Landslide-dammed lakes, which are formed by earthquake or heavy rainfall, are highly unstable, with more than 40% failing within 1 week after formation. Failure of such lakes poses severe threats to downstream communities.Rapid detection of the formation of landslide-dammed lakes and assessment of potential breach impacts are crucial for government authorities in preventing major catastrophes. Studies on landslide-dammed lakes have mostly simulated scenarios where inflow fills the barrier lake, leading to overtopping failure. Although overtopping from excessive
upstream inflow is a major cause of landslide-dammed lake breaches, many studies have neglected the influence
of heavy rainfall following earthquakes. This oversight can lead to the underestimation of breach risk, given that extensive rainfall markedly increases the risk of failure. In the present study, we developed a hybrid method for evaluating the effects of landslide-dammed lake breaches induced by heavy rainfall following earthquakes. First, precipitation forecast data from the Central Weather Administration and the distributed hydrological model wflow_sbm were combined to simulate catchment hydrological processes. Then, the HEC-RAS 2D hydraulic breach module was applied to simulate the flood wave propagation due to landslide-dammed lake breaches. Our findings suggest that heavy rainfall strengthens the effects of flood waves that occur because of landslide-dammed lake breaches. Overall, this study clarifies the effects of landslide-dammed lake breaches and provides valuable insights for disaster emergency response and public authority operational strategies.
Key Words: WFLOW, HEC-RAS, landslide-dammed lake breach, normalized difference water index, water body
detection