The Earth Story

Taum Sauk Mountain These photos come from Taum Sauk Mountain; found in the southeastern portion of the state of Missouri and reaching an elevation of 540 meters, this is the highest elevation in that state.

The Morning Glory Spillway

The Morning Glory spillway at Lake Berryessa, California - the spillway is flowing for the first time in years this year, and is back to looking like someone divided by 0.

Lake Oroville Dam Emergency

Edit2: Per press reports, by using low flows at the main spillway combined with the flow at the emergency spillway, they have dropped the lake level enough to limit overflow and headward erosion at the Emergency Spillway. They are hoping they will have a few days to drop sandbags and extra material into the emergency spillway to shore it up over the next few days, but I think these posts have made it clear how unpredictable this situation is right now.

Edit/Update: In the last hour the authorities in California have issued a warning for evacuations due to more erosion than expected on the emergency spillway. They expect it to begin failing within the hour. That will not lead to a full, uncontrolled release from the reservoir yet, but this situation is now much riskier. http://www.kcra.com/article/evacuation-orders-issued-for-low-levels-of-oroville/8735215

Lake Oroville in California is the tallest earthen dam in the United States and the second largest water reservoir in the state of California. It holds back the flow of the Feather River on its way to the Sacramento-San Joaquin Delta, and both stores water that is supplied around the state for agriculture and also helps limit floods in that part of the delta.

Dams do not do well when they are overtopped. If water levels rise above a concrete dam, the water flowing over the dam will form a waterfall that eats away at the concrete at the base. An earthen dam like Oroville is at even greater risk of erosion since it is not cemented together.

To prevent collapse of the dam, there are two major flood control measures at the dam. A concrete lined spillway sits at an elevation several meters below the top of the dam and it carries overflow down to the river below. To the left of that spillway sits a tree-lined slope that also has its peak at elevations below the top of the dam, so that it would be overtopped before the dam itself would be. The main spillway was built to prevent any overtopping of the dam, and the emergency spillway could be activated in the event of a failure of the main spillway. California’s Department of Water Resources was hesitant to use the emergency spillway as flooding over it was expected to dislodge trees that would have to flow downstream and could cause damage there.

California has been in a drought for years, but the 2016-2017 winter has been one of the rainiest on record. This both broke the drought and topped off Lake Oroville, causing use of the main spillway. Early last week, the concrete lined spillway failed. Water somehow got beneath the concrete, the concrete collapsed, and continuing water flow began digging a crater in the middle of the spillway. The more water flows over the spillway, the more it will eat away at the wall, potentially threatening the integrity of the dam. Drone video of the spillway after the initial damage can be seen here: https://www.youtube.com/watch?v=n1eLcSQPS8Q

Due to continued inflow of water from recent rains, on Saturday the DWR activated the emergency spillway, sending a plume of mud and trees down the river below. Drone video of the emergency spillway during and after its use is available here: https://www.youtube.com/watch?v=fA52L0eabNo.

At present, there is no expected permanent threat to the dam, but it will also take months and likely tens of millions of dollars to stabilize and reconstruct the concrete spillway before it can be safely used again. However, it’s uncertain how this situation will develop as the California rainy season continues, and the pictures and video of this engineering breakdown are dramatic. This event shows what can happen when water begins leaching around a dam; rapid erosion of loose ground. In this case, the emergency setup is currently able to handle the overflow for now, but this is also a lesson in the importance of maintaining and upgrading infrastructure. Eventually, concrete does fail, and costs do appear to keep systems operating.

-JBB

Image credits: California DWR https://twitter.com/CA_DWR http://bit.ly/2lFsIXb - SacBee

Oroville dam: https://www.parks.ca.gov/?page_id=462

Flooded land next to the Morganza Spillway in Louisiana. This spillway can be opened to relieve floods on the MIssissippi River - it diverts the water during floods to keep it from entering Baton Rouge and New Orleans downstream. 

THE MORNING GLORY SPILLWAY, AKA "THE GLORY HOLE".

The Monticello Dam holds back Lake Berryessa in Napa County, California, USA. The morning glory spillway associated with the dam is the largest in the world; it is a funnel-shaped outlet that allows water to bypass the Monticello Dam when it reaches capacity (1370 m³/s).

The Glory Hole is located about 61m from the dam; the distance from the funnel to the exit point - which is situated in the south side of the canyon - is about 213m. The outside diameter is 22m, slowly narrowing to 8.5m at the exit.

Water spills over the lip of the Glory Hole when the lake reaches 1,976,037,908 cubic metres (1,602,000 acre-feet). The spillway is designed to handle a maximum of 1,370,319 litres of water per second (362,000 gallons of water per second); this happens when the lake level rises to 4.7 metres (15.5 feet) above the level of the funnel.

Swimming near the glory hole is prohibited. Unfortunately in 1997 a UC Davis graduate student was pulled into the glory hole while swimming and drowned. Skateboarders and bikers sometimes use the spillway's horizontal exit as a half-pipe during the drier months, when the water levels are well below the rim of the glory hole. Due to the current drought in California, this site doesn’t look nearly as cool.

You can watch a video here of bikers using the tunnel: http://bit.ly/GXtpjR Video of the Morning Glory Spillway in action: http://bit.ly/1jmAYh

-TEL

http://daviswiki.org/Morning_Glory_Spillway, http://www.fogonazos.es/2007/02/largest-drain-hole-ever.html Image from Panoramio is by Auggee http://www.panoramio.com/photo/10262321

STAR-SHAPED SPILLWAY, ARMENIA Spillways, known in the UK as overflow channels, are structures that provide controlled release of flows from a dam or levee into an area downstream. They release floods so that water does not overtop and damage the dam; water does not usually flow over a spillway unless there is a flood. Typically spillways are round; this star-shaped one is found at the Kechut Reservoir near Jermuk in Armenia.  Unfortunately this glory hole for the Kachut Dam has inadequate capacity. The space available for a new spillway, between the dam and a water supply tunnel, is too limited to provide the capacity needed for a normal ungated spillway. The Armenian State Committee of Water Systems is looking to address this problem with the use of fuse gates. This construction is part of the country’s Dam Safety Project, a World Bank financed, nation-wide program for improving the safety of existing dams. You can view a video of the spillway here: http://www.youtube.com/watch?v=8zWqJ5rrguc -TEL http://twistedsifter.com/2012/06/picture-of-the-day-star-shaped-spillway-in-armenia/ http://www.civilica.com/Printable-SUADE01_018.html Image credit: unbdaveable on Flickr http://www.flickr.com/photos/unbdaveable/6156678754/in/photostream

Is this the result of dividing by zero? Nope - this is the Morning Glory Spillway, also known as "The Glory Hole".

This Spillway, the largest in the world, is the funnel-shaped outlet that allows water to bypass the Monticello Dam in California when it reaches capacity (1370 m³/s). The Glory Hole is located about 61m from the dam; the distance from the funnel to the exit point - which is situated in the south side of the canyon - is about 213m. The outside diameter is 22m, slowly narrowing to 8.5m at the exit. -TEL http://daviswiki.org/Morning_Glory_Spillway,http://www.fogonazos.es/2007/02/largest-drain-hole-ever.html

Is this the result of dividing by zero?

Nope - this is the Morning Glory Spillway, also known as "The Glory Hole". This Spillway, the largest in the world, is the funnel-shaped outlet that allows water to bypass the Monticello Dam in California when it reaches capacity (1370 m³/s). The Glory Hole is located about 61m from the dam; the distance from the funnel to the exit point - which is situated in the south side of the canyon - is about 213m. The outside diameter is 22m, slowly narrowing to 8.5m at the exit. -TEL http://daviswiki.org/Morning_Glory_Spillway, http://www.fogonazos.es/2007/02/largest-drain-hole-ever.html