Oct 07 2013

A Few Good Reads (10/7/13): Flooding in Southeast Asia continues, Aftermath of the Inundation in Colorado

This week: An update on the flooding in Southeast Asia, dealing with the St. Vrain’s new pathway in and around Longmont in Colorado, the safety hazards that remain from flood waters in Colorado, lessons that can be learned from the Colorado floods, Lake Powell rises 2 feet in September, and an amazing map of every river in the United States.

Scores of children among dead in South-East Asia flooding: officials (ABC)

In Cambodia, the death toll from floods since mid-September stood at 83 on Monday, nearly half of them children, according to the National Disaster Management Committee.

More than 10,000 families have been evacuated, while hundreds of schools and dozens of homes have been flooded.

Heavy rain and strong wind also uprooted a 30-metre tree and sent it crashing into the ancient Preah Khan temple in the country’s famed Angkor complex in the north-eastern Siem Reap province on Friday.

Bangkok residents warned over high tide (The Nation)

The first high-tide period in this month starts today and will run until tomorrow.

The second period will run from October 16 to October 22.

Sunsern said the water level in the Chao Phraya River might rise to 2.8 metres above mean sea level in communities without flood barriers. As of press time, the water level was 1.72 metres above the mean sea level.

Most communities along the Chao Phraya River’s stretch in Bangkok have the protection of flood barriers. The construction of the structures, however, has not taken place in some areas in the face of opposition from residents. According to Sunsern, the water situation for Bangkok overall is not worrying.

Big Thompson River overbank area

Flooding safety hazards remain even after water recedes (Julesburg Advocate)

The Northeast Colorado Health Department would like to remind everyone that receding flood waters don’t take all the danger with them. "Even though many residents may not have been directly affected by major flooding, there are still many lingering health and safety issues that all residents need to be aware of as we continue to clean-up and recover from this disaster," said Dr. Tony Cappello, NCHD’s public health director. Puddles, rivers and streams: While these may look like fun to play in, after a flood they can be deeper than they look and can be dangerous. In addition, flood waters should be considered contaminated, this water is not safe to be in at this time without proper protective equipment.

Longmont, feds ponder whether to restore St. Vrain’s course or let the river run (Longmont Times-Call)

FEMA already has said it will look at the river section by section when deciding which restoration plans should get funding. The Corps, meanwhile, is in talks with Longmont to decide which pieces of the river truly need to be restored. Rivers do move, after all.

"If we think we can get the river back into its channel with a reasonable amount of effort, and the Corps says it makes sense, we’ll do that," Rademacher said. "If the Corps says ‘Sorry, folks, that looks like a reasonably safe channel,’ we’ll start planning around that, too."

A week after the flooding surge had ended, areas adjacent to St. Vrain Creek between Lyons and Platteville remained under water. Photo on Sept. 21/Allen Best

What lessons can be gleaned from this Biblical deluge in Colorado? (Mountain Town News) (HT: Coyote Gulch)

But what lessons should be drawn from this rain and flooding along Colorado’s Front Range. The most notable takeaway is that even if this is a 1,000-year rainfall event in certain places, a conclusion not accepted by all meteorologists, the flooding was far less. In Boulder, it fell within the framework of a 50-year flood, maybe less. The flooding of St. Vrain Creek, which so heavily damaged Lyons and Longmont, may have been something approaching a 100-year event.

One note: a 100-year-flood doesn’t mean that you have to wait 100 years to have a flood of that size. That’s just the percentage chance on any given year of having a flood of that dimension. You can have two 100-year floods back to back.

In other words, the “big one” is yet to come.

Drought news: Lake Powell pool elevation rises two feet in September (Coyote Gulch)

Page, located above Glen Canyon Dam at the lake’s southern end, received 2.73 inches of rain in September, more than three times its monthly average. The 4.21 inches that Page had in August and September amounted to half of its annual average precipitation.

Further north, and in the Colorado River Basin that drains into the lake, the Animas River at Cedar Hill in New Mexico was resembling spring conditions by Sept. 22. The river topped 3,000 cubic feet per second (cfs), a faster rate than the peak of the spring runoff. The river’s normal flow rate for this time of year is 300 to 400 cfs, according to Friends of Lake Powell’s Paul Ostapuk.

Infographic: An Astounding Map of Every River in America (Wired)

To create All Rivers, first Minar gathered information from NHDPlus (National Hydrography Dataset) and put it in a database. He extracted the Strahler number, a measure of how significant a creek is, to determine how large the rivers would appear on the map. From there he built a web server that would allow him to serve the flowline data as vector map tiles, and finally he wrote a JavaScript program that did most of the cartography work for him.

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