# Presentation: 413447

## Slide 1

## Flood Warning and Forecasting Issues in the SRWMD

**Flood Warning and Forecasting Issues in the SRWMD**

## Suwannee River Basin

**Suwannee River 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 207**

**Only 43% of Basin is in Florida**

## Suwannee River Basin Non-Structural Floodplain Management Strategy

**Floodplain Regulation**
**Floodplain Acquisition**
**Forecasting and Education**

**Notes:**
Developed from observation of structural program in place in south Florida

Very consistent

## Floodplain Regulation

**Floodplain ****Regulation**

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

**Notes:**
District follows FEMA flood guideline standards - first floor elevation at least 1 foot above 100 year flood elevation

## 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**

## Flood Warning and Education

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

## Flood

**Flood**
**Monitoring**
**Network in the**
**Suwannee River**
**Basin**

**USGS-GA**

**USGS-FL**

**SRWMD**

## Flood

**Flood**
**Forecast**
**Points in the**
**Suwannee River**
**Basin**

**USGS-GA**

**USGS-FL**

**SRWMD**

## Automated Rainfall

- <date/time>

**Automated Rainfall**
**Network**

**Current Station**

**Planned Station**

## 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**

## 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**

## Slide 13

## 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**

## Rating Mechanics

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

## Rain, Soil Moisture,

**Rain, Soil Moisture,**
**       ****Travel Time**

**Notes:**
Model provides timing of flood crest

## Rose Creek/Walter Little Road

**Rose Creek/Walter Little Road**

**Notes:**
Calloway Estates near Lake City

## Slide 19

## Slide 20

## Vertical Datum

**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**

## Slide 22

## Suwannee River at Dowling Park

**Suwannee River at Dowling Park**

## Old Highway Bridge at Dowling Park

**Old Highway Bridge at Dowling Park**

## Slide 25