![]() ![]() Debris flow material blocked Mianyuan River, forming a dam that was 400 m long and 820 m wide. The debris flow peak discharge reached 1,530 m 3/s, and approximately 33.1 × 10 6 m 3 of loose material was transported to the gully mouth. Owing to heavy rainfall on August 13, 2010, the loose material in the channel of Wenjia Gully underwent violent erosion, resulting in a debris flow disaster. However, in the three rainy seasons immediately after the earthquake, five debris flow events were recorded here. Wenjia Gully, in Qingping Township, Mianzhu, Sichuan Province, China, was not a debris flow gully prior to the Wenchuan earthquake. Therefore, they seriously threaten human safety and endanger roads, bridges, houses, and other facilities ( Cui et al., 2013 Chen et al., 2015 Chen K.-T. Post-earthquake debris flows are characterized by their high destructive power, large scale, and the ease with which they form disaster chains (e.g., debris flows block river channels, causing river diversion and flooding of surrounding areas). For example, destructive debris flows are still known to occur in the areas affected by the 1999 Chi-Chi, 2008 Wenchuan, and 2015 Gorkha earthquakes ( Shieh and Tsai, 2009 Zhou et al., 2016 Dahlquist and West, 2019). In general, a devastating earthquake generates an adequate supply of sediment in the form of co-seismic collapses and landslides, which indirectly reduces the rainfall threshold required to trigger a debris flow ( Tang et al., 2012 Ma et al., 2017) catastrophic debris flows can be triggered even by low-intensity rainfall long after an earthquake has occurred. In particular, post-earthquake debris flows have been widely studied owing to their significant destructive power. Numerous studies have attempted to elucidate the debris flow formation process based on rainfall thresholds and sediment supply conditions ( Takahashi, 2007 Santi et al., 2008 Tang et al., 2012 Hungr et al., 2014 Zhang et al., 2014 Fan R. Steep topography, abundant loose material, and concentrated rainfall are three important factors influencing debris flow formation. These disasters are widespread and commonplace in mountainous areas. Four control modes for debris flow disasters in scenic areas are proposed, namely, “blocking + deposit stopping,” “deposit stopping,” “blocking,” and “drainage + deposit stopping,” which provide a systematic control strategy for post-earthquake debris flow disaster management in Jiuzhaigou Valley and other similar scenic areas.ĭebris flows are mixtures of sediment and water that flow down a slope under the influence of gravity. Moreover, based on the example of Jiuzhaigou Valley, corresponding control engineering schemes for debris flow gullies in Xiajijie Lake Gully, Zhuozhui Gully, Xuan Gully, Pingshitou Gully, and West-Zhuozhui Gully are formulated. Based on field investigations and data collected from debris flow control projects in gullies in Jiuzhaigou Valley, China, an engineering planning method for debris flow control projects in scenic areas is herein proposed, and the challenges confronting existing control projects in scenic areas are discussed. It is not possible to realize the rapid planning of any debris flow gully control project in a scenic area and to quantify the volume of debris flow material retained by each engineering structure. Currently, the systematic planning of the entire scenic area is not considered in the treatment of debris flows. Extreme rainfall events in the future will increase the complexities and challenges involved in debris flow control in scenic areas. 5Department of Soil and Water Conservation, National Pingtung University of Science and Technology, Pingtung, TaiwanĬompared with debris flows in other areas, debris flows in scenic areas not only seriously threaten residents, tourists, roads, walkways, and other infrastructure, but also cause considerable damage to the landscapes and ecosystems of these areas.4Compound Disaster Prevention Research Center, General Research Service Center, National Pingtung University of Science and Technology, Pingtung, Taiwan.3University of Chinese Academy of Sciences, Beijing, China.2China-Pakistan Joint Research Center on Earth Sciences, CAS-HEC, Islamabad, Pakistan.1Key Laboratory of Mountain Hazards and Earth Surface Processes, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, China.Xing-Long Gong 1,2,3 Xiao-Qing Chen 1,2,3 Kun-Ting Chen 4,5* Wan-Yu Zhao 1 Jian-Gang Chen 1 ![]()
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