Studies by USDA Agricultural Research Service Determine that the Way We Treat Our Land Impacts Water Availability
Media Contact: Maribel.Alonso@usda.gov
What impact, if any, do farming and ranching practices have on how much water is available downstream? That was the question scientists at the USDA Agricultural Research Service (ARS) Agroclimate and Hydraulic Engineering Research Unit in El Reno, Oklahoma, set out to answer in a series of studies conducted in Central and Western Oklahoma.
Beginning in 2003, ARS researchers, working in partnership with the USDA Natural Resource Conservation Service (NRCS), summarized the results of a series of earlier studies that looked at the impact land management and conservation practices had on soil and water resources. Their work showed that the conservation practices implemented since the 1950s, including terracing, no-till, and gully shaping, had reduced sedimentation into downstream water bodies by as much as 86 percent.
In a follow-up study, ARS researchers evaluated 12 reservoirs constructed between 1969 and 1982 under the USDA Watershed and Flood Prevention Operations Program (also known as the USDA Small Watershed Program) to determine how conservation practices installed upstream from these structures impacted soil erosion and with it, the annual level of sediment deposited in them.
Utilizing ultrasound tools, the research team determined that a series of conservation practices, including no-till, grass planting, and riparian restoration, had greatly reduced the overall level of sediment in the reservoirs, in some cases more than doubling their expected design life from 50 years to over 100.
“Conservation practices have had a huge impact on the life of these reservoirs,” said Dr. Daniel Moriasi, a research hydrologist with ARS and a lead member of the research team. “I think that because we don’t have a lot of studies looking at the impact of agriculture land practices on sedimentation in reservoirs, people fail to realize how taking care of the land can impact the life and viability of these structures.”
According to Moriasi, by targeting land treatment practices in areas that have physical characteristics that lead to a high propensity for soil erosion, such as sharp slopes, cultivated land, and certain soil types, agriculture producers and conservation professionals can do a lot to improve the life span and viability of water impoundments around the country.
“Some agricultural lands can be especially susceptible to erosion due to issues such as slope and soil type,” Moriasi said. “Increasing conservation practices in areas where we have the most vulnerable soils will result in the most benefit, in the field and in nearby reservoirs.”
According to Moriasi, this research work highlights one of the many benefits best management practices can generate when it comes to water; benefits that also include water quality protection; increased soil water holding capacity; and keeping soil in the fields—all of which can help both agriculture producers and downstream communities better adapt to extreme weather conditions.
“We don’t realize the good we accomplish for the whole system when we do the right thing,” Moriasi said.
—By Clay Pope, USDA’s Southern Plains Climate Hub.
You can read more about this research at: https://www.nrcs.usda.gov/publ...pperWashitaRiver.pdf
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