Characteristics and risk analysis of Qinglin debris flow induced by “5.12” Wenchuan Earthquake in Beichuan County, Sichuan, China

"5.12" Wenchuan Earthquake occurred in western Sichuan, China on May 12, 2008. Many potential geo-hazards, induced by this earthquake, were developing. Qinglin gully had no recorders of debris flow before the earthquake and has been the most serious one after that. Based on field survey, we studied the characteristics of debris flow in Qinglin gully by using GIS technology. Results show that three large scale landslides with 0.76 million m³, 0.94 million m³ and 12 million m³ in volume respectively, induced by the earthquake, were main sources of the debris flow. The debris flow, induced by intensive rainfall on 24 September 2008, was a large scale turbulent one. We analyzed the risk of Qinglin debris flow using the debris flow risk assessment model of momentum principle. Results illuminate that Qinglin gully has the characteristics of high frequency and large scale and severe risks after the earthquake. It was also found, even if vegetation was lush, big debris flows could occur due to background changing of disasters in quake-hit area. Consequently, the next researches should focus on potential debris flows, which is of great significance to post-disaster restoration and reconstruction.