The disastrous 23 July 2009 debris flow in Xiangshui Gully, Kangding County, Southwestern China |
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| Authors: | Chuan Tang Yonghong Yang Yongchao Su Jun Ding Wenjie Huang |
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| Institution: | TANG Chuan,YANG Yonghong,SU Yongchao,DING Jun,HUANG Wenjie State Key Laboratory of Geohazard Prevention and Geoenvironment Protection,Chengdu University of Technology,Chengdu 610059,China |
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| Abstract: | On 23 July 2009, a catastrophic debris flows were triggered by heavy rainfall in Xiangshui gully, Kangding county, southwestern
China. This debris flow originating shortly after a rainstorm with an intensity of 28 mm per hour transported a total volume
of more than 480×103 m3 debris, depositing the poorly sorted sediment including boulders up to 2–3 m in diameter both onto an existing debris fans
and into the river. Our primary objective for this study was to analyze the characteristics of the triggering rainfall and
the debris supply conditions, and to estimate debris-flow volume, mean velocity, and discharge. A comparison with adjacent
rain-gage records indicates that debris flows in this setting can be produced in response to as little as 17 mm/hour or 3.5
mm/10-minute of rainfall intensity with relatively lower amount of cumulative antecedent rainfall. The field measurement and
the interpretation of the Worldview image indicate that abundant landslides occurred on steep slopes within areas underlain
by highly weathered granite. Using empirical equations that combine flow depth and channel slope, the mean velocity and discharge
of the debris flow were estimated to be 9.2 m/s and 2150 m3/s, respectively. The results contribute to a better understanding of the conditions leading to catastrophic debris flows. |
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| Keywords: | Debris flow Rainfall intensity Debris supply Deposition Velocity China |
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