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Sand
in the wrong place
Erosion
itself is a natural process. Sand and gravel that erode
from the shore will deposit on the Bay floor and provide
a habitat for fish and bottom-dwelling organisms. Today's
increased erosion of the Chesapeake Bay shores, however,
has many negative consequences. The erosion is leading
to:
Loss
of land
The erosion is leading to a loss of public and
private land, recreational beaches, farmlands, and forests.
- Increased
flow of nutrients to the Bay
The nitrogen and phosphorus in the soil are carried
to the Bay, increasing the load on a waterway already
too rich in these nutrients. An overload of nitrogen
and phosphorus changes the conditions of the Bay waters,
stimulating the growth of microscopic-small algae that
may lead to toxic algal blooms or inhibit the growth
of other aquatic plants.
- Increased
turbidity, or cloudiness, of the water
The sediment suspended in the water column can
be a problem for water plants that are not right at
the surface. Because all plants need light, the ability
of the light to penetrate the water sets the limits
on where aquatic plants can live. High volumes of sand
can also simply smother beds of submerged aquatic vegetation
(or SAV beds).
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Vegetation
to prevent erosion
How
you can best prevent erosion depends a lot on the circumstances
of the property. The self-taught
education
unit about coastal shoreline defense structures (a pdf
document)
of the Center
for Coastal Resources Management
is a great resource to learn more about bulkhead, riprap,
marsh toe protections, and using vegetation to prevent
erosion.
Though
bulkheads (shown in the picture below) and rock riprap
can prevent erosion, they are not always the best choice.
Bulkheads, for example, are walls mounted into the shore
and the bottom and are designed to prevent wave-induced
erosion. A major problem of bulkheads, however, is that
they reflect most waves and, therefore, simply pass on
the erosion to the next strip of unprotected land.
Bulkheads
also limit the growth of salt marshes and create a direct
pathway into the Bay for runoff, containing contaminants,
from upland sources.
Picture:
Bulkhead used to prevent shoreline erosion. Though
a bulkhead can prevent erosion in one place, the structure
reflects the waves, often causing erosion of nearby unprotected
shores. Picture courtesy of NOAA, National Estuarine
Research Reserve Collection.
Research
has shown that for shorelines with less than a mile of
fetch, which is the distance the wind blows over water
before it reaches the shoreline, planting vegetation is
a great way to stop erosion.
Picture:
Planting Smooth Cord Grass can prevent erosion.
Picture courtesy of the University of Florida, Center
for Aquatic and Invasive Plants.
Plants
like smooth cord grass and salt meadow hay are good options;
their roots will hold the sand in place. The roots also
slow down the wave action and cause the sediment to deposit
along the shoreline. And planting vegetation is not only
the cheapest option, the vegetation also provides a habitat
for birds and other animals.
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References
and further reading
