Contents 



Preface 



V 



1 — Introduction j 



2 — Background 3 



Regional Coastal Processes and Geomorphology 3 



Site Conditions and Beach Nourishment History 3 



Discussion of Cohesive Shores g 



3 — Existing Data Sources 9 



Beach Profiles 9 



Lake Bed Bathymetry 9 



Wave and Water Level Data 9 



Shoreline Recession 14 



4 — Analyses of Coastal Processes and Geomorphology 16 



Results of the Alongshore Sediment Transport Calculations 16 



Single grain size across the profile 16 



Multiple grain sizes across a profile 18 



Annual variation in potential alongshore sediment transport 22 



Historic variability in potential alongshore sediment 



transport related to profile change 25 



Bypassing and channel infilling at St. Joseph Harbor 27 



Results of Cross-Shore Modeling with Multiple Grain Sizes 31 



COSMOS-3D Modeling 37 



Methodology 37 



General results 40 



Runs A to C (initial series) 41 



Runs D to F (post beachfill series) 48 



Runs G and H (2 mm, coarse sediment) 49 



Runs I and J (high water level) 49 



Runs K and L (pre- and post-fill with 0.5-m marker depth) 49 



Assessment of predicted glacial till downcutting 50 



Summary of the 3-D results 56 



Trends in Profile Change 57 



Long-term profile change 58 



Short-term profile change 60 



