Watching the river, 3/18/10
in Earth and Space Science, Physical Science, The Water Cycle, Weather and Climate, and Forces of Nature
If you're visiting the Science Museum of Minnesota, look out the windows from the Mississippi River Gallery on level 5. If you're in downtown St. Paul, stop by the museum and look at the river from the overlook on Kellogg Plaza. (City officials are asking folks not to flock to areas where barriers are going up - especially Harriet Island - but the view from in or around the museum is spectacular and safe.)
Kate's photos, 3/18 (3): Looks peaceful, doesn't it? Still, the city is warning people to stay off of the river, out of the low-lying parks, and away from Harriet Island and Water Street.
Courtesy Kate Hintz
The Mississippi is going up FAST today, and forecasters expect that the river will officially reach "flood stage" by early this afternoon. (It's 10:45am, and the river's at 11.67'. It's risen a foot and a half in the last 24 hours, should reach 12' ("action stage") pretty soon, and 14' ("flood stage") by late today.
Kate's photos, 3/18 (2): Look across the river to the floodwall: that's the high-water mark for the 1965 flood, the highest in recorded history. That year, the river crested here in downtown St. Paul at 26.01' and marked the end for the communities then down on the river flats.
Courtesy Kate Hintz
Kate's photos, 3/18 (1): Shepard/Warner roads will close from Chestnut Street to US 61 starting Saturday morning, and could remain closed for weeks. Take your river sightseeing drive/bike ride/walk before then!
Courtesy Kate Hintz
So what's going on around the river?
- The city has closed all city boat launches and temporarily banned all recreational boating within the city limits.
- Water Street will be entirely closed, starting this afternoon.
- Hidden Falls and Lilydale regional parks are closed.
- Flood barriers are going up at the St. Paul downtown airport and at Harriet Island.
- Harriet Island will close once the river reaches 17'.
- Warner/Shepard Roads will be closed from Chestnut Street to US 61 starting Saturday morning in preparation for the construction of a temporary levee that could withstand river levels to 26'. These roads could be closed for weeks, depending on the extent of the flooding.
Here's the latest hydrology graph:
3/18 hydrology graph, 10:15am
Courtesy USGS
Tags : High and fast
in Earth and Space Science, Math, The Water Cycle, Weather and Climate, and Forces of Nature
Look out the window or walk down the street to nearly any river or stream in Minnesota right now and you are likely to observe two things about the river:
- it is getting deeper (or “rising” in relation to the banks); and
- it appears to be moving faster.
You can, of course, confirm these observations by investigating reports from gauging stations along these rivers, maintained by the U.S. Geological Survey. (See data for the gauging station serving downtown St. Paul.) But what is really happening?
It may be high and fast...: ...but (as of today) the Mississippi at St. Paul is still in a bankfull state.
Courtesy Liza Pryor
Until a river flows over its banks, it is considered to be in a “bankfull” state. In this state, the water flowing through the river is confined to a relatively fixed channel area. Simply put, floods occur because more water is being introduced into this channel from upstream, due to snowmelt, heavy rains, or a dam breach. As this added volume of water moves through a fixed area, it both increases in velocity and in depth until it overflows the banks, at which point some, but not necessarily a lot, of the volume and velocity moving through the channel are reduced.
Scientists call the rate of flow through a channel “discharge." Discharge is defined as the volume of water passing through a given cross-section of the river channel within a specified period of time.A simple equation for determining discharge is
Q = D x W x V
where Q = discharge, D = channel depth, W = channel width and V = velocity.
Looking at this equation, it is easy to see that if discharge becomes greater and channel width is fixed, then an increase in both volume and depth (or height relative to the banks) is likely to be the cause. Discharge can be measured in cubic feet per second or cubic meters per second, for example.
But is the river flowing at the same rate at the surface as it does along its banks and beds? Understanding this requires investigating some more detailed equations, as the banks and bed introduce friction, which affects the rate of flow.
To learn more about rivers and how they flow, you may want to check out the works of Luna Leopold, and M. Gordon Wolman. In particular:
- Leopold, Luna B. (2006, reprint). A View of the River. Harvard University Press; and
- Leopold, Luna B.; Wolman, M. Gordon; and Miller, John P. (1995). Fluvial Processes in Geomorphology. Dover Publications, both classics for understanding how rivers work.
Also, check out our full feature on the 2010 Mississippi River flooding.
As of 11:19am, the US Geological Survey is forecasting that the Mississippi River will crest here in downtown St. Paul at 18 feet.
New flood crest prediction, 3/17
Courtesy USGS
That would put Water Street and the lower section of Lilydale Regional Park underwater (at 14'), require secondary flood walls at the St. Paul Downtown Airport (17'), submerge much of Harriet Island (17.5'), and make Warner Road impassable due to high water.
An 18-foot crest would also make this year's flood #9, historically speaking, bumping the flood of 1986 (16.10') off the top-10 list.
Also, check out our full feature on the 2010 Mississippi River flooding.
Watching the river, 3/16/10
in Earth and Space Science, Physical Science, The Water Cycle, Weather and Climate, and Forces of Nature
All day, up in the Mississippi River Gallery, people have been stopping to look out the window and watch the river.
Here's how the US Geological Survey sees it:
Mississippi River, actual vs. forecast, 3/16/10, 1pm
Courtesy USGS
The river's rising, but not as fast as yesterday. And yesterday's rise outpaced predictions by almost a foot, but today the rise matches the predicted curve almost exactly.
So what are folks seeing out the window? Take a look.
Also check out our full feature on the 2010 Mississippi River flooding.
Watch the steps: They're a good benchmark.
Courtesy Liza Pryor
Raspberry Island: Still high and dry
Courtesy Liza Pryor
Looking upstream: You're still looking at Harriet Island. But low-lying areas of Lilydale (upstream, south side of the river) get inundated when the river reaches 14 feet or so. Right now, that's predicted to happen sometime after 7pm on Sunday, 3/21.
Courtesy Liza Pryor
Photon computing
Diamond nanowires emit photons: A Harvard-based team has manufactured a matrix of diamond nanowires with defects called nitrogen vacancies. When stimulated with green light, these defects emit one red photon at a time. Such a construct is promising for the new field of quantum computing
Courtesy Zina Deretsky, NSF
Most computers and communications rely upon controlling the flow of electrons. Such devices would be faster and more secure if they used particles of light (photons).
A research team led by Marko Loncar just published how a "diamond nanowire device acts as a nanoscale antenna that funnels the emission of single photons from the embedded color center into a microscope lens."
"This exciting result is the first time the tools of nanofabrication have been applied to diamond crystals in order to control the optical properties of a single defect," said Loncar.
Faster and more secure
Not only is communicating through optical fibers more efficient, there is no easy way for eavesdroppers to "tap the line".
"The resulting device may prove easy to couple into a standard optical fiber. This novel approach is a key technological step towards achieving fast, secure computing and communication." nsf.gov/news
Learn more about diamond-based nanowire devices
Digging deep into diamonds Harvard Gazette
Science Friday logo
Courtesy Science FridayIt's Friday, so it's time for a new Science Friday video. This week,
"What is the future of sustainable architecture? Washington University's Tyson Living Learning Center in Eureka, MO, achieves the Living Building Challenge--a set of green guidelines that measure a building based on its performance. The building's architect Dan Hellmuth, of Hellmuth & Bicknese Architects in St. Louis, and Kevin Smith, associate director of Tyson Research Center, point out some of the Center's greenest features."
RHIC collision of gold ions: The tracks indicate the paths taken by thousands of subatomic particles produced in the gold ion collisions at RHIC.
Courtesy Argonne National Laboratory A heavy isotope of antihydrogen was created at the Relativistic Heavy Ion Collider (RHIC) on Long Island, New York. This antihydrogen isotope was heavier than the previous antimatter record-holder, antihelium. I say "was", because it only lasted a few hundred trillionths of a second.
Super smash-up
To make the antimatter, physicists smashed two gold nuclei against each other with enormous energies. The data resulting from the collision "literally looked like haystacks". Sophisticated software was used to make sense out of the debris and pick out the new antimatter.
To form the new antihydrogen isotope, first an antistrange quark binds with an antiup and antidown quark to make an antilambda -- an antineutron-like particle. The antilambda, which is fractionally heavier than a neutron, must then combine with a conventional antineutron and an antiproton. The chances of this happening are very slim: out of 100 million collisions, RHIC generated just 70 of the new antihydrogen isotopes.
Why?
Studying the properties of antinuclei such as these might help physicists study the primordial form of matter that existed in the universe shortly after the Big Bang and why the Universe is full of matter rather than antimatter.
Source article
Heavy antimatter created in gold collisions Scientific American
Chilean quake sped up Earth's rotation, tipped planet's axis
Earth spins faster
Courtesy NASA If you read the post about how earthquakes differ, you would know that in the Chile earthquake, a large amount of the Earth's crust plunged under its neighboring crust, bringing it closer to the center of the earth.
Just as Olympic figure skaters spin faster when their arms move closer to their body, the Earth is now spinning faster making our day about 1.26 microseconds shorter than it was before the quake.
Earth was also slightly tipped off balance, like when a spinning skater brings in one arm but not the other. The planet's axis tilted about 8 centimeters. This is insignificant compared to other wobbles measuring several meters resulting from winds and ocean currents.
So you want to jam like a rock star, but you don't want to shell out for an electric guitar? Make one yourself. Sound artist Ranjit Bhatnagar explains the art of a DIY instrument he calls a "junk guitar." You can piece one together using little more than a plank of wood, some wire, a magnet and a guitar string. Forget the air guitar solos. Plug in. Rock out.
To see more videos, visit the Science Friday website.
Waves
Courtesy skittzitilbyThree unusually large waves crashed into a Mediterranean cruise ship traveling between Barcelona, Spain and Genoa, Italy killing two passengers. Witnesses say the 26-foot waves smashed windows on the front of the ship. By freak wave standards these weren't by any means the largest (see Thor's huge wave post from a few years ago), but they were large enough to do damage. Rogue waves aren't uncommon, and sailing lore often mentions the "Three Sisters", abnormally large waves that come in sets of threes among smaller waves, like these recent ones did. This NOAA webpage attributes these kinds of freakish waves to storms and high winds, but is it possible these abnormal killer waves were generated by the recent earthquake in Chile? Just a thought.
SOURCE
BBC story
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