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Watersheds

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					Watersheds


   Fish 7380, Dr. e. irwin
Goals
   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?
   Watersheds provide boundaries for
    management.
   Definition is possible: it makes sense to
    manage on a waters.hed basis versus by
    political boundaries.
       Requires all land owners and water users in
        watershedmultiple-use ecosystems
Definitions
   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.
       USGS-HUCs (define)
Drainage divide
Topology
   Does a
    watershed
    need water to
    be one?
Evolution of dynamic understanding
   RCC  Watershed  Landscapes
   Structure and function of multidimensional
    systems  ecological processes
       Human impacts versus natural variation
     Anaxagoras of Clazomenenae
           (500-428 B.C.)
   “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
   Flow regime
       Quantity (magnitude and duration)
       Timing (duration and frequency)
   Quality-or nutrient budgets

   Factors that control streamflow
       Climate
       Topography
       Geology
       Vegetation
Riparian-Upland interactions
   Most dynamic component of watersheds
       Diverse areas; based on disturbance and
        heterogeneity of habitats
Riparian Function
     Dissipate flood energy
     Moderate drought
     Store surface waters
     Recharge ground water
     Moderate instream
      temperatures
     Reduce erosion
     Add instream habitat
      diversity
     Transport corridors
         Fish and wildlife
         Energy and materials
         Sediment
Riparian-River interactions
   Size and number of pools
       LWD, boulders from upslope areas
   Regulate sediment inputs via riparian
    vegetation
Riparian - Vegetation
   Function of climate, soils, topography and
    land use
   Controls timing and amount of water yield
   Controls amount of soil for downstream
    transport
Example
   48 inches of rainfall (P); 1000 acre watershed
       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
   4.75 billion acre-feet
       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.
       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
   Strait river channel
   Meandering river channel
    http://earthsci.terc.edu/content/visualizations/es1306/es13
    06page01.cfm?chapter_no=13
   Braided river channel
Strait river channel
Braided river channels
Meandering river channels
Name that river…..
Erosion and sediment transport
   Sediment is a major product of watersheds
       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
       Erosion is removal and sedimentation is
        deposition
Types of erosion
    Surface
    Mass movement
    Channel cutting
    Stream power = the rate at which a stream does work
Restore and protect = priority
   Importance of riparian zones outweighs the
    minor proportion they comprise in the
    watershed.
   National priority: NRC 1992
   Broad perspective needed (watershed)
       Scale?
       Must identify key ecological processes that
        historically provided structure and function
Water balance equation
   P = R + ET + S
       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
   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:
Bartow County
                        Partners
Cherokee County         Other Agencies and Organizations:
Cobb County             Atlanta Regional Commission
                        Cherokee County Water & Sewer Authority
Dawson County
                        Chestatee-Chattahoochee Resource Conservation &
Forsyth County                Development Center
Lumpkin County          Etowah Water & Sewer Authority
Paulding County         The Georgia Conservancy
Pickens County          Georgia Department of Natural Resources

Cities:                 Georgia Land Trust
                        Georgia Mountains Regional Development Center
City of Canton
                        Georgia Regional Transportation Authority
City of Cartersville
                        Kennesaw State University
City of Dallas
                        Lake Allatoona Preservation Authority
City of Dawsonville
                        Limestone Valley Resource Conservation & Development
City of Emerson               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
                        University of Georgia
City of Waleska
                        Upper Etowah River Alliance
City of Woodstock

				
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