The following story was written by a University of Missouri student as part of the 2012 Sonja Hillgren/Farm Journal Ag Journalism Field Reporting Institute. Learn more.
By Cade Cleavelin
Corning Conservation Area, a preserve hugging a bend on the Missouri River in the middle of some of Missouri’s most productive farmland, is extraordinarily untamed in contrast to the tidy cropland neighboring it.
Its tall grasses – gangly and disheveled – easily surpass eye level and obscure any reference to the horizon. It feels exotic. Trees are scattered and few, and only the very tops of the grasses fidget in the wind.
Photo: George Laur
Bushwhack, and the landscape eventually reopens, revealing a secret the vegetation hasn’t been able to conceal entirely – a broad, otherworldly sea of sand. Even the most industrious weeds can’t establish themselves here in the bald, monochromatic badlands of the conservation area.
Photo: Amy Bruer
Robert Jacobson, chief research hydrologist with the U.S. Geological Survey river studies branch in Columbia, Mo., calls it a "classic splay of sand." He also offers the somewhat romantic¬ alternative, "mega-dune."
"These sand splays are actually quite fascinating, because they effectively create a micro-ecosystem within the larger environment," Jacobson said.
Robert Jacobson, chief research hydrologist with the U.S. Geological Survey River Studies Branch in Columbia, Mo. Photo: J.B. Forbes
On a regional scale, sand splays are concentrated disasters, the products of isolated weaknesses in the levee system that heavy floods, like what occurred in 2011, can exploit.
"The flood water we see most of the time does not cause any damage," said Jud Kneuvean, chief of the Army Corps of Engineers emergency management branch in Kansas City.
"We knew several weeks in advance that we were going to have a flood emergency," Kneuvean said. "We did not know we were going to get 160,000 cubic feet per second."
Jud Kneuvean, chief of the Emergency Management Branch of the Army Corps of Engineers Kansas City District. Photo: George Laur
The speed and pressure were enough to scour channels underneath the levees, drag along millions of tons of heavier sediments, and spew sand and water out the other side like a broken fire hydrant. What’s left now are massive sand splays and the scour ponds they came from.
"You can see it’s very punctuated, all along the river," Jacobson said, later referring to a large satellite image taken of the region in November 2011. Roughly a dozen white splotches show where waters from the flood buried entire acreages under heavy sediment.
"There are some places where the sand might be 20 or 30 feet deep, so that land has basically been rendered permanently useless for farming," Jacobson said.
Matt Struckhoff, a USGS ecologist who’s studied floodplains for more than a decade, said the effects of sand in the soil are twofold.
"From an agricultural perspective, that sand is a big problem, because it's at the surface where the corn and soybeans roots are limited to," Struckhoff said. "That said, where you have a shallow deposition of sand over what farmers would call a ‘heavy soil’ it could have a benefit in what it provides to the soil’s physical properties."
In short, tilling a few inches of sand into the thick "gumbo" soil may help the soil drain better.
And to that effect, farmer Traci Barnes considers himself lucky. He owns 700 acres of land in the flood plain and, despite tilling a blanket of sand into his soil, harvested corn this year.
"For me, I really think it helped," Barnes said. "I think drainage is better now that all that gumbo isn’t as thick and mucky.
"I know a lot of people were really hit hard by the sands and may never farm that land again, but for me it just worked out."
The situation is not unprecedented. In 1993 a flood hit the lower Missouri River especially hard, similar to what the northern flood plain experienced in 2011.
At the intersection of I-70 and the Missouri River, the US Fish and Wildlife Service created the Big Muddy National Wildlife Refuge after the flood of ’93 irreparably destroyed farmland there. Twenty year later, the remnant mega-dune still looks like a desert.
"It’s an example of what folks in Holt and Atchison counties might expect if their fields are not renovated," Jacobson said.
Sand splays are not widely studied, but Wayne Thogmartin, a researcher with the USGS Upper Midwest Environmental Sciences Center in La Crosse, Wis., coauthored a paper in 2009 examining floodplain transformation at Big Muddy.
If Thogmartin’s models showed one thing, it’s that floodplain dynamics are not predictable. In an ecosystem as disaster prone as a flood plain, factors like elevation and proximity to the river are constantly in flux.
Thogmartin says flood plains must be understood as dynamic, niche ecosystems in an otherwise large region.
"As dramatic as those floods were, and as striking as those remnants are, they represent a really small percentage of the flood plain itself," Thogmartin said.
"We're talking orders of less than 1 percent. So, the potential impact of those types of communities on the whole regional ecosystem is really pretty small."