Managing weather extremes

Managing weather extremes

Engineers and conservationists are working on land use solutions that may help farmers and landowners manage both weather extremes of drought and flooding.

AS farmers work to produce more food for a growing population, good stewardship of natural resources becomes increasingly important, especially when it comes to water.

As climate change alters global weather patterns, scientists are observing more frequent occurrences of extreme weather events.

The National Oceanic & Atmospheric Administration's U.S. Climate Extremes Index, which aggregates extreme temperatures, precipitation and meteorological events, has risen steadily for the past four decades, indicating an increase in the frequency of potentially devastating weather extremes.

Although the memory of the 2012 drought is still very fresh, weather in 2011 was just the opposite, with massive flooding in highly productive agricultural regions. Serious water management issues have surfaced for two consecutive growing seasons now.

Engineers at Oregon State University have developed a new way of dealing with both problems by creating a system of small wetlands on midwestern farms. These wetland networks could prevent widespread spring flooding and capture water that might later be used to lessen the ravages of drought.

By recreating wetlands that once occurred naturally across the Corn Belt, the researchers are working to identify small areas that are best suited to such land uses, optimizing their location and size to restore the region's historic water storage capacity without sacrificing significant quantities of productive farmland.

Based on a pilot test of the concept in a crop-intensive region of central Indiana, the engineers found that they could capture runoff from 29% of a watershed using only 1.5% of the region's land.

Results of the project, which were published in the journal Ecological Engineering, highlight the need to find workable solutions to the dual problems of flooding and drought without sacrificing food production capacity.

"The lands of the Midwest, one of the great food-producing areas of the world, now bear little resemblance to their historic form, which included millions of acres of small lakes and wetlands that have now been drained," said Meghna Babbar-Sebens, a professor of civil and construction engineering at Oregon State. "Agriculture, deforestation, urbanization and residential development have all played a role."

Babbar-Sebens noted that large-scale flooding is happening more frequently, leading to additional runoff. By "re-naturalizing" the hydrology of the Corn Belt using small-scale wetlands, farmers might create a system to retain and slowly release water to use for crops and also to prevent flooding.

"Historically, wetlands in Indiana and other midwestern states were great at intercepting large runoff events and slowing down the flows," she said. However, "Indiana has lost more than 85% of the wetlands it had prior to European settlement."

The Oregon State researchers partnered with colleagues at Indiana University-Purdue University in Indianapolis, Ind., as well as the Wetlands Institute and the Environmental Protection Agency on engineering and simulating the optimal effectiveness of various land use changes to create the minimal alteration that would provide farmers and landowners with the maximum benefit.

A recent trend toward broader adoption of conservation structures and practices has helped retain and more slowly release water.

 

Nature's kidneys

Another benefit of wetlands is their function as a natural filter for runoff of fertilizers and sediment from farm fields.

Ecologists often refer to wetlands as "nature's kidneys" because these landforms tend to cleanse runoff of sediment and excess nutrients as part of the natural hydrologic cycle. One of the biggest water-related challenges for agriculture is managing those nutrients, as their buildup can lead to adverse biological reactions, such as the record-large algal bloom on Lake Erie in 2011 (Feedstuffs, April 8).

Producing high-yielding crops like corn and soybeans requires applying fertilizers containing nitrogen, phosphorus and potassium. Improper application practices or untimely rainstorms can allow those nutrients to run off into streams, rivers and lakes.

Along with utilizing conservation practices such as grass waterways and filter strips, farmers are also working to apply fertilizers more efficiently and effectively.

An analysis conducted by The Fertilizer Institute found that between 1980 and 2010, U.S. farmers nearly doubled corn production while using less fertilizer. In 1980, farmers grew 6.64 billion bu. of corn using 3.2 lb. of nutrients (nitrogen, phosphorus and potassium) for each bushel, and by 2010, they grew 12.45 billion bu. using 1.6 lb. of nutrients per bushel produced.

An 87.5% increase in production using 4% fewer nutrients is due, in part, to the implementation of precision agriculture practices that tailor the quantity of fertilizer to be applied to a specific crop in a specific farm field rather than a blanket application of a generic quantity of fertilizer that may be more than needed for optimal production.

 

Restoring floodplains

Engineers and scientists at the University of Illinois and Iowa State University recently studied the massive flooding in 2011 near the confluence of the Mississippi and Ohio rivers.

Their findings, published in the Journal of Soil & Water Conservation, examined the public and private costs of reclamation and repairs from the 2011 catastrophe.

Among the report's conclusions was that the current system of levees, floodwalls and the Birds Point-New Madrid floodway in southeastern Missouri has worked well for nearly 85 years but requires immense taxpayer funding and may not be sustainable if catastrophic flooding occurs more frequently. Dealing with the flood's resulting soil damage and erosion cost federal, state and local agencies more than $51 million, according to University of Illinois researcher Ken Olson.

Another $46 million in federal funding was allocated in 2012 as a result of last year's drought and to strengthen and improve levees and reclaim previously flooded areas. The opening of the 133,000-acre New Madrid floodway in 2011 also cost farmers nearly 40,000 acres of crop loss in the form of drowned winter wheat and prevented soybean plantings.

Olson and Iowa State University colleague Lois Wright recommended a revision to the comprehensive plan for the region that would better integrate the levee engineering infrastructure with the existing ecological infrastructure to mitigate future flooding of the area. One option would be to purchase additional acreage along the floodway and realign levees for expanded wetlands and parks rather than for continued agricultural use.

Volume:85 Issue:15

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