Research on the Debris Flow Hazards after the Wenchuan Earthquake in Bayi Gully, Longchi, Dujiangyan, Sichuan Province, China

摘要

Many debris flow hazards were triggered in Earthquake area after the Wenchuan Earthquake. In these debris flow hazards, the most notable one is the debris flow in Bayi Gully on Aug.13, 2010. Bayi Gully was a debris flow gully before the Wenchuan Earthquake, in the first three raining seasons after the Wenchuan Earthquake, there are 4 times debris flows were triggered, and the largest and most harmful debris flow was triggered on August 13, 2010. The total rainfall during the debris flow of August 13 was 229 mm, and the duration of debris flow was 1 hour and 40 min. The density of debris flow was 1.88g·cm~(-3), the discharge is 1 082m~3·s~(-1), the yield stress of debris flows is more than 6700 Pa, The volume of debris flow was 1.16million cubic meter. The debris flow claimed 2 people are lost, 1 people is wounded, 140 houses are seriously destroyed, DuWen road were silted and check dams, drainage engineering were destroyed. And 15 million (RMB) economic lost. Only 30% sediment of debris deposition was taken away by the 4 times debris flows. New debris flow will be triggered by rainfall in Bayi Gully in the future. It will be a long term work to prevent the debris flows in Bayi Gully.