w2rpy 0.1.21

Geospatial and Hydraulic Functions For Analysis of River Systems

w2rpy

terrain(dem_file)

• Returns Terrain object. Terrain object contains the following objects:
  • DEM, flow accumulation, flow direction, pysheds Grid, and coordinate system
• Input options:
  • dem_file: file path to a DEM raster (.tif, .vrt, etc…)

streamlines(terrain, pour_point, threshold=None, snap_threshold=None, save=None)

• Returns a geodataframe of delineated stream lines.
• Input options:
  • terrain: Terrain object
  • pour_point: file path to or geodataframe of points at the bottom of the desired watershed. Will only use the first point.
  • threshold: threshold for stream delineation in number of flow accumulated pixels. Defaults to number of pixels/100.
  • snap_threshold: threshold for snapping pour point to the flow accumulation raster. Defaults to number of pixels/10.
  • save: optional file path to save streamlines as shapefile rather than returning a geodataframe object.

catchment(terrain, pour_point, snap_threshold=None, save=None)

• Returns a geodataframe of delineated catchment.
• Input options:
  • terrain: Terrain object
  • pour_point: file path to or geodataframe of points at the bottom of the desired watershed. Will only use the first point.
  • snap_threshold: threshold for snapping pour point to the flow accumulation raster. Defaults to number of pixels/10.
  • save: optional file path to save catchment as shapefile rather than returning a geodataframe object.

get_xs(cl, xs_length, spacing, save=None)

• Returns a geodataframe of cross-sections.
• Input options:
  • cl: centerline, or any lines, to generate cross-sections along.
  • xs_length: length of cross-section from cl. Full XS length is xs_length*2
  • spacing: distance between cross-sections on cl.
  • save: optional file path to save cross-sections as shapefile rather than returning a geodataframe object.

get_points(lines, spacing, ep=True, save=None)

• Returns a geodataframe of cross-sections.
• Input options:
  • lines: centerline, or any lines, to generate cross-sections along.
  • spacing: distance between points on lines.
  • ep: option to include end point on line. Either True or False.
  • save: optional file path to save points as shapefile rather than returning a geodataframe object.

inundate(raster, rel_wse_list, largest_only=False, invert=False, remove_holes=False, save=None)

• Returns a geodataframe of polygons showing inundation extent for given relative WSEs.
• Input options:
  • raster: file path to DEM or REM to perform inundation on.
  • rel_wse_list: list for WSEs to create inundation polygons for. (Example: [1,3.5,7,10])
  • largest_only: True/False to return only the largest inundated polygon. Helpful for channel delineation.
  • invert: True/False to select the are below or above a given WSE.
  • remove_holes: True/False option to remove all holes within inundation extent polygons.
  • save: optional file path to save the inundation extents as shapefile rather than returning a geodataframe object.

sample_raster(raster, points, buff=None, metric='min', multiband=False, crs=None)

• Returns list of values sampled from raster at location of points.
• Input options:
  • raster: file path to DEM or imagery to sample data.
  • points: geodatabase or file path of points to sample.
  • buff: optional buffer distance to around each point to sample.
  • metric: suite of options to sample for including ‘min’, ’mean’, ’max’, and ‘mode’
  • multiband: True/False option to include samples from all bands, otherwise it only returns the first band.
  • crs: option to convert points to specific coordinate system, only use if raster has no set coordinate system.

zonal_stats(df,raster,metric='mean',band=1)

• Returns list of values sampled from raster within extent of given polygons.
• Input options:
  • raster: file path to DEM or imagery to sample data.
  • df: geodatabase or file path of polygons to sample.
  • metric: suite of options including ‘min’, ’mean’, ’max’, ‘sum’, and ‘nonzero’
  • band: integer value of which raster band to sample data from.

edit_raster(raster, output, crs=None, resample=None, resample_method='bilinear', clip=None, nodata=None)

• All in one function to edit or warp rasters in various ways. Saves output to a new tif file.
• Input options:
  • raster: file path to DEM or imagery to warp/edit.
  • output: file path to save new raster.
  • crs: coordinate system to reproject raster to.
  • resample: pixel size to resample raster to.
  • resample_method: options for resampling (‘bilinear’,’nearest’,’mean’)
  • clip: geodataframe or path to polygons to clip raster to.
  • nodata: will set the nodata value for the output raster.

merge_rasters(rasters, output, method='first', compression=None, nodata=None)

• Merges rasters into a single tif file. This does not build a mosaic, be wary of resulting file sizes.
• Input options:
  • rasters: list of file paths to DEM or imagery to merge.
  • output: file path to save new raster.
  • method: options for merging rasters including ‘first’, ‘last’, ‘max’ and ‘min’. See rasterio documentation for more info.
  • compression: option to compress merged raster. Best to use are ‘JPEG’ or ‘LZW’.
  • nodata: will set the nodata value for the output raster.

difference_rasters(r1, r2, output, match_affine='first', method='nearest')

• Will match the extent and resolution of both rasters then difference. Output = r2 – r1.
• Input options:
  • r1: file path to DEM or imagery.
  • r2: file path to DEM or imagery.
  • output: file path to save new raster.
  • match_affine: If ‘first’ then will warp r2 to match r1 extent and resolution. If ‘last’ then will warp r1 to match r2 extent and resolution.
  • method: method for raster transformation includes ‘nearest’ and ‘bilinear’

create_REM(dem, xs, output, sample_dist=3, smooth_window=5, buffer=1000, limits=[-50,50], method='min', vb=None, ret_xs=False, wse_path=None)

• Will create a REM from a given DEM and set of cross-sections.
• Input options:
  • dem: file path to DEM.
  • xs: file path or geodataframe of cross-sections to use.
  • output: file path to save new REM raster.
  • sample_dist: Length along cross-sections to sample elevation data.
  • smooth_window: number of cross-sections to average using rolling window.
  • buffer: clips new raster to include buffer around total bounding box of cross-sections.
  • limits: sets all data above or below limits to nodata.
  • method: Option to use ‘min’ or ‘mean’ sampled elevation per cross-section
  • vb: geodataframe or path to valley bottom polygon to clip cross-sections.
  • ret_xs: will return XS if set to true, no need to use this.
  • wse_path: file path to save WSE/GGL surface raster.

htab(station, elevation, slope, D50, max_depth=10, breaks=None, save=None)

• Returns dataframe of hydraulic table (htab) calcs for a given cross-section. Htab table returns either the sum (for discharge, area, and perimeter) or discharge-weighted average (for roughness, hydraulic radius, and velocity) across all flowing channels.
• Input options:
  • station: list , array, or series of station data.
  • elevation: list , array, or series of elevation data.
  • output: file path to save new raster.
  • slope: dimensionless slope for hydraulic calcs. Constant across all flows/depths.
  • D50: representative grain size used for bathhurst calcs to vary roughness with depth.
  • max_depth: depth from thalweg to perform calcs from. Splits this range in 25 WSEs to build rating curve.
  • breaks: station values to split hydraulic calcs by. Helpful for separating channel from floodplain.
  • save: optional file path to save htab as excel rather than returning a dataframe object.