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.
Very interesting. Does this thing showing in the water above the spillway pose a some kind of unresolvable danger of blockage to the outflow onto the spillway?
Exactly... why would the small muddy stream be clear in the one pic? That makes no sense.. it is eating through a saturated hillside, why is it not muddy in both images? That was what initially pointed me in the direction of exposure (blown highlights). While cloudy, lots of light still gets through, and in variable amounts with cloud cover... our eyes are not that sensitive to changes in light, believe it or not, but digital I,aging devices with more limited dynamic range can be quite finicky in shadows and highlights, leading to some pretty nasty artifacts. I’m hoping that is all these images show, but only about 70% confident.
Water flow under the main spillway?
My understanding was the the lower power plant area was flooded. I see the drain capable of pulling down as 16k cfs +/- but it is routed through, and probably controlled by the power plant.
I have read nothing that says it can be cranked open or closed with the power plant area flooded.
At least 5 inches of rain due Sunday - Tuesday in the mountains above Oroville.
Inflows have the potential to exceed 200,000cfs.
https://www.wunderground.com/cgi-bin/findweather/getForecast?query=Paradise%2C+CA
Did debris fall into the dam or is the weir/spillway breaking apart on the dam side?
Death knell for the main spillway.
She’s gonna blow Captain.
I wonder if they can even shut it off?
There was heavy discussion on the inlet turbulence as there were other photographs taken from directly above that showed brownish discoloration in the waterflow. Throughout the discussion there was no talk of “blockage”, just if there is scouring occurring on the inlet flow substructure.
There is a break in the dam in front of the weir or just behind it on the dam side?
you all amaze me with the attention to detail, stuff I don’t see. I am a big picture thinker.
Hope the workers get out in time.
>>>Water flow under the main spillway?<<<
This crest is most likely from the high volume flow over the main spillway surface (i.e. very unlikely from anything under the slabs). The symmetrical shape of the crest infers a collision of flow from the inlet - analogous to “streams” colliding.
Still, you always seek to maintain a laminar smooth flow. The image is not completely definitive but it looks as if the crest is away from the side wall.
The concrete of the main spillway has a large number of microcracks that are repaired by maintenance - in addition to the concrete slab joints. However, one section of the seam of the main spillway experienced a “slumping” (believed to be from undercutting erosion under the slabs). This is what led to the blowout in the midsection of the main spillway (i.e. the fix to this “slumping” was not adequate over time).
>>There is a break in the dam in front of the weir or just behind it on the dam side?<<
No breaks. See reply to Mariner post 1332
If that is a side structure realigned by the flow above the throat of the outlet, in your post, we have a bad bad problem.
I hate to sound like that repeating wizarding professor, but, “We may have to close Hogwarts.”
Is there any possibility of that brown water coming from the side of that big @$$ hill that is dividing the water flow?
Those water-fowl will foul your water.
>>Is there any possibility of that brown water coming from the side of that big @$$ hill that is dividing the water flow?<<
Since the brown water “image capture” is to the left and the right of the spillway, this would indicate that an infusion of a notable amount of soil occurred from the action of the turbulent hydraulic scouring of the big “main spillway” hole.
What makes this interesting is that there seemed to be “good bedrock” just down from the main spillway hole. To cause a break away or infusion of brown material (color matches soil) from this hole is the question. What broke? Did a section of the “good bedrock” finally give way to expose another fractured bedrock/soil pocket a little further? Did the hole go deeper?
It is also possible, that part of a hill landslided into the flow. Only before/after pictures could give a clue.
Comment at # 1,319 then see Photos at # 1,320 # 1,326 .
And other comments as well.
Thanks, EarthResearcher333 .
What did you do to compare color spectral density? Are you just talking RGB histograms? Both images are so poorly exposed from a detail retention perspective (there is no detail in most of the water due to overexposure) that it is hard for me to say with confidence that the drastic change in the local coloration is due to increased sediment. It probably is sediment given the context, so I’m probably suffering from a little bias here! Just curious what you actually did to come to your confident conclusion.
Would be nice to know the times of capture as well... if this was while they were reducing the flow rate, would not the flow velocity come down a bit as well? The water flowing off the damaged end of the spillway could be landing further uphill and eroding hillside that was untouched or only slightly impacted at higher flow rates?
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