Flooding northern California

[cpaharley2008]

Saw a video od the people leaving the area around the Oroville Dam and there was a f/g camper in the evacuation line, looked like a Trillium. Hope everyone stays safe
http://timesofindia.indiatimes.com/w...w/57125735.cms

[Leej]

They have a familiar place to lay their head...
My husband's brother and family had to evacuate, it is a huge upheaval for them all, with no idea when they can go home to Gridley...
We have decided to make our casita our bug out bag..poor folks..
We have another huge warm storm coming,Wednesday night so hold on folks.

[stude]

Originally Posted by cpaharley2008

Saw a video od the people leaving the area around the Oroville Dam and there was a f/g camper in the evacuation line, looked like a Trillium. Hope everyone stays safe
oroville dam: Nearly 200,000 people told to flee crumbling California dam spillway - Times of India

: they showed the amount of water they let out and the damage to the causeway what has happened is the dam is made of earth and the dam side has concrete on the face about a foot thick when they saw a crack they got people moving and started letting water out so they could fix the problem but now the causeway has a big tear in it and they are about to start dropping huge bags full of rock into the hole to help fill it and hope it holds up when they start pouring more water out of it as they are expecting more snow and rain.
Stude

[Raspy]

Originally Posted by stude

: they showed the amount of water they let out and the damage to the causeway what has happened is the dam is made of earth and the dam side has concrete on the face about a foot thick when they saw a crack they got people moving and started letting water out so they could fix the problem but now the causeway has a big tear in it and they are about to start dropping huge bags full of rock into the hole to help fill it and hope it holds up when they start pouring more water out of it as they are expecting more snow and rain.
Stude

No. There are no cracks in the dam. The problems are with the two spillways.

They stopped using the regular spillway because its channel failed about 1/2 mile down its length near the river. This spillway has controllable gates. Nothing to do with the dam structure.

With no outlet and huge storms, the lake overtopped the emergency spillway that had never been used. It's just a 1700 foot long wall about 30 feet high and set lower than the top of the dam, but higher than the regular spillway. It has no controllable gates.

When water goes over that wall it pours onto a dirt hillside and runs down to the Feather river, about a mile away, with no defined channel. That dirt hillside began to undermine which could cause the spillway wall to fail and suddenly lower the lake by 30 feet, and possibly set off a cascade of events that could drain the lake.

They are frantically filling the undermined area with big bags of rocks dropped in by helicopter. They have reopened the regular spillway, in spite of it's damaged channel, to get the lake level down as far as possible before the next rain. Now the regular spillway channel is completely gone in a section from the tremendous water flow of about 100,000 cu ft per second. This flow is what is being shown on the news. It is way down the hill and not threatening the dam. They are also running about 15,000 cu ft per second out through the powerhouse at the bottom of the dam.

At one point they said the emergency spillway was going to fail in about an hour. This was during the evacuation. But of course it didn't. No one seems to know how stable it is, but it's a bad design.

So, the hope is that the next few storms won't refill the lake to where it runs over the emergency spillway again.

Now, both spillways will need a lot of work when the season is over.

[stude]

Originally Posted by Raspy

No. There are no cracks in the dam. The problems are with the two spillways.

They stopped using the regular spillway because its channel failed about 1/2 mile down its length near the river. This spillway has controllable gates. Nothing to do with the dam structure.

With no outlet and huge storms, the lake overtopped the emergency spillway that had never been used. It's just a 1700 foot long wall about 30 feet high and set lower than the top of the dam, but higher than the regular spillway. It has no controllable gates.

When water goes over that wall it pours onto a dirt hillside and runs down to the Feather river, about a mile away, with no defined channel. That dirt hillside began to undermine which could cause the spillway wall to fail and suddenly lower the lake by 30 feet, and possibly set off a cascade of events that could drain the lake.

They are frantically filling the undermined area with big bags of rocks dropped in by helicopter. They have reopened the regular spillway, in spite of it's damaged channel, to get the lake level down as far as possible before the next rain. Now the regular spillway channel is completely gone in a section from the tremendous water flow of about 100,000 cu ft per second. This flow is what is being shown on the news. It is way down the hill and not threatening the dam. They are also running about 15,000 cu ft per second out through the powerhouse at the bottom of the dam.

At one point they said the emergency spillway was going to fail in about an hour. This was during the evacuation. But of course it didn't. No one seems to know how stable it is, but it's a bad design.

So, the hope is that the next few storms won't refill the lake to where it runs over the emergency spillway again.

Now, both spillways will need a lot of work when the season is over.

:Raspy thanks for correcting my mistakes on the dam problem. We have quite a few of this type of dam in British Columbia, thankfully they are in areas where not many people live. One 20 miler drains into another which then drains through large and I mean largest Pipes I have ever seen through a mountain and down to a Hydro Plant at Seton Portage then from there into Seton Lake which is ice cold finally draining into the Fraser River. THis main river was once called the Bridge River but a big portion of it us under water, occasionally u can sit on the road and watch them blow water out of the Spillway into the Bridge River to help the fish come upstream. Mostly the water is used to make power.
But they have cracks in the concrete face and every so often they drop the lake right down and you get to see foundations of homes, the old hwy, old mines etc.
Stude

[Gilda]

A chilling reminder to me to never live in the potential path of a failed dam! Even camping in the path of a dam is chilling. This is a devastating scenario prompting we Californians and all others to "shore-up" if not re-build our dams and spillways. Dams were never built to last forever.

[Glenn Baglo]

So many ways to die, so little time.

[Raspy]

These dams are really fascinating and chillingly powerful. Just draining off a bit of water is absolutely frightening and mesmerizing.

Just when I think everything is fine, I discover that cost was a driver in decisions related to this enormous structure. The incalculable power stored there is held by the most "cost effective" or "probable" analysis. Then, when the obvious problems get pointed out, the denial is based on politics or statistics. Oh my!

Then when failure happens, the original decision makers are no where to be found and the repair costs are astronomical. Innocent people living nearby are told to run for their lives. Using helicopters to move giant rock filled sandbags into holes?! Sheesh. What's wrong with this picture?

I looked carefully at the news analysis over and over and on different networks. They were all so far away from the actual situation in their stories that it was disgusting or disappointing. So sensational and broadcast world wide.

I've recently been studying dams and related reservoirs and water patterns in the reservoirs. I recently drove over Oroville dam and looked at the place. That main spillway is enormous! Just looking at it gave me chills.

[Paul O.]

I have always been fascinated by dams, why some fail and learning what it takes to make them NOT fail. Hopefully the Oroville dam will be fixed properly.

It is not a huge leap from considering this flood that they just avoided, to something real but in distant past. Earthen or ice dams are a natural occurrence during the ice ages, and they held huge lakes and some did fail. Lake Bonneville, Lake Missoula, Lake Agassiz are just some of them. Here is a simulation of one of those catastrophic floods. Nothing man-made comes anywhere close to the scale of those dams.

https://www.youtube.com/watch?v=27BP4CL66Tk

The Channeled Scablands of Washington State are still on my bucket list.

Channeled Scablands of Washington

The story of discovery and understanding of these things is a great read.

[Mitzi Agnew-Giles]

Thank you for the links, Paul. I am an unlettered geology geek and I really unjoyed watching those.

[steve dunham]

There are several interesting documents discussing the fact that back in 2005 they were aware of problems with this dam and its' spillways . The people in charge at that time appear to have taken the politically easy route and decided to ignore the problems.
The kicking the can down the road to after the next election approach seems all to prevalent these days .
Our constantly declining and unsafe infrastructure is a prime example.
This time they were able to dodge the bullet , next time we may not be so lucky.

[Paul O.]

Originally Posted by Mitzi Agnew-Giles

Thank you for the links, Paul. I am an unlettered geology geek and I really enjoyed watching those.

You are welcome.
Several years ago, I think it was Norm, mentioned this book: 101 American Geo-sites you've gotta see by Albert B. Dickas, 2012. It has become my coffee table book and a trip planning necessity.
Another one is The Making of a Continent by Ron Redfern, 1983 (Companion to the PBS Series).
The books provide just the right amount of detail for me as a non-geologist.

[slowpat]

Kind of off topic--I guess I can say that my day worked on the construction on a few of the Columbia dams and on the third powerhouse project on Grand Coulee.

A couple folks are interested in visiting the coulee country. I like to stay at Steamboat Rock State Park. It has interesting kayaking in Banks Lake. Banks Lake is a reservoir and part of the Grand Coulee project. It stores irrigation water for the Columbia Basin.

If you don't like the high camping fees, there are boondocking spots along the highway. I do not recommend Sun Lakes State park for camping. It does have one new section, but for the most part is old fashioned tent sized spots within elbow length of your neighbor.

Upstream, on the Columbia River are National Park campgrounds. They have no hookups but do have water and dumping stations and are quite a bit cheaper than our state parks. That area is the Lake Roosevelt National Recreation Area and is along the "lake" formed behind Grand Coulee.

Oh, and you can hike on trails around the area. Beware of rattlesnakes in the coulees. I spotted two on one warm day. You can hike and scramble to the top of Steamboat Rock and get a good view of the geology and then drive to the Dry Falls visitor's center for more info.

[Mike Magee]

The opposite situation took place in southern Montana in 1959. An earthquake caused 80 million tons of rock to break loose and slide downhill to the Madison River. Unfortunately, a campground was in the landslide's path and 28 campers were killed. The event created a natural dam which resulted in present-day Quake Lake.

Folks can be camped or living somewhere, minding their own business, and something happens. Life comes with no guarantees. Of course we don't take unnecessary risks (most of us anyway), but I'll not spend time worrying about the "might happen" scenarios.

[slowpat]

This is the reservoir that Taidnapum is on. Guess the Oroville thing is a heads up.

Lewis County Sirens.com » New earthquake analysis leads to lowering Riffe Lake reservoir » Print