基于SPOT6影像的玛旁雍错湖泊面积变化研究

Study on Mapang Yongcuo Lake Area Change Based on SPOT6

针对高原湖泊面积监测问题,采用2017年4月和2018年4月的SPOT6遥感影像,结合DEM数据,首先对数据进行图像镶嵌、正射校正和Gram-Schmidt Pan Sharpening算法融合等处理;再利用归一化差异水体指数提取湖泊整体;然后通过高斯低通滤波器突出水体特征,结合目视解译,选取合适的阈值精确划分水体边界;最后统计得到玛旁雍错湖泊的面积。结果表明,截至2018年4月,玛旁雍错湖泊总面积由412万km2减少到411.4万km2,平均退缩率为0.1%。通过分析普兰气象站的气象数据发现,玛旁雍错湖泊的萎缩与当年降水量变化和气温变化有关,降水量减少、气温升高导致湖泊萎缩,说明气象变化对玛旁雍错湖泊面积变化具有一定的影响。

To address the plateau lake area monitoring problem, we used SPOT6 images from April 2017 and April 2018 and combined them with DEM data. The data was firstly processed with image mosaicing, orthorectification and Gram-Schmidt Pan Sharpening algorithm. Secondly the lake as a whole was extracted with normalized difference water index. The image enhancement was performed with Gaussian Low Pass filter to highlight water body characteristics. Combined with visual interpretation, an appropriate threshold was selected to divide water boundary precisely. Finally the Mapang Yongcuo Lake area was calculated. The results show that as of April 2018, the total area of Mapang Yongcuo Lake has decreased from 4.12 million km2to 4.114 million km2, a decrease of 0.6 million km2, with an average shrinkage rate of 0.1%. Through the analysis of meteorological data from Pulan Meteorological Station, it is found that the shrinkage is positively correlated with the precipitation change in that year, and negatively correlated with temperature change, indicating that meteorological changes have a certain impact on the Mapang Yongcuo Lake area change.