xrspatial.hydro.flow_direction_dinf.flow_direction_dinf#

xrspatial.hydro.flow_direction_dinf.flow_direction_dinf(agg: DataArray, name: str = 'flow_direction_dinf', boundary: str = 'nan') → DataArray[source]#

Compute D-infinity flow direction for each cell.

Determines flow direction as a continuous angle toward the steepest downslope facet, following the Tarboton (1997) algorithm. The 3x3 neighborhood is divided into 8 triangular facets; the steepest downslope plane gives the flow angle.

Parameters:

  • agg (xarray.DataArray or xr.Dataset) – 2D NumPy, CuPy, NumPy-backed Dask, or CuPy-backed Dask xarray DataArray of elevation values. If a Dataset is passed, the operation is applied to each data variable independently.

  • name (str, default='flow_direction_dinf') – Name of output DataArray.

  • boundary (str, default='nan') – How to handle edges where the kernel extends beyond the raster. 'nan' - fill missing neighbours with NaN (default). 'nearest' - repeat edge values. 'reflect' - mirror at boundary. 'wrap' - periodic / toroidal.

Returns:

2D array of continuous flow direction angles in radians. Valid values are in the range [0, 2*pi). -1.0 indicates a pit or flat with no downslope neighbor. Edge cells and cells with NaN in their 3x3 window are NaN.

Return type:

xarray.DataArray or xr.Dataset

References

Tarboton, D.G. (1997). A new method for the determination of flow directions and upslope areas in grid digital elevation models. Water Resources Research, 33(2), 309-319.