藏北高原砾石粒径高光谱特征及遥感定量反演研究

Hyperspectral Characteristics and Quantitative Remote Sensing Inversion of Gravel Grain Size in the North Tibetan Plateau

藏北高原地区草地不断退化,荒漠化日剧严重;估算砾石粒径对于荒漠化评价及动态监测具有重要意义。基于高光谱遥感技术,结合地面调查、GPS定位、砾石光谱测定和砾石粒径测定,优选出与砾石粒径相关性最高的波段,并建立砾石粒径与敏感波段之间的线性拟合模型,利用高分五号高光谱影像对实验区的砾石粒径空间分布特征进行了提取。主要结论:相关性较好的波段在369.9、371.5和910.5 nm,其中一阶导数在910.5 nm处的光谱值与砾石粒径的拟合效果是最好的(R^(2)=0.738);不同光谱吸收参数与砾石粒径的拟合对比,在2340 nm附近的吸收面积与砾石粒径建立的拟合回归模型的拟合精度是比较高的(R^(2)=0.728);对砾石粒径进行空间遥感反演,精度达到70%,并简要分析砾石粒径的空间分布特征,为藏北高原的荒漠化分析提供了参考依据。

As grassland degradation and desertification are becoming more serious in the northern Tibetan plateau,estimating gravel grain size is important for desertification evaluation and dynamic monitoring.Based on hyperspectral remote sensing technology,this paper combines ground survey,GPS positioning,gravel spectroscopy and gravel grain size determination,preferably selecting the waveband with the highest correlation with gravel grain size,and establishes a linear fitting model between gravel grain size and sensitive waveband,and extracts the spatial distribution characteristics of gravel grain size in the experimental area using hyperspectral images of HMS-5.The results show that:the bands with better correlation are at 369.9,371.5 and 910.5 nm,where the first-order derivative at 910.5 nm has the best fitting effect with gravel grain diameter(R^(2)=0.738);the fitting comparison of different spectral absorption parameters with gravel grain diameter,the fitting accuracy of the fitted regression model established by the absorption area near 2340 nm and the gravel grain diameter is The fitting accuracy of the fitted regression model is relatively high(R^(2)=0.728);in the inversion of gravel grain size by spatial remote sensing,the accuracy reaches 70%,as well as briefly analyzing the spatial distribution characteristics of gravel grain size,which provides a reference basis for the desertification analysis of the northern Tibetan plateau.