Transcript Watersheds - Auburn University College of Agriculture

Watersheds
Fish 7380, Dr. e. irwin
Goals
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Review components of catchments
Understand structure and function of
watersheds
Faunal relations and/or ecological
processes
Restoration and management: where are
the pressure points?
Why do we care?
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Watersheds provide boundaries for
management.
Definition is possible: it makes sense to
manage on a waters.hed basis versus by
political boundaries.
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Requires all land owners and water users in
watershedmultiple-use ecosystems
Definitions
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Watershed-any sloping land surface that
sheds water; more functionally-all land
enclosed by a continuous hydraulic
drainage divide and lying upslope from a
specific point on a stream.
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USGS-HUCs (define)
Drainage divide
Topology
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Does a
watershed
need water to
be one?
Evolution of dynamic understanding
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RCC  Watershed  Landscapes
Structure and function of multidimensional
systems  ecological processes
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Human impacts versus natural variation
Anaxagoras of Clazomenenae
(500-428 B.C.)
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“Rivers depend for their existence on the
rains and on the waters within the earth, as
the earth is hollow, and the water in its
cavities”
Function of a watershed=produce water
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Flow regime
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Quantity (magnitude and duration)
Timing (duration and frequency)
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Quality-or nutrient budgets
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Factors that control streamflow
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Climate
Topography
Geology
Vegetation
Riparian-Upland interactions
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Most dynamic component of watersheds
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Diverse areas; based on disturbance and
heterogeneity of habitats
Riparian Function
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Dissipate flood energy
Moderate drought
Store surface waters
Recharge ground water
Moderate instream
temperatures
Reduce erosion
Add instream habitat
diversity
Transport corridors
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Fish and wildlife
Energy and materials
Sediment
Riparian-River interactions
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Size and number of pools
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LWD, boulders from upslope areas
Regulate sediment inputs via riparian
vegetation
Riparian - Vegetation
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Function of climate, soils, topography and
land use
Controls timing and amount of water yield
Controls amount of soil for downstream
transport
Example
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48 inches of rainfall (P); 1000 acre watershed
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50% is realized as streamflow (48 x 0.5 =24 inches)
Total volume of water yield/year =2,000 acre feet
(24 inches x 1,000 acres x 1 ft/12 inches)
Average discharge/year = 2.72 cfs (2,000 acre
feet/year x 43,560 ft2/acre-ft x 1yr/365d x
1d/86,400 s)
US precipitation-annual average = 30 inches
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4.75 billion acre-feet
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3.4 billion (70%) lost to ET
3% lost consumptively, remaining 27% is streamflow
In general, the % of precipitation resulting in
streamflow increases with increased precipitation.
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ET is the most constant variable in the water equation.
When requirement met, the rest is available for
runoff.
As elevation increases, runoff increases
Water supply problems often are not related to water
quantity; timing is important
Channel morphology
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Strait river channel
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Meandering river channel
http://earthsci.terc.edu/content/visualizations/es1306/es13
06page01.cfm?chapter_no=13
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Braided river channel
Strait river channel
Braided river channels
Meandering river channels
Name that river…..
Erosion and sediment transport
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Sediment is a major product of watersheds
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Important to measure
Estimated 80% of WQ degradation results from
erosion
 Sediment interacts strongly with other WQ
components
 Sediment yield is directly affected by land use
activities
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Erosion is removal and sedimentation is
deposition
Types of erosion
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Surface
Mass movement
Channel cutting
Stream power = the rate at which a stream does work
Restore and protect = priority
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Importance of riparian zones outweighs the
minor proportion they comprise in the
watershed.
National priority: NRC 1992
Broad perspective needed (watershed)
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Scale?
Must identify key ecological processes that
historically provided structure and function
Water balance equation
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P = R + ET + S
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Where:
P = precipitation during time interval t
R = total water yield or streamflow at t
ET = Evapotranspiration at t
S =  storage as t , S approachs zero
Rearrange R = P – ET - S
ET
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Transpiration and evaporation are difficult
to measure
Equation for ET
The Etowah Regional Habitat Conservation Plan
The unique fish of the Etowah face an uncertain future as
rapid development degrades their habitat. Federal
regulations to protect the fish can impose costly delays and
restrictions on growth. The solution is to develop a regional
Habitat Conservation Plan that minimizes the impacts of
growth, ensuring long-term environmental and economic
health for the region.
http://www.etowahhcp.org/index.html
Counties:
Partners
Bartow County
Cherokee County
Other Agencies and Organizations:
Cobb County
Atlanta Regional Commission
Dawson County
Cherokee County Water & Sewer Authority
Forsyth County
Chestatee-Chattahoochee Resource Conservation &
Development Center
Lumpkin County
Etowah Water & Sewer Authority
Paulding County
The Georgia Conservancy
Pickens County
Georgia Department of Natural Resources
Cities:
Georgia Land Trust
City of Canton
City of Cartersville
City of Dallas
City of Dawsonville
Georgia Mountains Regional Development Center
Georgia Regional Transportation Authority
Kennesaw State University
Lake Allatoona Preservation Authority
City of Emerson
Limestone Valley Resource Conservation & Development
Center
City of Holly Springs
Mountain Conservation Trust of Georgia
City of Kennesaw
The Nature Conservancy
City of Marietta
U.S. Army Corps of Engineers
City of Roswell
U.S. Fish & Wildlife Service
City of Waleska
City of Woodstock
University of Georgia
Upper Etowah River Alliance