Figure 13. Spatial distributions of (a) potential maximum erosion, (b) slope, and (c) risk of sediment disaster in the catchment area.
The risk of sediment disasters in the Chenyulan River catchment area could be determined using the potential maximum erosion and slope. To explore the difference between analytical results and the actual situation, actual landslide data were investigated. This study ranked the risk of sediment disaster of 269 subdivisions from largest to smallest, and the first 1, 5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, and 196 subdivisions were extracted to estimate their landslide rates (cumulative landslide area of the subdivision/total landslide area in the catchment area). Figure 14 shows that in the top 20 subdivisions, the cumulative landslide area accounted for 40.1% of the total landslide area in the catchment area. For the top 196 subdivisions, the cumulative landslide area accounted for 100% of the total landslide area in the catchment area. The results indicated that the cumulative number of subdivisions was positively correlated with the landslide rate. In areas with limited data, the relational curve between the cumulative number of subdivisions and landslide rate could be used to determine subdivisions with management priorities. This study investigated the number of subdivisions and their spatial distribution in a 70% landslide rate scenario; Figure 14 shows that the number of subdivisions corresponding to this rate was 80. Figures 15 and 16 indicate that the results between the selected subdivisions and actual landslides were mostly consistent.