Rising Water Levels, Reduced Sand Supplies and Coastal Erosion

Session: 51. - Coastal Resilience

Jim Selegean, U S Army Corps of Engineers, Detroit District, [email protected]
Tim Calappi, US Army Corps of Engineers - Detroit, [email protected]
Heidi Wadman, U S Army Corps of Engineers - FRF, [email protected]
Justin Gresell, U S Army Corps of Engineer - Detroit, [email protected]
Joshua Friend, U S Army Corps of Engineers, [email protected]

Abstract

Recent rising water levels have caused the eroding portion of the coastal profile to shift landward, resulting in more erosional energy spend on the beach and coastal bluff rather than the lakebed. Additionally, sand supplies to the coastal zone play a critical role in determining what erodes. While waves and water levels are easy to track, quantifying changes in the sand supply is more elusive. In this work, we reoccupied 8 lines from previous geophysical surveys nearly 30 years ago to assess the change in sand stored in the nearshore and on the beach in southeastern Lake Michigan. We used a variety of geophysical techniques (sub-bottom profiling chirp system, side scan sonar and seismic survey) along with a single beam bathymetric survey and numerous grab samples and cores to aid with the geophysical interpretation. We will discuss the cause of the sand supply change and the likely prognosis for Lake Michigan beaches in the future.

1. Keyword
coastal processes

2. Keyword
Lake Michigan

3. Keyword
sediment load