Monday, 23 January 2012
A Study of Rain-Induced Erosion in the Badlands National Park
Hall E (New Orleans Convention Center )
The Badlands National Park in South Dakota is an area affected by erosion since its formation millions of years ago. Present research is looking into quantifying the amount of rain-induced erosion (wet erosion) as a function of rainfall rates for rain events occurring during May - October, 2011. An OTT Parsivel disdrometer instrument was installed in the Badlands National Park, SD, and it measures raindrop sizes and their fall velocities. The data will be used to calculate the kinetic energy fluxes of individual rain events. A rain gauge has been also installed to compare its data with the disdrometer-calculated rainfall amounts. The amount of soil erosion on a slope is estimated using erosion pins and its quantification is done with very high resolution photogrammetry and laser scanning devices of sub-millimeter resolution. The site features a north-facing slope of 28 degrees, and a south-facing slope of 33 degrees, both of which have been equipped with erosion pins since May 2011. Since then, the north-facing slope shows about 3 mm of erosion at the top, about 15 mm of erosion at mid slope, and approximately 2 mm of deposition at the toe. The south-facing slope has shown about 4 mm erosion at the top of the slope and around 1 mm deposition at the toe. Differences are most likely due to direction of precipitation related to each slope and intensity.
The rainfall (R-Factor) factor of the Revised Universal Soil Loss Equation (RUSLE) has previously been calculated using rain gauge data alone. It is anticipated that, with the Parsivel disdrometer data, a better estimation of the R-Factor in the RUSLE equation will be possible and therefore a better quantification of the erosion rates in the Badlands National Park will be obtained. This presentation will address the results of the current research and compare them to the original methods used to calculate the R-Factor in the RUSLE.