【摘要】 2008年5月12日,中国四川汶川发生里氏8.0级地震,对四川和甘肃的13个县市造成了严重破坏。强烈的主震和余震在地震区造成了大量的滚石、崩塌、滑坡、泥石流、碎屑流等次生山地灾害,大规模滑坡崩塌堵断河道形成堰塞湖。利用5月15日~28日期间基本覆盖重灾区的124幅ADS40航空影像,解译出地震滑坡和崩塌堵塞河道形成的存留时间14天以上的堰塞湖256处。遥感调查发现,堰塞湖集中沿地震破裂带呈带分布,沿河流成串珠状分布的特征;堰塞湖数量分布与地震破裂带距离的关系符合对数衰减规律,负相关系数达到0.9699。结合部分野外实际考察资料,选择物质组成、坝体结构、坝高和最大库容等作为堰塞湖危险性评估指标,制定出极高危险、高危险、中危险和低危险四个危险等级,对查明有危害的32个堰塞湖进行了溃决危险性分级和排序,除已经溢流的11处堰塞湖以外,共分出极高危险的1处、高危险的7处、中危险的5处和低危险的8处。评价结果全部被国家抗震救灾指挥部水利组采纳,用于堰塞湖应急排险工程布设,在堰塞湖应急排险中发挥了作用。并且,对堰塞湖的发展趋势进行了分析,震后5至10年内,由于斜坡失稳,物源丰富,仍有可能产生新的大规模滑坡和泥石流,堵塞河流形成堰塞湖;但随着其后滑坡和泥石流活动趋于减弱,堰塞湖的形成概率将逐渐降低。更多还原

【Abstract】 On 12 May 2008,a devastating mega-earthquake of magnitude 8.0 struck the Wenchuan area,northwestern Sichuan province,China.Wenchuan earthquake with Seismic has intensity 11 inevitably impaired the stability of mountains in the course of massive reverse-thrust strike-slip motion in the fault zone.Geohazards approaching of about 20 thousands were triggered with the types of rock fall,rock avalanches,landslides,debris flows,and earthquake-lakes.The features of the debris dams were examined using the 124 breadth of ADS40 images obtained by airplane during 15 to 28 May 2008,which figured out the 256 dammed lakes with the features of distributing along ruptured zone and river channel.The farther analysis found that the number of dammed lakes reduce with the increase of distance to rupture and obey exponential relation with the correlation coefficient of 0.9699.According to the investigation data,a quick risk evaluation on the potential of outburst of dammed lakes was performed using the indices of material composition of dam,dam height,and water storage capacity of the dam.The dammed lakes were classified as extremely high risk,high risk,medium risk and low risk.The failure risk of 21 debris dams were evaluated according to the indices as 1 with an extremely high danger risk,7 with a high danger,5 with a medium danger and 8 of low danger.The risk evaluation result was totally accepted by state earthquake disaster relief office.And emergency dam treatment for risk reduction was planned based on the assessment which was carried out in successful.The earthquake destroyed the stability of the slopes and produced numerous loose soil and debris in tributaries,which resulting in a prolonged geo-hazards for the area.Landslides and debris flows will continue to develop for at least five to ten years after the Wenchuan earthquake and will cause additional dammed lakes.After then,the probability of dammed lake formation will go down as less activation of landslides and debris-flows.更多还原