Beach and Dune Response to Seasonal Water Level Rise in the Laurentian Great Lakes: Implications for Coastal Geomorphic Response to Rapid Sea Level Rise

E. Theuerkauf, K. Braun

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Water level exerts a primary control on beach and dune geomorphic response along oceanic, estuarine, and lacustrine shorelines. Coastal systems respond to water level variations across time scales ranging from minutes (i.e. storm surges and seiches) to months (i.e. seasonal cycles and sea-level anomalies) to millennia (i.e. long-term sea-level rise). It is well-understood that high water levels translate wave energy landward resulting in higher beach and dune erosion, however, few field studies have documented the interplay between rising water levels, waves, and beach and dune morphologic response across timescales that yield insight into how sandy coastal systems respond to rapid sea-level rise. Seasonal water level rise in the Laurentian Great Lakes provides a window into the hydrodynamics associated with accelerated rates of sea-level rise and can be used as a natural laboratory to investigate how sandy beach and dune systems may respond. Here, we present the results of geomorphic monitoring at a beach ridge complex along Western Lake Michigan during and after a 10 cm abrupt rise in water level. Water level remained high for several months after the peak and was co-incident with several low-magnitude storms. The observed morphologic response of these sites to rapid water level rise followed the expected response based on common coastal geomorphic paradigms and models. Sites with low elevation dunes and narrow beaches eroded immediately in response to rising water level and average wave conditions. Sites with wider beaches and higher dunes were more resistant to rising water level and only began to erode when high water level coincided with low-magnitude storm events. Sand-starved sites immediately downdrift of shore protection were the most vulnerable to erosion and overwash from abrupt changes in water level. These observations suggest that the initial evolution of sandy beach and dune systems to abrupt sea level rise is likely to be accurately predicted using existing models and equations.
Original languageEnglish (US)
Title of host publicationAGU Fall Meeting Abstracts
Volume23
StatePublished - 2018

Keywords

  • ISGS

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