University to Study Critical Earth Zone
Researchers at the University of Georgia are joining with the U.S. Forest Service to calculate how past land use—particularly primitive, landscape scarring agricultural practices—has influenced the present environment. UGA researchers will help establish the new Calhoun Critical Zone Observatory located in South Carolina’s Sumter National Forest.
Sumter National Forest was heavily logged forest and farmland before its creation in the 1930s, and has suffered greatly from soil erosion and land degradation. The U.S. Forest Service has spent decades attempting to restore the land, including conducting longterm studies.
Using old and new data, the researchers hope to better understand the earth’s “critical zone,” the thin outer layer of the planet, including soil, which is most important for human life. Studying the forest can reportedly, “Give us a better idea of how we can manage our ecosystems in a sustainable way,” said researcher and Professor Daniel Marewitz.
County Commission Ratifies $14 Million Dam Fix
Manatee County, Florida, has ratified a $14 million contract for emergency repairs to the Lake Manatee Dam. The need for repairs was verified when engineers conducted tests that found that voids beneath the downstream spillway structure were causing soil erosion. Test samples also identified loose material within the earthen dam’s core. The presence of loose material showed that the core of the dam is compromised—likely by heavy rains—and allows water to seep under and through the dam.
The plan to fix the dam calls for two phases of work. The first will be reinforcing the dam through mixing soil and a binder of clay/cement to form a homogenous, impermeable water barrier. The second phase will involve work on the downstream side of the spillway.
Recent annual inspections gave the first clues that the dam is compromised. Since then, the local county commissioners have declared repairs on the dam to be an emergency, and adopted a budget amendment to pay for the project. The dam provides water for Manatee and Sarasota County residents through a treatment plant.
Maine River Dredging to Repair Erosion
The U.S. Army Corps of Engineers has begun a $1.7 million project to dredge the Scarborough River. The project will remove about 114,000 cubic yards of soil from the river’s bottom, and move the material to Western Beach. This will help restore some of the beach that has eroded, and create new habitat for an endangered species of shorebird.
The Army Corps said the project involves dredging an 8-foot-deep entrance channel and a 6-foot-deep anchorage. The dredged material will be removed using a hydraulic dredge and pipeline.
Landowner Liable For Dust Problem
The Kern County Board of Supervisors may declare a local 80- acre plot of land a nuisance, due to excessive dust and erosion. The land’s owner stripped it of its topsoil and vegetation back in 2013, but has since done nothing to further develop the land.
A nearby residential community, Black Mountain Estates, has complained that the land is eroding into their community due to dust whipped up by strong winds. The owner said he has done everything the county and East Kern Air Pollution Control District has asked of him. According to the county though, it has not been enough. The land is suspected to be the cause of a dust storm on March 26.
The owner had planned to plant Pistachio trees on the land, but so far that plan has not come to fruition. If the erosion is not soon contained, the owner may face fines in excess of $25,000.
Grass Strips Help Curb Soil Erosion
Atrazine has been used extensively to prevent the emergence of weeds for decades, but because its a highly detected contaminant of drinking water, it has raised ecological concerns. Applying grass filter strips in riparian zones not only curbs soil erosion but it can also help block and degrade the widely used herbicide.
Riparian zones are transitional areas between upland surfaces, such as crop fields and water bodies. The grass and other vegetation in these zones helps reduce pollution in streams and lakes. Bob Lerch, soil scientist in the ARS Cropping System and Water Quality Research Unit in Columbia, Missouri, is studying the effects of different grass species on herbicide transport and degradation in field and growth chamber studies.
So far, studies have shown that grass buffers reduce the transport of herbicides to shallow groundwater and in runoff. These buffers can reduce herbicide transport through trapping of sediment and by increased infiltration of water into the soil.