HR: 0800h
AN: H51E-0826    [Abstracts]
TI: Quantifying the Spatial Distribution of Hill Slope Erosion Using a 3-D Laser Scanner
AU: * Scholl, B N
EM: bnscholl@earthlink.net
AF: Soil Erosion Research Laboratory, San Diego State University Department of Civil and Environmental Engineering, San Diego, CA 92182-1324, United States
AU: Bogonko, M
EM: michael.bogonko@gmail.com
AF: Soil Erosion Research Laboratory, San Diego State University Department of Civil and Environmental Engineering, San Diego, CA 92182-1324, United States
AU: He, Y
EM: yhe@mail.sdsu.edu
AF: Soil Erosion Research Laboratory, San Diego State University Department of Civil and Environmental Engineering, San Diego, CA 92182-1324, United States
AU: Beighley, R E
EM: beighley@mail.sdsu.edu
AF: Soil Erosion Research Laboratory, San Diego State University Department of Civil and Environmental Engineering, San Diego, CA 92182-1324, United States
AU: Milberg, C T
EM: cmilberg@mail.sdsu.edu
AF: Soil Erosion Research Laboratory, San Diego State University Department of Civil and Environmental Engineering, San Diego, CA 92182-1324, United States
AB: Soil erosion is a complicated process involving many interdependent variables including rainfall intensity and duration, drop size, soil characteristics, ground cover, and surface slope. The interplay of these variables produces differing spatial patterns of rill versus inter-rill erosion by changing the effective energy from rain drop impacts and the quantities and timing of sheet and shallow, concentrated flow. The objective of this research is to characterize the spatial patterns of rill and inter-rill erosion produced from simulated rainfall on different soil densities and surface slopes using a 3-D laser scanner. The soil used in this study is a sandy loam with bulk density due to compaction ranging from 1.25-1.65 g/cm3. The surface slopes selected for this study are 25, 33, and 50 percent and represent common slopes used for grading on construction sites. The spatial patterns of soil erosion are measured using a Trimble GX DR 200+ 3D Laser Scanner which employs a time of flight calculation averaged over 4 points using a class 2, pulsed, 532 nm, green laser at a distance of 2 to 11 m from the surface. The scanner measures point locations on an approximately 5 mm grid. The pre- and post-erosion scan surfaces are compared to calculate the change in volume and the dimensions of rills and inter-rill areas. The erosion experiments were performed in the Soil Erosion Research Laboratory (SERL), part of the Civil and Environmental Engineering department at San Diego State University. SERL experiments utilize a 3-m by 10-m tilting soil bed with a soil depth of 0.5 meters. Rainfall is applied to the soil surface using two overhead Norton ladder rainfall simulators, which produce realistic rain drop diameters (median = 2.25 mm) and impact velocities. Simulated storm events used in this study consist of rainfall intensities ranging from 5, 10 to 15 cm/hr for durations of 20 to 30 minutes. Preliminary results are presented that illustrate a change in runoff processes and erosion patterns as soil density increases and reduces infiltration characteristics. Total soil loss measured from the bottom of the erosion bed is compared to the volume of soil loss determined using the laser scanner. Due to soil consolidation during the experiment, the accuracy of measured soil loss from the laser scanner increases with increasing soil density. Ratios of rill and inter-rill erosions for each experiment are also presented. URL: http://spatialhydro.sdsu.edu
DE: 1815 Erosion
DE: 1826 Geomorphology: hillslope (1625)
DE: 1894 Instruments and techniques: modeling
DE: 1899 General or miscellaneous
SC: Hydrology [H]
MN: 2007 Fall Meeting