HR: 1340h
AN: H43F-1688    [Abstracts]
TI: Comparing Burned and Unburned Forest Conditions Using Simulated Rill Experiments
AU: * Robichaud, P R
EM: probichaud@fs.fed.us
AF: USDA Forest Service, Rocky Mountain Research Station, 1221 S. Main St, Moscow, ID 83843, United States
AU: Brown, R E
EM: bbrown02@fs.fed.us
AF: USDA Forest Service, Rocky Mountain Research Station, 1221 S. Main St, Moscow, ID 83843, United States
AU: Wagenbrenner, J W
EM: jwagenbrenner@fs.fed.us
AF: USDA Forest Service, Rocky Mountain Research Station, 1221 S. Main St, Moscow, ID 83843, United States
AB: Despite the dominance of concentrated flow or rill erosion in the erosion processes in disturbed forests, few studies have quantified the effects of different types of forest disturbance on rill erosion. This study quantified the effects of four forest conditions—natural (recently undisturbed), low soil burn severity, high soil burn severity, and skid trails—on rill runoff quantity, runoff velocity, and rill erosion. Simulated rill experiments were conducted at sites in eastern Oregon (Tower Fire) and in northern Washington (North 25 Fire) on forested slopes with granitic and volcanic soils, respectively. The natural and skid trail conditions were established near each burned area in unburned forest. For each rill experiment, concentrated flow was applied at the top of the plot through an energy dissipater at five inflow rates for 12 min each. Runoff was sampled every 2 min and runoff volume and sediment concentration were determined for each sample. The runoff velocity was measured using a dyed calcium chloride solution and two conductivity probes placed a known distance apart. Runoff volume, runoff velocities, and sediment concentrations increased with increasing levels of disturbance. The natural plots had very low runoff rates and sediment concentrations at both the Tower and North 25 sites. The low soil burn severity plots had greater responses than the natural plots, but the responses in the two sites were different as a result of variability in effect of burning and differences in time between burning and the rill experiments. The high soil burn severity and the skid trail plots had the highest runoff ratios, runoff velocities, and sediment concentrations and the responses were similar at both sites. These results suggest that any differences in responses related to soil type or other site factors were masked by the increase in response resulting from the high levels of disturbance.
DE: 1815 Erosion
DE: 1850 Overland flow
SC: Hydrology [H]
MN: 2007 Fall Meeting