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Forum Presentation March 18

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Forum Presentation March 18 Powered By Docstoc
					Mid-Range Streamflow
Forecasts for River
Management in the
Puget Sound Region
   Richard Palmer
   Matthew Wiley
   Department of Civil and Environmental Engineering




                                   March 21, 2005
n   Center for Water Resources
    Management and Drought
    Planning

n   The Climate Impacts Group


n   PRISM, Puget Sound Regional
    Synthesis Model
Outline
n   Region’s Water Supply Basins
    ¨   Models
    ¨   Current Conditions
n   Forecast Methods
    ¨   ESP, Extended Streamflow Prediction
    ¨   CPC, Climate Predication Center

n   Current Forecasts
    ¨   Water Snowpack Modeling

    ¨   Streamflow Forecasts
                                              Special Thanks to the Water
    ¨   Impacts on Storage                    Forum for Funding the Mid-
                                                   Range Forecasts
Hydrologic Model - DHSVM
n   Physically based, distributed model
n   Calculates energy and water balance
    at the grid cell level
n   150 meter resolution, 3hr time-step
n   Station based meteorology
n   Output streamflows are aggregated
    to monthly total volume
n   Recently incorporated an
    experimental groundwater
    component
n   Sultan River
    ¨   Snohomish PUD
        Hydropower project
    ¨   Everett Water Supply
n   S.F. Tolt River
    ¨   Seattle Water Supply
n   Cedar River
    ¨   Seattle Water Supply
n   Green River
    ¨   Flood Control
    ¨   Tacoma Water Supply
n   All have environmental
    flow requirements
Streamflow Forecasts
n Initialize basin models to current conditions using recent
observed meteorology
n   ESP (Extended Streamflow Prediction)
     ¨   Project 13 months into the future using each year in the historic
         record as one of many possible scenarios (traces).
     ¨   Forecast can be conditioned using subsets of years based on
         observed climatologically conditions, such as ENSO state
n   CPC (Climate Prediction Center)
     ¨   Seasonal outlooks of the probability of deviations from normal
         temperature and precipitation for 13 months
     ¨   Each season's outlook and probability that a temperature or
         precipitation quantity will be exceeded for a climate region at the
         given lead time of two weeks to a year.
Green River into Howard Hansen Reservoir
CPC forecast: April
Modeling Snowpack
n   DHSVM allows evaluation of snowpack
    conditions over time
n   Provides graphical presentation of basin state
n   Estimate of total water storage as snow
n   Essential for evaluating the future based on
    current conditions
n   Provide spatial information to complement
    Snotel and Snow Course information
n   Forecasts Results
    ¨ USGS     12137290
    ¨   SULTAN1: Inflow to Spada


    ¨ USGS 12147600
    ¨ TOLT1: Inflow to SFT
    ¨ TOLT2: Below SFT


    ¨ USGS 12115000
    ¨ USGS 12117000
    ¨ CEDAR1: Inflow to CM
    ¨ CEDAR2: Below CM


    ¨ HH_INFLOW:    Inflow to
        Howard Hansen
Cedar River above Chester Morse Reservoir
S.F.Tolt River above S.F.Tolt Reservoir
Green River into Howard Hansen Reservoir
All Inflows into Spada Reservoir
Implications to Water Supplies
n   Factors to Consider
    ¨ Current  storage
    ¨ Inflows to reservoirs
    ¨ Inflows below reservoirs that contribute to fish
      requirements
    ¨ Average demand and effect of conservation
    ¨ Availability of supplemental groundwater supplies
    ¨ “Normal” versus “Low” versus “Critical” instream flows

n   Examined Seattle and Tacoma systems
Implications for Puget Sound Water
Supply Systems
n Inflows to reservoirs expected to be only
  40% to 50% of average, higher in the
  Everett system.
n 60% chance of the Seattle system not
  completely refilling this spring ( ~32 billion gal.)
n 10% chance of the Tacoma system not
  completely refilling this spring (~10 billion gal.)
Implications for Puget Sound Water
Supply Systems
n   Inflows to reservoirs expected to be only 40% to
    50% of average, slightly higher in the Everett
    system.
n   60% chance of the Seattle system not
    completely refilling this spring ( ~32 billion gal.)
n   10% chance of the Tacoma system not
    completely refilling this spring (~10 billion gal.)
n   If NO action is taken:
         “Normal fish flows, average demand)
    ¨ (i.e.
    ¨ 10%-15% of shortfall by October.
Implications for Puget Sound Water
Supply Systems
n   A 10% reduction in consumption reduces
    probability to around 5% chance of shortfall
n   Current snowpack is only half of the picture,
    spring rains can also refill reservoirs
n   10-12 inches* (at Seatac) between March 1 and
    July 1 will get us to near average storage by
    September 1                   *(Average precip is 9.5 inches)
n   In an average year there is a considerable
    “surplus” of water in the basins
Implications for Puget Sound Water
Supply Systems
n   Actions have already being taken
n   Actual operations are very dynamic with
    considerable flexibility and continual adjustments
    based on evolving conditions
n   Minimizing ecological damage and preventing
    disruptions to customers are primary goals
n   A “serious” situation requires several events (low
    snow pack, below average summer flows, late
    return of rain)
Questions ?
CPC forecast: MAM
CPC forecast: MJJ
CPC forecast: JJA
CPC forecast: JAS
CPC forecast: ASO
CPC forecast: SON
Cedar River above Chester Morse Reservoir
S.F.Tolt River above S.F.Tolt Reservoir
All Inflows into Spada Reservoir
Cedar River above Chester Morse Reservoir
Taylor Creek below Chester Morse Reservoir
S.F.Tolt River above S.F.Tolt Reservoir
S.F.Sultan River above Spada Reservoir
Green River into Howard Hansen Reservoir
All Inflows into Spada Reservoir

				
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posted:12/17/2013
language:English
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