Abstract
The 2008 Wenchuan earthquake destroyed large areas of vegetation in the Baisha River and Longxi River basins, in Dujiangyan County, China. There were several debris flow events in these mountainous river basins after 2008. Currently, these damaged vegetation areas are in various stages of recovery. This recovery vegetation improves the resistance of slopes to both surficial erosion and mass wasting. We introduce a probabilistic approach to determining the relationships between damaged vegetation and slope materials’ stability, and model the sediment and flow (hydrological) connectivity index to detect the hydrological changes in a given river basin, using the multi-temporal (1994–2014) remote-sensing images to monitor the vegetation recovery processes. Our results demonstrated that the earthquake-damaged vegetation areas have coupling relationships with topographic environment and slope material properties, and can be used to assess the slope material stability. Further, our analysis results showed that the areas with horizontal distance to river streams <500 m are areas that actively contribute sediment to the stream channel network, and are main material sources for debris flow processes in one given mountainous basin.
Highlights
The 2008 Wenchuan Earthquake with its strong ground motion triggered a great number of landslides [1,2,3,4,5] that caused large areas of vegetation destruction in the vegetation-covered mountain areas
The results indicated that high susceptibility areas were zonally distributed along the steep slopes of the stream channels and the bare areas of the mountain top (Figure 7a), the susceptibility of these vegetation-damaged areas had an obvious increase after the earthquake (Figure 7b), and the slope material stability in these damaged areas showed some improvement with the vegetation recovery a few years after the earthquake (Figure 7c)
We presented a probabilistic approach for slope material stability analysis that quantitatively relates the earthquake-damaged vegetation data with topographical and material properties in a given river basin
Summary
The 2008 Wenchuan Earthquake with its strong ground motion triggered a great number of landslides [1,2,3,4,5] that caused large areas of vegetation destruction in the vegetation-covered mountain areas. Most of the damaged vegetation was distributed along both sides of the river, causing erosion and formation of debris flows [2,7]. The areas of damaged vegetation are at various stages of recovery, and some fully recovered within only a few years of the earthquake. These recovered vegetation areas improve the resistance of slopes to both surficial erosion and mass wasting.
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