State of the Beach/State Reports/IN/Beach Erosion
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Coastal Dynamics includes discussions of Fluctuations of Great Lakes Levels, Coastal Erosion, and High Erosion Hazard Areas.
Conditions Along the Indiana Coastline summarizes the results of coastal surveys by the U.S. Army Corps of Engineers and the Great Lakes Coastal Research Laboratory of Purdue University during the late 1970s through the mid 1980s. For the purposes of the surveys, Indiana's 45 miles of shoreline were divided into six distinct segments or reaches, separated, in most cases, by the presence of a man-made coastal structure. The reaches, moving from east to west along the coast, were identified as follows:
- Reach 6 (CZM): Indiana-Michigan border to the Michigan City Harbor.
- Reach 1: Michigan City Harbor to boundary between the Town of Beverly Shores and the Indiana Dunes State Park at Kemil Road.
- Reach 2: Kemil Road to the east side of the Burns International Harbor complex.
- Reach 3: USX and Gary Harbor complex: Burns International Harbor to the USX- Gary Harbor complex.
- Reach 4: Buffington Harbor to the Indiana Harbor and Ship Canal complex.
- Reach 5: Indiana Harbor and Ship Canal to the Calumet Harbor in Illinois.
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.
Erosion is a significant coastal hazard in Indiana. In particular, three areas of Indiana’s coast experience increased erosion rates and lack enough sand to maintain sufficient beach widths as well as the offshore sand bars necessary to protect the shoreline. Mt. Baldy and Ogden Dunes experience severe sand-starved conditions and the highest erosion rates on Indiana’s coast. These areas are located immediately downdrift of major sand-trapping structures. Beverley Shores is also sand-starved, but to a lesser degree than Mt. Baldy and Ogden Dunes.
The USGS publication Our Changing Landscape: Indiana Dunes National Lakeshore discusses erosion issues at that location, causes of the erosion and efforts to mitigate it. From that report:
In Indiana Dunes, the 18-mile shoreline retains much of its natural character. Adjacent to the park's beaches, however, the shoreline has been altered by the construction of harbors and industrial complexes and the use of rip rap (large boulders) to protect the shore. Of the 41 miles of shoreline between Michigan City, Ind., and the Illinois border, more than half have been altered to protect private residential or industrial properties. Structures, such as the jetties at Michigan City, Burns Harbor, and U.S. Steel, interrupt the normal longshore (parallel to the beach) transport of sand. The beach is built up as sand accumulates on the updrift side of structures; the beach erodes as sand is then removed on the downdrift side.
Shoreline erosion in the park results especially from storms in the early spring and late fall and during mild winters, when ice on Lake Michigan does not freeze to the shore. In March 1964, Lake Michigan began rising until it reached a record high for the century in 1986. When lake levels are high, the beaches become narrow. The waves break at the base of the dunes and erode them. Narrow beaches provide less space for the 2 million visitors who use the beaches during the summer. People are forced onto the foredune, where they interfere with the plants and animals present and cause trail erosion. High lake levels and their resultant narrow beaches also reduce the sand supply available to replenish and build the dunes.
Indiana Dunes State Park suffered severe erosion due to a storm in mid-December 2010 that was termed the most intense storm since 1993. Large waves chopped off the dunes, destroying the gradual slope, and creating a sharp, cliff-like drop of up to 12 feet, all along Porter County and parts of Lake County and possibly into LaPorte County, according to park staff.
In December 2010 the National Park Service invited the public to comment on the problem of shoreline erosion at Indiana Dunes National Lakeshore, as part of the process to develop a long-term plan to restore and manage the Dunes.
A source of information on coastal erosion in Indiana (southern Lake Michigan) is the USGS Fact Sheet Coastal Erosion of Southern Lake Michigan.
General Erosion Data Reference Documents
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.
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