Landslide zoning analysis in Zhouqu under different rainfall warning levels

Landslide zoning is crucial for disaster prevention and reduction in areas of rainfall-triggered landslides. A shallow-layer landslide assessment model was established for Zhouqu area, simulation of the slope stability of extensive area was applied to predict the potential landslide fairly, and evaluation of the migration and conversion laws were performed to determine quantitatively the effect of rainfall on landslide under different rainfall warning levels. The results show that all 169 recorded landslide scars were classified as lower stability-to-defended by SINMAP model, and the susceptible landslide distribution in low-lying area is consistent with that in areas with relatively high topographic precipitation. With the rainfall intensity increases from 10 to 56 mm/h, the landslide and rainfall were found to exhibit a growing power function relation; the potentially unstable region is always the highest, highlighting a critical problem. Moreover, as the basically stable region and potentially unstable region gradually transition into the unstable region and extremely unstable region, respectively, the landslide potential increases gradually, and the hazard level becomes increasingly aggravated; consequently, the potential threat is more serious. When the hourly rainfall exceeds 20 mm, the slope stability is gradually weakened in the stable region, which is gradually migrating into the unstable region, thus triggering landslides, debris slides and flows. When the hourly rainfall exceeds 32 mm, the hazard degree changes qualitatively, caused by the quantitative change, and the geological hazard degree increases significantly. The study can provide a scientific basis for landslide zoning, monitoring, and early warning in the Zhouqu area as well as other alpine gully area.