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Project Tour - page 2
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Approach and Methods
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| The OSGP uses a variety of approaches to better understand past, present, and future conditions of Ozark streams. This is a summary of
some of the project's geological and biological tools. More information is available
in many technical publications -- the references in parentheses are listed on the publications page of this web site. |
Understanding Historical Stream
Conditions:
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- STRATIGRAPHY
- Sediments and soils preserved in flood plains provide the best geologic record of past
Ozark stream conditions. The geologist in the picture to the left is using a drill
rig to sample old stream sediments buried in the flood plain. Stratigraphic studies of these deposits provide
information about the type of sediments streams carried. When pieces of charcoal or
old wood are found in the deposits, their age can be determined with radiocarbon dating. Stratigraphic studies
provide information about Ozark channels over the last several thousand years.
(Jacobson and Pugh, 1992)
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- HISTORICAL RECORDS
- Historical records such as old photographs, census data, oral histories, and aerial
photographs provide information about the more recent history of Ozark streams.
These records document how land use has changed in the Ozarks and provide information
about past stream conditions (Jacobson and Primm, 1997). Aerial photographs are
available from each decade since the 1930s -- we have used these photos to map broad-scale
rates of channel change and determine whether channel movement can be related to local
vegetation characteristics. (Jacobson and Pugh, in press)
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Understanding Present Stream
Conditions and Processes:
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- CHANNEL MONITORING
- Channel monitoring provides information about the rates of and controls on current Ozark
stream processes. Since 1992, we have surveyed annually a network of 101 cross
sections on 7 stream segments on the Little Piney, Jacks Fork, and Buffalo Rivers.
Click on the image to the left to see an example cross section. These cross sections
document year-to-year changes in the shape of the channel at a scale that is applicable to
stream communities. This dataset provides information about parameters such as the
amount of gravel eroded or deposited from channel segments annually and the time frames
over which particular habitats persist. (McKenney and Jacobson, 1996)
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- GEOGRAPHIC INFORMATION SYSTEMS
- Geographic information systems
(GIS) allow maps of basin-wide features such as geology, topography, and land use to be
overlain with detailed stream channel maps. This technique has been used to look for
correlations between stream characteristics and spatial factors such as geology,
topography, vegetation, road density, and land use. Click on the image to the
left to have a better look at a GIS. (Jacobson and Gran, in prep; Jacobson and Pugh,
in press; McKenney, 1997)
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- HABITAT SAMPLING
- Biological sampling and field mapping of stream habitats provide information about
organisms and the stream conditions they prefer. We developed a habitat
classification system based on channel shape and physical factors such as depth, velocity,
and bed material. Sampling within these habitats allowed biologists to make
correlations between organisms and the stream conditions the prefer. In the picture
to the left, collaborating biologists from the University of Missouri-Columbia are netting
off and sampling a run habitat. We have used data
from channel monitoring to determine how the distribution and area of these habitats
change annually. (McKenney, 1997; Peterson, 1996; Rabeni and Jacobson, 1993;
Peterson and Rabeni, in prep; Doisy and Rabeni, in prep)
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Anticipating Future Stream
Conditions:
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- HYDROLOGIC RECORDS
- Hydrologic data collected at stream gages provide information about how stream flow has
varied over the past several decades. The USGS of Missouri and Arkansas maintains stream gages at numerous
locations in the Ozarks--some of these gages have continuously recorded the amount of
water flowing past them since the 1920s. Gage records document how stream flow has
varied in years of heavy rainfall and years of drought. Analysis of these records
provides a reference for how Ozark streams might respond to future changes in
rainfall. (Panfil and Jacobson, 1999)
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- COMPUTER MODELING
- Computer modeling helps anticipate how future changes in stream flow might affect the
habitats available for stream communities. The image to the left shows a modeled
section of the Jacks Fork River. For a particular discharge,
the model determines the velocity and depth of water throughout the channel. This
information can then be used to classify the channel into habitats. Modeling
different discharges is a way to anticipate how the areas of different habitats may change
in response to climatic shifts and changes in stream flow. (Panfil and Jacobson, 1999)
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For more of the tour click: 
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