You may have seen this picture somewhere on the internet. It captures a huge, deep crater in the water – where tons of water are being sucked in like a portal to an underground world or even another dimension.
The surreal feeling that the photo creates makes many people think that this is a product of Photoshop. Someone must have drawn this picture, but water can’t flow like that. It’s virtual!
But no, this photo is completely real, and it captured a rare moment in Lake Beryessa, California, USA. The water hole itself is also real. But if so then you might ask where is the water going?
As it turns out, Berryessa is actually a lake on top of a dam. The water flowing into that hole still obeys the laws of physics, they flow down below the foot of the Monticello Dam, up to 86 meters above the water.
In 2019, a video was recorded of a duck swimming into this hole. Miraculously, it survived. But before that in 1997, a woman was swimming on Lake Beryessa and was swallowed by a hole and did not survive.
This water hole is real
Monticello Dam and the rare bell overflow door in the world
The history of the Monticello Dam dates back to the early 1950s, when the state of California noticed its 39,000-acre farmland in Solano and Yolo counties was always short of water in the summer.
To be able to store water for irrigation, the state irrigation department has proposed to the US Department of the Interior a project to build a dam, blocking the Putah creek at the location of the Berryessa valley and the town of Monticello. In 1953, the project was officially approved and went into construction.
It took a total of 4 years and $37 million for the Americans to complete the Monticello Dam. It is a concrete arch dam, 30 m wide, 93 m high and 312 m long. Crossing the valley, it would take another five years to fill the Berryessa reservoir it created.
In 1962, Berryessa became the second largest reservoir in the state of California, with a surface area of 8,400 hectares, a water column height of up to 130 meters and a capacity of about 2 billion cubic meters of water.
Like any dam and reservoir in the world, to ensure its safety when the water level exceeds its storage capacity, an overflow outlet must be designed. Normally, the overflow outlet will be designed in the form of a trough channel, located right on the edge of the dam edge.
However, the problem with the Berryessa valley is that it is so small and narrow that there is no room for this overflow channel design. The Monticello architects therefore chose a rarer built spillway, the Bell-mouth spillway.
The bell mouth overflow door is actually a hollow pillar, built from the bottom of the reservoir into the air, like an upside down bell with an opening at the bottom. This is an uncontrolled overflow design, meaning it does not have a door that opens and closes at will.
Instead, the height of the bell mouth is pre-calculated so that whenever the water stored in the reservoir exceeds the allowable capacity, they will naturally overflow through the bell mouth and exit below the dam.
With the Berryessa reservoir, the bell-shaped spillway was built 130 m high. The bell mouth diameter is 22 m wide and gradually narrows to 8.5 m at the bottom exit. It allows a maximum flow of 1,370 m3 water flows through every second.
In addition to Monticello, the number of dams in the world with a bell-shaped spillway design can be counted on one finger including: the Hungry Horse dam in the state of Montana, USA, the Covão dos Conchos dam in Portugal, Geehi Dam in Australia, Nekogahora Pond Dam in Japan, Ladybower Reservoir Dam in the UK and Shing Mun Dam in Hong Kong.
The video of the drone going inside shows you the structure of a bell-shaped overflow door
Covão dos Conchos Dam, Portugal
Ladybower Dam in England.
Popular events and videos
It should be said that bell overflow gates very rarely work because the water in the reservoirs for which they are designed is rarely full. When there is no water flowing through it, the concrete structures simply rise above the water and do not create dramatic scenery.
Only the spillway at the Monticello Dam in recent years has been the most active. Back in the 1950s, the engineers who built it calculated that it would take 50 years for the water in the Berryessa Reservoir to fill up once.
But heavy rains in California over the past decade have caused the bell mouth in Monticello to overflow three times. The last two times were in 2017 and 2019, when water overflowed there, thousands of people gathered around the mouth of this bell to witness the event.
Most of the photos and videos you see on the internet today were taken and recorded in those two years.
One of the most famous videos of the spillway at the Monticello Dam shows a duck being sucked into it during the 2019 event. Many people have wondered if the duck is still alive?
A duck drifted into the mouth of a spillway at Lake Berryessa in 2019
Rick Fowler, who filmed the video that year, said: “The duck is definitely alive. I ran right to the other end to see if he could get out and what would happen.
Finally, I saw that the duck had been blown out like a torn doll. I thought it must be dead, but it’s not. After a minute or two, the duck took off and landed in a calmer body of water downstream. It gently shakes people.”
Many people also wonder if anyone has fallen through this spillway or not? In fact, Lake Berryessa has banned swimming and boating around this spillway. But it seems that the ban was only enacted after an unfortunate accident in 1997.
The victim was Emily Schwalek, a 41-year-old woman living in Davis City. It was a Sunday afternoon in 1997, when Schwalek was swimming near the mouth of the spillway when he was sucked in by its current.
Despite trying to grab hold of the concrete edge of the dam door and stay there for 20 minutes, the rescue team called in could not reach and save Schwalek. She lost her strength and fell down.
It took several hours for Schwalek’s body to be found.
After this unfortunate accident, the spillway area at Lake Berryessa was fenced off. Swimming there is also strictly prohibited. Instead, visitors can only observe it from above.
Since then, local authorities have not recorded any more accidents that cause damage to people related to the spillway here.
However, every year in the rainy season, security activities in this area are still tightened, because often thousands of tourists flock there to pray for the rain to continue, to witness firsthand the majestic scenery when it rains. The overflow door comes into operation.
Synthetic
at Blogtuan.info – Source: Soha.vn – Read the original article here
