TY - JOUR
T1 - Great lakes urban pocket-beach dynamics
T2 - A GIS-based analysis of infrastructure-design influences on geomorphic development
AU - Mattheus, Christopher R.
AU - Braun, Katherine N.
AU - Theuerkauf, Ethan J.
N1 - Funding Information:
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. It was made possible through ongoing collaborative efforts between the Chicago Park District, the Illinois Coastal Management Program, and the Illinois State Geological Survey. We hope to expand upon our insights from Chicago beaches with data from wave/beach-camera installations and topographic/bathymetric monitoring efforts, all funded by the Illinois Coastal Management Program. We extend our gratitude to Jennifer Santoro (at Villanova University) for assistance with GIS-based analyses and would also like to acknowledge Casey Sebetto (Coastal Management Program) and Kendall Anderson (Chicago Park District) for encouraging this work and paving the way for a monitoring study of priority beach sites.
Publisher Copyright:
© 2021 International Association for Great Lakes Research
PY - 2022/2
Y1 - 2022/2
N2 - Chicago's lakefront beaches experienced inundation and coastal erosion when Lake Michigan's mean annual water level rose by >1.5 m between 2013 and 2019. Understanding beach geomorphic response to this type of lake-level event is important, as future climate predictions call for a continuation of decadal oscillatory patterns. A GIS-based study of beach change was conducted along the city's urban lakefront, where sand is embayed by groins, jetties, and revetments. Morphologic changes associated with the most recent decadal lake-level rise were evaluated in context of the surrounding infrastructure. Beach morphometrics, derived from historical aerial images and available LiDAR products, were compared against the characteristics of the fixed urban infrastructure. Overwash volumes associated with an ∼1 m-rise in lake level scaled well with beach size (R2 = 0.88), suggesting that the creation of new sediment accommodation and its spatial distribution along the urban lakefront during lake-level rise is an important control on beach morphodynamic behavior. Overwash patterns were influenced by embayment orientation and groin characteristics. Counterclockwise beach rotation of up to 21° occurred in places where shorelines were exposed to the open lake. More tightly enclosed beaches retreated more uniformly along strike due to passive inundation of terrain with lake-level rise. Our insights provide managers with useful information on key beach behavioral patterns and how they are influenced by infrastructure design, allowing for the possibility of mitigation strategies to be emplaced in anticipation of future lake-level oscillations.
AB - Chicago's lakefront beaches experienced inundation and coastal erosion when Lake Michigan's mean annual water level rose by >1.5 m between 2013 and 2019. Understanding beach geomorphic response to this type of lake-level event is important, as future climate predictions call for a continuation of decadal oscillatory patterns. A GIS-based study of beach change was conducted along the city's urban lakefront, where sand is embayed by groins, jetties, and revetments. Morphologic changes associated with the most recent decadal lake-level rise were evaluated in context of the surrounding infrastructure. Beach morphometrics, derived from historical aerial images and available LiDAR products, were compared against the characteristics of the fixed urban infrastructure. Overwash volumes associated with an ∼1 m-rise in lake level scaled well with beach size (R2 = 0.88), suggesting that the creation of new sediment accommodation and its spatial distribution along the urban lakefront during lake-level rise is an important control on beach morphodynamic behavior. Overwash patterns were influenced by embayment orientation and groin characteristics. Counterclockwise beach rotation of up to 21° occurred in places where shorelines were exposed to the open lake. More tightly enclosed beaches retreated more uniformly along strike due to passive inundation of terrain with lake-level rise. Our insights provide managers with useful information on key beach behavioral patterns and how they are influenced by infrastructure design, allowing for the possibility of mitigation strategies to be emplaced in anticipation of future lake-level oscillations.
KW - Littoral
KW - Sediment accommodation
KW - Shoreline morphodynamics
KW - Urban beach
KW - Wave refraction
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U2 - 10.1016/j.jglr.2021.10.020
DO - 10.1016/j.jglr.2021.10.020
M3 - Article
AN - SCOPUS:85118699782
SN - 0380-1330
VL - 48
SP - 68
EP - 83
JO - Journal of Great Lakes Research
JF - Journal of Great Lakes Research
IS - 1
ER -