This tool can be used to identify the main channel in a stream network. The user must input a D8 pointer (flow direction) raster (d8_pointer), and a streams raster (streams_raster
). The pointer raster is used to traverse the stream network and should only be created using the d8_pointer tool. By default, the pointer raster is assumed to use the clockwise indexing method used by WhiteboxTools:
. | . | . |
64 | 128 | 1 |
32 | 0 | 2 |
16 | 8 | 4 |
If the pointer file contains ESRI flow direction values instead, you must set esri_pointer=True
parameter must be specified.
The streams raster should have been created using one of the DEM-based stream mapping methods, i.e. contributing area thresholding. Stream grid cells are designated in the streams image as all positive, non-zero values. All non-stream cells will be assigned the NoData value in the output image, unless the user sets zero_background=True
.
The algorithm operates by traversing each stream and identifying the longest stream-path draining to each outlet. When a confluence is encountered, the traverse follows the branch with the larger distance-to-head.
def find_main_stem(self, d8_pointer: Raster, streams_raster: Raster, esri_pointer: bool = False, zero_background: bool = False) -> Raster: ...