I really like the way those videos were presented. Silently, looping, laid out one on top the other, each with a one line description. If that was one long video i would have kept jumping backwards to rewatch all the scenes. Final thought, drone footage continues to blow me away.
I feel like I learned more from watching these videos than I did on many of the numerous news articles written at the time. Granted, they were after the fact, but wow.
These images still didn't even show the dam itself, nor the water being released from the normal pathways in the dam, where they also had a few problems (which I can't describe in detail due to ignorance.. I believe it was related to backup of mud and debris from the spillway problems causing backwash that clogged up some of the main dam works). And yet I agree, this has been the best presentation of the event so far.
There is also the issue they are addressing now where debris has blocked water from exiting the power plant pool, preventing operation of the power plant.
If they can get the power plant running things will be much improved, as they will be able to continue to drain the reservoir without further erosion of the main spillway and also until it is below the level of the main spillway (which will stop the small amount of water that is currently leaking through the control gates).
Noted, though "normal" and "major" are somewhat semantic.
The main spillway is the mechanism by which, when needed on a normal basis, major discharges can be accomplished. That is: its design intent is to accommodate such flows, without failure of itself or incapacitating damage. To that extent, the spillway damage was a massive management failure.
The emergency spillway, as I've only learnt reading up on this story within the past day, was designed as a "use once" capability. It isn't designed for repeated usage, requires massive reconstruction after such uses, and (in conjunction with the parking lot), provides the basis for a "soft failure" of the dam as a whole, as opposed to the prospect of the entire dam face collapsing.
The Auburn Coffer Dam engineered failure has been mentioned (though not linked -- it's easy enough to find on YouTube) elsewhere in this thread. That was a 1986 event during an extreme rain event. The dam, also an earthen structure, was designed with an intentionally soft "plug", that could and would erode before the main dam face, but in a slow fashion, such that the dam would fail over the course of hours, rather than minutes.
The rate of occurrence of things matters, and a factor of 60 or so (as above) is tremendous. As a comparison, you're in a car moving at 100 kph, and are later moving at 0 kph. How do you feel?
If the interval is 20s, probably pretty good. If it's 0.02s, likely not so hot.
That's a rate difference of 1,000 fold. Something to keep in mind in the context of other stories, such as, say, the fact that climate is change at a rate of roughly 1,000,000x faster than normal, presently.
A point Tucker Carlson apparently cannot grasp, given a recent appearance of Bill Nye on his programme.
The normal way water flows out of the dam is entirely different from the major way in which water was flowing out of the dam during the specific event.
The normal way water flows out of that dam has nothing whatsoever to do with either the spillway, or the emergency spillway, and was not shown in the series of photos.
Semantic means "relating to meaning" and indeed different words have different meanings. Meanings actually matter, it turns out. In this case, the meanings are different enough that you would have to take a two minute or so walk to get from one water outlet (the normal one) to another (either of the two spillways).
The value of the montage here is editing down a large set of images and footage to the critical and suffient element.
As is writing, or audio, or anything else.
I see far too many people who think recording is synonymous with authoring or creating. As Stephen Colbert commented some time back (and many others before him), steganography isn't news.
I've been kicking around a lot of ideas concerning narrative, the thread that organises a story -- fictional, expository, explanatory, whatever. P.D. James' quote on what the heart of a novel is, bringing order to mystery, is apropriate as well.
I found myself watching some of the videos over and over, and skipping others with only a cursory glance. The text was easy to read.
When I watch videos with text I find myself pausing a lot. And nothing is more annoying than trying to rewind a long video to re-watch a 5 second clip: I'm always overshooting and wasting a ton of time.
Life Pro Tip: In youtube, you can use the hotkeys 'j', 'k', and 'l' to jump back 10 seconds, pause, and jump forward 10 seconds. It's very convenient. If you want to rewind a minute, hit 'j' 6 times quickly.
But news stories are not usually presented like this. That's really the thing being commented on is that the imgur style of presentation was an excellent match for this content, which usually is much more text.
I have used Imgur plenty especially r/diy but I don't remember seeing an album comprised solely of animated GIFs. It's typically albums with captioned static images.
I generally tend to think AR und VR are heavily overhyped and I don't believe they will become the next big thing. But I surely hope that we will be able to use VR to better convey the dimensions of things, their size, depth, steepness, and height, things that are almost impossible to convey on normal screens.
I disagree. I found the looping animations jarring and having 3 or 4 of them on screen at once is really distracting, and the image quality is very poor. The animation isn't even showing anything informative, just rushing water. The underlying damage isn't even visible.
Reuter's had a picture gallery just a couple days ago that shows the damage much better:
I disagree that that's a better collection, on a number of counts:
1. The presentation is a fixed-size image on the page, which cannot be maximised (or the controls for such maximisation are highly nonobvious). Which means that I'm seeing a roughly 1/4 size image with vastly less detail than in the Imgur collection.
2. Despite what is clearly access to an arial vehicle (probably a helicopter), the Reuters images present a much smaller set of viewpoints, perspectives, and scales. The flexibility of a drone to go virtually anywhere within the area of interest, the specific focus on both the main spillway and the emergency overflow, the massive erosion along the latter, and the ability to either move in (not just zoom in via lens), or back out for an overview, is highly apparent in the Imgur photosets.
3. By contrast, the drone images provide a range of perspectives, sightlines, an distances from the subject, giving a much better overview of the full scope of the incident.
4. The Reuters images are static, not animated. Whilst I'm among the first to agree that animations can be, and are, overused, their use to show dynamic changes or events is exceedingly useful, and used to exceedingly good effect in the Imgur set.
5. Several of the Imgur images (you have to expand to see the full set) do show the extreme extent of the damage, including the void carved out below the initial failure, the gully formed by the free-flowing water, and the damage downstream of the spillway collapse showing visible rebar at the spillway lip, erosion of that lip, damage to the water diverting teeth at the bottom of the spillway, and several sections of channel wall which have been destroyed upstream of the lip. Also shown are multiple shots with humans visible for scale (and a banana).
6. The captioning of the Imgur slides is far more descriptive than those of the Reuters shots. Passive voice is avoided in the Imgur captions. Because passively voicing your captions is not only dry as fuck but creates a massive tendency to eliminate virtually any informative value from those captions.
7. Finally, the Imgur collection can be contrasted with the imagery which typically accompanies news stories: close-in shots generally of either emergency workers, evacuees, or onlookers, with little or no contextualisation of the larger picture. If you're exceedingly lucky, a small line map with minimal detail may be provided, showing approximate locations, but virtually nothing of interest as to the situation or considerations of the scene or its larger surroundings. For broad-scale disasters (fires, floods, hurricanes, earthquakes), there's almost never a map showing extents, damage, or more critically, safe evacuation zones in the immediate vicinity of an event. This is where I've found Wikipedia to be almost without exception the single best source of information an overview of an ongoing event, in that it synthesises the overall understanding of an event to that point in time, rather than providing a drip of what is almost always very little news, that entirely uncontextualised, and in broadcast media, an absolutely insane amount of space-filling tap dancing and repetition.
My vote goes with the Imgur collection.
Incidentally, Imgur allows animations to be stopped, via most clients, by clicking the image or the animation controls themselves. You don't have to leave them running. I also find muliple simultaneous animations distracting.
California had a gold rush - part of the gold mining was done using "hydraulic mining", where you use water to scrub away rock and direct it into a channel for the runoff to be run through mining equipment.
Be sure, there are plenty of gold prospectors downstream panning or perhaps even using metal detectors in the areas where the waters have receded, looking for golden flakes ("flour") and nuggets.
I don't know the exact law in CA but in general you can use human-powered methods without mechanical assistance, to pan for gold (basically what looks like a pie-pan which has ridges inside to catch the heavier gold).
That was my thought exactly, but I was less eager to share. Gold is often found in association with serpentine (I would bet that has something to do with it being California's state rock) and I saw a lot of serpentine in that gouge caused by the side offshoot. Oroville is not too far from Sutter Mill, where gold was first discovered in California. The Feather River is one of the main river systems in what is known as the 'Mother Lode' area of California (yes, that is where that phrase comes from).
minor footnote: serpentine is interesting as the state rock and a host for gold, and also as a host for chrysotile asbestos. there was some discussion five or ten years back about changing California's state rock to something else because of that.
The Oroville Dam is really a crazy undertaking when you consider: 1) it primarily serves to move water all the way from north of Sacramento to San Joaquin Valley / Southern California, 2) despite generating some amount of electricity, it actually consumes 3/4 of that energy just in transporting the water (over mountain ranges). More generally, the State Water Project (of which the dam is a part) is the largest electricity consumer in the state of California.
That's actually kinda beautiful from an infrastructure point of view -- the infrastructure is self-sufficent and powered using it's own energy.
Or more accurately, it jiu-jitsu's the potential energy in the system to redistribute the resource in a more optimal way (optimal defined as "best for the human economy of california")
What isn't discussed much in the press is how close they came to the largest dam disaster in US history.
As you can see from the pictures, the "bedrock" under the emergency spillway erodes quickly, even with a modest amount of water flowing over it. How would it have handled a flow 100x larger, if the spillway structure had collapsed?
It could have easily eroded down 100 or 200 feet under the intense flow. That would have discharged 50% of the total reservoir volume, destroying tens of billions in real estate and possibly killing thousands.
Fortunately, the dam inflow slowed enough, combined with the main spillway outflow, to stop flow over the emergency spillway before it collapsed. So lucky.
I think this was intentional. A friend of mine who was a geologist working for the Park Service before he got the coding bug and I hired him in the dot com days told be while this was going on, "You know they are lying right?"
I asked about that and he pointed out that the dam was failing, and we were watching it fail. He pointed out the spillway shooting sideways and the amount of progress it had made in just the couple of days between the emergency spillway issue and then. He drew a line on the screen showing how the water cuts away the rocks and that the material above falls in, and becomes like sanding bits in the water flow to cut away still more rock. He estimated that two more weeks of rain at the levels we had experienced would result in total failure.
None of which the press was reporting. And we talked about why that might be. And other than the loss of life (which could be minimized by an evacuation order) there wasn't a whole lot they could do. They certainly couldn't repair the dam while water was flowing out of it. But at the same time they would have a several days at least of knowing it was going to fail before it actually did because of the amount of material that would need to be removed.
He suggested that it was in everyone's best interest to keep the panic and stress levels low until they needed to be higher. And I can't say I disagreed although felt it would be really annoying to have my stuff washed away when folks knew it was a possibility and didn't even offer me the chance to move it first.
So cross your fingers for a sunny March and a slow melt of the Sierra snow pack.
> it would be really annoying to have my stuff washed away when folks knew it was a possibility and didn't even offer me the chance to move it first.
They were more concerned about getting the evacuees out of the way before they were worried about getting the evacuees' stuff out of the way. Houses, furniture, and belongings can be replaced after a disaster. A bunch of people twiddling their thumbs in anxiety over a potential failure while not ordering evacuations to minimize or prevent loss of life is potentially criminal.
Also, people tend to panic. Telling them that there is a probable problem, and ordering a mandatory evacuation long before danger is imminent so that, if the worst case scenario occurs, the evacuees will live gives people hope that officials are just being overly cautious. Telling people that they have 5 hours to evacuate before it is guaranteed that all of their belongings, and their lives, will be lost forever will cause panic and potentially loss of life in the chaos alone.
I agree with you. The interesting question in the discussion was how you weigh panic, economic cost, and human cost. I hope that we'll get to see the decision tree they used at some point.
> But at the same time they would have a several days at least of knowing it was going to fail before it actually did because of the amount of material that would need to be removed.
That's the part where they risk being wrong and end up getting a thousand people killed. The notion of cutting that so close, such that just several days is the buffer between killing a thousand or more people and not, is a very obnoxious premise if that's what they were actually doing.
Yes I think they were utterly bonkers to assume that a failure of the emergency spillway would be limited to "only" the top 30 feet of water. It seems likely that the torrent would have quickly cut down deeper than just the bottom of the wall.
Looks like the side of the spillway or roadway was damaged, since the concrete appears to be broken, although the spillway wall itself might be ok below that vantage point. It's just really hard to tell from that angle, but all of the official drone footage/photos from DWR don't include that area of the spillway, which is curious.
Just moved here. I just realized after looking at a map, it's clear a dam failure would have had little to no impact on the sea level closest to San Jose.
Does anybody happen to know why the water flows down the spillway in waves? Best seen right in the first GIF. I am curious what the mechanism behind that is. Is this a general phenomenon of water flowing down an inclined plane or is it caused by other oscillations, waves on the reservoir, resonances in the outlet system, or something along that line?
"The uniform, free surface, turbulent water flows down an inclined, wide, rectangular
open channel may become unstable spontaneously, if some sufficient conditions
are satisfied. As a result, steady hydraulic conditions are interrupted, including the
water depth (or pressure) and flow velocity. When the channel is sufficiently long,
the small instabilities on the water surface will develop to a series of intermittent
shock-like waves separated by sections of the gradually varying flow."
It basically signifies a loss of energy. You can think of it in the context of collisions, except with a continuous distribution of fluid instead of a discrete distribution of objects.
We know that momentum (mv) is always conserved. In this context, we can replace mass with cross-sectional area, because mass in a given cross-section is proportional to the area. V is flow velocity in length/time. So momentum is flow in length^3/time.
Energy is 1/2mv^2. If you lose energy, mv is constant and m*v^2 decreases, meaning that v must decrease and m must increase. In this context, that means that the flow is slower with a larger area. This corresponds to an "inelastic collision". In fluid dynamics this is a hydraulic jump.
In this situation, most of the energy loss is near the surface, so you end up with moving hydraulic jumps on top of a laminar flow. This doesn't really happen in natural situations, because riverbeds generally aren't this smooth.
This doesn't really happen in natural situations, because riverbeds generally aren't this smooth.
When I first noticed it, I was reminded of waterfalls, especially the way they were portrayed in 8 bit games. [1] It turns out not to be that easy to find a good real world example, at least not without watching hours of waterfall footage, but this one [2] does an acceptable job showing it. I have no idea if this could be caused by the same or at least a similar mechanism.
Seeing what was done here in the matter of days make you realize how things like the Grand Canyon formed over millions of years - then wonder how it isn't bigger. Can't imagine the wealth of knowledge that has been been gained by just watching the erosion patterns as the failure evolved.
First, you went from a prolonged severe drought to a very intense rainfall in a very short amount of time, extremely not helped by the massive surface runoff when the emergency spillway was put in use. I don't know all of the geological processes involved, but the upper soil layers were probably made far more mobile and less stable by the drought.
Second, the massive erosion is happening on a slope, whereas the Grand Canyon is (comparatively) flat. A steeper gradient means less force is needed to set sediment in motion.
If you want impressive floods, the Bonneville and Missoula floods are the largest known floods in history. Imagine floods with hundreds or thousands of times the flow rate of Niagara Falls, which cumulatively scoured the Columbia river region by hundreds of feet.
Yeah, the ice age water flows were quite something: similar to the spillway in question just slightly bigger, a natural spillway of Lake Agassiz, River Warren have first cut the Traverse Gap, a mile wide and 130 feet gap into the Big Stone moraine and then created a riverbed five miles wide (!!!) and 250 feet deep.
Tell me about it! I was cycle-touring in the USA many decades ago and maps back then were Rand McNally, not Google... So it was always a matter of guessing where the hills were. So, I get to Colorado, cycling down through Four Corners with the 'Mittens' etc, hope to get to the camp sites in Grand Canyon. So I follow the 'Little Colorado'. My geography skills told me that the road going next to the river would be going downhill, but I wasn't thinking properly!!!
So I follow the Little Colorado expecting an easy drift into camp but instead I have a gale force headwind and serious bits of uphill. So I didn't get there and I had to sleep in the tent held up by rocks with no let up in the wind, with an electrical storm to follow, one where I was the highest metal object around...
Next morning I woke up rough and set off on my bike, literally 1/2 mile away up the road were a group of cycle tourists from Yugoslavia and they pitched up in one of the roadside stalls. Had I not given in so easily the previous night I would have had a fun time meeting up with them and drinking properly... I was also oblivious to the time zone change so the next day came with a 'free' hour too.
I did go down to the very bottom of the Canyon and up the other side to continue my cycle tour of the wonderful U.S.A. These crazy dams (every river is dammed) were a huge part of my time there, riding across them and camping by them.
The land might have uplifted, but the river still had to carve the same depth nonetheless. I don't think the land happened to raise just on both sides of the river and not below it.
Yes, of course the river has to erode away the rising land but it is staying roughly where it is rather than digging down through land that isn't rising.
"U.S. Geological Survey hydrologist Jim O'Connor and Spanish Center of Environmental Studies scientist Gerard Benito have found evidence of at least twenty-five massive floods, the largest discharging ≈10 cubic kilometers per hour (2.7 million m³/s, 13 times the Amazon River). Alternate estimates for the peak flow rate of the largest flood include 17 cubic kilometers per hour and range up to 60 cubic kilometers per hour."
The specific mechanisms of those is pretty fascinating: During glaciation periods, ice dams would form, creating massive headwaters. The dams themselves would fail, as Hemming way, gradually, then suddenly: water would first start trickling through, then both erode and melt the dam, until its integrity was compromised and the entire face would fail.
Fascinating geology and scarily impressive traces. Makes me wonder what will happen on Greenland or Antarctica.
We're about to see a new piece of ice cleave off about the size of Delaware in Antartica. As ridiculous as that is, I think the most worrisome part is that it will further destabilize the ice shelf and the rate of it falling apart is only supposed to increase by this.
As such things go, the West Antarctic Peninsula calving is not particularly significant in terms of being or enabling large-scale changes in sea level. The shelf is a shelf, that is, it is already floating in the ocean, and its status as solid or liquid doesn't affect net sea levels. The peninsula itself is a long and thin landmass, which contains relatively little ice. Loss of the shelf does not, of itself, create the risk of greatly accellerated large scale icecap loss.
The symbolic and scientific significance are large. This is an exceedingly large ice mass, it may persist for years, possibly decades, in the Southern Ocean. It may pose a threat to shipping (though there's comparatively little through the region), and may have impacts on local biology and ecosystems (habitat loss, habitat gain, habitat change).
The mechanisms of loss, calving, migration, persistence, and of resulting changes to land-based glacial flow, will be fascinating.
But in terms of portending a drastic increase of ice flows local to it, the calving has little impact, as compared to, say, a shelf loss proximate to the primary Antarctic land mass -- the Ross or Weddel shelves, for example, which have behind them a thousand kilometers and more of kilometer-thick ice. That will be an interesting occurrence.
Or the formation and destruction, say, of ice dams, on the Antarctic continent or Greenland, creating meltwater pools, perhaps hundreds of kilometers in extent, and suddenly releasing those, as the dams erode, into the oceans. Similar mechanisms created a badlands landscape in eastern Washington State as the prehistoric Lake Missoula formed and drained, perhaps dozens of times, releasing cubic kilometers of water in massive scours. A similar mechanism, probably in Canada, triggered a catastrophic sea-level rise, measured as I recall in meters, over the course of days to a month.
That would also make for an interesting news cycle.
Contextualisation of these types of events in the press is exceedingly poor, with a small handsful of exceptions. I've already mentioned Brad Plumer's Vox coverage in this thread, he's among the exceptions.
That scour reminds me of what happened after the Taum Sauk hydroelectric reservoir in Missouri failed in 2005, which sent 20 feet of water down a small mountain:
There are two spillways, the main spillway and the emergency spillway.
The main spillway is the concrete spillway, and it developed a hole in late January. Due to very real concerns that it would deteriorate, the decision was made to use the emergency spillway until the concrete spillway would be fixed.
The emergency spillway is basically a concrete weir--when the lake level reaches a certain height, it spills out over concrete and runs down the hillside. This is considered an emergency spillway, and erosion is usually expected for such spillways (the regulatory definition of an emergency spillway is basically "it can be used once and then it needs a long downtime while it's repaired).
When the emergency spillway was in use, what happened was the very same erosion that was underpinning the main spillway was also occurring near the concrete weir. If left unchecked, the fear was that it would start eroding the concrete weir leading to potential collapse of the concrete weir. This prompted the decision to evacuate as much water as possible using the damaged main spillway which greatly exacerbated the damage (as the pictures show, a large section of the spillway now fails to exist, and it looks like most of the lower spillway would need to be torn up instead of being unused).
I'm not a geologist, and I certainly don't have detailed nature of the local geology. But my suspicion is that the prolonged drought followed by the intense wet season destabilized the slope (by weakening the organic stabilization of the slope and then loading it heavily with water), so spilling any dam water anywhere on it would lead to massive erosion (including undermining the concrete structures). The emergency spillway is supposed to be able to carry far more water loads. I don't think the severe-drought-then-extreme-rain scenario was envisioned during the dam construction (although it really should be after this event), so I don't know if the spillway would have performed as badly in "expected" conditions.
Also not a geologist, and not familiar with local geology. Packing so much water in a very small channel really helps water erode anything. If i remember correctly, it's thought Niagara falls moved a few miles in a day. That seems terrifying to me, it's a long drop down. Waterfalls slowly work their way upstream, obviously. Less obviously, a little weakness lets more water though, compounding the abrasive effects. Which allows more water, which cuts away the land faster.
So yeah, i don't think the dryness had anything to do with destabilizing anything. Water is just really good at cutting. The dam created a huge reserve of water, so lots is available to cut.
This is my understanding: the regular spillway suffered damage while it was being used, and had to be shut off. I don't think it's clear whether that was due to some kind of oversight or it "just happened". If the damage had not occurred, everything would've been fine, but it forced the use of the earthen emergency spillway, which eroded faster than anticipated. There had been calls to upgrade the emergency spillway to concrete, but these were not pursued for reasons of cost. So it was a combination of unexpected damage to the regular spillway and inadequate construction for the emergency one.
There is often the case of why was there so much water in the first place. I dont know much about this dam but here in Sweden the companies running water dams have been known to save up too much water in expectation of better prices. This leads to emergency dumping of water if it rains too much and the downstream areas gets flooded. Not this badly but a few houses gets water in the basement sort of flooding.
In California, sometimes they save up too much water, but it's because rain patterns are hugely variable. They don't know if the next big rainstorm will be next year or next month. So sometimes they get it wrong, but better to have too much water than too little.
There was previously observed damage to the primary spillway noted in 2005. A $100m repair was requested of state and federal (FERC) authorities, during the GOP-lead Bush and Schwarzenneger (national and state) administrations, but was rejected.
Present damages now exceed $100m, and repairs are likely to be several times the initial estimates.
So Brown and the CA Democrats are off the hook for ignoring a $100M repair, because Ahnold didn't fix it? IMO that makes them both the same. Actually, it makes the current administration worse because the increase in damage happened on their watch.
From my understanding, it wasn't so much the rainfall/flow as it was the damage to the spillway.
If the spillway doesn't experience structural failure, there's no problem. But it did, so flow through the spillway had to be reduced, which led to the emergency spillway coming into play and they had to continue using the damaged spillway, failure or not.
I guess it ends up depending on how failure is defined for a given context. It didn't fail in the sense that the area still holds back water. It did fail in the sense that they believed it to be unsafe to continue using it.
Considering they kept using the spillway even though it was damaged (because they hadn't repaired it as they should have due to lack of funds), and they had to use the emergency spillway (which wasn't reinforced because they didn't do it 12 years ago when they should have). I vote more than expected rainfall (216% of normal by some accounts - though they might have also been storing more water than normal due to the drought) and lack of proper funding to keep the engineering tolerances where they were supposed to be.
But I'm more inclined to suspect the problem is larger. For example that anthropogenic climate change is increasing the amplitude of the El Nino effect.
More than a decade ago, federal and state officials and some of California’s largest water agencies rejected concerns that the massive earthen spillway at Oroville Dam — at risk of collapse Sunday night and prompting the evacuation of 185,000 people — could erode during heavy winter rains and cause a catastrophe.
Three environmental groups — the Friends of the River, the Sierra Club and the South Yuba Citizens League — filed a motion with the federal government on Oct. 17, 2005, as part of Oroville Dam’s relicensing process, urging federal officials to require that the dam’s emergency spillway be armored with concrete, rather than remain as an earthen hillside.
The groups filed the motion with FERC, the Federal Energy Regulatory Commission. They said that the dam, built and owned by the state of California, and finished in 1968, did not meet modern safety standards because in the event of extreme rain and flooding, fast-rising water would overwhelm the main concrete spillway, then flow down the emergency spillway, and that could cause heavy erosion that would create flooding for communities downstream, but also could cause a failure, known as “loss of crest control.”
Agree that deferred maintenance is the primary culprit, based on what everyone is saying... The spillway should have withstood the flow of water from the extensive rainfall if operating within specifications.
While there was a lot of rain, and climate change is affecting long-term weather patterns, I think it would be misleading to associate the Oroville Dam problems to climate change.
Water management is difficult in California because you never know if this rainstorm will be the last of the season, or if the next one will overflow everything. It becomes a balancing act of when to let water out of the dams.
As I've commented at length just now, this is an excellent set of visualisations of the damage, and history, of this story. It exceeds all media coverage I've seen of the event (though I've not canvassed all of that coverage).
I'd like to also present Wikipedia's article on the Oroville Dam Spillway Crisis of 2017, which is another example of exemplary coverage, and what's been a consistent model for me for vastly better coverage of ongoing large-scale events since the Boxing Day Earthquake and Tsunami of 2004, the first time I'd followed a major story by way of Wikipedia:
In roughly 25 paragraphs, plus an SVG image essay showing the progression of the damage, apparently original work by a Wikipedia editor, this spells out the background, event, development, implications, and history of the failure.
Both the Imgur essay and the Wikpedia article are vastly more informative than any news coverage I've seen. In the case of Wikipedia, much of that comes from its ability to synthesize information from multiple sources and place it in a coherent context. But in both cases, much of the value also comes from a focus on what I see as the salient factors, and an avoidance of fluff.
Taking a quick second look at the Wikipedia page, the one fault I'd give it is that for someone immediately affected by evacuation orders, there is insufficient information about what routes were recommended or deprecated. For that, some local news accounts (I'd read the Sacramento Bee and SF Chronicle's coverage in particular) was perhaps more useful, but only just.
I'd put hard to the press just what they see their mission as in reporting on such events. Because, much as I appreciate the media, they fell down here.
Addendum: Brad Plumer, at Vox, has previously caught my attention as an exceptionally good reporter. His article explaining the Oroville Dam crisis is cited by Wikipedia, and is itself also excellent. I'm calling it out specifically as an example of How to Do Coverage Right:
Lot's of infrastructure was built in 1950s/60s/70s. A reminder if we let rot our infrastructure, it's not good at all. (not implying it's the case with Oroville dam, haven't followed all news articles) Many concrete and steel structures have a limited life-time of 60-100 years (or so). Big infrastructure projects were built with ease back then, compare it too overblown "paper work" nowadays (not speaking about engineering, but bureaucracy). We should really look how asian countries excel at building infrastructure nowadays (they nowadays build multi-level highways and bridges in no time with ease, whereas building a bridge/tunnels in the west takes many years and cost way too much) and look back in history how to maintain infrastructure well over a timeframe of a few centuries. How many 1950s/60s/70s structures (big things like skyscrappers, dams, bridges, tunnels, subways, etc) are a risk, need repair or are beyond repair and need a replacement - is there a map? Is there a documentation about this topic or some interesting research in this field?
I don't have an official source, but the spillway will be rebuilt. It can be completely closed for an extended period once the rain/melt up season is over. I guess they might have to prepare a diversion to do it, if the work cannot be completed in months.
The water management and power provided by the dam pretty much guarantee it will be repaired and continue operating.
I wonder if they will reroute the main spillway down its new channel. That looks like it might be easier than trying to fill the hillside back up all the way to the previous level.
Currently living up in the Sierras along the Feather River, it's no surprise the amount of water that went rushing down into the Oroville reservoir. Even at about 4500 feet, you had about 3-4 feet of snow that ended up being melted by a significant amount of rain.
That is quite a bit of water rushing down that way.
Interesting times and the videos are quite educational.
the latest is that the banks of the Feather river have collapsed after the huge amounts of water receded. Amazing the power of water...
"With high water no longer propping up the shores, the still-wet soil crashed under its own weight, sometimes dragging in trees, rural roads and farmland, they said.
“The damage is catastrophic,” said Brad Foster, who has waterfront property in Marysville (Yuba County), about 25 miles south of Lake Oroville.
The farmer not only saw 25-foot bluffs collapse, but also lost irrigation lines to his almonds. “When the bank pulled in,” he said, “it pulled the pumps in with it. It busted the steel pipes.”
A classical "we've found a problem. let's fix it later, when it will be too late" approach to infrastructure.
I'm sure there will be dozens of "good reasons" why the repairs could not have been done in time, but the theme of the approach to infrastructure problems is disheartening.
So they built a big strong dam and a "protected" it with a smaller, weaker dam. Seriously, what was the rationale for this design? No criticism or Monday morning quarterbacking here. I'm genuinely curious what the original engineers were thinking.
When the evacuation was announced I sort of hastily pasted into a chat channel that the dam was going to fail.
The main dam of course did not fail, but looking at the recent photos, the overall system sure did fail. I hadn't realized the extent to which the spillway had continued to erode.
There's basically no chance of the main dam failing. A failure of the emergency spillway is basically the worst case scenario. For the main dam to fail, water would have to get over the top, and the emergency spillway ensures that the lake stays below that level.
A failure of the emergency spillway would still be quite destructive, of course.
The base of the emergency spillway is bedrock, so it can only erode down that far. That's 30ft below the top of that spillway, which is why everyone talks about potentially having a 30ft wall of water hit downstream communities.
I'm not a geologist, but... Didn't the main spillway failure erode some of what was considered "bedrock"? Isn't the bedrock somewhat more erodable than the term "bedrock" would lead you to expect?
Some…yeah, where some is the 1.7 million cubic yards of rubble now clogging up the Thermalito Diversion Pool. [1]
When you look at photos or drone videos of the erosion near the main spillway, it's clear that an immense amount of rock has been eroded away (the color changes from brown to gray). [2]
Juan Browne discusses the type and strength of the rock in one of his excellent videos about the Oroville crisis. [3] (Note that he demonstrates the weakness of the rock where he is standing, which is across the river from the spillway and might not be the same rock.)
I'm not either, and I don't know! Total speculation: water partway down the spillway is considerably more violent than water just spilling over the top, so while bedrock may not resist the former, it can resist the latter.
Another wild guess: the main spillway hasn't eroded any bedrock, just concrete, dirt, loose rocks, etc.
If anyone actually knows versus my wild guesses, I'd be most interested.
Don't know the details of the projects but from the pictures posted (here and elsewhere) it seems that only topsoil was eroded.
Yes, bedrock is not indestructible, it could get eroded from water, but it takes times. Plus it get eroded slowly over time. The main concerns was the use amount of water released by the failure of the spillway. For sure the water keep flowing over the collapse spillway would erode the bedrock lowering it, but at a slower pace...
One thing I'm really impressed with is how many redundancies are built in to dams, and how their failures are intended to be gradual and not catastrophic and sudden with a full release of the reservoir contents.
ie, use the water to generate electricity. If that's not enough outflow, use the spillway. If the spillway isn't enough, the emergency spillway will drain more.
There's even another contingency (with more details), described here, that I haven't heard anywhere else:
> The emergency spillway is not auxiliary, and i don’t believe any competent geologist present during it’s construction would have considered its use as anything but a last ditch effort. It was designed as a fail-safe to prevent the loss of the main dam during the event of a half a million cfs inflow to the lake during a 200 to 1000 year event. The ogee weir extending from the main spillway gates was likely built to protect the main spillway gates. The bedrock was excavated deeper below the ogee weir to find more competent bedrock than the concrete wall extending northwards from the ogee weir, which was built to protect the ogee weir. The lack of concrete in the far NW corner of the parking lot where we saw considerable erosion and helicopters lowering bags of rocks into is not lack of foresight, but designed weakness built into a weak structure. The parking lot is built on highly weathered bedrock and is designed to function as a sacrificial plug located as far from the dam itself as possible, similar to the Auburn coffer dam failure of 1986. As headcutting progresses into the parking lot, water at elevation 900 and above is skimmed off. Once headcutting reaches the lake, then downcutting commences, “safely” lowering the lake till competent bedrock is found, maybe a hundred feet down, leaving the vast majority of the lake still in the lake and Oroville dam still standing, no matter the magnitude of the storm.
The normal water exit from the dam is through the power plant. If either spillway is moving too much water, the level of the pool below rises, and the power plant turbines can't run because there's backpressure at their exit. That happened this time, which increased the load on the spillway.
Right now, the lake level has been dropped to 50 feet below the dam top, to provide some safety margin for later storms. The crisis is probably over, and there will be heavy construction this summer.
