environmentaltools.processes.closure_depth

environmentaltools.processes.closure_depth(data, Hallermeier=True)[source]

Compute closure depth using Hallermeier or Birkemeier empirical formula.

Calculates the depth beyond which significant seabed changes are unlikely to occur over an annual cycle. Uses wave statistics exceeded 12 hours per year.

Parameters:

  • data (pd.DataFrame) – Wave characteristics time series with columns: - Hm0 : Significant wave height (m) - Tp : Peak wave period (s) Index should be datetime format

  • Hallermeier (bool, optional) – If True, use Hallermeier (1981) formula; if False, use Birkemeier (1985). Default: True

Returns:

dc – Closure depth (m)

Return type:

float

Notes

Hallermeier (1981) formula:

dc = 2.28 * H₁₂ - 68.5 * (H₁₂² / (g * T₁₂²))

Birkemeier (1985) formula:

dc = 1.75 * H₁₂ - 57.9 * (H₁₂² / (g * T₁₂²))

where H₁₂ and T₁₂ are wave height and period exceeded 12 hours per year.

The closure depth separates the active nearshore zone from the inactive offshore zone.

References

  • Hallermeier, R. J. (1981). A profile zonation for seasonal sand beaches from wave climate. Coastal Engineering, 4, 253-277.

  • Birkemeier, W. A. (1985). Field data on seaward limit of profile change. Journal of Waterway, Port, Coastal, and Ocean Engineering, 111(3), 598-602.