Premium
A surfzone morphological diffusivity estimated from the evolution of excavated holes
Author(s) -
Moulton Melissa,
Elgar Steve,
Raubenheimer Britt
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl060519
Subject(s) - geology , bedform , bed load , sediment transport , thermal diffusivity , bathymetry , seafloor spreading , geomorphology , sediment , geophysics , oceanography , physics , quantum mechanics
Downslope gravity‐driven sediment transport smooths steep nearshore bathymetric features, such as channels, bars, troughs, cusps, mounds, pits, scarps, and bedforms. Downslope transport appears approximately as a diffusive term in the sediment continuity equation predicting changes in bed level, with a morphological diffusivity controlling the rate of seafloor smoothing. Despite the importance of surfzone sediment transport and morphological evolution, the size of the downslope transport term in nearshore models varies widely, and theories have not been tested with field measurements. Here observations of the infill of large excavated holes in an energetic inner surf zone provide the first opportunity to infer the morphological diffusivity in the field. The estimated diffusion coefficient is consistent with a theoretical bedload morphological diffusivity that scales with the three‐halves power of the representative bed shear stress.