flood

The latest edition of the USGS Corecast has been posted today and features a video of the Glen Canyon Dam High Flow experiment. There is some impressive footage and it’s a well put together video. Check it out. (Warning: Link goes to Quicktime Movie)

Dr. Robert E. Criss, a professor of earth and planetary sciences at Washington University in St. Louis, says that patterns from this winter’s storms are eerily similar to those that preceded the Great Flood of 1993 in the Midwest. The Great Flood of 1993 was responsible for $20 billion in economic losses and destroyed 50,000 homes.

Parallels this year include abnormally high levels of precipitation in late winter and early spring and early flooding in various regions, such as the floods of late March in Missouri, Arkansas and Illinois and the Ohio River watershed. An unknown factor is the effect of the snow melt – Wisconsin, for instance, had record amounts of snow this winter – on river systems this spring and summer.

Despite the similarity in conditions, and periods of flooding nearly every year after those flood years more than a decade ago, one thing Midwesterners have not learned is “geologic reality.”

Criss’ arguments come across as harsh, but he raises completely valid points against development in floodplains and the consequences of levee systems.

[Via Eurekalert]

Preliminary analysis indicates that last week’s manmade flood of the Grand Canyon was a success. The three day flood redistributed sediment in the canyon, modifying old sand bars and creating many new ones as well (some of which are the size of football fields).

From the article:

During the flood, flows in the Grand Canyon increased to 41,000 cubic feet per second for nearly three days - four to five times the normal amount of water released from the Glen Canyon Dam. Water levels along the river rose between 2 and 15 feet and left sediment behind when the four giant steel tubes releasing the water from the dam were closed.

Officials released similar manmade floods into the canyon in 1996 and in 2004.

But those floods actually resulted in a net reduction in overall sandbar size because they were conducted when the Colorado River was relatively sand-depleted, according to the U.S. Geological Survey. Officials believe this year’s flood will be beneficial because sand levels in the river are at a 10-year high and are three times greater than 2004 levels.

Whatever benefits come from this year’s flood, however, will be eroded within 18 months without additional floods every year to 18 months depending on the amount of sediment available, Martin said.

In its environmental assessment on Glen Canyon Dam releases, the U.S. Bureau of Reclamation calls for no other high-flow releases until after 2012.

The benefits of the flooding are obviously beneficial. It’s a shame they don’t actually have plans to do this every year (probably due to the demands that must be met by the Colorado River Compact).