Depressions, otherwise known as pits, are areas of a landscape wherein flow ultimately terminates without reaching an ocean or the edge of a digital elevation model.
Depressions, Pits, and Sinks¶
Depressions have been called by a variety of names. To clarify this mess, Lindsay (2016) provides a typology. This typology is followed here.
For reference, the original DEM appears as follows:
import richdem as rd import numpy as np beau = rd.rdarray(np.load('imgs/beauford.npz')['beauford'], no_data=-9999) beaufig = rd.rdShow(beau, ignore_colours=, axes=False, cmap='jet', figsize=(8,5.5))
Depression-breaching is used to dig channels from the pit cells of a DEM to the nearest cells (in priority-flood sense) outside of the depression containing the pit. This resolves the depression as all cells in the depression now have a drainage path to the edge of the DEM.
The result looks as follows:
beau_breached = rd.BreachDepressions(beau, in_place=False) beaufig_breached = rd.rdShow(beau_breached, ignore_colours=, axes=False, cmap='jet', vmin=beaufig['vmin'], vmax=beaufig['vmax'], figsize=(8,5.5))
We can visualize the difference between the two like so:
beau_diff = beau_breached - beau beaufig_diff = rd.rdShow(beau_diff, ignore_colours=, axes=False, cmap='jet', figsize=(8,5.5))
Complete Breaching is available via the following commands: