Source code for netsse.model.bathymetry
# -*- coding: utf-8 -*-
"""
Retrieve and process **bathymetry** information.
.. dropdown:: Copyright (C) 2023-2026 Technical University of Denmark, R.E.G. Mounet
:color: primary
:icon: law
*This code is part of the NetSSE software.*
NetSSE is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your
option) any later version.
NetSSE is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License along
with this program. If not, see https://www.gnu.org/licenses/.
To credit the author, users are encouraged to use below reference:
.. code-block:: text
Mounet, R. E. G., & Nielsen, U. D. NetSSE: An open-source Python package
for network-based sea state estimation from ships, buoys, and other
observation platforms (version 2.2). Technical University of Denmark,
GitLab. February 2026. https://doi.org/10.11583/DTU.26379811.
*Last updated on 20-02-2026 by R.E.G. Mounet*
"""
from glob import glob
import io
import zipfile
import requests
import cartopy.io.shapereader as shpreader
import numpy as np
[docs]
def load_bathymetry(lonmin, lonmax, latmin, latmax, zip_file_url=None):
"""Retrieve, read, and process a zip file from Natural Earth containing bathymetry shapefiles.
The function reads the shapefiles contained in the zip file using the `cartopy.io.shapereader` module. The shapefiles are sorted by depth, from the surface to the bottom. The function returns a dictionary containing the shapefiles and a list of the depths in the shapefiles.
Parameters
----------
lonmin : float
Minimum longitude of the area of interest in degrees East.
lonmax : float
Maximum longitude of the area of interest in degrees East.
latmin : float
Minimum latitude of the area of interest in degrees North.
latmax : float
Maximum latitude of the area of interest in degrees North.
zip_file_url : str, optional
URL of the zip file containing the shapefiles. By default, the function accesses the bathymetry data from Natural Earth through the Amazon Web Services (https://registry.opendata.aws/naturalearth).
Returns
-------
depths : list
List of the depths in the shapefiles for the specified area.
shp_dict : dict
Dictionary containing the shapefiles.
See Also
--------
netsse.tools.viz.plot_bathymetry : Plot the bathymetry map.
References
----------
1. North American Cartographic Information Society. "AWS Marketplace: Natural Earth". Amazon
Sustainability Data Initiative, https://registry.opendata.aws/naturalearth (accessed on 25-03-2025).
2. Natural Earth (2009-2025). Free vector and raster map data.
https://www.naturalearthdata.com/ (accessed on 25-03-2025).
3. Met Office (2010-2015). Cartopy: a cartographic Python library with a Matplotlib interface.
Exeter, Devon, UK. https://scitools.org.uk/cartopy (accessed on 25-03-2025).
Example
-------
>>> depths, shp_dict = load_bathymetry(lonmin=0, lonmax=10, latmin=50, latmax=60)
"""
# Default URL for Natural Earth bathymetry data
if zip_file_url is None:
zip_file_url = (
"https://naturalearth.s3.amazonaws.com/"
+ "10m_physical/ne_10m_bathymetry_all.zip"
)
# Download and extract shapefiles
r = requests.get(zip_file_url)
z = zipfile.ZipFile(io.BytesIO(r.content))
z.extractall("ne_10m_bathymetry_all/")
# Read shapefiles, sorted by depth
shp_dict = {}
files = glob("ne_10m_bathymetry_all/*.shp")
assert len(files) > 0
files.sort()
depths = []
for f in files:
depth = "-" + f.split("_")[-1].split(".")[0] # depth from file name
depths.append(depth)
bbox = (lonmin, latmin, lonmax, latmax) # (x0, y0, x1, y1)
nei = shpreader.Reader(f, bbox=bbox)
shp_dict[depth] = nei
depths = np.array(depths)[::-1] # sort from surface to bottom
return depths, shp_dict
