Migrating from PCRaster

earthkit-hydro can be used as a drop-in replacement for PCRaster in many cases, offering a substantial speedup. As a design decision, it does not attempt to match PCRaster’s API, meaning that migrated code may look slightly different.

Here is a useful summary table of some common translations between earthkit-hydro and PCRaster.

PCRaster	earthkit-hydro	Note
accuflux	upstream.sum
catchmenttotal	upstream.sum
downstream	move.upstream
upstream	move.downstream
catchment	catchments.find
subcatchment	catchments.find	overwrite=False
path	upstream.max
ldddist	distance.min	friction input is slightly different from weights; by default, distance between two nodes is one regardless of diagonal
downstreamdist	distance.to_sink	Same caveats as for ldddist
slopelength	distance.to_source	path=”longest”; same caveats as for ldddist
lddmask	subnetwork.from_mask
abs, sin, cos, tan, …	np.abs, np.sin, np.cos, np.tan, …	Any array operations can be directly used (example shown for NumPy backend)

Points of difference

• earthkit-hydro treats missing values as np.nans i.e. any arithmetic involving a missing value will return a missing value. PCRaster does not always handle missing values exactly the same.

• earthkit-hydro can handle vector fields.