摘要
震区滑坡易堵塞河道形成高危型堰塞湖,一旦坝堤溃决,将释放巨大能量,造成严重的地震次生水灾。本文利用多源遥感数据,旨在研究一种检测河道滑坡的快速有效的方法,迅速判断出滑坡位置,为救援减灾提供重要信息。首先,对于灾前CBERS-02B星CCD数据,通过归一化水体指数(NDWI)来提取灾前水体信息主要为河道;由于灾后震区天气状况恶劣,故采用Radarsat-1SAR数据。利用水体在SAR影像上的特性,经过多次试验后使用阈值法来提取河道范围。再对两幅影像提取结果中的河道区域进行交集运算,检测出河道范围内的变化部分。通过上述方法提取的河道信息较为模糊、零散,这些模糊、零散并非都由滑坡堵塞河道造成,而是受噪声影响,在此对河道交集影像做膨胀处理,达到突出滑坡信息的目的,进而得以提取河道真实堵塞范围。最后进行人机交互判读,提取滑坡区域。实验以四川省北川县滑坡灾害为例,证明了本文方法的高效性与可靠性。
Landslides caused by earthquake are prone to block the river channels, leading to the formation of highrisk barrier lake. With the water line rising, these barrier lakes can be highly dangerous. Once the dam of the barrier lake bursts, it will release enormous energy and cause severe earthquake secondary flood disaster. In this paper, multi-source remote sensing data are employed to investigate a fast and effective way to detect landslides, which block the rivers, and quickly locate those disasters. As a result, this detection is able to provide critical in- formation to people who in charge of rescuing sufferers and mitigating the disasters. First, adopting CCD data acquired from CBERS-02B as pre-disaster image, this research extracted river channel information by applying NDWI method, which is based on the difference between Green and NIR bands. Radarsat-lSAR data was used hired as post-disaster image for the reason that optic images are unable to work in the condition of bad weather. Due to its particular characteristic, the post-disaster river channel range extracting was conducted by using threshold method after several trails. Second, it operates intersection of these two extracting results to delect the changing sections of the channel. The river channel information obtained by generating the above procedure is vague and discontinuity. And these unexpected phenomena are not all brought by the landslides blockage. Meanwhile it results from speck- les, which come fi＇om the data themselves. Subsequently, this research generated expansion algorithm to the river channel intersection, so that to weaken the speckle effect, and to manifest the characteristic of landslides. The last step is to identify the exact range of landslides via human-computer interacting interpretation. Landslides disaster happening in Beichuan County of Sichuan Province are used in this research to validate the effectiveness and relia- bility of the above methodology.
出处
《自然灾害学报》
CSCD
北大核心
2011年第1期97-104,共8页
Journal of Natural Disasters
基金
国家863重点项目(2007AA120205,2007AA120306,2008AA121305,2009AA12Z101)
重庆市科委科技项目(CSTC2009CB2015)
