Its happening now. What caused it? How does this compare to the big flood of 1964?

Note: This is not a little flood. Its a serious flood for all of Western Washington and Oregon and as of Feb 8 at 2 PM - all rivers are still rising. By any reasonable estimate, this flood will equal that of 1964. It will likely exceed that in many specific locations.

Okay, you weren't kidding!.

• CNN archive
• Lots of Pictures Around the Salem Area (a slow site; many of those images are stored locally on this server
• Very comprehensive Resource and Reporting
• County Assessments of Damage
• Multnomah County Library Site

Record Crest Levels Predicted for Many Rivers in Washington State

Quick Synopsis as of 9:30 PM Feb 8:

• River level plots will be updated tomorrow. By now the situation should be clear anyway
• The most serious flooding in the Willamette Valley is around the Salem Area where upwards of 15,000 people have been evacuated (mostly in the Keizer area).
• There is probably 2--4 hours of more rain, and it will be tapering off. Extended clearing period should begin sometime around noon on Friday.
• I5 is completely shutdown due to mudslides south of Olympia WA
• Maximum river levels in Washington and Oregon should be occurring in the next few hours.
• Latest predicted flood crests for Oregon:
  • Salem: 36.5 feet (flood stage = 25 feet)
  • Portland: 29 feet (one foot lower than earlier forecast)
  • Oregon City: 44.5 feet
  • Albany 31 feet

• First Image
  
• Second Image

Thursday Flood Warnings: !

Friday Morning Flood Warnings: READ THIS

Some Storm Damage Reports in Seattle Area

Current River Level Data:(as of Friday Morning, most river levels are decreasing or rising only very slowly and will shortly decrease). Use the Reload Page feature of your browser if the data do not read 09 Feb 1996.

• Willamette River at Salem (over the gauge as of 4 pm Thursday )
• Willamette River at Harrisburg
• Willamette River at Albany
• Willamette River at Corvallis
• Willamette River at Oregon City
• Willamette River at Portland
• Willamette River at Eugene
• Long Tom River at Monroe (note it went above the gauge!)
• South Santiam River at Waterloo
• Santiam River at Jefferson

At 7 am the morning of Friday Feb 9, the Willamette river in Portland overflowed the lowest point of the Sea Wall. CNN coverage can be found here

Go here for daily and monthly level reports Notice the large fluctuations since November 1 on virtually all rivers. This is related to significant wet periods over this time interval followed by cold dry spells.

The Flood of Late December 1964:

• Significant Snowfall and cold temperatures occurred in early december.
• Around december 19th, the weather warmed dramatically and almost a foot of rain fell over the next 5--7 days
• Snow in the Western Cascades melted very rapidly and the runoff was greatly exacerbated due to the frozen ground
• There were fewer flood control dams on the Willamette River system than there are now
• Major flooding occurred up and down the Willamette; Downtown Salem was inundated with 10 feet of water. The Willamette was at the tip of the sea wall in Downtown Portland
• The Flood of 1964 was characterized as the 100 year flood

What's different between 1964 and 1996:

• Significant increase in logging in the local watersheds. This increases runoff as well as debris clogs in the river systems.
• A significant increase in development along the river systems. An example would be McNary Estates in Keizer Oregon, which had to be evacuated and which totals several million dollars worth of homes.
• Significant increase in fish hatcheries along the river systems for purposes of stabilizing a healthy fish population. Large floods are a serious problem

More Images and Information from Oregon State University Climate Service

Causes:

• Approximately 6--12 inches has of rain has fallen over Western Oregon from Feb 5--7.
• River systems were already fairly full from the significantly above average rain which has fallen since Nov 1. This was not the case in 1964.
• Heavy mountain snow in late January combined with 3--4 day cold spell in early February produced frozen ground conditions, conducive for massive runoff should the temperature warm up.
• Well, its about 65 degrees currently in Eugene for Feb 8(!) and so the temperature has warmed dramatically causing a rapid rise in the freezing level and lots of runoff in the mountains
• Rapid runoff combined with heavy logging activity over the last 30 years results in above average sediment and debris loads which only makes the problem worse.
• Sediment load on dams can represent a point of failure and hence dams have no choice but to let the water through.

Other Dangers:

• The incredible volume of water that is currently stored in the ground would greatly increase the damage done if any earthquake were to occur now. Essentially, the ground would quickly liquify (hell, its practially there already) thus amplifying the waves generated by crustal motion.

How the Fish Hatcheries fared in the flood

The information on this page comes from the Army Corp of Engineers, The National Weather Service, the Oregon Department of Fish and Wildlife, and CNN. The words are wrapped around the information for purposes of using this material for today's lecture in Environmental Studies 202: Natural Sciences, at the University of Oregon. ___________________________________________________________________