Just an Intro to the Understanding of the Earthcache
When the National Forest System was established in 1905, one
of
its first mandates was to restore the watershed function of
forests. Today an estimated 80 percent of U.S. freshwater
resources
originate in forests, with much of the nation’s
drinking
water coming from the estimated 192 million acres of our
national
forests, which actually make up only 30 percent of U.S.
forested
land. According to the U.S. Environmental Protection Agency,
more
than 60 million people in 3,400 communities rely directly on
national forests for their drinking water. Thats alot of mouths
to
need water to drink!!!!
What is a watershed
watershed is a basin of sloping land surrounded by ridges
and
drained by a stream. The Coweeta basin, which contains dozens
of
separate watersheds, is ideal for hydrologic research. The site
was
strategically selected due to its topography and aspect and
the
unusually high rainfall (70 to 90 inches per year). The solid
bedrock underlying the soils permits the hydrologist to account
for
most of the rainfall that enters the basin. Many of the
watersheds
in the basin are very similar in terms of size, climate, soils,
and
vegetation. The relationship between rainfall and streamflow
before
disturbance has been charted for many of the watersheds since
1934.
To test a theory or evaluate a management practice, scientists
can
manipulate conditions on a watershed and then compare results
with
those from a similar undisturbed watershed that serves as a
reference.
Since the 1930s, 32 weirs, or stream gauging stations, have
been
installed on streams in the Coweeta basin; 16 of these weirs
are
currently operational. Streamflow data has been collected from
the
weirs since the 1930s using automatic recorders that
continuously
monitor the height of the water in the weirs which is later
translated into streamflow using a mathematical formula based
on
the dimensions of the weir blade. Because the weirs were
precisely
constructed, streamflow can be calculated day and night,
through
storm and sunshine, throughout the year. Sediment that
accumulates
in the ponding basin constructed behind each weir can also be
measured and streamwater chemistry data has been monitored
since
1972.
Water quality in the South has been shaped by three centuries
of
intensive land use, with clearing for agriculture starting in
the
1700s, and unregulated logging beginning shortly after the
Civil
War and lasting through the 1920s. The period between 1860 and
1920
was the most destructive known, with widespread clearing of
southern forests without any few erosion control measures.
Logging
peaked in 1909 and stayed high until 1920, when only a few
stands
of virgin forest remained. Rivers were filled with sediment
from
mountain slopes; many still run muddy from those times.
Like most of the Southern Appalachians, the Coweeta basin
was
heavily harvested in the 1920s. At the time, very little
scientific
information was available about the impacts of unregulated
logging
on water quality, but it was clear to the naked eye that
large
amounts of sediment had reached the streams when mountain
watersheds were logged. How sad is that.
Sediment from Roads
Sediment is one of the most significant stream pollutants in
the
eastern United States. High sediment loads in streams have
negative
effects on aquatic insects, animals, and plants and can
substantially increase the cost of water treatment. Non-point
sediment from un-surfaced roads contributes to the majority
of
sediment present in southern Appalachian streams. One study
estimated that unpaved roads, ditches, and road banks were
responsible for 85% of the stream sediment load in a large
watershed in the southern Appalachians.
Roads in the southern Appalachians vary from improved
paved
roads to poorly constructed and maintained dirt roads. Past
research has generated a range of Best Management Practices
(BMPs)
designed to limit the production and movement of road
sediment.
Despite the development and implementation of these BMPs,
road
sediment continues to be a major challenge to private and
public
land managers. To address this challenge, land managers need
information and tools to assess the relative differences in
sediment generated from a range of existing road conditions, and
to
evaluate potential improvements after BMPs are put in place.
In one study, Coweeta researchers measured the particulate
matter of total suspended solids (TSS) and total petroleum
hydrocarbons (TPH) from an array of typical road conditions
found
on public and private land in the southern Appalachians.
These
included paved roads, gravel roads with routine maintenance,
gravel
roads with sediment control BMPs, and poorly constructed
roads
receiving minimal maintenance. Results showed the lowest amount
of
sediment production came from the paved roads and the most
sediment
production came from the poorly constructed roads receiving
little
or no maintenance. Properly installing and maintaining BMPs
effectively reduced sediment delivery to streams. TPH was found
to
be in very low concentrations in paved road runoff, and was
not
found in nearby stream water or bottom sediments. These
results
held for both fresh and older paved surfaces. Paved surfaces
generate less sediment, and that in combination with little or
no
TPH in runoff from these surfaces adds paving as an option to
forest managers where critical aquatic habitat may be at risk
to
sedimentation from unpaved road surfaces. This information,
combined with computer-based models that apply these values to
the
watershed scale, is currently being used by land managers to
estimate current sediment yield and evaluate how improved
road
surfaces (either by paving or using BMPs) will impact future
amounts of stream sediment.
Getting credit for the Earthcache
Please answer the following and also remember that you do
not
need a pciture in you log but if you like to include one then
please do
1.)How important are forests to maintaining high quality
water
in the southern Appalachians?
2.) What is elevation at the brown sign that states
"Coweeta
Hydrologic Laboratory"
3.) What types of rocks can be found where you are
standing
at?
4.) Why is this area so imprtant to the Appalachain Region?
Hope you enjoy this earthcache
