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Flood Warning and Forecasting Flood Warning and Forecasting Issues in the SRWMDIssues in the SRWMD
Suwannee Suwannee River BasinRiver Basin
Georgia
Florida
240 Miles Long, 9,950 Square Miles
Headwaters
Okefenokee Swamp: Suwannee River
Cordele, GA: Alapaha River
Tifton, GA: Withlacoochee River
State Line at River Mile 207Only 43% of Basin is in Florida
Suwannee River BasinSuwannee River Basin Non-Structural Floodplain Non-Structural Floodplain
Management StrategyManagement Strategy
Floodplain RegulationFloodplain Regulation Floodplain AcquisitionFloodplain Acquisition Forecasting and EducationForecasting and Education
Floodplain Floodplain RegulationRegulation
Elevate StructuresElevate Structures Limit Fill and Obstructions in Limit Fill and Obstructions in
FloodplainFloodplain Riverbank Setbacks and Erosion Riverbank Setbacks and Erosion
ControlControl
Floodplain Acquisition Floodplain Acquisition StrategyStrategy
Provide natural storage for flood Provide natural storage for flood waterswaters
Reduce loss of life and property due Reduce loss of life and property due to floodsto floods
Protect ground and surface water Protect ground and surface water resourcesresources
Protect natural systems associated Protect natural systems associated with floodplain ecosystemswith floodplain ecosystems
Flood Warning and EducationFlood Warning and Education Emergency Management Emergency Management
CoordinationCoordination Flood Forecast ModelingFlood Forecast Modeling Forecast DisseminationForecast Dissemination– TelephoneTelephone– InternetInternet– NOAA Weather RadioNOAA Weather Radio
Georgia
Florida
FloodMonitoringNetwork in theSuwannee RiverBasin
USGS-GA
USGS-FL
SRWMD
Georgia
Florida
FloodForecastPoints in theSuwannee RiverBasin
USGS-GA
USGS-FL
SRWMD
Automated Automated RainfallRainfallNetworkNetwork
Current StationCurrent Station
Planned StationPlanned Station
Major Floods in the Suwannee Major Floods in the Suwannee BasinBasin
1928 - Earliest Documented Flood1928 - Earliest Documented Flood 1948 - Flood of Record on Alapaha, 1948 - Flood of Record on Alapaha,
Withlacoochee, Suwannee below Withlacoochee, Suwannee below EllavilleEllaville
1964 - Hurricane Dora - Flood of 1964 - Hurricane Dora - Flood of Record on Santa Fe RiverRecord on Santa Fe River
1973 - Flood of Record at White 1973 - Flood of Record at White Springs and Suwannee SpringsSprings and Suwannee Springs
1998 - Roughly a 20-year flood1998 - Roughly a 20-year flood
Recent Flood Events on the Recent Flood Events on the Santa FeSanta Fe
March/April 1991 - Last major March/April 1991 - Last major Suwannee flood before 1998 El NiñoSuwannee flood before 1998 El Niño
1992 – October Surprise 1992 – October Surprise February/March 1998 - Highest water in February/March 1998 - Highest water in
upper Santa Fe since 1964upper Santa Fe since 1964 March 2003 – NWSRFS Model Tune-upMarch 2003 – NWSRFS Model Tune-up
STAGE-STAGE RELATIONSHIPThree Rivers Estates and near Fort White
6
10
14
18
22
26
30
21 23 25 27 29 31 33Santa Fe River near Fort White
Sa
nta
Fe
Riv
er
at
3 R
ive
rs E
sta
tes
10/929/85 9/88
Pure Santa Fe Flood
3/91
3/98
3/86
2/91
4/84Pure Suwannee Flood
4/91
2/98
Mixed Flood
Monitoring GoalsMonitoring Goals Obtain near-real-time river level and Obtain near-real-time river level and
rainfall data for forecast model inputrainfall data for forecast model input
Improve our understanding of the Improve our understanding of the interaction between ground and surface interaction between ground and surface waterwater
Develop/maintain tools for evaluating Develop/maintain tools for evaluating changes in flow ratings in the changes in flow ratings in the Suwannee River BasinSuwannee River Basin
Rating MechanicsRating Mechanics
Primarily stage versus dischargePrimarily stage versus discharge Model mechanicsModel mechanics If stage-discharge relationship is If stage-discharge relationship is
unreliable, river forecast results will unreliable, river forecast results will be unreliable.be unreliable.
Sample River at Suchandsuch, FLFlow Rating Curve
104
105
106
107
108
109
110
111
112
0 1000 2000 3000 4000 5000 6000
Flow (cubic feet per second)
Elev
atio
n (fe
et a
bove
mea
n se
a le
vel)
Rain, Soil Moisture, Travel Time
Rose Creek/Walter Little Road
Precipitation Depth-Duration-Frequency Table (rainfall amounts in inches)
ReturnPeriodin Years 1 day 2 day 3 day 4 day 5 day 6 day 8 day 10 day 30 day 60 day CAL YEAR
2 3.57 4.38 4.79 4.89 5.02 5.42 6.14 6.64 11.17 17.36 n/a5 4.87 5.99 6.51 6.74 6.97 7.46 8.23 8.93 14.2 21.43 n/a
10 5.73 7.01 7.59 8.05 8.45 8.96 9.63 10.54 16.11 24.1 n/a20 6.52 7.95 8.59 9.31 9.93 10.42 10.95 12.1 17.88 26.6 n/a25 6.77 8.24 8.9 9.71 10.4 10.89 11.37 12.6 18.42 27.38 n/a40 7.29 8.83 9.54 10.54 11.41 11.87 12.22 13.63 19.54 28.99 n/a50 7.53 9.11 9.83 10.93 11.88 12.34 12.63 14.12 20.06 29.74 n/a
100 8.26 9.95 10.73 12.15 13.36 13.77 13.85 15.61 21.64 32.03 n/a200 8.98 10.76 11.6 13.34 14.84 15.21 15.06 17.1 23.17 34.27 n/a
1000 10.59 12.59 13.54 16.09 18.28 18.51 17.78 20.5 26.6 39.33 n/a10000 12.83 15.08 16.2 19.97 23.19 23.2 21.58 25.3 31.28 46.34 n/a
PMP 24.86 30.88 33.06 35.27 37.67 39.18 40.42 44.22 61.01 84 n/a
Record 8 10.3 11.69 15.1 17.5 18.2 18.48 21.03 28.95 37.13 82.96 Maximum Record 1920 2004 1964 2004 2004 2004 2004 2004 2004 2004 1964 Year
Precipitation Depth-Duration-Frequency Table (rainfall amounts in inches)
ReturnPeriodin Years 1 day 2 day 3 day 4 day 5 day 6 day 8 day 10 day 30 day 60 day CAL YEAR
2 3.57 4.38 4.79 4.89 5.02 5.42 6.14 6.64 11.17 17.36 n/a5 4.87 5.99 6.51 6.74 6.97 7.46 8.23 8.93 14.2 21.43 n/a
10 5.73 7.01 7.59 8.05 8.45 8.96 9.63 10.54 16.11 24.1 n/a20 6.52 7.95 8.59 9.31 9.93 10.42 10.95 12.1 17.88 26.6 n/a25 6.77 8.24 8.9 9.71 10.4 10.89 11.37 12.6 18.42 27.38 n/a40 7.29 8.83 9.54 10.54 11.41 11.87 12.22 13.63 19.54 28.99 n/a50 7.53 9.11 9.83 10.93 11.88 12.34 12.63 14.12 20.06 29.74 n/a
100 8.26 9.95 10.73 12.15 13.36 13.77 13.85 15.61 21.64 32.03 n/a200 8.98 10.76 11.6 13.34 14.84 15.21 15.06 17.1 23.17 34.27 n/a
1000 10.59 12.59 13.54 16.09 18.28 18.51 17.78 20.5 26.6 39.33 n/a10000 12.83 15.08 16.2 19.97 23.19 23.2 21.58 25.3 31.28 46.34 n/a
PMP 24.86 30.88 33.06 35.27 37.67 39.18 40.42 44.22 61.01 84 n/a
Record 8 10.3 11.69 15.1 17.5 18.2 18.48 21.03 28.95 37.13 82.96 Maximum Record 1920 2004 1964 2004 2004 2004 2004 2004 2004 2004 1964 Year
Vertical DatumUpgrade 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
Suwannee River at Dowling Park
Old Highway Bridge at Dowling Park