide return period. The feasibility of this method was validated at a potential landslide site in Majian Town, Zhejiang Province. The predicted return period for the landslide is 17 years. It is recommended that relevant preventive and mitigation measures be implemented to reduce potential disaster losses.