Geographic Data with GeoPandas

This tutorial extends the basic GeoPandas introduction to oceanographic datasets.

We’ll use Exclusive Economic Zones (EEZ) data from the Marine Regions project. The EEZ defines the sea zone over which a state has special rights regarding exploration and use of marine resources.

import geopandas as gpd
import matplotlib.pyplot as plt
import cartopy.crs as ccrs
import cartopy.feature as cfeature

1. Loading EEZ Data

Download the EEZ shapefile from Marine Regions EEZ and IHO areas v5.

Make sure you unzip it, and replace the file path below with the location of the .shp file.

# Load EEZ shapefile (update path to your local copy)
eez_path = "/Users/tgstone/data/SIO_software_carpentries/Intersect_EEZ_IHO_v5_20241010/Intersect_EEZ_IHO_v5_20241010.shp"  # Example path
eez = gpd.read_file(eez_path)

# Display data file
eez.head()

	MRGID	MarRegion	MRGID_SOV1	SOVEREIGN1	UN_SOV1	ISO_SOV1	MRGID_SOV2	SOVEREIGN2	UN_SOV2	ISO_SOV2	...	ISO_TER3	EEZ_MRGID	EEZ	IHO_MRGID	IHO_Sea	AREA_KM2	Latitude	Longitude	MRGID_comb	geometry
0	25614	Albanian part of the Adriatic Sea	2153	Albania	8	ALB	0	None	0	None	...	None	5670	Albanian Exclusive Economic Zone	3314	Adriatic Sea	12127.0	40.93096	19.11030	3314_5670	POLYGON ((19.9858 39.74337, 19.95858 39.7432, ...
1	25622	Albanian part of the Ionian Sea	2153	Albania	8	ALB	0	None	0	None	...	None	5670	Albanian Exclusive Economic Zone	3351	Ionian Sea	39.0	39.69394	19.97118	3351_5670	POLYGON ((20.00835 39.69182, 20.0081 39.69187,...
2	25603	Algerian part of the Alboran Sea	2152	Algeria	12	DZA	0	None	0	None	...	None	8378	Algerian Exclusive Economic Zone	3324	Alboran Sea	7045.0	35.58150	-1.74716	3324_8378	POLYGON ((-1.18826 35.57788, -1.18973 35.5758,...
3	25180	Algerian part of the Mediterranean Sea - Weste...	2152	Algeria	12	DZA	0	None	0	None	...	None	8378	Algerian Exclusive Economic Zone	4279	Mediterranean Sea - Western Basin	124141.0	37.29350	3.83338	4279_8378	POLYGON ((7.81205 38.00998, 7.81355 38.00945, ...
4	25525	Angolan part of the South Atlantic Ocean	2150	Angola	24	AGO	0	None	0	None	...	None	8478	Angolan Exclusive Economic Zone	1914	South Atlantic Ocean	495860.0	-11.70110	11.03537	1914_8478	MULTIPOLYGON (((13.42086 -5.8734, 13.39728 -5....

5 rows × 35 columns

2. Plotting EEZ Boundaries

We can visualize all EEZ boundaries in the world.

# Basic plot of EEZ polygons
eez.plot(figsize=(15, 10), color="lightblue", edgecolor="black")
plt.title("Exclusive Economic Zones (EEZs) - Global")
plt.show()

3. Overlay EEZ with Land Boundaries

Let’s overlay EEZ boundaries with a world basemap from GeoPandas’ built-in dataset.

fig, ax = plt.subplots(figsize=(15, 10), subplot_kw={'projection': ccrs.PlateCarree()})

# Add land feature for world basemap
ax.add_feature(cfeature.LAND, facecolor='lightgray', edgecolor='black')
ax.coastlines()

# Plot EEZ boundaries using GeoPandas with Cartopy axes
eez.boundary.plot(ax=ax, color="blue", linewidth=0.5, transform=ccrs.PlateCarree())

plt.title("World Map with EEZ Boundaries (Cartopy)")
plt.show()

4. Filtering EEZ for a Specific Country

We can filter the EEZ dataset by the SOVEREIGN1 field to show only one country’s EEZ.

usa_eez = eez[eez["SOVEREIGN1"] == "United States"]

fig, ax = plt.subplots(figsize=(15, 7), subplot_kw={'projection': ccrs.PlateCarree(central_longitude=180)})

# Add land feature for world basemap
ax.add_feature(cfeature.LAND, facecolor='lightgray', edgecolor='black')
ax.coastlines()

# Add longitude and latitude gridlines
gl = ax.gridlines(draw_labels=True, dms=True, x_inline=False, y_inline=False)
gl.top_labels = False
gl.right_labels = False

# Center the map on 180W (central_longitude=180) and set a reasonable extent
ax.set_extent([120, 250, -20, 90], crs=ccrs.PlateCarree())

# Plot United States EEZ polygons using GeoPandas with Cartopy axes
usa_eez.plot(ax=ax, color="lightblue", edgecolor="black", transform=ccrs.PlateCarree())

plt.title("United States Exclusive Economic Zone (Centered on 180W)")
plt.show()