基于多源遥感数据的青藏公路走廊积雪灾害评价

Evaluation on snow calamity along Qinghai-Tibet Highway corridor based on multi-source remote sensing data

利用多源遥感数据信息,开展了青藏公路走廊所在区域的积雪空间分布特征调查,对重点路段进行了积雪灾害评估。充分考虑了地形和山地积雪特征,采用多种去云过程和步骤相结合,完成逐日积雪云量消除。利用无云MODIS逐日积雪面积数据统计年均积雪日数,在大尺度范围内提取公路积雪信息,判断整个线路中重点积雪路段。利用Landsat影像的高空间分辨率特性,采用归一化差值积雪指数阈值法识别重点积雪路段各里程处积雪和非积雪区域,有效提取了公路重点积雪路段积雪空间分布信息,更加精确地对公路积雪灾害进行监测和评估。基于影像时空信息对云覆盖像元下地表温度信息进行了重建,并对代表性问题进行分析验证,采用重建的MODIS逐日地表温度计算年均地表温度,对青藏公路走廊沿线重点积雪路段的积雪灾害信息进行判断提取。分析结果表明:评价方法可以有效地对青藏公路走廊沿线积雪分布进行监测与提取,重点积雪区域主要分布在昆仑山、五道梁、风火山、唐古拉山,其中部分路段积雪量较大且易发生道路结冰现象。

Based on the multi-source remote sensing data, the spatial distribution characteristic of the snow cover along the Qinghai-Tibet Highway corridor was surveyed, and the snow calamity was evaluated for key road sections. Terrain and mountain snow cover characteristics were fully considered, the cloud-removing of daily snow cover was finished by jointly using of types of cloud-removing processes and steps. The annual average snow cover days were statistically counted by the data of cloud-removed MODIS daily snow cover area. The highway snow cover information within a large scale was extracted and used to determine the key snow cover sections along the entire road. Taking the advantage of high spatial resolution of Landsat images, the snow area and snow-free area of key sections were identified by using normalized difference snow index threshold method, the spatial distribution information of snow cover of key sections along the highway was effectively extracted, which would contribute to more accurate observation and evaluation on highway snow calamity. Based on the temporal-spatial information of images, the ground surface temperature information under cloud cover was rebuilt, and the representative questions were analyzed and verified. Using the reconstructed MODIS daily ground surface temperature, annual average ground surface temperature was computed, the snow calamity information in the key snow cover road sections along the Qinghai-Tibet Highway corridor were determined and extracted. Analysis result indicates that evaluation method is able to effectively monitor and extract the snow cover distribution along the Qinghai-Tibet Highway corridor, and the key snow cover regions are Kunlun Mountains, Wudaoliang, Fenghuo Mountain and Tanggula Mountains, part of road sections have large amount of snow accumulation and are subject to road icing. 1 tab, 12 figs, 31 refs.