State of the Beach/State Reports/MN/Beach Erosion
|Home||Beach Indicators||Methodology||Findings||Beach Manifesto||State Reports||Chapters||Perspectives||Model Programs||Bad and Rad||Conclusion|
|Minnesota Home||Beach Description||Beach Access||Water Quality||Beach Erosion||Erosion Response||Beach Fill||Shoreline Structures||Beach Ecology||Surfing Areas||Website||Coastal Development||Sea Level Rise|
The state of Minnesota’s coastline on Lake Superior is dominated by rocky shores and cobble beaches. The MLSCP’s Section 309 Assessment and Strategies reports that the highest coastal hazard risk is from episodic erosion, while storm surge and other types of erosion (chronic and dune) are ranked at a medium risk level.
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.
Approximately 60 miles of unstable clay embankment areas exist along the Minnesota shore of Lake Superior. Approximately 70,000 tons of soil erode each year from the Minnesota Lake Superior shoreline alone, causing economic and environmental losses and damages. To address this problem, since 1991 the Great Lakes Basin Program has supported 14 soil erosion and sediment control projects in Minnesota totaling over $424,000, with an additional $140,000 being leveraged from non-federal sources. Minnesota projects have focused primarily on lakeshore/shoreline erosion problems associated with Lake Superior's highly erodible clay soils. Many of those projects have developed institutional capacity to manage these erosion problems. Over 43 acres are under some form of soil erosion and sediment control, thereby preventing the loss of over 58,500 tons of soil annually. Benefits include improved water clarity and nearshore fish spawning habitat.
A survey was carried out in summer 1987 to assess the effects of the 1985–86 high water levels on Minnesota Point. Minnesota Point, also called Park Point, is a well-known Duluth neighborhood that has a population of about 1,500; it is a major year-round recreational area with beaches and an airport. Minnesota Point is located at the western tip of Lake Superior, at the mouth of its largest tributary, the St. Louis River. The project was conducted by the geography departments at both the University of Minnesota Duluth and Lakehead University, and by the Minnesota Sea Grant Extension Program. This survey obtained information on structure setbacks, erosion rates, flooding problems, and shore protection measures.
The Website of the Great Lakes Information Network has multiple links to information on Soil Erosion and Sedimentation in the Great Lakes Region.
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.
Hazard Avoidance Policies/Erosion Response
See the Erosion Response section.
|State of the Beach Report: Minnesota|
|Minnesota Home||Beach Description||Beach Access||Water Quality||Beach Erosion||Erosion Response||Beach Fill||Shoreline Structures||Beach Ecology||Surfing Areas||Website|