机载LiDAR技术在密林区低频泥石流沟调查中的应用

Investigation of Low Frequency Debris Flow Gully in Dense Forest Area on Airborne LiDAR Technology

机载LiDAR是一种主动扫描式遥感技术,其激光脉冲信号能部分穿过多层植被的间隙直达地表,快速获得剥离植被层后的地表高精度三维数据与影像,从而实现真实刻画地貌轮廓和精细揭示地表特征。低频泥石流沟发生间歇期长,地表植被较茂盛,常用的光学影像、InSAR等遥感技术对其解译存在一定的局限性。盐田区地质灾害详细调查采用机载LiDAR技术,提取了0.2 m分辨率的地表DEM数据,生成了精细的山体阴影图像,初步建立了泥石流机载LiDAR图像遥感解译标志,在此基础上对17条沟谷进行了判释,最终确定了4条低频泥石流沟,再结合机载LiDAR的DEM影像详细调查了泥石流沟的形态特征、物源分布,初步分析了泥石流沟的现今活动性。实践证明,在植被覆盖率高的地区,机载LiDAR图像的可解译性明显好于传统的光学遥感,适用于泥石流等地质灾害隐患的早期识别与后续调查。

Airborne LiDAR is an active scanning remote sensing technology.Its laser pulse signal can partially pass through the gap of multi-layer vegetation to the surface,and quickly obtain high-precision three-dimensional data and images of the surface after stripping the vegetation layer,so as to truly depict the landform contour and finely restore the surface features.The low-frequency debris flow gully has a long intermittent period and the surface vegetation is relatively lush.The commonly used remote sensing technologies such as optical image and InSAR have certain limitations on its interpretation.The pilot work of airborne LiDAR was carried out for the detailed investigation of geological disasters in Yantian District.The surface DEM data with a resolution of 0.2 m was extracted,and the fine mountain shadow image was generated.The remote sensing interpretation mark of debris flow airborne LiDAR image was preliminarily established.On this basis,17 gullies were interpreted,and finally 4 low-frequency debris flow gullies were determined.Combined with the DEM image of airborne LiDAR,the morphological characteristics and material source distribution of debris flow gullies were investigated in detail,and the present activity of debris flow gully was preliminarily analyzed.Practice has proved that in areas with high vegetation coverage,the interpretability of airborne LiDAR images is significantly better than that of traditional optical remote sensing,and is suitable for early identification and follow-up investigation of hidden dangers of geological disasters such as debris flow.