pyvalleys

This package is used to delineate the valley floor polygons of a river network.

Setup

1. Install poetry
2. Install python 3.10+, recommend use pyenv and set project-specific python version
3. Install whiteboxtools and record the path to the directory containing the whitebox executable
4. run poetry install

For some reason, initializing the whiteboxtools class from 'whitebox' will download whiteboox tools. Even if you intend to directly pass the executable path to the instance. This will only happen the first time and can be ignored.

Usage

Input is a DEM raster and a vector of the river network. Parameters for the algorithm are passed from a toml config file. Output is a shapefile of the valley floor polygons as well as a directory with all the derived terrain attributes used for the algorithm.

This code can be used as a library or invoked from the command line.

Command line usage:

poetry run python -m pyvalleys <dem_path> <flowlines_path> <config_path> <wbt_exe_path> <terrain_attributes_dir> <ofile>

The workflow for extracting valleys can be seen in 'pyvalleys/workflow.py'.

Input Data

Recommend USGS 10m DEM and NHD medium resolution flowlines.

Flowlines need to have a column called 'StartFlag' that indicates if the segment is a first order stream.

For NHD flowlines it is best to filter the raw flowline data to only include segments for streams/rivers by FTYPE before passing through the workflow. Optionally can remove streams that are small and first order.

Config

An example config.toml file:

tolerance = 20 # for the simplification of the flowline
xs_spacing = 10 # spacing of cross-sections
xs_width = 100  # total width is twice this value
xs_point_spacing = 10 # spacing of points along cross-sections
quantile = 0.75 # sets the hand threshold
buffer = 2 # add to hand threshold 
slope_threshold = 14.1 # a little more than 25% slope

peak_threshold = 0.002
bp_slope_threshold = 20