A Distributed Flash Flood Forecasting Rainfall-Runoff Model Applied to Watersheds in the Northeast United States

Michael SchaffnerNOAA National Weather ServiceWFO Binghamton, NY

Carl UnkrichUSDAARS Tucson, AZ NROW

November 6, 2008

Flash Flood Monitoring and Prediction Program (FFMP)

• This allows the forecaster to pinpoint (i.e. provide site specific information) which basins are receiving the heaviest rainfall.

• Does not allow the forecaster in most cases to determine the timing and magnitude of an event.

Above image from: http://www.tucson.ars.ag.gov/kineros/

Plan View Schematic View

• Distributed Model composed of a cascade of planes and channel elements.• Takes into account spatial distribution of soil type, land use, topography, and

rainfall.• Kinematic wave equations for channel routing.• Model functions in real-time with radar interface.• Allows the user to run ensembles to investigate either multiple Z-R

relationships or variability in model parameters.

Outlet

Bush Kill near Arkville

Setting up KINEROS

• Delineate watershed boundary and interior sub-watersheds using a GIS application.

• Collect in the field stream manning roughness values.

• Collect channel width measurements from field work or using high resolution remote sensing.

Model Calibration

• Each event was calibrated for the magnitude and the timing of the peak flow.

• Calibration was accomplished by adjustment of multipliers that globally adjust individual model parameters.

• Saturated Hydrologic Conductivity (Ks) multiplier was utilized to calibrate the magnitude of the peak flow.

• Channel length multiplier was utilized to calibrate the timing of the peak flow.

Platte Kill near Dunraven

• 34 square miles.• Catskill mountains.• USGS stream gage. Outlet

Typical Hydrograph for Platte Kill

• Reasonable simulation of primary and secondary peak magnitude and timing.

• Later and more rapid rate of rise than seen in the gage record.

• More rapid rate of fall than seen in the gage record.

Platte Kill near Dunraven

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500

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1500

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7/23/200812:00

7/23/200814:24

7/23/200816:48

7/23/200819:12

7/23/200821:36

7/24/200800:00

Date and Time

Discharge (cfs)

Gage

Simulation

Additional Platte Kill Hydrographs

Platte Kill near Dunraven

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6/26/2006

07:12

6/26/2006

09:36

6/26/2006

12:00

6/26/2006

14:24

6/26/2006

16:48

6/26/2006

19:12

6/26/2006

21:36Date and Time

Discharge (cfs)

Gage

Simulation

Platte Kill near Dunraven

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100

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600

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3/7/2008

14:24

3/7/2008

16:48

3/7/2008

19:12

3/7/2008

21:36

3/8/2008

00:00

3/8/2008

02:24

3/8/2008

04:48

3/8/2008

07:12

3/8/2008

09:36

3/8/2008

12:00

3/8/2008

14:24

Date and Time

Discharge (cfs)

Gage

Simulation

Platte Kill near Dunraven

0

200

400

600

800

1000

1200

3/8/200812:00

3/8/200814:24

3/8/200816:48

3/8/200819:12

3/8/200821:36

3/9/200800:00

3/9/200802:24

3/9/200804:48

Date and Time

Discharge (cfs)

Gage

Simulation

Platte Kill near Dunraven

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8/28/200619:12

8/29/200600:00

8/29/200604:48

8/29/200609:36

8/29/200614:24

8/29/200619:12

8/30/200600:00

Date and Time

Disc

harg

e (c

fs)

Gage

Simulation

Hydrographs point to the need for an additional model component

• Discussions with USDA and Peter Troch (UA) on the addition of his shallow-sub-surface lateral flow model (hsB) into KINEROS.

• We are actively seeking funding to incorporate this model into KINEROS.

Platte Kill Calibration for Operational Use

• Poor R-square when all events are taken into account.

• Decided to consider only those events where the basin average rainfall would have hydrological significance.

Platte Kill near Dunraven

R2 = 0.02

0.00

0.50

1.00

1.50

2.00

2.50

0 2 4 6 8 10 12

Ks Multiplier

Channel Length Multiplier

Platte Kill Calibration for Operational Use Continued

• Good trend in both channel length and Ks multipliers for events of 1 inch or greater basin average rainfall.

• Good R-square when only considering events such events.

Modeling Un-gauged Basins

• Modeling of un-gauged basins represents a significant challenge and operational need within the NWS.

• Watersheds in the Town of Colchester, Delaware County, NY were impacted by flash floods on June 19, 2007 and July 23, 2008.

• Time and magnitude of the peak flow and associated impacts were determined.

• Watersheds were calibrated to these flash flood events.

Spring Brook near Roscoe• 9 square miles• 4 lives lost on June 19,

2007• Multiple sections of

Route 206 impassible• Several homes

washed off their foundations

Spring Brook Hydrograph for June 19, 2007

• Flash flood warning issued at 7:01 PM.

• Major flash flooding and loss of life reported at 7:50 PM.

• KINEROS first began to forecast major flash flooding at 5:30 PM.

Berry Brook near Roscoe

• 4.5 square mile

Plane View

Indirect discharge measurement cross section for June 19, 2007 flash flood event located along Berry Brook Road

Berry Brook Hydrograph for June 19, 2007

• Flash flood warning issued at 7:01 PM.

• Major flash flooding and multiple wash- outs along Berry Brook Road were reported at 8:30 PM.

• KINEROS first began to forecast major flash flooding at 6:10 PM.

Future Work

• Test KINEROS on larger sized basins (200 – 250 square miles).

• Add ability for the forecaster to add QPF.• Have undergraduate intern work with KINEROS over

summer 2009.• Produce NWS technical publication on results.• Test KINEROS in areas outside of the Binghamton

forecast area.• Add shallow groundwater flow model component (funding

required)• Simple snow model (long term).

Questions / Comments?