Kilian Vos1, Mitchell D.
Harley1, Kristen D. Splinter1,
Andrew Walker1, Ian L. Turner1
1 Water Research Laboratory, School of Civil and
Environmental Engineering, UNSW Sydney, 110 King Street, Manly Vale, NSW
2093, Australia
Corresponding author: Kilian Vos
(k.vos@unsw.edu.au)
Key Points [140 characters each]:
- Novel remote sensing technique to estimate beach-face slopes from
satellite imagery and modelled tides.
- Time-series of shoreline change are transformed into frequency domain
to find the slope that minimises high-frequency tidal fluctuations.
- Validation against in situ data shows high accuracy across sites
ranging in grain size, tidal range and wave climate.
Abstract [150 words]
The steepness of the beach face is a fundamental parameter for coastal
morphodynamic research. Despite its importance, it remains extremely
difficult to obtain reliable estimates of the beach-face slope over
large spatial scales (1000’s of km of coastline). In this letter, a
novel approach to estimate this slope from time-series of
satellite-derived shoreline positions is presented. This new technique
uses a frequency-domain analysis to find the optimum slope that
minimises high-frequency tidal fluctuations relative to lower-frequency
erosion/accretion signals. A detailed assessment of this new approach at
8 locations spanning a range of tidal regimes, wave climates and
sediment grain sizes shows strong agreement (R2 =
0.93) with field measurements. The automated technique is then applied
across 1000’s of beaches in Eastern Australia and California USA,
revealing similar regional-scale distributions along these two
contrasting coastlines and highlights the potential for new global-scale
insight to beach-face slope spatial distribution, variability and
trends.