NLDI Flowtools Documentation
Version: 0.3.5
Introduction
NLDI Flowtools provides basin delineation and flow path tracing services for a given a longitude and latitude coordinate pair.
Functions
splitcatchment(): delineates drainage basins from a longitude, latitude point.
flowtrace(): traces the flow path of water from a longitude, latitude point to the nearest stream.
Splitcatchment Tool
The Splitcatchment tool delineates the drainage basin for a given point. It identifies the National Hydrography Dataset (NHD) catchment that contains the point, selects the area within the catchment that drains to that point, and, if specified, merges this split catchment polygon with upstream NHD catchments to return the entire drainage basin. Alternatively, the function can return only the split catchment polygon without merging it with upstream catchments.
Flowtrace Tool
The Flowtrace tool traces the flow path of water from a given point to the stream it drains into. Given a longitude, latitude coordinate, Flowtrace determines the flow path from that point to the intersecting NHD stream segment. Additionally, it can split the stream segment and return either the downstream, upstream, or the entire segment.
About NLDI Flowtools
NLDI Flowtools was developed by the USGS as an open-source project. It relies on various open-source Python packages to provide basin delineation and flow path tracing services.
Installation
You can install NLDI-Flowtools via pip from PyPI:
pip install nldi-flowtools
Acknowledgments
This toolset was originally forked from @marsmith’s repo ss-delineate.
For the actual hydrologic delineations, we use the package Pyfwldir.
This project was done in colaboration with @rmcd’s NLDI XStools.
The flow direction raster used for the delineations was put together as a cloud optimized geotiff and hosted it in AWS S3 by @dblodgett.