HR: 1330h
AN: H32A-0522    [PDF]
TI: Effects of Surface Sealing, Soil Moisture Evolution, and Rainfall Intensity on Runoff From Hillslope Plots Burned by Wildfire
AU: * Kinner, D A
EM: dakinner@usgs.gov
AF: U. S. Geological Survey, 3215 Marine St, Boulder, CO 80303
AU: Moody, J A
EM: jamoody@usgs.gov
AF: U. S. Geological Survey, 3215 Marine St, Boulder, CO 80303
AU: Martin, D A
EM: damartin@usgs.gov
AF: U. S. Geological Survey, 3215 Marine St, Boulder, CO 80303
AB: The High Meadow Fire burned 43 square kilometers of mountainous semi-arid terrain southwest of Denver, CO during June of 2000. Burned areas like Hi Meadow are prone to extreme post-fire geomorphic responses including rill, sheet and channel erosion if the fire is followed by a significant rain event. As all of these processes are related to runoff development, it is important to develop accurate hillslope runoff models before developing erosion models. In this study, we examine the dynamics of near surface runoff-generation processes on burned hillslopes by integrating plot-scale measurements and physical models. In the summers (May-September) of 2002-2003, four 1 square meter plots were monitored for precipitation, soil moisture, sediment movement and runoff data. Sediment and runoff were collected on a daily basis, whereas soil moisture was collected every 15 minutes and the rainfall record was continuous. Measurements from the four plots were averaged to account for spatial variability. The largest rainfall event for which data were collected produced 0.026 m of runoff. The largest monitored events for which data were collected were of similar magnitude to those that have lead to catastrophic floods from burned areas in the past. Modeling of infiltration-excess processes using Richard's Equation were conducted to evaluate the effects of surface sealing from raindrop impact, soil moisture evolution and rainfall intensity. Soil particle size analyses, infiltration experiments, and soil moisture-suction curves were used to parameterize the models. The plot experiment results show the importance of antecedent soil moisture in runoff production. Modeling infiltration at this scale is the first step to predicting overland flow over entire hillslopes in burned regions.
DE: 1860 Runoff and streamflow
DE: 1866 Soil moisture
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2003 Fall Meeting