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March Meanderings

Cross-posted at Highly Allochthonous

It all began at the end of February, when I travelled to La Crosse, Wisconsin to the Upper Midwest Stream Restoration Symposium, which was a really stimulating and vital mix of academics, consultants, and government folks all interested in improving the state of the science and practice of stream restoration. I gave a talk on Evaluating the success of urban stream restoration in an ecosystem services context, which was my first time talking about some hot-off-the-presses UNCC graduate student research, and I learned a lot from the other speakers and poster presenters. While the conference was incredibly stimulating, travel delays due to bad weather on both ends of my trip made for a somewhat grumpy Anne (nobody really wants to spend their birthday stuck in a blizzard in O’Hare), so I’ll be thinking carefully about how to plan my travel to the Upper Midwest during future winters. Nonetheless, the view from the conference venue was phenomenal.

icy river and snowy land

View of the Mississippi River from the Upper Midwest Stream Restoration Symposium in La Crosse, WI. Not shown: bald eagles that frequent the open water patches of the river.

March proper saw me give variations of the restoration talk two other times. On the 15th, I gave it as the seminar for Kent State’s Biological Sciences department, and on the 26th, I gave it at the North Dakota State University Department of Geosciences (more about that trip below). In between, I gave a seminar on the co-evolution of hydrology and topography to the Geology Department at Denison University in Granville, Ohio. Students in that department had just returned from a trip to Hawaii, and a very memorable dialogue occured in the midst of me talking about the High Cascades:

“You’ve seen a young lava flow. What would happen if you poured a bottle of water on it?” “It would steam!” “Not that young!”

Closer to home I also hosted a couple of prospective graduate students, helped interview candidates for a faculty position in our department, and went with a colleague to visit an acid mine drainage site about an hour to the south of Kent. In one fairly small watershed, we were able to tour a number of different remediated and unremediated sites, and it certainly lent a whole different perspective to the ideas of stream restoration and constructed wetlands to look at a landscape irrevocably scarred by mining activities.

Orange water flowing from a tube down a hill and into a stream.

Unremediated acid mine drainage flow directly into Huff Run. The orange is iron precipitate.

Wetland plants and a concrete inlet weir.

Constructed wetland as the second stage of acid mine drainage remediation in the Huff Run watershed.

At the end of the month, we finally got our turn for spring break. I ended up with a somewhat epic combination of mounds of work and a big trip to take, possibly the worst combination of the untenured and tenured professor spring break stereotypes (see this PhD comics strip). The first half of the week, I spent in Fargo, North Dakota, home to the famously flood-prone Red River of the North. (I’ve blogged before about why the river so often produces expansive floods.) It was truly fascinating to put my feet on the ground in a place that I’ve read about and watched from afar for years. And my visit was made all the more interesting by my host and guide, Dr. Stephanie Day, a geomorphologist newly at NDSU and who may well unravel some of the Red’s geomorphological peculiarities.

Scientist in foreground, river in midground, background = flat, snowcovered ground.

Stephanie Day, Assistant Professor of Geosciences at North Dakota State University beside the Red River in Moorhead Minnesota. The flat surface in the background is the approximate elevation of the land for miles around.

Looking towards downtown Fargo, ND from the river side of the levee.

Looking towards downtown Fargo, ND from the river side of the levee.

snow and ice covered river, not in much of a valley.

River’s edge view looking towards downtown Fargo. Snow well over knee deep here on 25 March, by my measurements. As all that snow starts to melt, the water will rise.

There’s a pretty good chance we’ll see a major flood on the Red River later this spring, as the >24″ of snow melts out of the watershed, runs off over frozen ground, and enters the northward flowing river. The Fargo Flood page is the place to go to follow the action, and you can count on updates (and more pictures) here as events unfold.

The latter half of my spring break saw me diagonal across the state of Minnesota to my beloved Driftless Area, back across the Mississippi River, and into the state of Wisconsin. I saw my family, finished paper revisions, and wrote part of a grant proposal. Then I flew home, with nary a weather delay in sight.

If March was a tight, recursive meander of talks and trips to the Upper Midwest, then April promises to be a bit anastomosing with lots of different threads woven together to make another month of scientific delight.

The Great Flood of 1913

The 100th anniversary of Ohio’s greatest disaster is just days away. This epic hydro-meteorological event utterly ravaged river towns from Illinois to Ohio and beyond, but it seems like the event has largely been forgotten in history’s annals. Even flood-obsessed me had lived in Ohio for a few months before I even began to piece together the full extent of the disaster. For a crash course in the events of March 23rd-27th, 1913, navigate through this Prezi:

If you want to know more, there’s lots of details at the Silver Jackets’ 1913 Flood website and you can follow along as historian Trudy Bell researches a book on the flood.

EGU Abstract: Potential impact of lava flows on regional water supplies: case study of central Oregon Cascades volcanism and the Willamette Valley, USA

This abstract was just submitted to the European Geosciences Union meeting for a session on “NH9.9. Natural hazard impact on technological systems and urban areas.” I won’t get to go to Vienna in April, but at least a little bit of my science will. Thanks to Natalia for finding a graceful way to integrate our work.

Potential impact of lava flows on regional water supplies: case study of central Oregon Cascades volcanism and the Willamette Valley, USA

Natalia I. Deligne, Katharine V. Cashman, Gordon E. Grant, Anne Jefferson

Lava flows are often considered to be natural hazards with localized bimodal impact – they completely destroy everything in their path, but apart from the occasional forest fire, cause little or no damage outside their immediate footprint. However, in certain settings, lava flows can have surprising far reaching impacts with the potential to cause serious problems in distant urban areas. Here we present results from a study of the interaction between lava flows and surface water in the central Oregon Cascades, USA, where we find that lava flows in the High Cascades have the potential to cause considerable water shortages in Eugene, Oregon (Oregon’s second largest metropolitan area) and the greater Willamette Valley (home to ~70% of Oregon’s population). The High Cascades host a groundwater dominated hydrological regime with water residence times on the order of years. Due to the steady output of groundwater, rivers sourced in the High Cascades are a critical water resource for Oregon, particularly in August and September when it has not rained for several months. One such river, the McKenzie River, is the sole source of drinking water for Eugene, Oregon, and prior to the installation of dams in the 1960s accounted for ~40% of river flow in the Willamette River in Portland, 445 river km downstream of the source of the McKenzie River. The McKenzie River has been dammed at least twice by lava flows during the Holocene; depending the time of year that these eruptions occurred, we project that available water would have decreased by 20% in present-day Eugene, Oregon, for days to weeks at a time. Given the importance of the McKenzie River and its location on the margin of an active volcanic area, we expect that future volcanic eruptions could likewise impact water supplies in Eugene and the greater Willamette Valley. As such, the urban center of Eugene, Oregon, and also the greater Willamette Valley, is vulnerable to the most benign of volcanic hazards, lava flows, located over 100 km away.

Storm Comin’

Cross-posted at Highly Allochthonous

If you live in the eastern 1/3 of the US and you haven’t started paying attention to Hurricane Sandy, today is THE day. This odd late-season storm is going to hit the northeastern and mid-Atlantic coast hard, having already stormed across the Caribbean, killing at least 48 people.

5-10 storm surge predicted by Accuweather

Accuweather map of predicted storm surges along the east coast. Click image for source. Note: I had a hard time finding both a detailed and quantitative map of predicted surges. If anyone knows of a better map, please let me know in the comments.

Much like we saw with Isaac earlier this year, the damage in slow-moving and relatively weak hurricanes (Sandy is a Category 1 currently) comes from all of the water in inland flooding and from the storm surge along the coast. When Sandy hits shore someplace between Delaware and New York City on Monday night, the storm surge is expected to be especially fearsome. As Ben Strauss at Climate Central explains:

  1. Sandy is projected to create tall storm surges, due to an enormous wind field influencing wide areas of ocean.
  2. The surge may be prolonged, due to the storm’s large size and slow movement. This means many areas will experience surge combined with at least one high tide.
  3. With a full moon near, tides are running high to begin with.
  4. Rivers swollen by significant rainfall may compound tides and surge locally.
  5. Sea level rise over the past century has raised the launch pad for storms and tides to begin with, by more than a foot across most of the Mid-Atlantic. Sinking land has driven part of this rise, but global warming, which melts glaciers and expands ocean water by heating it, appears to be the dominant factor across much of the region.

In Sandy’s path, as with Irene last year, lies the densely populated east coast. Which is why knowledgeable people are now talking about Sandy as likely to be a multi-billion dollar disaster. Jeff Masters of Weather Underground estimates that there could be as much as a billion dollars of wind damages and associated power losses, with flooding costing another billion in losses, and if the New York City transit system floods losses could run into the tens of billions.

Deeply dipping jet stream, high pressure off of NE Canada and Hurricane Sandy

Credit: Remik Ziemlinski, Climate Central. Click image for source.

And all of that is just the hurricane. Added on top of that is the potential convergence of the hurricane with a very deep upper-level trough over the central U.S. and unusually strong high-latitude blocking. Blocking occurs when a high pressure dome stays in the same place for several days or longer, blocking eastern flow of the polar jet stream, producing “seemingly endless stretches” of the same weather, and pushing storms far off their usual tracks. As explained by Will Komaromi of the Rosenstiel School of Marine and Atmospheric Science at the University of Miami:

“Normally a hurricane weakens as it moves northward, as it encounters an increasingly unfavorable environment. This means greater wind shear, drier air, and lower sea surface temperatures. However, with phasing [convergence] events, the tropical system merges with the mid-latitude system in such a way that baroclinic instability (arising from sharp air temperature/density gradients) and extremely divergent air at the upper-levels more than compensates for a decreasingly favorable environment for tropical systems.”

Komaromi goes on to explain that the Atlantic Gulf Stream is unusually warm for this time of year, allowing Sandy to remain stronger than it might have while out to see. Also, the extra strong blocking over the North Atlantic will mean that the hurricane moves very slowly and the storm will track farther west over the US rather than curving out to the mid-ocean. Komaromi shows that this is extremely similar to the 1991 “Perfect Storm”, subject of the book and movie of the same name.

The fallout of all this meteorological fury is likely to be felt both at the coast and far inland. The quantitative precipitation forecast for NOAA for the next five days shows eight states with areas expected to receive more than 4 inches (101 mm) of precipitation. Far more unusual than lots of rain is the possibility that Sandy will be a “snow-i-cane” dumping up to 12 inches (304 mm) of snow in the mountains of Virginia and West Virginia, and possibly into Tennessee and North Carolina. With leaves still on the trees in southern and coastal regions, the wind, rain, and snow will play havoc with above ground power lines. Widespread power outages are considered likely all the way into western Pennsylvania, New York, and West Virginia. Even in Ohio, my area is considered in the “possible” zone for power failures.

highest precip in the Delmarva Peninsula and whole map covered with ~2 inches or more

NOAA’s Hydrometeorological Prediction Service quantitative precipitation forecast for the next 5 days. Click image for more information.

In addition to watching the weather and taking the necessary steps to prepare ourselves for whatever blows our way, a small group of scientists will be collecting precipitation samples for isotopic analyses by Gabe Bowen’s group at the University of Utah. If you live in the area affected by Sandy and want to help collect precipitation, look for more information here. I’ve already gotten 1.2 inches (30 mm) of rain since yesterday afternoon, and we’re not even seeing the storm effects yet. I’m likely to get another 4 inches (100 mm) by Thursday.

A somewhat larger group of geoscientists will be working on their posters and talks while hoping to avoid power outages and travel delays that could scuttle plans to attend the Geological Society of America meeting in Charlotte, North Carolina. Charlotte is not at all in the storm’s path, so if we can get there, everything should be fine.* I’m hopeful that the freeways will be open through West Virginia by Friday night, when I’ll drive south to convene two sessions, lead a field trip, and present a poster. But I worry for colleagues in the full brunt of the storm and hope that they have both adequate time to prepare for and attend the meeting. I’m also crossing my fingers that virtually all infrastructure is functioning again by Tuesday, November 6th, and that everyone affected by the storm will be able to cast their votes in a very important election.

As I contemplate coming events, I find the song “Storm Comin'” by The Wailing Jennys has been playing in my head almost constantly. I love how it captures the tension and anticipation of a storm rolling towards you across the plains or ocean.** Unfortunately, I wouldn’t recommend following this advice for emergency preparedness, instead you should take a make an emergency kit along the lines of this one and pay attention to watches, warnings, and evacuations in your area. Be safe everyone.


The Wailing Jennys perform their song "Storm Comin'"

*Disclaimer here about being neither a meteorologist nor a disaster recovery expert, so don’t take my word as a guarantee. Also I’m glad I’m not in Italy.

**For me, music is poetry, so consider this my entry from the upcoming Accretionary Wedge carnvial on geo-poetry.

In slow-moving hurricanes, the danger comes from all the water

Cross-posted at Highly Allochthonous When Hurricane Isaac passed over New Orleans as a Category 1 storm on the seventh anniversary of the disastrous Hurricane Katrina, everyone in the US let out a big sigh of relief. A category 1 storm, the lowest level of hurricane intensity on the Saffir-Simpson scale, meant sustained winds in the 74-95 mile per hour (119-153 km/hr) range, which are described as “very dangerous winds [that] will produce some damage.” There were few, if any, mandatory evacuation orders in Louisiana, and the media interviewed people saying that they heard Isaac would be a Category 1 storm so they “didn’t think it would be that bad.” Those people opted to stay in their homes Louisiana’s Plaquemines Parish, along the Mississippi River near New Orleans. Indeed, as the early reports from Louisiana came out, it sounded as if the storm had been relatively low in drama.

Hurricane swirl as Isaac makes landfall in Lousiana contrasts with the bright city lights in the southeastern US

This will be the iconic image of Hurricane Isaac. NASA/NOAA/DoD VIIRS image of the hurricanes clouds superimposed on the city lights on the southeastern US. All those clouds are full of water. Image source: http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=79023

Only later did reports start to trickle out of levees overtopped, and people stranded on rooftops and in attics, being rescued by neighbors with boats. The flooding this time wasn’t in New Orleans itself, but in nearby Plaquemines Parish, where levee upgrades weren’t scheduled to be completed for a few more years. At least one levee overtopped, flooding the town of Braithwaite and surrounding areas where about 1700 people live, with up to 4.3 m (14 ft) of water. That water ended up trapped between the federal, main Mississippi River levee and more locally managed back levees. State officials have now breached those back levees to more quickly drain the water out of the town, rather than slowly pump the area dry. But several people died inside their flooded homes.

Aerial view of flooding in Louisiana Parish

US Coast Guard photo of floodwaters in Plaquemines Parish, Louisiana

It’s not clear to me from the news reports whether the levee overtopped from a wind- and pressure-driven storm surge or whether it overtopped from the sheer amount of rain that fell on the area, but in either case the slow-moving nature of Hurricane Isaac turned out to make the meager Category 1 hurricane into something much more horrific for some Lousiana communities. A reporter on the scene in Braithwaite described the eyewall, with the most intense winds and rain, stalling out in the area, but throughout its life Isaac was a fairly slow moving tropical cyclone. As it moved across Louisiana, its center was moving north about 9 miles per hour (14.5 km/hr). Typical hurricanes move about 15-20 mph (24-32 km/hr), and some can move up to 60 mph (96.5 km/hr).

The problem with a slow-moving hurricane is that vast amount of precipitation can occur in the affected areas. In some parts of Louisiana, Alabama, Mississippi, and Florida more than 15 inches (380 mm) of rain have fallen in the last week. In New Orleans, the Hydrometeorological Prediction Center reports that 20.08 inches (510 mm). In the image below, you can also see the northward progression of the storm since making landfall.

Colorful image of rain in Louisiana, Florida, Arkansas and Missouri as a result of Isaac.

NOAA's Advanced Hydrologic Prediction Service (AHPS) map of rainfall accumulations for the week leading up to September 1, 2012.

All that water can lead to levee over-topping, like in Plaquemines Parish, and the risk of dam failures. Evacuations were ordered along the Tangipahoa River, which drains into Lake Pontchartrain, because of fears that Percy Quin Dam would fail. More than 50,000 people have been evacuated as the risk of dam failure or the need to intentionally breach the dam is still being evaluated. And, of course, while media attention (and this blog post, guilty as charged) focuses on the dramatic stories, there are many other areas in the Gulf Coast where flooding is on-going. Even as far north as Kansas City and southern Illinois, flood warnings are in effect.

Isaac is a good reminder why the primary cause of death in the US from tropical cyclones is from freshwater flooding. And it suggests that the single-minded focus on hurricane windspeeds may distract us from taking the flooding threat as seriously as we should. Those people who decided to stay in Plaquemines Parish because the Category 1 hurricane wouldn’t be that bad? When the interview was conducted, they were expressing their regret. The president-elect of the American Meteorological Society, J. Marshall Shepherd, wrote a blog post about the Lessons from Isaac, in which he suggested: “Is it time to consider an augmentation of the Saffir Simpson scale to capture the rainfall-flood threat? It is a difficult science problem, but probably one worth investigating. I also argue that our media colleagues must consider their coverage strategy and category “anticipation” or hype carefully.”

Flooding around the world (early June edition)

Cross-posted at Highly Allochthonous

Got flood fatigue yet? Too bad, because the wet weather and the high water keeps coming. Here is a quick round up of the notable flood-related news of the week.

High water on the Mississippi River, La Crosse, Wisconsin, 21 April 2011

Front row seats for water levels above flood stage on the Mississippi River, La Crosse, Wisconsin, 21 April 2011

Mississippi River

Floodwall (with emergency height added) in Omaha, Nebraska during the record 1952 floods.

Floodwall (with emergency height added) in Omaha, Nebraska during the record 1952 floods. Will that record be broken this year? (Image from Nebraska DNR.)

Missouri River

Heavy snowpacks in the Missouri River watershed (an areally large, but volumetrically smaller contributor to the Mississippi) have led to near-record flooding that is on-going along its whole length from Montana to Missouri. It’s not getting as much media attention as the Mississippi River, but water levels may stay above flood stage for months. Right now there are heavy rains occurring in parts of the basin, with more rain in the forecast, which will only add to flood problems.

Like the Mississippi, the Missouri is heavily managed by the Corps of Engineers, which is taking some criticism for residents in affected cities. There have also been evacuations because of seepage under levees and concerns about the possibility of failure. Like all big river/developed world flood stories, this one is a complicated mix of huge volumes of water, complicated multi-purpose river management plans, and unwise historical floodplain development.

  • In Historic Flooding On Mississippi River, A Missed Opportunity To Rebuild Louisiana:
    http://www.huffingtonpost.com/2011/06/09/in-historic-flooding-on-m_n_873623.html
  • Flooding from heavy rain in Guizhou province, southwestern China on 6 June 2011 (photo: Xinhua)

    Flooding from heavy rain in Guizhou province, southwestern China on 6 June 2011 (photo: Xinhua)

    China

    For months, China has been stricken by its most intense drought in 60 years, but right now it’s too much, not too little, water that is the problem. Flooding since the 1st of the month has affected East China’s Jiangxi Province and 12 provinces in central and southern China, and more rain is in the forecast for many areas. Intense rains over the last few days have caused the evacuation of more than 100,000 people and killed at least 54.

    Elsewhere

    The Flood Observatory is also reporting on-going flooding in Colombia, the Philippines, Algeria, Haiti and the Dominican Republic, Canada, India, and Upstate New York/Vermont’s Lake Champlain area. In every one of these places, people are losing their homes and lives. While volcanoes and earthquakes shake things up spectacularly now and again, every single day, somewhere in the world, there’s a devastating flood going on.

    Lingering flooding along the Middle Mississippi River and tributaries

    Cross-posted at Highly Allochthonous

    NASA MODIS image of flooding along the Middle Mississippi, 20 May 2011

    Figure 1. NASA MODIS image of flooding along the Middle Mississippi, 20 May 2011.

    One week ago today (28 May 2011), I had the chance to explore the lingering flooding along the Mississippi River and its tributary Big Muddy River in southern Illinois. The area was long past its crest; it is upriver of Cairo and the Birds Point Floodway. Around Carbondale, evidence of the recent high water was still visible in all of the drainages, but the water was back well within the stream banks. Closer to the confluence with the Mississippi though, high water levels on the Mississippi were still forcing backwater flooding of the floodplain and the Big Muddy River.

    Driving and hiking along the escarpment of the LaRue-Pine Research Natural Area afforded expansive views of the flooding – and the remnant landscapes of previous millenia of river activity.

    Foreground: An abandoned channel remains as a wetland. Background: Levees and flooding along the Big Muddy River.

    Figure 2. Foreground: An abandoned channel remains as a wetland. Background: Levees and flooding along the Big Muddy River. (Click for larger version)

    Flooding along the Big Muddy River, 28 May 2011

    Figure 3. Flooding along the Big Muddy River, 28 May 2011 (Click for larger version)

    Once we descended from the hills and onto the floodplain, we were immediately greeted by floodwaters.

    Flooded bottomlands

    Figure 4. Flooded bottomland forest along the Big Muddy River.

    Driving away from the hills towards the Mississippi, our road took us along the top of the levee, giving us close up views of the effects of leveeing, levee repairs, and local wildlife.

    Big Muddy inside the levee

    Figure 5. A barn and fields protected from flooding by the levee on which we drove. (View out the window on the south side of the car.) (This barn is visible in the middle left of Figure 3).

    Big Muddy outside the levee

    Figure 6. The Big Muddy River, in flood, contained by the levee we drove along. (View out the window on the north side of the car, immediately opposite Figure 5.)

    Levee repair along the Big Muddy

    Figure 7. Temporary levee repair along the Big Muddy. The plastic sheeting and sandbags may be covering an area that had cracked or started to erode (click for larger).


    Snapping turtle

    Figure 8. Why did the snapping turtle cross the levee road?

    After crossing the Big Muddy River, we drove along a state highway that was not atop a levee, and only a few feet above flooded fields. Egrets and herons were everywhere in the standing water, and a pleasant breeze whipped up waves on the water. But we were reminded that this scene was normally not so watery…in the image below, you might be able to see a center pivot irrigation line in the field, standing in the flood waters.

    Flooded fields and an irrigation line

    Figure 9. A flooded field, with an irrigation line. Normally, this landscape would not be so blue. (Click for larger)

    Finally we reached the Mississippi itself, in Grand Tower, Illinois. The river was definitely high, but open for business – we watched a tow and barges go by. The town of Grand Tower is situated immediately adjacent to the Mississippi – and protected by a big levee. Near the north end of town, the levee was a few feet lower than the rest, and here a metal floodwall had been constructed atop the levee. There was also evidence that a pumping operation had been set up – to pump water from behind the levee back into the river. Whether this pumping was necessitated by seepage or localized ponding, I couldn’t tell. But here, in a sleepy little town on the Mississippi, the effects of our efforts to keep floodwaters off the floodplain were in full display.

    Pumping set up and a floodwall atop a levee

    Figure 10. A pumping and a floodwall atop a levee (on right side of photo) in Grand Tower, Illinois.


    Mississippi River flooding, Grand Tower, Illinois

    Figure 11. Mississippi River flooding, Grand Tower, Illinois. Looking downstream, with a levee on the left side of the image.

    Anne in the news

    Flooding along the Mississippi River
    Last week, I wrote a post for the Scientific American Guest Blog on “Levees and the Illusion of Flood Control,” about the ways that while levees around individual communities may be good, the systematic leveeing of entire waterways is a bad long-term strategy. On Friday, that post was also featured on the front page of ScientificAmerican.com on their Science Agenda. (I’ll add a screenshot if I can dig it back up.)

    Linkages between climate change and severe weather
    This morning my name may be in your local newspaper, as I’m quoted in an article about how this spring’s severe weather (including flooding along the Mississippi) fits with scientific expectations about climate change. The article was written by the McClatchey syndicate and versions of it may appear in multiple newspapers. For example, here’s the Charlotte Observer’s version of the story.

    Flooding along the Mississippi River

    Cross-posted at Highly Allochthonous

    In case other events have crowded it out of your news feed, there’s record-breaking flooding going on in the Mississippi River basin. Snowmelt in the headwaters, combined with weeks of heavy rains in the middle reaches of the river basin, have pushed the system to its engineered limits. The Mississippi River basin is home to more than 100 million people, and when the water flows past Natchez, it’s carrying flow from 41% of the contiguous United States, making it the third largest river basin in the world. The volume of water carried by the Mississippi River in flood can be measured in the same unit as ocean currents — within the next few days, the Mississippi River at Natchez will be flowing more than 2 Million cubic feet per second.

    Flooding at the junction of the Mississippi and Ohio Rivers, 3 May 2011, NASA image

    Flooding at the junction of the Mississippi and Ohio Rivers, 3 May 2011, NASA image

    Start here

    For hands-down the best analysis on the flooding, the engineering, the politics, and the media coverage of the flooding, you need to turn to Steve Gough’s Riparian Rap blog. Go there now to get caught up. Then when you want some other perspective, check out the links and resources below.

    General information on the flooding

    Floodways doing what they were designed to do

    Edge of the inflow section, Bird's Point floodway. image by the US Army Corps of Engineers

    Edge of the inflow section, Bird's Point floodway. image by the US Army Corps of Engineers


    Early in the week the big Mississippi news story was on the opening of the Bird’s Point Floodway in Missouri. Media reports tended to focus on the sensationalist “us vs. them” people stories, with most of the stories completely missing the fact that the floodway was designed for this purposes and residents in it had known about and been compensated for its existence. Steve Gough had great coverage, including this piece.

    The next big to-do will be over opening the Morganza floodway in Louisiana, expected to happen on Thursday 12 May. So far, the news media seems to be taking a bit more reasonable perspective here, but I expect there will be hysterical stories as well. My two cents: Based on experience with devastating past Mississippi River floods, our national policy has been to design and designate floodways to relieve pressure on levees on the mainstem of the Mississippi River. This means that some people miles from the main river will lose homes and property (and have been compensated for that risk), but it is for the benefit of much larger populations. Further, the areas that lie in floodways are part of the natural floodplain of the Mississippi River, and they would flood much more frequently without the levees.

    More information on Bird’s Point and Morganza floodways can be found below.

    Background Reading

    1927 Mississippi River flooding, image from the Library of Congress

    1927 Mississippi River flooding, image from the Library of Congress


    The best general background information on floods and flood control on the Mississippi River can be found in John M. Barry’s book “Rising Tide: The Great Mississippi River Flood of 1927 and how it Changed America” and John McPhee’s essay on the Old River Control Structure in The Control of Nature, available on-line through The New Yorker.

    Floodwaters rising on the Red River

    Cross posted at Highly Allochthonous

    Fargo, North Dakota is coming out of its 3rd snowiest winter since 1885. Snow continued to fall into late March, and daytime temperatures have only been above freezing for few weeks. At night, it’s still below freezing, though starting tomorrow night the forecast calls for above freezing minimum temperatures. Soils are already saturated, and more rain is possible this weekend.

    In short, it is perfect flood weather for the Red River that runs along the Minnesota-North Dakota border and into Canada. This is a place with the perfect geography for extensive flooding, and a long history of big spring floods.

    Checking the water level on a bridge between Fargo and Moorhead. Photo from Minnesota Public Radio.

    Checking the water level on a bridge between Fargo and Moorhead. Photo from Minnesota Public Radio.

    Every town along the Red River has been devastated by a flood more than once. So they’ve all got emergency response plans in place for weather just like this. For example, Moorhead (Minnesota, across the river from Fargo) has a nifty GIS feature that shows how each foot of flood water affects each city block.

    Residents are already filling sand-bags to build temporary levees. But with year after year of flooding, and with successful sand bag efforts the last two years, some residents might be taking this year’s flood predictions in a somewhat complacent fashion. But looking at the National Weather Service’s North Central River Forecast Center projections, there’s plenty of reason for concern all along the Red River.

    As of 9 am Central time on 7 April 2011, most of the US portion of the Red River is already above flood stage, but water levels will continue to rise almost everywhere for at least the next week.

    Flood stages as of 9 am 7 April 2011. Screen grab from NCRFC.

    Current flood levels along the Red River and nearby drainages, as of 9 am, Thursday 7 April 2011. Orange circles indicate minor flooding, red indicates moderate flooding, purple indicates major flooding. Screenshot from the North Central River Forecast Center, using data supplied by the USGS.

    The flood wave will move downstream – from south to north. In Wahpeton, a crest is expected today, with a second – equally high if not higher – crest next week. There the flood crest is likely to fall a few feet short of record water levels set in 1997.

    Between Wahpeton and Fargo, tributaries to the Red River are having major flooding as well – in part because of backwater effects from the main river. If the Red River is flooding, there’s no place for water flowing down the tributaries to go. Instead they back up, causing even more widespread flooding.

    In Fargo (ND) and Moorhead (MN) – which have a combined population of 200,000 people – the flood will not crest until late Sunday. Right now, the National Weather Service is predicting a crest of 39.5 feet, which 1.3 feet short of the record flooding of 2009. However, there some chance that the river will crest at 41 feet, or even higher if there is precipitation in the next few days. Currently, 80% of the city is protected by sand bags and levees to a height of 41 feet, but those may need to go even higher.

    NWS Flood Forecast for Fargo, North Dakota (7 April 2011)

    NWS Flood Forecast for Fargo, North Dakota (7 April 2011)

    Two weeks ago, the National Weather Service issued a longer-term flood forecast for the Red River at Fargo. At that time they considered it a 10-50% percent chance that the river would reach 40 to 44.3 feet by mid-April. They provided a probability of exceedence curve for their modeled projections of this year’s flood season against the historical record of flooding, as shown below. To understand this graph, it helps to look at a few specific points. Right now, the river is at 35.32 feet. Based on the outlook from two weeks ago, it was virtually inevitable that the river would reach this level, with a probability greater than 98%, as shown by the black triangles. In contrast, 35.32 feet is reached less than 5% of the years in the historical record for Fargo, as shown by the blue circles. The current projected crest of 39.5 feet was given about a 50% chance of being exceeded as of two weeks ago, yet it has only be reached twice (1997, 2009) in 111 years of record. Two weeks ago, the National Weather Service was saying that there was a 25% chance the river could go above 42 feet, which is higher than the top of the sand bag levees now being prepared.

    NWS Chance of exceeding river levels on the Red River at Fargo, conditional simulation based on current conditions as of March 24, 2011

    NC River Forecast Center's 90 model showing the Red River at Fargo's chances of exceeding certain water levels, relative to the historical record.

    The short term forecasts, like the one two above, have better skill than long term forecasts like the immediately above, but the long term forecasts are vital for emergency managers, city officials, and riverside land-owners in making early plans for the flood. The reason they’ve got all the sand and sand bags on hand in places like Fargo is because they knew there was a good chance a really big flood was coming. They’ve been talking about it since January.

    Downstream (north) of Fargo-Moorhead lies Grand Forks, with about 100,000 people in its metropolitan area. Grand Forks was swamped by the flood of 1997, but the current forecasted peak stage this year is about 3.5 feet lower, though the crest won’t reach Grand Forks until late next week. For now, they are watching the water levels and making their preparations. Downstream further, lies Winnipeg, Manitoba. The flood crest won’t reach there until late April, but already the river is 17 feet above normal winter stage, and only 5 feet below the 2009 flood peak. Needless to say, they too are sand-bagging.

    But for the next few days, the action focuses on the Fargo-Moorhead area. You can check out the updated data and forecasts or you can watch the flood play out in Moorhead with a live webcam pointed at the downtown waterfront:
    http://www.justin.tv/widgets/live_embed_player.swfWatch live video from 702 Flood Cam – Moorhead on Justin.tv