EFHM quickstart — a 1-in-100-year flood-depth map¶

This notebook downloads the JRC European Flood Hazard Map for a small area of the Rhine delta (Netherlands) at the 100-year return period, reading only the AOI's pixel window over /vsicurl — so it transfers kilobytes, not gigabytes. The EFHM is CC-BY-4.0 (no licence warning).

In [ ]:

import tempfile
from pathlib import Path

import matplotlib.pyplot as plt
import numpy as np
from pyramids.dataset import Dataset

from earthlens.core import EarthLens

out = Path(tempfile.mkdtemp(prefix="efhm-"))
paths = EarthLens(
    data_source="jrc-flood",
    lat_lim=[51.7, 52.0],
    lon_lim=[4.6, 5.1],
    return_periods=[100],
    path=out,
).download()
paths

import tempfile from pathlib import Path import matplotlib.pyplot as plt import numpy as np from pyramids.dataset import Dataset from earthlens.core import EarthLens out = Path(tempfile.mkdtemp(prefix="efhm-")) paths = EarthLens( data_source="jrc-flood", lat_lim=[51.7, 52.0], lon_lim=[4.6, 5.1], return_periods=[100], path=out, ).download() paths

Map the water depth¶

Cells carry river-flood water depth in metres; -9999 marks no data (dry / outside the modelled river network).

In [ ]:

depth = Dataset.read_file(str(paths[0])).read_array().astype("float64")
depth[depth <= -9999] = np.nan

fig, ax = plt.subplots(figsize=(7, 5))
im = ax.imshow(depth, cmap="Blues", vmin=0)
ax.set_title("EFHM RP100 river-flood water depth (m)")
ax.set_xticks([])
ax.set_yticks([])
fig.colorbar(im, ax=ax, shrink=0.8, label="depth (m)")
plt.show()
print(
    f"flooded cells: {np.isfinite(depth).sum():,}; max depth: {np.nanmax(depth):.2f} m"
)

depth = Dataset.read_file(str(paths[0])).read_array().astype("float64") depth[depth <= -9999] = np.nan fig, ax = plt.subplots(figsize=(7, 5)) im = ax.imshow(depth, cmap="Blues", vmin=0) ax.set_title("EFHM RP100 river-flood water depth (m)") ax.set_xticks([]) ax.set_yticks([]) fig.colorbar(im, ax=ax, shrink=0.8, label="depth (m)") plt.show() print( f"flooded cells: {np.isfinite(depth).sum():,}; max depth: {np.nanmax(depth):.2f} m" )

Global vs European coverage¶

This is the higher-fidelity, Europe-focused EFHM. For the global JRC flood hazard (which also covers Europe, at ~90 m), use the gee backend with asset="JRC/CEMS_GLOFAS/FloodHazard/v2_1".