This tool identifs grid cells in a DEM for which the upslope area extends beyond the raster data extent, so-called 'edge-contamined cells'. If a significant number of edge contaminated cells intersect with your area of interest, it is likely that any estimate of upslope area (i.e. flow accumulation) will be under-estimated.

The user must specify the name (`dem`) of the input digital elevation model (DEM) and the output file (`output`). The DEM must have been hydrologically corrected to remove all spurious depressions and flat areas. DEM pre-processing is usually achieved using either the breach_depressions_least_cost (also breach_depressions_least_cost) or fill_depressions tool.

Additionally, the user must specify the type of flow algorithm used for the analysis (`-flow_type`), which must be one of 'd8', 'mfd', or 'dinf', based on each of the `D8FlowAccumulation`, `FD8FlowAccumulation`, `DInfFlowAccumulation` methods respectively.

## See Also

`D8FlowAccumulation`, `FD8FlowAccumulation`, `DInfFlowAccumulation`

## Function Signature

`def edge_contamination(self, dem: Raster, flow_type: str = "mfd", z_factor: float = -1.0) -> Raster: ...`

## Project Links

WbW Homepage User Manual Support WbW