State of the Beach/State Reports/MI/Beach Erosion
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The Heinz Center's Evaluation of Erosion Hazards (April 2000) states:
The Great Lakes coasts extend for 3,600 mi (Federal Emergency Management Agency, 1989), and are composed of a variety of shore types, ranging from high rock bluffs to low plains and wetlands. Coastal erosion in the Great Lakes is affected by many factors, including cyclically changing lake levels, disruption of longshore transport of beach building material, and storms. Rates of bluff and dune erosion along the shores of the Great Lakes vary from near zero to tens of feet per year because of annual variability in wave climate and lake levels (National Research Council, 1990). The Great Lakes have experienced a series of high lake levels in the past two decades, with the highest peak occurring in 1987 (U.S. Army Corps of Engineers Detroit District, 1997). High lake levels increase bluff recession rates by increasing wave attack on the base of the bluff.
In many areas of the Great Lakes, bluff erosion produces beach-building sediments. However, both tributary and shoreland sources of sediment are depleted by navigational improvements and dredged material disposal practices, which remove these sediments from the littoral system. Ice ridges that form and break up each winter along the shoreline also cause erosion by trapping sand in floating fragments of ice that are carried offshore into deep water. This continuing natural process is one of the principal mechanisms by which sand is lost from the nearshore system (U.S. Geological Survey, 1992). The hardening of the lakeshore with erosion control structures can also reduce sediment supply and adversely affect natural processes.
The report "State Coastal Program Effectiveness in Protecting Natural Beaches, Dunes, Bluffs, and Rock Shores" (T. Bernd-Cohen and M. Gordon), Coastal Management 27:187-217, 1999 indicates that the amount of critically eroding shoreline in Michigan is unknown.
"High risk" erosion areas are those shorelands of the Great Lakes and connecting waters where recession of the zone of active erosion has been occurring at a long-term average rate of one foot or more per year. The erosion can be caused from one or several factors. High water levels, storms, wind, ground water seepage, surface water runoff, and frost are important factors causing erosion. Anthropogenic causes of erosion (e.g., disruption of littoral drift by placement of shore-protection structures) can also exacerbate shoreline erosion in a regional sense. Approximately 300 miles of shoreline are classified as high-risk erosion areas. Many homes and other structures have been destroyed along areas of the Great Lakes subject to rapid shore erosion processes. This destruction has resulted in severe financial loss to property owners. Public losses to recreation facilities, roads, and other public works have also occurred.
The MDEQ Great Lakes Shorelands Management Program Website provides a useful summary on how beach erosion is categorized in Michigan.
The High Risk Erosion Areas have been identified through detailed recession-rate studies conducted by the Department of Environmental Quality. The recession rates are used to calculate the appropriate setback distances for coastal constructions. The High Risk Erosion Areas are mapped on a County basis. The maps show 30-year setbacks, which apply to small readily-moveable structures and 60-year setbacks which apply to large or non-readily moveable structures.
Michigan law requires that the MDEQ conduct erosion studies to document the long-term rate of shoreline movement. Initial, detailed erosion studies were completed in 1986, and updates of the recession rate studies are scheduled every ten years to reflect changing water levels and shore protection efforts. This data is used to identify hazard areas, and establish setbacks for new construction under state regulations.
Erosion rates are site-specific, and an interested person would need to contact the HREA Program to find out what the erosion rate is for a particular location. As high-risk erosion areas are designated or updated, the affected property owners are notified in writing by the Land and Water Management Division. Maps showing the hazard areas and construction setbacks may be obtained from the MDEQ Land and Water Management Division by calling (517) 373-1170. Recently, the High Risk Erosion Areas Digital Maps, organized by County and Township, have become available on their Website.
Here is a presentation Berrien County High-Risk Erosion Area Update. DEQ recently revised their setbacks for Berrien County as a result of a 30-year study.
Several research projects have been completed in recent years. Working collaboratively with the University of Michigan, the MDEQ have produced: Cumulative Impacts of Structures and Recurve Spit Dynamics at Tawas Point; Numerical modeling of shore-parallel structures; Identification of Offshore Erosion and its Correlation to Bluff Recession; Numerical Groin Model: Coastal Monitoring Program; A Predictive Tool for Determining Shoreline Erosion; Effects of Wave Energies on Lake Pentwater and Macatawa; and Review Criteria for Shore Protection Structures.
These studies have examined the impacts of shore protection structures on erosion and bluff recession rates, increased the understanding of recession rates as they vary with Lake Water Levels and the type of shore environment (natural, unstructured coasts to highly developed structured coasts). These efforts include the periodic monitoring of survey profiles along the coastlines of Lake Michigan and Huron, which provide information on nearshore profile changes that accompany fluctuations in Great Lakes water levels. The results of this work are culminating in the establishment of guidelines for the placement of shore protection structures on the Great Lakes and inland lakes of Michigan.
Michigan ranks second in the nation in the number of second homes, making its coastal region particularly vulnerable to the conversion of agricultural and forested land to residential development. The 2001 Assessment gives a thorough and well-written analysis of regional characterization of the conversion of agricultural land to other uses for the southeast Lower Peninsula, central and southwest Michigan, northeast Lower Peninsula, and northern Lower Peninsula. It reports a common pattern of 'hotspots' of increased development.
The Detroit District of the Army Corps of Engineers has a website with information on Shoreline and Lakebed Erosion.
The Army Corps of Engineers also maintains a Website on Great Lakes water levels.
General Erosion Data Resources
The Heinz Center's Evaluation of Erosion Hazards, conducted for the Federal Emergency Management Agency (FEMA), studied the causes of coastal erosion hazards and proposed a variety of national and regional responses. The study, published in April 2000, concentrates on the economic impacts of erosion response policies as well as the cost of erosion itself to homeowners, businesses, and governmental entities.
A NOAA website that has graphs of sea level data for many coastal locations around the country over the last 40 to 50 years and projections into the future is Sea Levels Online.
NOAA Shoreline Website is a comprehensive guide to national shoreline data and terms and is the first site to allow vector shoreline data from NOAA and other federal agencies to be conveniently accessed and compared in one place. Supporting context is also included via frequently asked questions, common uses of shoreline data, shoreline terms, and references. Many NOAA branches and offices have a stake in developing shoreline data, but this is the first-ever NOAA Website to provide access to all NOAA shorelines, plus data from other federal agencies. The site is a culmination of efforts of NOAA and several offices within NOS (including NOAA’s Coastal Services Center, National Geodetic Survey, Office of Coast Survey, Special Projects Office, and Office of Ocean and Coastal Resource Management) and other federal agencies to provide coastal resource managers with accurate and useful shoreline data.
A related site launched in 2008 is NOAA Coastal Services Center's Digital Coast, which can be used to address timely coastal issues, including land use, coastal conservation, hazards, marine spatial planning, and climate change. One of the goals behind the creation of the Digital Coast was to unify groups that might not otherwise work together. This partnership network is building not only a website, but also a strong collaboration of coastal professionals intent on addressing coastal resource management needs. Website content is provided by numerous organizations, but all must meet the site’s quality and applicability standards. More recently, NOAA Coastal Services Center has developed a Sea Level Rise and Coastal Flooding Impacts Viewer as part of its Digital Coast website. Being able to visualize potential impacts from sea level rise is a powerful teaching and planning tool, and the Sea Level Rise Viewer brings this capability to coastal communities. A slider bar is used to show how various levels of sea level rise will impact coastal communities. Completed areas include Mississippi, Alabama, Texas, Florida, and Georgia, with additional coastal counties to be added in the near future. Visuals and the accompanying data and information cover sea level rise inundation, uncertainty, flood frequency, marsh impacts, and socioeconomics.
Erosion Contact Info
Land and Water Management Division
Michigan Department of Environmental Quality
P.O. Box 30458
Lansing MI 48909-7958
Hazard Avoidance Policies/Erosion Response
See the Erosion Response section.
|State of the Beach Report: Michigan