us army corps of engineers building strong ® significance of snowmelt and river ice on flood...
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US Army Corps of Engineers
BUILDING STRONG®
Significance of Snowmelt and River Ice on Flood Damages
Meredith Carr
Research Hydraulic Engineer
Cold Regions Research and Engineering Lab, Hanover, NH
Missouri Basin River Forecaster’s Meeting
21 February 2013
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Objective
Flood Risk Reduction Mission► Feasibility and cost benefit analysis of flood control
projects► Management of existing projects► Development of tools and theories related to
predicting and designing for cold regions flooding
Quantify the significance of snowmelt, rain-on-snow and river ice related flooding► Property and crop damages► Injuries/loss of life
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Background
94 million acres of land in US estimated at risk for flooding
¾ of presidential disaster declarations associated with flooding
Annual average of $6 B damages and median of 81 lives lost (2006, 2008 studies)
Increase in flooding impact due to urbanization and coastal development
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Snowmelt Floods Factors affecting flood
severity:► fall soil moisture condition► ground frost► water content of snow► speed of melting► presence of heavy rain
Particular concern in Northeast, north central and eastern US, also downstream in large drainage basins
8 of 32 most significant floods of 20th century were related to snowmelt (Perry, 2000)
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Accumulated annual snowfall divided by annual runoff. Red lines indicate areas where streamflow is snowmelt dominated (Barnett et al, 2005)
Snowmelt Floods
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Rain on Snow Floods Common in the Pacific
Northwest, but also in other areas
Rain provides energy to melt the snow, releasing water and increasing runoff
Fig 4: Sites with Rain-on-Snow Events from 1949-2003 (McCabe et al., 2007)
Date Location DamagesFeb-05 California $7MDec-05 Oregon $57MJan-09 Washington State $57M
Jan-05 Utah, 6 deaths $300M
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Ice Jam/Action Floods ice cover breaks into large pieces
which move downriver and elevate water levels or form a jam
freezeup jams, which occur as ice forms dynamically at the onset of cold temperature, can cause long term flooding
Date Location Damages
Jan-01 Youghiogheny River at Mckeesport, PA $2M
May-02 Alaska Rivers $8M
Mar-07 Little Minnesota River and Lake Traverse, ND $5M
May-09 breakup of Kuwoskwim and Yukon Rivers $12M
Mar-09 Missouri R. at Bismark, ND $92M
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Ice Jam/Action Floods
Fig 7: Explosive Remnants on the Missouri River Ice Jam, March 2009 (Stromme, 2009)
Skunk River near Augusta, IA, 2010Yukon River near Eagle, AK, 2009
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Data and Analysis Data sources (2001-
2010):► Flood events from
the National Climatic Data Center Storm Events Database
► CRREL Ice Jam Database
► Snow water equivalent gridded data based on SNODAS data
► USGS gages along major snowmelt rivers
► Weather Review Journal articles
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Results Damages due to
snow and ice related flooding were most significant in Northern cold and snowy areas, but also extended to downstream areas such as the lower Mississippi River basin Fig 11: Percent of Flooding Damages Due to Snowmelt or Ice by Sub-Region
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Results Snow and ice related flood
damages, by Corps District Most significant damages in
the New England District, the Mississippi Valley Division and the Northwest Division.
Rain-on-snow events are common in the Northwest, contributing to the over 50% of flood damages due to snowmelt or ice in the Sacramento District.
Fig 13: Percent of Flooding Damages Due to Snowmelt or Ice by Corps district. Blue Circles Represent Flood Control Dams
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Results
Percent of Flooding Damages Due to Snowmelt or Ice
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Results
Total Property and Crop Damages 2001-2010
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Results
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Results Snow and ice related flooding
► contributed to 42% of flood events during the 10 year period► 48% of damages, 22% of fatalities, 10% of injuries► Event length of 3.1 d
• Snowmelt: 4.3 d, Ice action: 2.9 d, • Ice Jams: 2.1 d, Rain-on-snow: 1.8 d
Annual Economic
Losses ($M) Fatalities Injuries
Average Event
Length(days)
Number of Events
Hurricane/Coastal 169 52 138 1.8 192
Tornados 288 45 12 2.1 100
Snowmelt/Ice/Rain-on-Snow
1,480 140 217 3.1 376
Rainfall 1,185 412 784 1.7 217
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…..Discussion…..
Sunday, March 22, 2009 in Fargo (AP Photo/The Forum, Dave Wallis)
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Tornado Jun-07 Texas $81M 7 deaths
May-10 Tennessee $2B 10 deathsOct-09 Arkansas $21 M
Hurricane Aug-12 TS Fay, Florida and Georgia $84M Sep-04 Hurrican Ivan $375M Sep-10 TS Hermine, Texas $29M 6 deaths
Coastal
Apr-07 New Jersey, New York, Massachusettes $48M
Dec-07 Washington and Oregon $12M Sep-06 Virginia $47M Nov-09 North Carolina $6M
Rain only Oct-06 Lousiana, Texas, Mississippi $620M Jul-12 Illinois, Iowa, Wisconsin $376M
Jun-01 Virginia, Pennsylvania, Marlyand, Connecticut $35M