The Contribution of Wind-Generated Waves to Coastal Sea-Level Changes

Abstract

Surface gravity waves generated by winds are ubiquitous on our oceans and play a primordial role in the dynamics of the ocean-land-atmosphere interfaces. In particular, wind-generated waves cause fluctuations of the sea level at the coast over timescales from a few seconds (individual wave runup) to a few hours (wave-induced setup). These wave-induced processes are of major importance for coastal management as they add up to tides and atmospheric surges during storm events and enhance coastal flooding and erosion. Changes in the atmospheric circulation associated with natural climate cycles or caused by increasing greenhouse gas emissions affect the wave conditions worldwide, which may drive significant changes in the wave-induced coastal hydrodynamics. Since sea-level rise represents a major challenge for sustainable coastal management, particularly in low-lying coastal areas and/or along densely urbanized coastlines, understanding the contribution of wind-generated waves to the long-term budget of coastal sea-level changes is therefore of major importance. In this review, we describe the physical processes by which sea states may affect coastal sea level at several timescales, we present the methods currently used to estimate the wave contribution to coastal sea-level changes, we describe past and future wave climate variability, we discuss the contribution of wave to coastal sea-level changes, and we discuss the limitations and perspectives of this research field.

Coastal Sea Level rise at Senetosa (Corsica) during the Jason altimetry missions

“…The contribution of wind-generated waves to coastal sea level changes has been investigated in a number of recent studies (e.g., Melet et al, 2018, Dodet et al, 2019. As thoroughly discussed in Dodet et al (2019), wind-generated waves have the capability to significantly change sea level variations at the coast, even at the time scales of interest here. The shoaling and breaking of waves in the shelf shallow waters raises the mean water level in the so-called near-shore and surf zones (last ~1 km to coast), a https://doi.org/10.5194/os-2020-3 Preprint.…”

“…The relationship between offshore wave height and wave set-up is known empirically only (Dodet et al, 2019). To first order, wave set-up is related to offshore SWH, wave period and beach slope.…”

“…This is the case in particular for beach soil characteristics, sediment size, etc. A large variety of formulations have been proposed for this relationship, based on in situ observations collected at different coastal sites (e.g., Dodet et al, 2019). However these are not necessarily applicable to our study case as some local beach parameters are not known.…”

“…In the recent years, this data set has generated an abundant literature on the processes causing sea level change at global and regional scales, as well as on closure of the sea level budget (e.g., Church et al, 2013, Stammer et al, 2013, Dieng et al, 2017, Nerem et al, 2018, WCRP, 2018, SROCC, 2019. In addition to the global mean rise and superimposed regional trends, changes in small scale processes such as local atmospheric effects, baroclinic instabilities, coastal trapped waves, shelf currents, waves, fresh water input from rivers in estuaries, can substantially modify the rate of sea level change at the coast compared to open sea regions (Woodworth et al, 2019, Melet et al, 2018, Piecuch et al, 2018, Dodet et al, 2019, Durand et al, 2019. In addition, ground subsidence may amplify the rate of sea level change at the coast (Woppelmann and Marcos, 2016).…”

Guest Editorial: Relationships Between Coastal Sea Level and Large-Scale Ocean Circulation

“…Implications for coastal sea level variations in different regions of the world's oceans are discussed. Dodet et al (2019) focus on the contribution of windgenerated waves at the coast and their long-term effect on coastal sea level changes. The physical mechanisms are presented, as well as the limitations and perspectives for further process understanding and observational improvement.…”