An approach to study the effect of harvest and wildfire on watershed hydrology and sediment yield in a coast redwood forest
This article is part of a larger document. View the larger document here.Abstract
The Little Creek watershed, within California State Polytechnic University’s Swanton Pacific Ranch, is the location of a paired and nested watershed study to investigate the watershed effects of coast redwood forest management. Streamflow, suspended sediment, and stream turbidity have been collected during storms at two locations on the North Fork Little Creek and at the outlet of South Fork Little Creek from 2002 until present. In 2008, the watershed area between the two monitoring stations on the North Fork Little Creek watershed was harvested with an individual tree selection silvicultural system within the Santa Cruz County Rules of the California Forest Practice Rules. The South Fork Little Creek was left unharvested to serve as a control. In 2009, the Little Creek watershed was burned by a wildfire. The wildfire eliminated our control watersheds for the proposed Before After Control Intervention (BACI) study design. We present an alternative approach at detecting harvest and fire effects that uses rainfall/runoff models, soil erosion models, and sediment runoff relations to simulate runoff and sediment yield from the watersheds. The models and sediment runoff relationships will be developed within the framework of an uncertainty assessment to simulate pre-harvest and pre-fire conditions for the North and South Forks of Little Creek. The modeled results will be used as the control for the study which had been eliminated due to the wildfire in 2009. We use the HBV hydrologic model and sediment runoff relations to demonstrate our approach. An example of post-harvest and post-fire runoff and sediment changes within the uncertainty of the approach are demonstrated.