Embed Size (px)
Citation preview
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
