DEMDrainageBasin: Calculate basin delineation using a DEM
In ECCC-MSC/Basin-Delineation: Finds upstream area and upstream stations

Create a drainage basin shapefile using a DEM

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DEMDrainageBasin(point, DEM_path, DEM_source = "NTS", saga_env, outdir,
  pointbuffer = 50, clip_size = 50000, projected_CRS, upstr_method = "D8",
  upstr_threshold = 35000, prelim_basin = NULL, ...)

`point`	a SpatialPointsDataFrame corresponding to a hydrometric station. Must be in same coordinates system as DEM and coordinate system must be projected (not lat/long). Must have 'longitude' and 'latitude' columns in the data frame.
`DEM_path`	One of: (1) a file path to a directory containing DEM files either in the the format n tiles will be downloaded (if DEM_source='CDEM', 'CDED' etc.), (2) a file path to a dem file in SAGA format. The DEM should be in a projected coordinate system and the coordinate system should match that of the point (e.g. Canada Albers Conformal Conic)
`DEM_source`	character, one of: c('CDED', 'NED', 'CDEM, CDSM', 'SHEDS'). Ignored if a DEM file is supplied to DEM_path
`saga_env`	A SAGA geoprocessing object. Suggested version is 2.2.2.
`outdir`	Directory to output final upslope shapefile
`pointbuffer`	numeric, how much should the point be buffered (calculates upslope basin of buffered area)
`clip_size`	How big (in m) a clip should be generated from the original DEM (too big doesn't work and is slower)
`projected_CRS`	character vector (proj4) specifying "working" CRS in which area and distance calculations are to be done
`upstr_threshold`	integer, number of upstream cells required to initiate channel growth. A smaller number will yield more channels and will snap to smaller streams. Larger numbers will produce only major channel branches. For a 50k DEM, numbers between 20,000 and 50,000 are appropriate to reproduce the main channel network without many small branches. Numbers around 8,000 will produce most small branches, but tend to create many offshots in wide river sections. @prelim_basin (optional) if provided, uses an approximate basin outline (e.g. such as one derived from HydroBASINS) to determine the requisite size of DEM to clip out and process
`method`	character, one of ('D8', 'DINF'), specifying the hydrological pathing model