Vegetation map was downloaded from An updated Vegetation Map of China (1:1000000), and was cropped to the extent of study area.
DEM was obtained from open source ALOS PALSAR data. Spatial resolution is 12.5 m, search date range is from 2007-1-1 to 2007-2-28.
Sentinel-2 satellite images was pre-processed on Google Earth Engine with self written code.
I extracted streamline of Suli County following procedures provided by ESRI hydrology tools.
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Fill the sinks in above mentioned DEM products with default parameters (without specifying z value). Generally, there won't be many sinks in DEM product with ~10 m resolution.
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Calculate flow direction, values(1,2,4,8,16,32,64,128) indicating direction.
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Calculate flow flux, values indicating how many pixels lead to this pixel(?).
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Decide a flow threshold. Generally the threshold value is the flux value of the origin of the minimal stream of interest.
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Convert the flow flux raster to binary raster based on flow threshold.
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Use stream link function to assign unique values to sections of a raster linear network between intersections in case later stream order calculation.
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Vectorize stream link raster.