Geology Reference
In-Depth Information
TABLE 11.1 Primary Causes of Coastal Land Loss (continued)
Excavation
dredging (canal, pipelines, drainage)
mineral extraction (sand, shell, minerals)
pollutant discharge
traffic
pumping-induced saltwater intrusion
failed reclamation
burning
Wetland Destruction
Modified from
http://pubs.usgs.gov/of/2003/of03-337/intro.html
(downloaded September 17, 2007)
TABLE 11.2 Principles of Interaction of People with Coasts (Keller, 2000)
• Coastal erosion is a natural process that becomes a hazard when people build along the coast.
• Any shoreline construction causes change.
• Stabilization of the coastal zone by engineering protects the property of a few people at the cost to many (through state and
federal taxes and emergency assistance).
• Engineering structures that are designed to protect a beach can instead, given enough time, contribute to the destruction of
the beach instead.
• Once engineering structures are built, it can be very difficult to reverse their impacts.
Over 3 million people live in the Ohio counties
bordering Lake Erie. Land loss due to shoreline ero-
sion is a critical problem for those living immediately
adjacent to the lake, with millions of dollars of prop-
erty damage occurring annually.
The 220 miles of Ohio shore is made up largely of
regolith comprised of glacial till, clay, and sand, plus
resistant limestone and dolostone bedrock exposures
in the Catawba and Marblehead peninsula area at the
western end of the lake and shale exposures in the
Lorain and Cleveland area in the west central part of
the lake. Wetlands, low bluffs, and gently sloping
shores characterize the western one-third of the coast.
Sandy beaches generally overlie clay deposits along
the shore in this area.
The low relief and location of the western shoreline
make it susceptible to flooding because of wind setup
during storms out of the northeast. This wind setup,
usually associated with low atmospheric pressure
events (in which the water level rises), leads to a phe-
nomenon known as a
seiche,
where water that has piled
up at one end of the lake then sloshes back and forth in
the elongated basin of Lake Erie. The out-of-phase water
levels between Toledo and Buffalo (Figure 11.2) are an
example of this phenomenon.
Most of the eastern third of Ohio's Lake Erie
shoreline consists of nonresistant lake clay, sand, and
glacial till, which form bluffs 10-60 feet high. In this
section shoreline erosion has historically been a prob-
lem, just as it is today. Whittlesey (1838) reported that
most of the Ohio shoreline from the Pennsylvania line
to Marblehead had lost an average of 130 feet of land
to the lake between 1796 and 1838. Although natural
processes such as wave erosion and mass wasting
were almost solely responsible for the erosion
recorded in the earlier years, structures such as groins,
breakwaters, and dikes have had an influence in more
recent times (Carter, 1973).
The amount of land lost and rate of shoreline
recession over nearly a century (1876-1973) in an area
in Lake County, Ohio, east of Cleveland, is shown in a
diagram of shoreline locations taken from topographic
maps of the area (Figure 11.3). Aerial photographs
FIGURE 11.2
Water-level curves for Buffalo and Toledo during
the storm of December 15-16, 1987 (Fuller, 1988).
