Flood Warning and Forecasting Issues in the SRWMD

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Flood Warning and Forecasting Issues in the SRWMD
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Suwannee River Basin
240 Miles Long, 9,950 Square Miles
Headwaters
Okefenokee Swamp Suwannee River
Georgia
Florida
Cordele, GA Alapaha River
Tifton, GA Withlacoochee River
State Line at River Mile 207
Only 43 of Basin is in Florida
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Suwannee River Basin Non-Structural Floodplain
Management Strategy

• Floodplain Regulation
• Floodplain Acquisition
• Forecasting and Education

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Floodplain Regulation

• Elevate Structures
• Limit Fill and Obstructions in Floodplain
• Riverbank Setbacks and Erosion Control

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Floodplain Acquisition Strategy

• Provide natural storage for flood waters
• Reduce loss of life and property due to floods
• Protect ground and surface water resources
• Protect natural systems associated with
  floodplain ecosystems

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Flood Warning and Education

• Emergency Management Coordination
• Flood Forecast Modeling
• Forecast Dissemination
• Telephone
• Internet
• NOAA Weather Radio

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Flood Monitoring Network in the Suwannee
River Basin
USGS-GA
USGS-FL
SRWMD
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Flood Forecast Points in the Suwannee River Basin
USGS-GA
USGS-FL
SRWMD
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Automated Rainfall Network
Current Station
Planned Station
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Major Floods in the Suwannee Basin

• 1928 - Earliest Documented Flood
• 1948 - Flood of Record on Alapaha, Withlacoochee,
  Suwannee below Ellaville
• 1964 - Hurricane Dora - Flood of Record on Santa
  Fe River
• 1973 - Flood of Record at White Springs and
  Suwannee Springs
• 1998 - Roughly a 20-year flood

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Recent Flood Events on the Santa Fe

• March/April 1991 - Last major Suwannee flood
  before 1998 El Niño
• 1992 October Surprise
• February/March 1998 - Highest water in upper
  Santa Fe since 1964
• March 2003 NWSRFS Model Tune-up

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Monitoring Goals

• Obtain near-real-time river level and rainfall
  data for forecast model input
• Improve our understanding of the interaction
  between ground and surface water
• Develop/maintain tools for evaluating changes in
  flow ratings in the Suwannee River Basin

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Rating Mechanics

• Primarily stage versus discharge
• Model mechanics
• If stage-discharge relationship is unreliable,
  river forecast results will be unreliable.

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Rain, Soil Moisture, Travel Time
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Rose Creek/Walter Little Road
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Vertical Datum Upgrade Issues

• NAVD88 is about 9 inches below NGVD29
• All gages are currently in NGVD29
• All modeling is currently in NGVD29
• Not all surveying may be in NGVD29

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Suwannee River at Dowling Park
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Old Highway Bridge at Dowling Park
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