Simple and fast watershed delineation in python.

See examples/quickstart for more details.

Data available via the USGS HydroSHEDS project.

    # Read elevation and flow direction rasters
    # ----------------------------
    from pysheds.grid import Grid

    grid = Grid.from_raster('n30w100_con', data_name='dem')
    grid.read_raster('n30w100_dir', data_name='dir')
    grid.view('dem')

    # Delineate a catchment
    # ---------------------
    # Specify pour point
    x, y = -97.294167, 32.73750
    # Specify directional mapping
    dirmap=(64, 128, 1, 2, 4, 8, 16, 32)

    # Delineate the catchment
    grid.catchment(data='dir', x=x, y=y, dirmap=dirmap, out_name='catch',
               recursionlimit=15000, xytype='label')

    # Crop and plot the catchment
    # ---------------------------
    # Clip the bounding box to the catchment
    grid.clip_to('catch')
    grid.view('catch')

    # Calculate flow accumulation
    # --------------------------
    grid.accumulation(data='catch', dirmap=dirmap, out_name='acc')
    grid.view('acc')

    # Calculate distance to outlet from each cell
    # -------------------------------------------
    grid.flow_distance(data='catch', x=x, y=y, dirmap=dirmap,
                   out_name='dist', xytype='label')
    grid.view('dist')

    # Extract river network
    # ---------------------
    branches = grid.extract_river_network(fdir='catch', acc='acc',
                                          threshold=50, dirmap=dirmap)

    # Combine with land cover data
    # ---------------------
    grid.read_raster('nlcd_2011_impervious_2011_edition_2014_10_10.img',
                      data_name='terrain', window=grid.bbox, window_crs=grid.crs)
    grid.view('terrain')

• Hydrologic Functions:
  • flowdir: DEM to flow direction.
  • catchment: Delineate catchment from flow direction.
  • accumulation: Flow direction to flow accumulation.
  • flow_distance: Compute flow distance to outlet.
  • resolve_flats: Resolve flats in a DEM using the modified method of Garbrecht and Martz (1997).
  • fraction: Compute fractional contributing area between differently-sized grids.
  • extract_river_network: Extract river network at a given accumulation threshold.
  • cell_area: Compute (projected) area of cells.
  • cell_distances: Compute (projected) channel length within cells.
  • cell_dh: Compute the elevation change between cells.
  • cell_slopes: Compute the slopes of cells.
• Utilities:
  • view: Returns a view of a dataset at a given bounding box and resolution.
  • clip_to: Clip the current view to the extent of nonzero values in a given dataset.
  • resize: Resize a dataset to a new resolution.
  • rasterize: Convert a vector dataset to a raster dataset.
  • polygonize: Convert a raster dataset to a vector dataset.
  • check_cycles: Check for cycles in a flow direction grid.
  • set_nodata: Set nodata value for a dataset.
• I/O:
  • read_ascii: Reads ascii gridded data.
  • read_raster: Reads raster gridded data.
  • to_ascii: Write grids to ascii files.

pysheds currently only supports a d8 routing scheme

pysheds currently only supports Python 3

    $ git clone https://github.com/mdbartos/pysheds.git
    $ cd pysheds
    $ python setup.py install

Performance benchmarks on a 2015 MacBook Pro:

• Flow Direction to Flow Accumulation: 36 million grid cells in 15 seconds.
• Flow Direction to Catchment: 9.8 million grid cells in 4.55 seconds.