On September 26-27, 2024, a field seminar on debris flows in China will take place along the Chengdu – Qingping – Wenchuan – Yinxiu – Chengdu route that was the epicenter of the 2008 Wenchuan earthquake. On May 12, 2008, a catastrophic earthquake with an 8.0 magnitude occurred in Wenchuan County, China. This is one of the most destructive earthquakes in China since the last century. The Wenchuan earthquake impacted an area of 300,000 km2, most of the intensively affected area located in the Longmen Mountains of Sichuan Province. The earthquake triggered immediately 2,273 large-scale debris flows and resulted in long-term effects on the natural environment. We envisage visiting the post-earthquake debris flow gullies including Wenjia Gully, Qipan Gully, Chediguan Gully, Niujuan Gully, and Hongchun Gully.
1. Wenjia Gully
Wenjia Gully is a newly added debris flow ravine after the Wenchuan earthquake. The earthquake triggered a large-scale high-speed remote landslide-debris flow, laying a good material source foundation. Since the earthquake, Wenjia Gully has become the focus of research on earthquake induced landslides, landslide-debris flows, and post-earthquake debris flows. Currently, there are still many potential material sources in the gully, which is highly likely to cause large-scale debris flow disasters.
2. Qipan Gully
Qipan Gully is a gully where debris flow occurred frequently. A debris flow erupted after the Diexi earthquake in 1933; in the second half of the 1960s and 1970s, debris flows erupted more frequently, mostly once a year. In addition, the Wenchuan earthquake induced many collapse deposits, potential landslides and barrier dams, which made the Qipan Gully debris flow more active.
3. Chediguan Gully
Chediguan Gully is one of the most active debris flow gullies in Wenchuan earthquake-affected area. Affected by the Wenchuan earthquake, the debris flow material source of this gully is rich and debris flow erupts frequently. In 2010, 2011, 2013 and 2014, debris flows erupted many times, blocking road and Minjiang River repeatedly.
4. Hongchun Gully
On August 14, 2010, triggered by the rainstorm, the debris flow in Hongchun Gully erupted, and about 1 million m3 of material was washed down, blocking the Minjiang River and destroying many houses and water supply facilities in Yingxiu Town. During emergency treatment, an extreme rainstorm on August 18 triggered debris flow in the gully again, resulting in 13 deaths and 59 missing. More than 8,000 people were transfered, and the economic losses were serious.
5. Niujuan Gully
Niujuan Gully is located in the epicenter area of the Wenchuan earthquake. On the day of the earthquake, 11 debris flows occurred in the gully. After the earthquake, the large-scale debris flows occurred many times in 2008, 2010, 2013, and caused great economic losses and casualties.