Posted on 02/12/2017 4:26:47 PM PST by janetjanet998
Edited on 02/12/2017 9:33:58 PM PST by Admin Moderator. [history]
The Oroville Dam is the highest in the nation.
“it is a buzz saw of water action tearing into that area of the lake edge perhaps creating a deep failure.”
Wouldn’t the “buzz saw” be expected to cut down to bedrock within a few tens of feet after which not a lot more would happen in terms of erosion downward? (I realize 30 or 50 lake feet of water would be very bad for the valley). I stand ready to be corrected on the bedrock thing.
The term bedrock is usually applied to thicker rock layers. These rock layers can be granite, sandstone, limestone or whatever shelf layer is in the area. Sometimes that rock is very solid and sometimes it is fractured, interbedded with other materials, or it is much less solid than what one would imagine.
If we see any canyon in the west we see that rock is cut by water erosion just as earthen materials are cut. Gravely alluvial soil washes away in hours and rock can wash away in days.
We are back at 100% chance of rain in the drainage area above this lake in 48 hours. Lets hope that the spillway can be run without damaging severely the overall lake dam integrity.
The scour shown in 617 shows though there is rock, it is badly fractured and jointed allowing water to dislodge and move it away. The photo that is most telling for me is the one in #589 which shows how close the scour came to the north-end base of the emergency spillway - maybe only 25-30 feet based on the workers (shown in the picture for scale).
No planned time to lift evacuations near Lake Oroville
No estimate yet for evacuees.
Lots more photos at this link:
http://www.latimes.com/visuals/photography/la-me-lake-oroville-spillway-pictures-photogallery.html
Valuable information, thanks. I am in the Missoula flood plain of eastern WA so I have seen the cataclysmic effects that flowing water can have. On the other hand, the “normal” flow of the Columbia River during my lifetime hasn’t really resulted in much visible erosion.
The hole near the bottom of this photo is the area of concern.
That is unexpected erosion below the face of the Emergency Spillway that has progressed backward toward the spillway face. Were it to progress too far, there could be a rupture of the Emergency Spillway that would expose everything downstream to the uncontrolled release of some 30 to 40 feet of water depth across the entirety of the lake; over 600,000 acre-feet of water. This is NO joke.
Here’s some more pics of the scour area.
http://www.sacbee.com/news/state/california/water-and-drought/article132463009.html
Thanks for posting Cahill’s new article.
That level of damage is enough to send the USA into a recession.
Besides great fly fishing, watching U2's and other planes regardless of what what was going on taking off from or landing at Beale was part of the day.
I went up the week after 9/11 to get away from the tv. It was a typical beautiful early Indian Summer day. The difference was the high plane traffic going into and out of Beale.
A little after about 3 pm, a young man wearing an Air Force Jumpsuit and camo Airforce hat drove up an asked if I was Dave.
At first I was afraid that something had happened at home. He said no problem at home he was at Beale for a day or two until heading a long way west. He said the owner of the ranch had to him to look me up to show him what flies to use and how to use them.
So I geared up his rod and reel with a floating line and a long tippet and attached a Lower Yuba top/dry fly and a dropper fly going underwater at the same time. Then, I showed him how to see the fish feeding on the top and the silver flashes under the surface.
He was a good caster and soon was hooking fish and sometimes doubles.
Later, he explained to me the U2's were watching our dams, bridges and railroads across N. Ca. in case of terrorists. He was a Capt. and a pilot for the Air Force. His wife and family were back east. I replied the Cuban Missile Crisis and how I was away from my wife and our families waiting for a ship heading towards Cuba about 37 years ago before 9/11. That, we had survived that and would survive 9/11.
Then, I gave him my flies for the lower Yuba, more leaders and tippets and told him to keep the fly line. I let him have my drive home lunch to fish until dark. We saluted each other.
Since I had sons and nephews his age, I probably embarassed him. I gave him a hug and told him, "There are old pilots, there are bold pilots, but there are no old, bold pilots". We told each other good bye and good fishing.
Besides great fly fishing, watching U2's and other planes regardless of what what was going on taking off from or landing at Beale was part of the day.
I went up the week after 9/11 to get away from the tv. It was a typical beautiful early Indian Summer day. The difference was the high plane traffic going into and out of Beale.
A little after about 3 pm, a young man wearing an Air Force Jumpsuit and camo Airforce hat drove up an asked if I was Dave.
At first I was afraid that something had happened at home. He said no problem at home he was at Beale for a day or two until heading a long way west. He said the owner of the ranch had to him to look me up to show him what flies to use and how to use them.
So I geared up his rod and reel with a floating line and a long tippet and attached a Lower Yuba top/dry fly and a dropper fly going underwater at the same time. Then, I showed him how to see the fish feeding on the top and the silver flashes under the surface.
He was a good caster and soon was hooking fish and sometimes doubles.
Later, he explained to me the U2's were watching our dams, bridges and railroads across N. Ca. in case of terrorists. He was a Capt. and a pilot for the Air Force. His wife and family were back east. I replied the Cuban Missile Crisis and how I was away from my wife and our families waiting for a ship heading towards Cuba about 37 years ago before 9/11. That, we had survived that and would survive 9/11.
Then, I gave him my flies for the lower Yuba, more leaders and tippets and told him to keep the fly line. I let him have my drive home lunch to fish until dark. We saluted each other.
Since I had sons and nephews his age, I probably embarassed him. I gave him a hug and told him, "There are old pilots, there are bold pilots, but there are no old, bold pilots". We told each other good bye and good fishing.
Yeah, that’s a good thing given the progress of the erosion over the relatively short time that spillway was in use.
The major threat is alleviated and a secondary threat created: 110,000cfm of water being dumped down the Main Spillway into the Feather River is WAY more volume than normal, and it is THAT volume of water that is the real and present flooding concern.
“That looks like from today. Water was still coming over the weir at dark yesterday.”
Thanks, that was what I thought or remembered.
One heck of a lot of erosion, but the water was away from the sinkhole or just hole in the rocks.
Thanks old FRiend.
Some really scary pictures from this morning showing how out of control the rushing water was last night.
On another thread I was giving my impression of the area levees south of this lake and on the Sacramento based on what I had seen in 2008 and 2009 when I was working in the area.
I think that there are going to be some failures however, if they stop this out-flow for anything less than a critical dam threat, they are stupid beyond belief.
I think the next thing to bring up somewhere is to explain to people what a “sand-boil” is in the area of a flooded levee. Ground water being so high in the Sacramento river basin.
Thanks, La Slimes makes you disable Ad Blocker Plus ghostery.
I will not do that.
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