This tool takes an input digital elevation model (DEM) and creates an output raster where every grid cell contains the flood order of that cell within the DEM. The flood order is the sequence of grid cells that are encountered during a search, starting from the raster grid edges and the lowest grid cell, moving inward at increasing elevations. This is in fact similar to how the highly efficient Wang and Liu (2006) depression filling algorithm and the Breach Depressions (Fast) operates. The output flood order raster contains the sequential order, from lowest edge cell to the highest pixel in the DEM.

Like the fill_depressions tool, flood_order will read the entire DEM into memory. This may make the algorithm ill suited to processing massive DEMs except where the user's computer has substantial memory (RAM) resources.

## Reference

Wang, L., and Liu, H. (2006). An efficient method for identifying and filling surface depressions in digital elevation models for hydrologic analysis and modelling. International Journal of Geographical Information Science, 20(2), 193-213.

## See Also

fill_depressions

## Function Signature

`def flood_order(self, dem: Raster) -> Raster: ...`

## Project Links

WbW Homepage User Manual Support WbW