汶川地震对千佛山风景区造成严重的影响,直接诱发滑坡10处,崩塌数十处,形成大小堵塞坝4座,由此形成的松散物质总量大于1 700×104m3。2008年雨季有5条支沟暴发泥石流。在泥石流成因分析的基础上,选择流域形状、流域发育程度、沟床纵比降、山坡平均坡降、地层岩性和距发震断层距离6个指标,利用潜在泥石流判识模型,对流域内其余9条支沟进行了判断。结果显示,大部分沟道都具备形成泥石流的潜在条件。2009年雨季研究区全面暴发的大规模泥石流,验证判识的可靠性,表明该模型可以用于灾区潜在泥石流的判识。
Qianfoshan scenic spot,located in northwest of Anxian County,Sichuan Province,was heavily hit by the Wenchuan Earthquake.Taking the scenic spot as study area,researches on characteristics and discrimination of debris flows following the Earthquake were conducted.Based on remote sensing interpretation and field survey,it was found out that 10 landslides and dozens of rock avalanches and 4 barrier dams were induced by the earthquake,which could provide abundant loose materials for the subsequent debris flows and totaled up to 17 million m3 in the study area.There were 14 branches in this area and most of them were still in its infancy,which favored the formation of flow concentration and surface runoff.Additionally,rainfall is abundant in the area,and therefore 5 debris flows had been occurred during the rainy season of 2008.To study the properties of the other 9 branches,on the basis of cause analysis of debris flows in this area,the watershed integrity coefficient,relative cutting degree,mean channel gradient,mean mountain slope,stratum lithology and the distance of geometrical center to the fault were selected as discrimination parameters.Using these parameters,the 9 branches were discriminated by the Fisher Discrimination Model.Results showed that most branches were potential debris flow gullies.In August 2009,all branches burst out large-size debris flows in the study area,which verified effectiveness and feasibility of the model.However,this model had still room for much improvement.
[1] 唐川,梁京涛.汶川震区北川9.24暴雨泥石流特征研究[J].工程地质学报,2008,16(6):751～758.
[2] 游勇,柳金峰,陈兴长.“5.12”汶川地震后北川苏保河流域泥石流危害及特征[J].山地学报,2010,28(3):358～366.
[3] 胡凯衡,游勇,庄建琦,等.北川地震重灾区泥石流特征与减灾对策[J].地理科学,2010,30(4):566～570.
[4] 崔鹏,韦方强,何思明,等.5.12汶川地震诱发的山地灾害及减灾措施[J].山地学报,2008,26(3):280～282.
[5] 谢洪,钟敦伦,矫震,等.2008年汶川地震重灾区的泥石流[J].山地学报,2009,27(4):501～509.
[6] 胡凯衡,李泳,韦方强.泥石流流域集水区面积限值与一级水系数目关系[J].地理科学,2005,25(4):473～477.
[7] 徐刚.坡面泥石流流域地貌要素的概率分布[J].自然灾害学报,2005,14(2):70～74.
[8] Chen J C,Lin C W,Wang L C.Geomorphic Characteristics of Hillslope and Channelized Debris Flows:A Case Study in the Sh-itou Area of Central Taiwan[J].Journal of Mountain Science, 2009,6:266-273.
[9] 陈杰,韦方强,崔鹏.小江流域泥石流堆积扇形成的制约因素及其特征[J].地理科学,2005,25(6):704～708.
[10] 李泳,胡凯衡,苏凤环,等.流域演化与泥石流的系统性-以云南东川蒋家沟为例[J].山地学报,2009,27(4):449～456.
[11] 崔鹏.泥石流地貌要素的统计分析[C] //唐邦兴.第二届全国泥石流学术会议论文集.北京:科学出版社,1991:296～302.
[12] 李泳,胡凯衡,崔鹏,等.泥石流流域的形态特征[J].山地学报,2002,20(1):1～11.
[13] Li Y,Su P C,Cui P,et al.A Probabilistic View of Debris Flow[J].Journal of Mountain Science,2008,5(2):91-97.
[14] 陈兴长.汶川地震极震区泥石流活动特征与潜在泥石流判识[D].成都:中国科学院成都山地灾害与环境研究所,2010: 104～110.
[15] 马宗晋.中国大陆地震分区及其动力学讨论[C] //中国地质学会构造地质专业委员会.国际大陆岩石圈构造演化与动力学讨论会——第三届全国构造地质会议论文选集(Ⅱ):前寒武纪构造、活动构造与地震以及其他.北京:科学出版社, 1990:86～89.
[16] 张培震,徐锡伟,闻学泽,等.2008年汶川8.0级地震发震断裂的滑动速率、复发周期和构造成因[J].地球物理学报,2008,51(4):1066～1073.
[17] Lin A M,Ren Z K,Jia D,et al.Co-seismic thrusting rupture and slip distribution produced by the 2008 Mw 7.9 Wenchuan earthquake,China[J].Tectonophysics,2009,471(3-4):203-215.
[18] 唐川,朱大奎.基于GIS技术的泥石流风险评价研究[J]. 地理科学,2002,22(3):300～304.
[19] 唐川,张军,万石云,等.基于高分辨率遥感影像的城市泥石流灾害损失评估[J].地理科学,2006,26(3):358～363.
[20] 原立峰.基于SVM的泥石流危险度评价研究[J].地理科学, 2008,28(2):296～300.
[21] 刘希林,陈宜娟.泥石流风险区划方法及其应用——以四川西部地区为例[J].地理科学,2010,30(4):558～565.
[22] Huang R Q,Li W L.Development and distribution of geohazards triggered by the 5.12 Wenchuan Earthquake in China[J].Sci-ence in China Series E:Technological Sciences,2009,52(4): 810-819.
[23] 黄润秋,李为乐.汶川大地震触发地质灾害的断层效应分析[J].工程地质学报,2009,17(1):19～28. Characteristics and Discrimination of Debris Flows
