Submitted to: Earth Surface Processes and Landforms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/7/2003
Publication Date: 8/1/2003
Citation: Wilson, C.G., Matisoff, G., Whiting, P.J. 2003. Short-term erosion rates from a 7be inventory balance. Earth Surface Processes and Landforms. 28: 967-977. Interpretive Summary: Soil erosion, which results from storm runoff, is a process that occurs on relatively short time scales. However, the ability to quantify the localized soil erosion in a single field during one runoff event is very difficult. Soil erosion studies often focus on larger areas and longer time periods. To quantify the localized erosion in a small plot in an agricultural field related to a series of runoff-producing thunderstorms occurring over three days, a budget for a naturally-occurring unstable element delivered in the rain was used to calculate sediment erosion in a small plot at the USDA-ARS Deep Loess Research Station in Treynor, IA, USA. The budget included determination of soil profiles and inventories of the element before and after the storm-event, as well as its delivery in the rain during the storm event. The amount of erosion calculated in the field plot using the budget was 0.058 g/cm2, which is similar to the 0.059 g/cm2 of erosion estimated from the amount of sediment collected during the study period at the bottom of the field, which contained the sample plot, and adjusted for the different area sizes. This budget provides a new means for measuring soil erosion over a time period similar to the source of the erosion, the rain event.
Technical Abstract: Detailed soil erosion studies benefit from the ability to quantify the magnitude of erosion over time scales appropriate to the process. An inventory balance for 7Be was used to calculate sediment erosion in a 30.73 m2 plot during a series of runoff-producing thunderstorms occurring over three days at the Deep Loess Research Station in Treynor, IA, USA. The inventory balance included determination of the pre- and post-storm 7Be inventories in the soil, the atmospheric influx of 7Be during the event, and profiles of the 7Be activity in the soil following the atmospheric deposition. The erosion calculated in the plot using the 7Be inventory balance was 0.058 g/cm2, which is 23 percent of the annual average erosion determined using 137Cs inventories. The calculated erosion from the mass balance is similar to the 0.059 g/cm2 of erosion estimated from the amount of sediment collected at the outlet of the 6 ha field during the study period and the delivery ratio (0.64). The inventory balance of 7Be provides a new means for evaluating soil erosion over the time period relevant to quantifying the prediction from runoff.