基于LiDAR、SRTM DEM的祁连山黑河流域十一冰川2000—2012年物质平衡估算

Estimation of Mass Balance of Shiyi Glacier in the Heihe River Basin,Qilian Mountains during 2000-2012 Based on Li DAR and SRTM

以祁连山黑河流域十一冰川为例,利用机载三维激光扫描数据(Light Detection And Ranging,Li DAR)和SRTM DEM数据,在LiDAR点云数据预处理、高程数据配准、校正、误差评估的基础上,建立基于大地测量法的冰川物质平衡计算流程。表明:2000—2012年十一冰川冰面高程变化为-7.47±0.92 m,变化率为-0.62±0.08 m·a^(-1),估算十一冰川的年均物质平衡为-0.53±0.07 m w.e.,累积物质平衡为-6.35±0.78 m w.e.,折合水当量约为(330.4±40.8)×10~4m^3;与其他典型监测冰川物质平衡进行对比和分析,论证了估算结果的可靠性;LiDAR数据具有非常高的精度和空间分辨率,目前关于其在冰川物质平衡研究中的应用很少,论文尝试将其应用于冰川物质平衡变化研究中,具有广阔的发展前景。

Glacier mass balance is the most direct reflection of climate, and its dynamic fluctuation can cause the changes of glacier morphological characteristics and melt water runoff. Usually, glacier mass balance is measured with glaciological and geodetic methods. In this study, geodetic method is used to measure the mass balance of Shiyi Glacier in the Heihe River Basin. Based on Airborne Laser Scanning （Light Detection and Ranging, LiDAR） point cloud data and SRTM （Shuttle Radar Topography Mission） DEM, we establish the process for glacier mass balance calculation. Firstly, LiDAR point cloud data are preprocessed, including filtering （classification） and interpolation. Triangulated irregular network （TIN） filtering algorithm can easily realize the point cloud data filtering to obtain precise ground point cloud data. Based on TIN filtering algorithm, we obtain the ground point cloud. And the DEM is generated from LiDAR data based on natural neighborhood interpolation method, and is resampled to the resolution of 1 m. Then, taking LiDAR DEM as the reference data, multi- source DEM data are matched with cosine curve fitting. The maximum terrain curvature of LiDAR DEM is extracted, and the spatial resolution error is corrected. After those processes, based on error analysis and accuracy assessment, we acquire ice surface change of Shiyi Glacier. Result shows the ice elevation of Shiyi Glacier changed-7.47±0.92 m from 2000 to 2012, with a glacier thinning rate of 0.62±0.08 m· a^-1. According to other related studies, the volume-mass conversion parameter is assumed to be 850±60 kg· m^-3. It is estimated that the average mass balance of Shiyi Glacier is- 0.53 ±0.07 m w.e.· a^-1, and the cumulative mass change of the glacier is-6.35±0.78 m w.e., which is about （330.4±40.8） × 10^4 m^3 water equivalents. Compared to other typical monitors on glacier mass balance, the results is reliable. The summer temperature rise in the study area caused serious mass loss of Shiyi Glacier in recent years. LiDAR point cloud data have high precision and spatial resolution, however it is less used in glacier volume research at present. In this paper, it is applied in measuring glacier mass balance changes, showing the promising prospects and practicability of both the data and the method.