And so, judging by the video, the spillway simply cannot cope and began to collapse from such a flow of water
Therefore, the engineers reduced the discharge of water, well, the water reached the emergency spillway. And that was used for the first time since the construction of the dam. But then there was another school of engineers, the reverse side of the emergency spillway began to erode, which created the threat of its destruction with an understandable result.
And the media have already picked up the hysteria. The main dam, as I understand it, is safe.
Original taken from antizoomby in Photos of drought in California.
Lake Oroville, California.
California is suffering from a severe drought:
In May, 100% of California faced "severe" drought (it was exposed to level 3 out of 5 possible). But after the new numbers came in, that percentage was dropped to 99.8%, according to the U.S. Drought Monitor.
Meanwhile, about 82% of California continues to experience "extreme" drought, and more than half of the state experiences "exceptional" drought, according to established categories.
Californians have been suffering from the effects of drought for quite some time. Local officials are imposing restrictions on water consumption and are pleading with residents to conserve water in every possible way. Hell, even running the Ice Bucket Challenge ice-water flash mob faces serious problems due to the reluctance to waste water.
Below are some shocking photographs that show the severe impact of the California drought.
Boats at Lake Oroville.
Lake Shasta.
Lake Shasta.
Folsom Lake Dam.
Lake Folsom.
Lake Oroville.
A few more explanatory photos (as well as visual comparisons with the recent past) from (it is recommended to follow the link - there more photos and they are of better quality).
Lake Shasta, California, USA, August 30, 2014. About 30% of the water remains. (Photo by Justin Sullivan | Getty Images)
Dry part of Lake Shasta, California, USA, August 30, 2014. Ahead is a buoy. (Photo by Justin Sullivan | Getty Images)
Lake Oroville, June 20, 2011. (Photo by Paul Hames)
This is how the place looked on August 19, 2014. (Photo by Justin Sullivan | Getty Images)
Lake Oroville again, June 20, 2011. (Photo by Paul Hames)
Another location at Lake Oroville, June 20, 2011. (Photo by Paul Hames)
Same location on 19 August 2014. (Photo by Justin Sullivan | Getty Images)
Lake Oroville and Bridge, June 20, 2011 (Photo by Paul Hames)
And this is the aftermath of a drought in California: same location on August 19, 2014. (Photo by Justin Sullivan | Getty Images)
A dam spillway at Lake Oroville, California, August 19, 2014. Stands dry, idle. (Photo by Justin Sullivan | Getty Images)
Lake Oroville and Ships, California, August 19, 2014. It currently contains 32% of its water. Photo by Justin Sullivan | Getty Images)
Neighboring Yuba City was also completely evacuated and its streets were eerily empty. All schools were closed, many of them hastily converted into temporary shelters for refugees. Intelligence agencies even removed 500 prisoners from the Butte County jail.
All this reminded me of the Chernobyl exclusion zone, which to this day operates in some regions of Belarus and Ukraine.
Local farms, flooded with water, also stood silent, like in Hollywood zombie films. Let's not forget that all three counties (Butte, Yuba, and Sutter) that have declared mandatory evacuation are located in an agricultural region of California that has been badly hit by five years and the accompanying fires. Therefore, the news of a possible flood has stirred up a large part of the population, who knows firsthand what happens when it gets into dry soil. a large number of moisture in a short period of time. Indeed, recently we ourselves have witnessed numerous landslides and sinkholes that have occurred throughout California due to the abundance of rainfall.
Beyond Marysville is the small town of Oroville, which sits at the foot of the tallest dam in the United States. It actually looked like a ghost town from the films about the Wild West: shops are locked, without exception, all businesses are closed, belated tenants take out things and even furniture from their houses... The last townspeople in great panic left the deserted settlement.
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Oroville
Live broadcasts from Oroville's webcams in real time. Popular webcams are shown first. Oroville is a city and county seat in Butte County, California, USA. Oroville was founded as a navigation point on the Feather River for the supply of gold during the California gold rush. The settlement was originally named Ophir City. The name was changed to Oroville in 1854 when the first post office was opened here.
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#Oroville, #webcams, #online, # real time, #California
Residents of Oroville, California and surrounding areas have been ordered to leave their homes immediately as parts of the components of the Oroville Dam, the tallest dam in the United States, are undergoing severe structural collapse.
Damage to the main structure of the dam is expected within an hour. After this structure collapses, over two cubic miles of water will be released. The flood will wipe an entire area off the face of the earth.
Oroville Reservoir is located 240 kilometers from San Francisco. The lake town of Oroville has a population of 16,000. The dam in question is the tallest in the United States at 235 meters. The reservoir is also the main source of water for California, Central Valley agriculture, and state businesses.
An old video showing how the Oroville spillway should look like in normal mode:
This is how it looks now:
Whereas earlier the water extinguished its energy, smoothly flowing down from a height of 770 feet, today, after spontaneous damage to the spillway about a week ago
due to a series of rainstorms that flooded the region, the lower part of the structure looks like a seething stream of water with flying blocks of reinforced concrete, eroding the surface to the very rocks.
Evacuation Zone Maps:
Here's what American bloggers think about the situation:
Flyingcuttlefish: Several years ago, I spoke with a volunteer lifeguard from North Carolina. He secretly, fearing that someone would overhear us, told me that they were conducting special exercises in case the dam upstream of a large settlement was destroyed. He even gave me an approximate date when this might happen. The words of the rescuer were not a surprise to me and only confirmed my suspicion. The fact is that somehow strangely coincided and it turned out that the army of engineers of the United States built more than 50% of its dams in places of active underground faults and in places where large groups of the population were gathered down the river. But what if the dams were built on purpose - in anticipation of future events, natural disasters? Or even artificial disasters such as devices like HAARP. If the flood kills a lot of people, destroys the local economy - HAARP can influence not just the weather, but politics.
Jim Stone: All dam maintenance records show that the spillway was in excellent condition until recently. I analyzed many hours of video from the dam surveillance camera and in some frames it is noticeable that the pieces of concrete flooring seem to bounce high in the air. So I think the spillway was blown up. Or is it some kind of deliberate sabotage. Obviously, I have no evidence of deliberate digging under the gutter or traces of explosives, but you must agree - this is a completely rational explanation. Even engineers are terribly surprised how this happened. And that means a lot. Therefore, I have doubts that everything will end well. If the dam collapses, it will be double Niagara Falls... Or even Niagara times four.
Based on materials
The accident with the simultaneous destruction of all the spillways of the dam in Oroville, California served as a prime example of a big problem arising from a small but systematic oversight. The destructive processes, which were not identified in time by the responsible services, ultimately led to a serious threat and the need to promptly evacuate hundreds of thousands of people, use colossal forces to eliminate the accident and spend hundreds of millions of dollars on the operation. Until the situation turned into a catastrophic stage - the water did not break into the dam, however, it revealed the problems of the existing system of servicing hydraulic structures, and destroyed the guarantees that a real tragedy would not occur in any of the regions of the world.
What is a California dam
Oroville Dam is the tallest in the United States. The height of its soil part reaches 235 meters. The dam is located on the Feter River (a tributary of the Sacramento River). A stone dam with a clay core forms the Oroville Reservoir with a surface area of ββ10.2 thousand square kilometers and a water volume of 4.3 cubic kilometers.
The reservoir itself is part of a complex that includes an 819 MW hydroelectric power plant with six generators, a Hyatt power plant, a Thermalito pump-generator station, and a fish factory. The main tasks of the complex are water supply to the region, flood control and power generation. The facility was built in 1961-1968.
The buildings of the complex are located on the right side of the river. The object closest to the dam is an operational spillway (reinforced concrete flume) for normal water operation. Even more to the right is an emergency discharge in case of catastrophic floods. It was not in use until the February incident, as there were no such floods. According to statistics, large-scale floods in this region can occur no more than once every ten thousand years.
The discharge looks like a 100-meter wall with a height of 10β20 meters. The incoming water should be overflowed without regulation, while its layer will be tens of centimeters. Further, at the junction with the right bank of the valley, there is a blank section of the dam with a height of up to 30 meters.
Chronology of the incident
Since the beginning of 2017, the water level in the Oroville Reservoir has been rising at an intermittent rate. However, the record belongs to the summer of 1983, but then no emergency situations was not observed. In January 2017, the amount of precipitation in the region exceeded the norm by three times. Since the beginning of February, the weather was extremely warm, even at night it did not fall below 10 degrees Celsius.
Already on February 7, a large washout was identified in the middle part of the spillway. The karst sinkhole, as experts from the CIS believe, happened due to the leaching of the rocky base. While the repairmen were examining the damage, water in the reservoir was rapidly accumulating. When it reached a critical point, which already threatened the safety of the dam itself, the emergency crews left the zone of the failure and the water was sent to discharge.
The consequences were not long in coming. The concrete fastening on the bottom of the structure was destroyed, after which the water began to wash out the rock under the drain. The destructive process began at the moment of water consumption at the level of 1.4 thousand cubic meters per second. For comparison, in 1997, the dam passed a flow of 4 thousand cubic meters per second without any problems. The gap has reached a size of 150 by 90 meters and a depth of 14 meters.
The engineers who identified the problem expected that the structure would collapse at any moment, therefore, they reduced the water flow by 15%, using an emergency discharge that had not been used before, and by February 10 it turned out that the basement of the backup drain was also damaged, and the reason for the violation of integrity it was not possible to find out the object.
The flow of water carried fragments of rock into the river bed, so the operation of the hydroelectric power station had to be stopped, otherwise, due to backwater, it could be flooded. Meanwhile, the fracture pit on the main fault widened, destroying its walls and eroding the adjacent slope. The situation at the emergency drain has become critical. The decision was made to resume the boosted flow through the main spillway, despite the threat of loss of control over the dam due to possible runoff destruction.
Accident elimination and preventive measures
Since the threat of destruction of the dam's infrastructure, California Governor Jerry Brown has asked President Donald Trump to send federal forces and funds to respond to the emergency. In his appeal, the official noted that assistance should also be provided to the districts in which residents evacuated from areas of possible flooding are accommodated.
On Monday, February 13, the Governor of California introduced a state of emergency in the region, in the territory of three counties - Yuba, Sutter and Butte. Units of the National Guard of the state were alerted. The White House reported that the president had instructed the Federal Emergency Management Agency of the Ministry of Homeland Security to coordinate the emergency response. In addition, the Ministry of Defense of the country was also involved in the work. Pronedra wrote earlier that Trump also declared an emergency regime in the disaster zone.
The Russian side immediately offered its help. The Center for the Development of the Water Management Complex of the Ministry of Natural Resources of the Russian Federation said that domestic specialists could work on solving the problem of the emergency state of the dam, including by providing appropriate scientific advice. Such tasks are not new to the Russians; Moscow has already provided assistance to countries in Africa and Southeast Asia in case of similar emergencies.
Large forces were put on alert in the United States - a total of about 20 thousand servicemen. 125 construction teams and four dozen heavy vehicles were sent directly to the work area. Aviation was involved, including the National Guard helicopters, with the help of which bags of sand and rock began to be dropped at the places where the drain was washed. Sandbag fences are being erected around the dam. Every hour, about 1.2 thousand tons of rock debris are placed in the gullies.
The state authorities informed that the work carried out by February 15 made it possible to stop the development of the catastrophic situation, and the expected storm with precipitation was not as significant as anticipated. In general, the cost of priority measures was estimated at $ 200 million. It is not yet known how the condition of the spillways will affect the further operation of the dam. The work continues. Thanks to the measures taken, the dam is already able to receive an additional inflow of water. At present, the volume of discharge is 2.8 thousand cubic meters per second, while the rains do not stop and will continue for several more days.
According to RusHydro, measures are being taken to lower the reservoir level by 2.5 meters per day in order to safely receive the upcoming precipitation. In the riverbed, debris is being dismantled to prevent possible flooding of the HPP structures. The launch of the plant's capacities will allow unloading some part of the operational discharge. If the latter is to be restored, it will be repaired. In case of impossibility of repair work, a new spillway will be built. It is possible that it is necessary to strengthen the slope of the emergency discharge with concrete and, in general, to assess the possibility of its use in the future.
Evacuation, panic and looting
After the emergence of information from the California Department of Water Resources about the threat of an imminent dam break (later it turned out that the forecasts were unreasonably exaggerated), the state authorities decided to evacuate the local population. Until February 13, a total of 188 thousand people were taken out or left on their own from the cities of Yuba City, Gridley, Olivehurst, Plumas Lake, Wheatland, Marysville and Live Oak. But the route of the evacuees was observed with colossal traffic jams. Temporarily resettled citizens were placed in different areas at a distance of 32-120 kilometers from the zone of possible flooding.
Controversial statements by officials, in particular, the emergence of information about the possible destruction of the dam in a matter of hours, played a significant role in causing the panic. Already on February 15, the exported residents were told that they could return to their homes, although it was noted that the threat of flooding still remained and, perhaps, citizens would have to leave the dangerous area again. Citizens who returned to their homes faced the consequences of looting in their cities. Such reports came from Oroville, where, in the absence of residents, there was massive theft in abandoned stores.
Forecast of the development of the situation in the near future
The state authorities initially took a pessimistic position in terms of predicting the development of events. The California Department of Water Resources admitted that if the dam structure is damaged, the forecast may be unfavorable. According to the local police, who interviewed experts in the field of hydraulic engineering, a hole in the spillway could jeopardize the integrity of the entire dam. However, experts emphasize that dams using concrete components are usually not very susceptible to erosion processes.
However, if the structure is damaged, it can also cause it to collapse. The Russian Institute for Hydraulic and Power Engineering believes that the dam can survive if the excess water flow is discharged through the open gates. A disaster is potentially possible if the spillway does not function.
The gloomiest predictions came on February 11, when the state announced an imminent rise in the river's water level to a critical level due to a possible dam break. Although the very next day it was announced that the threat had passed, on February 13, reports reappeared about the threat of the destruction of the dam. The negative scenario provides for the speed of wave propagation over flat terrain within 25 kilometers per hour, in mountainous areas - up to 100 kilometers per hour. It is argued that the height of the breakthrough wave for small reservoirs with a water volume of up to 50 million cubic meters will be up to one meter, but in the case of Oroville, whose capacity is eight and a half times larger, the wave will reach a height of up to nine meters.
Recall that in this case, there will be six settlements in the flood zone with a total population of up to 200 thousand people. In turn, RusHydro noted that as of February 12, when signs of active erosion of rocks were noticed on the slope section below the emergency discharge, a certain threat arose for the residents of the region. If the overflow wall collapsed due to intensive erosion, it could cause an uncontrolled discharge of a layer of about 12 meters in height of the reservoir.
There are also alternative points of view. The forecast for the next few days is a difficult matter, say the hydraulic engineers from the CIS, interviewed by journalists. It is more likely that the dam will remain unharmed, while the spillways - both the main and the emergency - will be washed out to the stage of complete destruction, however, there will be no significant damage to the population and infrastructure. Overflowing through the dam will stop after some time, or the process of erosion of the weir will take a long period - within one month, which will not cause drastic changes in the situation and the problem will not become more complicated.
RusHydro believes that the current data give grounds to assert that there is no threat of dam destruction, but the structures for the spillway are in disrepair. The crest of the dam is six meters higher than the emergency discharge mark, therefore, an abnormal overflow of water is also excluded. If the erosion of the drainage will move to the spillways themselves, then the latter are likely to be destroyed. Directly the pit at the spillway stopped active expansion, reaching the rocky base after the fragile rocks were washed out.
Meanwhile, after the accident at one dam, the other "hot spots" in California were simply forgotten. Reservoir overflow due to heavy rainfall is a problem not only for the Oroville Dam, but also for most of the California Valley hydraulic structures. Concerns are caused by the situation on the Sacramento River in the area of ββthe city of the same name. The dam on the river shows signs of deformation after prolonged exposure to water currents. Some of the water has already seeped through the dam and ended up in the city park, which is located by the river. In addition, a threatening situation is observed in the area of ββthe dam on the San Joaquin River.
In addition, the water level at the Don Pedro reservoir dam has almost reached the top of the structure. If a snow storm hits the Sierra Nevada mountains in eastern California, flooding is likely to be unavoidable. To prevent the destruction of these structures, the state authorities decided to deliberately destroy the dam on the Moklamne River, which led to the flooding of nearby agricultural land, but reduced the threat of large-scale accidents.
Possible versions of the causes of the accident
Potential problems with the dam became known long before the February 2006 accident. Even then, experts discovered minor violations of the integrity of the main spillway, but the facility was recognized as suitable for operation. Major repairs on the dam have not been carried out for half a century - from the day it was put into operation. The dam has been operating under a temporary license for the last decade. Probably, the reason for the indefinite status of the dam is associated with an attempt to issue a permit for a period of 50 years by the Californian authorities and the subsequent reaction of public figures.
In 2005, a group of environmental activists - the South Yuba Citizens League, Sierra Club and Friends of the River - demanded that the authorities reinforce the emergency discharge with concrete instead of an earth base. In a joint letter from the organizations, it was argued that during the winter rains, water will begin to overflow through the main spillway, which will eventually lead to erosion with further destruction of structures and floods. Proposals were submitted to the presidential administration and the Federal Energy Regulatory Commission, but they rejected the initiative based on the conclusions of the California Department of Water Resources about the inexpediency of such work. According to the authors of the letter, the authorities simply decided to save money, since it would cost millions of dollars to strengthen the spare spillway with concrete. Now the department claims that the reason for the formation of erosion on drainage is unknown.
Like any serious threat, the situation with the risk of dam destruction has already been overgrown with rumors and exotic theories. In particular, it is assumed that the possible catastrophe was deliberately provoked in order to smooth out the discontent of the population of California, most of which voted for Hillary Clinton in the presidential election. A great misfortune can rally a nation and eliminate political divisions. In addition, it should be borne in mind that public figures in California are actively calling for the separation of the region from the United States.
Conspiracy theorists believe that the failure of the main spillway was of a controlled nature and was the result of sabotage - the leak arose by interfering with the work of an already worn-out infrastructure. In addition, there were statements that the rescue services conducted exercises several years ago, during which they practiced actions in the event of a dam failure. At the same time, the almost exact date of a possible event has already been stipulated in the scenario of the maneuvers.
If we talk about real facts, then RusHydro, which analyzed the development of the emergency situation and possible prerequisites, came to a number of conclusions. It is noted that the destruction of the operational spillway occurred suddenly, and the levels of water consumption were not at all maximum. Thus, we should talk about the insufficient degree of control over the state of the hydraulic structure, which did not allow timely identification of damage, the company noted.
It is difficult to call the design decision itself correct, connected with the discharge of water masses onto an ordinary unequipped slope. Spillways must pass mandatory tests. Nevertheless, it should be noted that the safety factor of the dam turned out to be sufficient, despite the fact that accidents happened at both spillways. Thus, large hydraulic structures in general can be considered reliable structures, the company noted.
Regardless of what the conclusions of the accident investigation turn out to be, it is obvious even to non-specialists that, apart from the dubious theories of sabotage or sabotage, the unsatisfactory condition of both spillways was most likely the result of the usual negligence of the services, which did not track the process of damage to structures due to natural wear processes. The lack of preventive measures almost caused a large-scale tragedy, and for the happy outcome of the situation, we can only thank the reliability of the dam itself, which acted as insurance against the negligence of industry services.
