Understanding the hydrologic consequences of timber-harvest and roading: four decades of streamflow and sediment results from the Caspar Creek experimental watersheds

Abstract

The Caspar Creek Experimental Watersheds were established in 1962 to study the effects of forest management on streamflow, sedimentation, and erosion in the rainfall-dominated, forested watersheds of north coastal California. Currently, 21 stream sites are gaged in the North Fork (473 ha) and South Fork (424 ha) of Caspar Creek. From 1971 to 1973, 65% of the timber volume in the South Fork was selectively cut and tractor yarded, and from 1985 to 1991, 50% of the North Fork basin was harvested, mostly as cableyarded clearcut. The South Fork logging resulted in annual suspended sediment load increases exceeding 300%. Mass-wasting has been predominantly associated with roads, landings, and tractor skid trails in the South Fork. Accelerated mass-wasting and renewed sediment mobilization in the South Fork have occurred since 1998. Peak flow increases detected following North Fork logging are attributable to reduced canopy interception and transpiration. These recovered to pretreatment levels about 10 years after logging, followed by renewed increases from pre-commercial thinning. Annual sediment loads increased 89% in the partially clearcut North Fork and 123% to 238% in 4 of 5 clearcut sub-basins. Twelve years after logging, elevated storm-event sediment yields persist in some clearcut tributaries.

Citation

Keppeler, Elizabeth; Lewis, Jack. 2007. Understanding the hydrologic consequences of timber-harvest and roading: four decades of streamflow and sediment results from the Caspar Creek experimental watersheds. In: Furniss, M.; Clifton, C.; Ronnenberg, K. eds. Advancing the fundamental sciences: proceedings of the Forest Service National Earth Sciences Conference, San Diego, CA, 18-22 October 2004. Gen. Tech. Rep. PNW-GTR-689. Portland, OR: U.S. Forest Service, Pacific Northwest Research Station: 191-196.