Sediment-related disasters occur frequently in Taiwan because of special geography environments and torrential rainfall. This study collected 494 cases of severe sediment-related disasters triggered by rainfall from 2006 to 2020. Based on the cases and effective accumulated rainfall (EAR) data that were obtained using quantitative precipitation
estimates, the spatial and temporal characteristics of sediment-related disasters in Taiwan were analyzed.
Moreover, a visual representation of the peak distribution of the EAR in Taiwan was created. The results revealed that
slope failure was the most common disaster (46%), followed by debris flows (27%). The results also indicated that the
peak period of sediment-related disaster was June to October. Such disasters occurred more frequently at night than during the daytime. The relationship between accumulated rainfall and serious sediment-related disasters demonstrated that 90% of the major disasters occurred when the accumulated rainfall was greater than 200 mm. Additionally, the type of sediment-related disaster varied as the amount of rainfall increased or decreased. In all cases, the more rainfall that occurred, the higher that the proportion of debris flow was among the various types of disaster. Furthermore, some trends of sediment-related disasters were identified, which could be used in future disaster prevention measures.
Key Words: Rainfall, landslide, debris flow, quantitative precipitation estimates