Abstract

Based on images from the Sentinel-2 satellite taken in 2017–2019, a map of shallows in the Yenisei delta was compiled. This paper highlighted the methodological problems that arise at using satellite images for research and mapping of underwater relief; the ways of their solution are offered. Consideration of the depth of penetration of sunlight into the water and analysis of the spectral brightness of underwater objects allow for the determination of the spectrum zone (red zone) optimal for interpreting sandy riverbanks and options for color synthesis. At a limited choice of cloudless images in the Arctic to have images obtained during the minimum water level, not only the imaging season (low-water period) but also interannual runoff fluctuations are taken into account. The water turbidity limits the possibility to interpret the underwater relief. Images obtained with minimal turbidity are selected, and in the case of spreading of turbid waters, multi-temporal images are compared to separate the image of volatile turbid waters from more stable bottom objects; color synthesis is applied at different times. The identification of sandbanks, ridged forms of relief, and the contours of underwater channels are performed by direct interpreting by the variations in the brightness of the image in the red zone. To identify sandy-silty and silty shallows, indicative interpreting based on the distribution of aquatic vegetation on silty deposits is used. The identification of sandbanks, ridged relief forms on them, and the contours of underwater channels are performed by direct interpreting by the variations in the brightness of the image in the red zone. To identify sandy-silty and silty shallows, indicative interpretation of the distribution of aquatic vegetation on silty deposits is used. To highlight the fuzzy boundaries between the shallows and core zones of streams, the brightness quantization of images is applied. Comparison of the Yenisei River delta shallows map compiled from modern photographs with topographic and pilot maps of the 1970–1980th shows a reduction in the area of shallows adjacent to the tips of large islands in the eastern part of the delta. This is in accordance with earlier revealed activation of the erosion of the banks of the branches of the Yenisei delta in the XXI century.

中文翻译：

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从空间影像研究河三角洲水下浮雕的方法论问题（以叶尼塞河三角洲浅滩测绘为例）

摘要

根据 Sentinel-2 卫星在 2017-2019 年拍摄的图像，编制了叶尼塞三角洲浅滩地图。本文重点介绍了使用卫星图像进行水下地形研究和制图时出现的方法问题；提供了他们的解决方法。考虑阳光进入水中的深度并分析水下物体的光谱亮度，可以确定最适合解释沙质河岸和颜色合成选项的光谱区域（红色区域）。在北极无云图像选择有限以获取最低水位期间的图像时，不仅考虑了成像季节（低水位期），还考虑了年际径流波动。水的浊度限制了解释水下地貌的可能性。选择浑浊度最小的图像，在浑水扩散的情况下，通过多时相图像对比，将挥发性浑水图像与更稳定的水底物体分离；在不同的时间应用颜色合成。沙洲、脊状地貌和水下通道的轮廓的识别是通过直接解释红色区域中图像亮度的变化来执行的。为了识别砂质粉质浅滩和粉质浅滩，使用基于粉质沉积物上水生植被分布的指示性解释。沙洲、其上的脊状浮雕和水下通道的轮廓的识别是通过直接解释红色区域中图像亮度的变化来执行的。为了识别沙质粉质和粉质浅滩，使用了粉质沉积物上水生植被分布的指示性解释。为了突出流的浅层和核心区之间的模糊边界，应用了图像的亮度量化。将现代照片编制的叶尼塞河三角洲浅滩地图与 1970 年至 1980 年代的地形图和先导图进行比较，发现三角洲东部大岛尖端附近的浅滩面积有所减少。这与早先揭示的二十一世纪叶尼塞三角洲支流侵蚀的激活是一致的。将现代照片编制的叶尼塞河三角洲浅滩地图与 1970 年至 1980 年代的地形图和先导图进行比较，发现三角洲东部大岛尖端附近的浅滩面积有所减少。这与早先揭示的二十一世纪叶尼塞三角洲支流侵蚀的激活是一致的。将现代照片编制的叶尼塞河三角洲浅滩地图与 1970 年至 1980 年代的地形图和先导图进行比较，发现三角洲东部大岛尖端附近的浅滩面积有所减少。这与早先揭示的二十一世纪叶尼塞三角洲支流侵蚀的激活是一致的。