Coastal topography and hydrogeology control critical groundwater gradients and potential beach surface instability during storm surges

Author(s)Paldor, Anner
Author(s)Stark, Nina
Author(s)Florence, Matthew
Author(s)Raubenheimer, Britt
Author(s)Elgar, Steve
Author(s)Housego, Rachel
Author(s)Frederiks, Ryan S.
Author(s)Michael, Holly A.
Date Accessioned2023-02-23T16:44:39Z
Date Available2023-02-23T16:44:39Z
Publication Date2022-12-02
DescriptionThis article was originally published in Hydrology and Earth System Sciences. The version of record is available at: https://doi.org/10.5194/hess-26-5987-2022
AbstractOcean 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 three dimensions. The analysis is based on a threshold value obtained for quicksand formation 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 levels 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 to include other topographic features.
SponsorThis research has been supported by the National Science Foundation (grant nos. OCE1848650, OIA1757353, OCE1829136, EAR1933010, and CMMI-1751463, and a Graduate Research Fellowship) and the US Geological Survey (grant no. NIWR 2018DE01G), a Vannevar Bush Faculty Fellowship, the US Coastal Research Program, and the Woods Hole Oceanographic Institution Investment in Science Program.
CitationPaldor, A., Stark, N., Florence, M., Raubenheimer, B., Elgar, S., Housego, R., Frederiks, R. S., and Michael, H. A.: Coastal topography and hydrogeology control critical groundwater gradients and potential beach surface instability during storm surges, Hydrol. Earth Syst. Sci., 26, 5987–6002, https://doi.org/10.5194/hess-26-5987-2022, 2022.
ISSN1607-7938
URLhttps://udspace.udel.edu/handle/19716/32346
Languageen_US
PublisherHydrology and Earth System Sciences
TitleCoastal topography and hydrogeology control critical groundwater gradients and potential beach surface instability during storm surges
TypeArticle
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