to the Sichuan earthquake disaster area stretching across 30 counties (districts), including Chengdu,
Mianyang, Deyang, Guangyuan, Aba and Ya’an, as well as six cities – a total land area of 76 142 km2
with a population of 13 856 300 (Figure 1).
The study area lies in the transition area from the Tibetan Plateau to Sichuan Basin Since the geology
and geomorphology of the area are complex, it is prone to landslides and debris flows. The climate in this