CA Valley Floors

A Python-based workflow for generating high-resolution valley floor polygons across California using 10m Digital Elevation Models (DEMs) and National Hydrography Dataset (NHD) flowlines.

Overview

This project uses valleyx to extract valley floor boundaries from:

• USGS 3DEP 10-meter Digital Elevation Models
• NHD Medium Resolution Flowlines

The workflow processes data by Hydrologic Unit Code (HUC) regions, allowing for flexible regional analysis and parallel processing.

Coverage

There are 1070 HUC10s genereated by the filtering in the generate_targets rule. These include all HUC10s that are within the California Region (HUC2: 18) and all the HUC10s that have CA as part of their state attribute.

Some HUC10s are not processed due to missing data as a result of:

• No flowlines in the region (e.g. Farallon Islands)
• No DEM or flowlines data available (outside of the US)

IGNORE_LIST = [
    "1805000506",  # farallon islands no flowlines
    "1807030501",
    "1807030502",
    "1807030503",
    "1807030504",
    "1807030506",
    "1807030507",
    "1710031206",  # oregon coast no flowlines
]

A map of the coverage. Huc10 boundaries are black, floors are colored by their huc06 region. Notice that there are no floors in the farallon islands, oregon coast, and in Mexico.

Features

• Automated downloading of DEM and flowline data
• Parallel processing support through Snakemake
• Configurable parameters for valley floor extraction
• Tools for mosaicking and clipping results
• California-specific boundary and ocean clipping

Prerequisites

• Python 3.10 or higher
• Poetry for dependency management
• Git for version control

Installation

1. Clone the repository:

git clone [email protected]:avkoehl/ca-valley-floors.git
cd ca-valley-floors

2. Install dependencies:

# Basic installation
poetry install

# With development tools (matplotlib, jupyter)
poetry install --with dev

Workflow Steps

The workflow below outlines the steps to generate valley floor polygons for all the huc10s in California.

1. Setup and Configuration

Setup

Run the setup rule to initialize whitebox, download necessary data files such as the land masks.

poetry run snakemake setup -j1

To generate the list of all HUCs in California. This is optional if you already have a list of HUCs you want to process. It will save the list of HUCs to a file called data/target_huc10s.csv.

poetry run snakemake generate_targets -j1

Configuration

Copy the default configuration file:

cp config.yaml.example my_config.yaml

Edit the configuration file to set the hucs_file, params_file, and output_dir for the run:

output_dir: "/path/to/output"
hucs_file: "/path/to/hucs.csv"
params_file: "/path/to/params.toml"

Alternatively, you can set these variables using the --config flag when running snakemake. e.g.:

poetry run snakemake process --config hucs_file=./data/target_huc10s.csv params_file=params/my_params.toml output_dir=./data/output -j 4

2. Download DEM and Flowline Data

Download DEMs and flowlines for the target HUCs:

poetry run snakemake download --resources download_slots=4 --configfile my_config.yaml -j4

This download rule is optional and is meant as a convenience to separate the download step from the processing step. If you run the processing step without downloading the data, the workflow will automatically download the data as needed.

3. Valley Floor Extraction

Process the target HUCs to extract valley floors:

poetry run snakemake process --configfile my_config.yaml -j4

4. Results Post Processing

Mosaic results and clip to California boundary:

poetry run snakemake mosaic --configfile my_config.yaml -j1

Customizing Valley Floor Parameters

1. Create a custom parameters file:

cp params/params_10m.toml params/my_params.toml

2. Update the configuration to use your parameters:

params_file: 'params/my_params.toml'

Project Structure

ca-valley-floors/
├── Snakefile            # Snakemake workflow file
├── params/             
│   └── params_10m.toml  # Valley floor extraction parameters for 10m DEMs
├── data/                # Data directory for files used in the workflow
└── README.md           

Support

For questions or issues, contact:

• Arthur Koehl
• Email: avkoehl at ucdavis.edu