sandplover.plan.compute_shoreline_roughness_radius

sandplover.plan.compute_shoreline_roughness_radius(shore_mask, origin=(0, 0), calculate_length=False, **kwargs)

Compute shoreline roughness, as shoreline count over mean radius.

Computes the shoreline roughness metric:

\[R = \frac{N}{(\bar{r} / dx)} \approx \frac{L_{shore}}{\bar{r}}\]

where R is the roughness of the shoreline, N is the number of pixels in the shoreline in the shore_mask, \(dx\) is the grid spacing, and \(\bar{r}\) is the mean shoreline radius (after [1]).

Note

Internally, compute_shoreline_distance is used to compute the mean shoreline distance \(\bar{r}\).

See also

This function is similar to, but distinct rom compute_shoreline_roughness_area, which uses an approach ased on the shoreline convexity to characterize the shoreline.

[1]

Liang, M., Voller, V. R., and Paola, C.: A reduced-complexity model for river delta formation – Part 1: Modeling deltas with channel dynamics, Earth Surf. Dynam., 3, 67–86, https://doi.org/10.5194/esurf-3-67-2015, 2015.

Parameters:

• shore_mask (ShorelineMask, ndarray) – Shoreline mask. Can be a ShorelineMask object, or a binarized array.

• origin (tuple, np.ndarray, optional) – Origin from which the distance to all shoreline points is computed, specified in data dimensions (not indices) along dim1, dim2 of the data. Default (0, 0).

• calculate_length (bool, optional) – If calculate_length=True, then compute_shoreline_length is used to calculate the length of the shoreline explicitly, rather than counting the pixels in shore_mask. Default is False.

• **kwargs – Passed to compute_shoreline_length.

Returns:

roughness – Shoreline roughness, computed as described above.

Return type:

float

Examples

Calculate the shoreline roughness.

>>> from sandplover.mask import ShorelineMask
>>> from sandplover.plan import compute_shoreline_roughness_radius
>>> from sandplover.sample_data.sample_data import golf

>>> golf = golf()
>>> sm = ShorelineMask(
...     golf["eta"][-1, :, :], elevation_threshold=0, elevation_offset=-0.5
... )
>>> sm.trim_mask(length=golf.meta["L0"].data + 1)
>>> origin = (
...     np.array([golf.meta["L0"].data, golf.meta["CTR"].data])
...     * golf.meta["dx"].data
... )

Compute roughness

>>> rough = compute_shoreline_roughness_radius(sm, origin=origin)

>>> fig, ax = plt.subplots()
>>> sm.show(ax=ax)
>>> _ = ax.set_title("roughness = {:.2f}".format(rough))

(Source code, png, hires.png)

See also

See this example, which compares all of the “shoreline roughness” metrics implemented in sandplover.