Alumnus Claudia Young, who completed her master's degree in geography fall 2014, received the 2017 Distinguished Master's Thesis Award. The $500 award, given by the SDSU Graduate School recognizes scholarship and research.
Her thesis, which estimated soil erosion and deposition at local and regional scales, will be considered for the national award sponsored by the Midwestern Association of Graduate Schools. The winners will be announced this spring.
“I was interested in understanding how erosion on the landscape happens and how that soil erosion impacts carbon dynamics,” she explained. Changes in land use and precipitation are key factors in this dynamic.
The Colombia native came to South Dakota as a visiting scientist for the United Nations Environment Program office at the U.S. Geological Survey Earth Resources Observation and Science (EROS) Center in 2007. She did her graduate work while working full-time as a geographic information systems specialist and software engineer for ERT Inc., a subcontractor company of the Technical Support Services Contract group at EROS.
Tracking erosion in Midwest Corn Belt
Her adviser, geography professor Darrell Napton, said, “This research provides a tool that can be used to map and monitor the flow of carbon through the Midwestern/Corn Belt agricultural system.” He commended Young’s work as doctoral-caliber research.
Despite the increased use of conservation measures, a 2008 research study stated that the problem of soil erosion still remains. How and where that eroded soil is being redistributed can impact, not only agriculture, but also the amount of carbon released into the atmosphere or transported to other systems, according to Young.
When soil erodes, it moves from higher to lower ground either as a result of tilling or rainfall. During that movement, some carbon can be released into the atmosphere. “Carbon in the soil can be a measure of quality and protection —farmers want it in the soil and no one wants it in the atmosphere,” Young explained. Her research focused on estimating where that displaced soil is subsequently deposited and what that means in terms of carbon dynamics.
“The data and maps provided by Claudia's method can be used to target places on the landscape and farming techniques where changes can be implemented to reduce or stop the oxidation of soil organic carbon,” Napton explained. That reduction will help slow greenhouse gas emissions.
Evaluating modeling tools
Young first linked two soil models that are commonly used in the United States. The United-Stream Power-based Deposition (USPED) method analyzes erosion and deposition caused by water, while the Tillage Erosion Prediction Aid (TEP-A) method analyzes erosion and deposition caused by tillage. The linked methods produced one result of soil redistribution by water and tillage erosion.
A more complex model, the Landscape Process Modeling at Multidimensions and Scales (LAPSUS) tool, which had not been tested in the United States, was the second of the two analytical tools compared.
“In the USPED model, soil redistribution is controlled by the change in the overland flow depth and by the local geometry of the terrain,” Young explained. “Along with the controls used in the USPED, the LAPSUS model uses a digital-elevation model and its derived topography and discharge as driving forces behind geomorphic processes.”
Though Young anticipated the more complex model would yield better results, her research showed that the linked USPED+TEP-A model framework provided results in better agreement with test field analysis. She then used that model to estimate and predict soil redistribution and carbon dynamics at the regional scale.
Napton pointed out, those developing the LAPSUS model could use Young’s results to modify their model so that it could one day be used to evaluate erosion and carbon dynamics in the Midwest.