TY - JOUR
T1 - Sedimentary in-filling of an urban Great Lakes waterfront embayment and implications for threshold-driven shoreline morphodynamics, Montrose Beach, SW Lake Michigan
AU - Mattheus, Christopher R.
AU - Theuerkauf, Ethan J.
AU - Braun, Katherine N.
N1 - Publisher Copyright:
© 2022 International Association for Great Lakes Research
PY - 2022/10
Y1 - 2022/10
N2 - This paper addresses subaqueous and subaerial patterns of geomorphic change across Montrose Beach, an urban embayment along Chicago's engineered SW Lake Michigan coastline. Our goal was to better characterize the urban littoral zone, its sediment-transport processes, and associated shoreline morphodynamics (from the early 1950s to present). Succinct beach geomorphic responses to decadal base-level changes (i.e., regression during lake-level fall and transgression during lake-level rise) occurred once a morphologic threshold in the subaqueous portion of the system had been crossed. Despite continuous sand trapping, nearshore elevations were initially not conducive to promoting expansion of the subaerial beach environment, regardless of water-level condition. Rapid beach expansion after 1990 (by a factor of four in <25 years) was facilitated by prior decades of nearshore accretion. Shoreline morphodynamic trajectories and degree of coupling to nearshore sedimentary processes are important considerations for developing long-term beach-management strategies. Rapid cross-shore movements of the shoreline in response to oscillatory base levels are expected to persist at Montrose and other urban beaches of similar design (and nearshore conditions). This has important implications for managing urban lakefront ecosystems, including coastal dunes and shore-bird habitats. Few datasets have thus far quantified time-variant and threshold-driven patterns of beach geomorphic development along engineered coastlines. Such insights should help coastal managers better understand littoral sediment interconnectivity across the urban lakefront and anticipate future geomorphic trajectories of beach environments with anticipated decadal-scale oscillatory patterns in lake level.
AB - This paper addresses subaqueous and subaerial patterns of geomorphic change across Montrose Beach, an urban embayment along Chicago's engineered SW Lake Michigan coastline. Our goal was to better characterize the urban littoral zone, its sediment-transport processes, and associated shoreline morphodynamics (from the early 1950s to present). Succinct beach geomorphic responses to decadal base-level changes (i.e., regression during lake-level fall and transgression during lake-level rise) occurred once a morphologic threshold in the subaqueous portion of the system had been crossed. Despite continuous sand trapping, nearshore elevations were initially not conducive to promoting expansion of the subaerial beach environment, regardless of water-level condition. Rapid beach expansion after 1990 (by a factor of four in <25 years) was facilitated by prior decades of nearshore accretion. Shoreline morphodynamic trajectories and degree of coupling to nearshore sedimentary processes are important considerations for developing long-term beach-management strategies. Rapid cross-shore movements of the shoreline in response to oscillatory base levels are expected to persist at Montrose and other urban beaches of similar design (and nearshore conditions). This has important implications for managing urban lakefront ecosystems, including coastal dunes and shore-bird habitats. Few datasets have thus far quantified time-variant and threshold-driven patterns of beach geomorphic development along engineered coastlines. Such insights should help coastal managers better understand littoral sediment interconnectivity across the urban lakefront and anticipate future geomorphic trajectories of beach environments with anticipated decadal-scale oscillatory patterns in lake level.
KW - Beach-sand volumetrics
KW - Coastal management
KW - Engineered shorelines
KW - Sediment transport
KW - Shoreline dynamics
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U2 - 10.1016/j.jglr.2022.06.008
DO - 10.1016/j.jglr.2022.06.008
M3 - Article
AN - SCOPUS:85133758334
SN - 0380-1330
VL - 48
SP - 1147
EP - 1158
JO - Journal of Great Lakes Research
JF - Journal of Great Lakes Research
IS - 5
ER -