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Impact of Northeast Flooding on Chesapeake Bay
The extensive flooding due to Tropical Storm Lee is impacting the Chesapeake
Bay with sediment-laden flood waters. Satellites are being used to track the
extent of the plume of sediment and to help understand the effects of sediment
pollution on the Bay's ecosystem. The satellite images below are maps of
total suspended matter -- a measure of how much material (mud, silt,
debris) is in the surface water. These satellite images were taken by the
MODIS instrument on NASA's Aqua satellite and processed by NOAA CoastWatch.
Current Satellite Images: Total Suspended Matter
click on an image for a larger version
(due to data transmission and processing time, most recent image available
is from previous day)
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Mapped Satellite Swath
(yesterday) |
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Daily Composite
(2 days ago) |
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Ongoing: Daily Tracking of the Sediment Plume
click on an image for a larger version
Shown below are satellite images before
and after the storms Irene and Lee (before: Aug 23, 2011 / after:
Sep 11, 2011). The September 11 images show the sediment-laden waters that have
entered the Chesapeake Bay.
True Color Images
click on an image for a larger version
Before:
August 23 |
After:
September 11 |
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Total Suspended Matter
click on an image for a larger version
Before:
August 23 |
After:
September 11 |
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Sediment poses a hazard to the Chesapeake Bay by reducing the Bay's water
quality. Oysters that normally filter the water can be smothered by the
sediment. In addition, sediment reduces the light needed by sea-grass beds,
which ordinarily provide nursery grounds for many species of fish and crabs.
The restoration of oysters and sea grasses has been a priority in efforts to
revive the health of the Bay, but catastrophic events such as those brought
by Tropical Storm Lee hamper these efforts. Management practices, that will
bring about long-term reduction in sediment and nutrient pollution from
upstream agricultural and urban/suburban sources, will have a positive impact
on the Bay by making the Bay more resilient when catastrophic events occur.
The deluge of rain from Tropical Storm Lee caused the third highest
flooding on the Susquehanna River, the largest tributary entering the Bay,
with a peak river discharge of 778,000 cubic feet per second on September 9,
2011. Sediment pollution is carried with the flood waters into
the Bay, along with debris, garbage, and nutrient pollution from fertilizer
and sewage overflows. There is concern that the nutrient pollution will
create a dead zone of low-oxygen water later this fall, making it
difficult for aquatic life to survive.
Scientists create satellite-derived maps of total suspended matter
by relating in-water sediment concentration measurements to the amount of
light leaving the water -- the light that is eventually seen by the satellite
(Ondrusek et al., 2012). Satellites can thereby be used to estimate the
sediment concentration in the surface water, which is useful for ecologists
studying the effect of sediment-laden water on aquatic life.
Ongoing True Color Images
Data & Images: Direct Download
Research on the Sediment Plume's Effects on the Bay
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