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Title: Soil water repellency and ground cover effects on infiltration in response to prescribed burning of steeply-sloped sagebrush hillslopes

Author
item WEIGEL, ANDREW - Boise State University
item Pierson Jr, Frederick
item Kormos, Patrick
item Williams, Christopher - Jason
item PIERCE, JEN - Boise State University

Submitted to: Trans American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: 9/10/2008
Publication Date: 12/15/2008
Citation: Weigel, A.B., Pierson Jr, F.B., Kormos, P.R., Williams, C.J., Pierce, J.L. 2008. Soil Water Repellency and Ground Cover Effects on Infiltration in Response to Prescribed Burning of Steeply-Sloped Sagebrush Hillslopes. EOS Transactions, American Geophysical Union 89(53), Fall Meeting Supplement, Abstract H33D-1036.

Interpretive Summary: Rangeland managers and scientists are in need of predictive tools to accurately simulate post-fire hydrologic responses and provide hydrologic risk assessment. Rangeland hydrologic modeling has advanced in recent years; however, model advancements have largely been associated with data from gently sloping sites and have not included the effects of soil water repellency on runoff generation. This study seeks to enhance current understanding of post-fire hydrologic responses on steeply-sloped sagebrush rangelands, emphasizing the influences of soil water repellency and ground cover on the post-fire runoff generation. The Northwest Watershed Research Center conducted small plot rainfall simulations on a sagebrush-dominated mountainous site in the Reynolds Creek Experimental Watershed, Idaho, USA. This site is characterized by steep slopes, fine grained volcanic soils and a northeasterly aspect which affords it more moisture than several of the surrounding hillslopes due to drifting snow. Soil water repellency was assessed using the water drop penetration procedure and ground cover was measured using point frame methodologies. Experiments were conducted immediately before and one year following prescribed burning of the site. The study results explain the collective interaction of soil water repellency and ground cover effects on infiltration and runoff under burned and unburned conditions and provide insight for expansion and improvement of process-based rangeland hillslope hydrologic models.

Technical Abstract: Rangeland managers and scientists are in need of predictive tools to accurately simulate post-fire hydrologic responses and provide hydrologic risk assessment. Rangeland hydrologic modeling has advanced in recent years; however, model advancements have largely been associated with data from gently sloping sites and have not included the effects of soil water repellency on runoff generation. This study seeks to enhance current understanding of post-fire hydrologic responses on steeply-sloped sagebrush rangelands, emphasizing the influences of soil water repellency and ground cover on the post-fire runoff generation. The Northwest Watershed Research Center conducted small plot rainfall simulations on a sagebrush-dominated mountainous site in the Reynolds Creek Experimental Watershed, Idaho, USA. This site is characterized by steep slopes, fine grained volcanic soils and a northeasterly aspect which affords it more moisture than several of the surrounding hillslopes due to drifting snow. Soil water repellency was assessed using the water drop penetration procedure and ground cover was measured using point frame methodologies. Experiments were conducted immediately before and one year following prescribed burning of the site. The study results explain the collective interaction of soil water repellency and ground cover effects on infiltration and runoff under burned and unburned conditions and provide insight for expansion and improvement of process-based rangeland hillslope hydrologic models.