Research Experiences for Undergraduates
Program in Water Research at 
Colorado State University

Mentor Information

Name Lee MacDopnald

Title Professor

Department Earth Resources

Work Phone 970-491-6109

FAX 970-491-6307


Project Title Measurement of Post-fire Runoff and Erosion Using a Rainfall Simulator

Project Abstract In June 2000 the Bobcat Fire burned over 40 km2 of forested lands west of Fort Collins. Previous studies have shown that high severity fires in the Colorado Front Range can greatly increase runoff and erosion rates (Morris and Moses, 1987; Moody and Martin, 2001), but we have had relatively little data on the factors that control the magnitude of these increases at the site scale, or the pattern of hydrologic recovery over time. In both 2000 and 2001 we measured runoff and sediment production from small plots using a rainfall simulator, as this methodology allows us to systematically vary the site conditions and apply a relatively uniform amount of rainfall to each site. Data from the first two years indicates that erosion from sites burned at high severity is at least twenty times larger than erosion rates from sites burned at low severity and unburned sites (Benavides-Solorio and MacDonald, 2001). Differences in runoff rates between burned and unburned sites are significant but much smaller in magnitude, and this is due in part to the relatively high intensity of the simulated rainfall (approximately 80 mm/hr). Surprisingly, runoff and erosion rates from the simulations conducted in 2001 were very similar to the values measured in first summer after burning, even though there was less soil hydrophobicity (Huffman and MacDonald, 2002) and more vegetative cover.

The purpose of this project is to conduct additional rainfall simulation experiments on unburned sites and sites burned at varying severities in the Bobcat Fire. A REU student (Dennis Leikman) assisted with this project in summer 2001, and we are seeking another student to work on this project in 2002. The exact topic of the research is somewhat flexible, in that they could focus on some aspect of the variations in runoff between sites or over time, or some component of the sediment production. A focus on runoff is probably more feasible because the samples do not require extensive processing in the lab. The student will need to be able to carry moderately heavy loads in steep, forested terrain. Because the site is close to Fort Collins, they will not need to stay overnight in the field.