Development of Empirical Threshold Models for Ice Jam Forecasting and Modifications to FLDWAV to...

Development of Empirical Threshold Development of Empirical Threshold Models for Ice Jam ForecastingModels for Ice Jam Forecasting

and and Modifications to FLDWAV to Model River Modifications to FLDWAV to Model River

IceIce

Dr. Steven F. DalyDr. Steven F. DalyERDC/CRRELERDC/CRREL

Hanover , NH 03755Hanover , NH 03755US Army CorpsUS Army Corpsof Engineers of Engineers ®®Engineer Research and Engineer Research and Development CenterDevelopment Center

Overview

• Objective: The overall object is to improve the National Weather Service River Forecast Centers ability to forecast wintertime flooding due to river ice.

• Development of Empirical Threshold Models for Ice Jam Forecasting

• Modifications to FLDWAV to Model River Ice

Empirical Threshold Models for Ice Jam Forecasting

• The goal is to develop empirical threshold indicators of river ice formation, ice cover breakup, jam formation, and ice jam flooding. The indicators will be based on information that is readily available to the RFC's or could be easily derived from existing data sources. Proposed indicators include Accumulated Freezing Degree Days (AFDD), rate of change of discharge, maximum discharge, and other factors.

Modifications to FLDWAV to Model River Ice

• The effects of an ice cover will be incorporated into the NWS FLDWAV model which is part of the National Weather Service River Forecast System (NWSRFS) to model ice jams under unsteady flow conditions.

• Platte River 243• Yukon River 211• Kuskokwim River 194• Connecticut River 90• Milk River 60• Kankakee River 40• Allegheny River/Oil Creek 33• Mohawk River 30 • Missouri River at Williston, ND 29• Salmon River 25 • Weiser River 20TOTAL 1075

Analysis

• Assigned each ice event to the next d/s flow gage & assigned each gage to a met station, average flow over POR, DA, Average maximum AFDD

• For each ice event:– Base flow (lowest 40 days discharge in the since the

start of the water year)– Q, the flow associated with the event– DelQ, the flow increase– Tp, the time to peak– AFDD, the accumulated Freezing degree days

Analysis

• For all the ice events assigned to each gage, we then found the overall average of– Base flow (lowest 40 days discharge in the

since the start of the water year)– Q, the flow associated with the event– DelQ, the flow increase– Tp, the time to peak– AFDD, the accumulated Freezing degree days

0

50000

100000

150000

200000

250000

300000

350000

1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

Drainage Area (Sq Miles)

Del

ta Q

CT River Flow Gages:

Kankakee River Flow Gages:

Kuskokwim Flow Gages:

Milk River Flow Gages:

Mohawk River Flow Gages:

Oil City Flow Gages:

Platte River Flow Gages:

Salmon River Flow Gages:

Weiser Flow Gages:

Yukon River Flow Gages:

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

Drainage Area (Sq Miles)

Del

ta Q

cfs

CT River Flow Gages:

Kankakee River Flow Gages:

Kuskokwim Flow Gages:

Milk River Flow Gages:

Mohawk River Flow Gages:

Oil City Flow Gages:

Platte River Flow Gages:

Salmon River Flow Gages:

Weiser Flow Gages:

Yukon River Flow Gages:

10

100

1000

10000

100000

1000000

1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

Average Flow

Del

ta Q

CT River Flow Gages:

Kankakee River Flow Gages:

Kuskokwim Flow Gages:

Milk River Flow Gages:

Mohawk River Flow Gages:

Oil City Flow Gages:

Platte River Flow Gages:

Weiser Flow Gages:

Yukon River Flow Gages:

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

Drainage Area (Sq Miles)

Tim

e to

Pea

k (D

ays)

CT River Flow Gages:

Kankakee River Flow Gages:

Kuskokwim Flow Gages:

Milk River Flow Gages:

Mohawk River Flow Gages:

Oil City Flow Gages:

Platte River Flow Gages:

Salmon River Flow Gages:

Weiser Flow Gages:

Yukon River Flow Gages:

0

5000

10000

15000

20000

25000

30000

35000

1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

Drainage Area (Sq Mile)

Del

Q/T

p

CT River Flow Gages:

Kankakee River Flow Gages:

Kuskokwim Flow Gages:

Milk River Flow Gages:

Mohawk River Flow Gages:

Oil City Flow Gages:

Platte River Flow Gages:

Salmon River Flow Gages:

Weiser Flow Gages:

Yukon River Flow Gages:

0%

20%

40%

60%

80%

100%

120%

140%

160%

1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

Drainage Area (Sq Miles)

AFD

D/A

vera

ge M

ax A

FDD

CT River Flow Gages:

Kankakee River Flow Gages:

Kuskokwim Flow Gages:

Milk River Flow Gages:

Mohawk River Flow Gages:

Oil City Flow Gages:

Platte River Flow Gages:

Salmon River Flow Gages:

Weiser Flow Gages:

Yukon River Flow Gages:

0%

20%

40%

60%

80%

100%

120%

140%

160%

0% 200% 400% 600% 800% 1000% 1200% 1400% 1600% 1800% 2000%

Delta Q/Average Q

AFD

D/A

vera

ge M

ax A

FDD

CT River Flow Gages:

Kankakee River Flow Gages:

Kuskokwim Flow Gages:

Milk River Flow Gages:

Mohawk River Flow Gages:

Oil City Flow Gages:

Platte River Flow Gages:

Salmon River Flow Gages:

Weiser Flow Gages:

Yukon River Flow Gages:

0%

20%

40%

60%

80%

100%

120%

140%

0% 50% 100% 150% 200% 250% 300% 350% 400% 450% 500%

Delta Q/Average Q

AFD

D/A

vera

ge M

ax A

FDD

CT River Flow Gages:

Kankakee River Flow Gages:

Kuskokwim Flow Gages:

Mohawk River Flow Gages:

Oil City Flow Gages:

Platte River Flow Gages:

Weiser Flow Gages:

Yukon River Flow Gages:

Summary

• Thresholds can be developed for each reach based on %AFDD and DelQ or other

• There will be uncertainty because of large variation in data

• High, medium, low probability of ice event

• Salmon River true freeze up case.

• Remains to write up