Preprints
https://doi.org/10.5194/egusphere-2022-67
https://doi.org/10.5194/egusphere-2022-67
30 May 2022
 | 30 May 2022

Hydrogeological controls on the spatio-temporal variability of surge-induced hydraulic gradients along coastlines: implications for beach surface stability

Anner Paldor, Nina Stark, Matthew Florence, Britt Raubenheimer, Steve Elgar, Rachel Housego, Ryan S. Frederiks, and Holly A. Michael

Abstract. Ocean surges pose a global threat for coastal stability. These hazardous events alter flow conditions and pore pressures in flooded beach areas during both inundation and subsequent retreat stages, which can mobilize beach material, potentially enhancing erosion significantly. In this study, the evolution of surge-induced pore-pressure gradients is studied through numerical hydrologic simulations of storm surges. The spatiotemporal variability of critically high gradients is analyzed in 3D. The analysis is based on a threshold value obtained for momentary liquefaction of beach materials under groundwater seepage. Simulations of surge events show that during the run-up stage, head gradients can rise to the calculated critical level landward of the advancing inundation line. During the receding stage, critical gradients were simulated seaward of the retreating inundation line. These gradients reach maximum magnitudes just as sea level returns to pre-surge level, and are most accentuated beneath the still-water shoreline, where the model surface changes slope. The gradients vary along the shore owing to variable beach morphology, with the largest gradients seaward of intermediate-scale (1–3 m elevation) topographic elements (dunes) in the flood zone. These findings suggest that the common practices in monitoring and mitigating surge-induced failures and erosion, which typically focus on the flattest areas of beaches, might need to be revised.

Journal article(s) based on this preprint

02 Dec 2022
Coastal topography and hydrogeology control critical groundwater gradients and potential beach surface instability during storm surges
Anner Paldor, Nina Stark, Matthew Florence, Britt Raubenheimer, Steve Elgar, Rachel Housego, Ryan S. Frederiks, and Holly A. Michael
Hydrol. Earth Syst. Sci., 26, 5987–6002, https://doi.org/10.5194/hess-26-5987-2022,https://doi.org/10.5194/hess-26-5987-2022, 2022
Short summary

Anner Paldor et al.

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Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
ED: Publish subject to revisions (further review by editor and referees) (23 Aug 2022) by Albrecht Weerts
AR by Anner Paldor on behalf of the Authors (05 Sep 2022)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (05 Sep 2022) by Albrecht Weerts
RR by Damien Sous (14 Sep 2022)
ED: Publish as is (08 Nov 2022) by Albrecht Weerts
AR by Anner Paldor on behalf of the Authors (15 Nov 2022)

Journal article(s) based on this preprint

02 Dec 2022
Coastal topography and hydrogeology control critical groundwater gradients and potential beach surface instability during storm surges
Anner Paldor, Nina Stark, Matthew Florence, Britt Raubenheimer, Steve Elgar, Rachel Housego, Ryan S. Frederiks, and Holly A. Michael
Hydrol. Earth Syst. Sci., 26, 5987–6002, https://doi.org/10.5194/hess-26-5987-2022,https://doi.org/10.5194/hess-26-5987-2022, 2022
Short summary

Anner Paldor et al.

Anner Paldor et al.

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Short summary
Ocean surges can impact the stability of beaches by changing the hydraulic regime. These surge-induced changes in the hydraulic regime have important implications for coastal engineering and for beach morphology. This work uses 3D computer simulations to study how these alterations vary in space and time. We find that certain areas along and across the beach are potentially more vulnerable than others, and that previous assumptions regarding the most dangerous places may need to be revised.