Watershed Analysis Methods

[ecor]

Dear Developers,

I kindly submit my contribution to "terra" package adding some watershed analysis functions which I need and I have developed within the package in my fork ecor/terra.

Here find attached a summary of the added functions written in C/C++ and declared as methods in R:

help("watershed2") ## it extracts a watershed from D8 flow direction
help("flowAccu2") ## Flow Accumulation
help("flowAccu2_weight") ## Flow Accumulation with weight for each pixels (e.g. Total Contributing Area expressed in m2 or km2 if the CRS is lat lon )
help("pitfinder2") ## it finds pits in a digital elevation model through D8 flow directions
help("NIDP2") ## Number of immediate adjacent cells flowing into each cell (Watershed Analysis)

See also discussions about the need of this kind of tools in the following issues:

#1221
#1180

I 'm available for any possible discussion.

Thank you for the job

Best

Emanuele Cordano
@ecor

[rhijmans]

Thank you very much for all this work. I have been a bit busy but will have a look asap.

[ecor]

Thanks for accepting pull request. I just saw that the "watershed analysis" function names was changed. I will update the examples with the new names in order that all checks on examples work correctly. I will do ASAP and submit a new pull request. I also corrected my name and surname in the DESCRIPTION file.