DISTURBANCE ASSESSMENT AND MITIGATION OF GREAT BASIN RANGELAND
Location: Watershed Management Research
Title: Estimating concentrated flow erodibility parameters from pre- and post-fire rangeland field data for physically-based erosion modeling
Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: September 16, 2011
Publication Date: December 5, 2011
Citation: Al-Hamdan, O.Z., Pierson, F.B., Williams, C.J., Nearing, M., Stone, J., Kormos, P.R., Boll, J., and Weltz, M.A. 2011. Estimating concentrated flow erodibility parameters from pre- and post-fire rangeland field data for physically-based erosion modeling. Abstract H31B-1141. Presented at the 2011 Fall Meeting of the American Geophysical Union, December 5-9, 2011, San Francisco, CA.
In physically based soil erosion models a concentrated flow erodibility parameter is necessary to run the model. This parameter is usually set to a relatively insignificant value when applying models on rangeland ecosystems as soil erosion induced by concentrated flow on these ecosystems tends to be low compared with those on cropland. However, after a fire, concentrated flow is often the dominant source of water erosion especially on steep slopes. Hence, the erodibility parameter becomes a very important factor in estimating the erosion rate after such disturbance. In this study, we estimated the concentrated flow erodibility using field experimental data over diverse rangeland landscapes within the Great Basin Region, United States. The vegetation community ranges from sagebrush steppe to pinyon-juniper woodland. Many of the sites exhibit some degree of wildfire or prescribed fire. The erodibility parameters were measured before and after fire. In some sites erodibility was also measured one, two, and three years after fire. The results showed that in general concentrated flow erodibility increased significantly after fire. In some sites, erodibility continued to increase until the second year after fire where erodibility starts to decline. The results also show that concentrated flow erodibility was not constant within each experimental run where in most cases erodibility has a high value at the beginning and then starts to decline due to reduction of sediment availability. Using the data in this study we developed an empirical equation to predict the change of erodibility as a function of cumulative unit discharge. The empirical function can be used for parameterizing the concentrated flow erosion component of physically based models on burned rangeland.