Hydrologic influences on stream temperatures for Little Creek and Scotts Creek, Santa Cruz County, California

Abstract

Stream temperature impacts have resulted in increased restrictions on land management, such as timber harvest and riparian restoration, creating considerable uncertainty for future planning and management of redwood (Sequoia sempervirens (D.Don) Endl.) forestlands. Challenges remain in the assessment of downstream cumulative stream temperature effects given the complexity of stream temperature dynamics. The goal of this research is to identify processes and measurements that can aid the assessment of risk of downstream temperature heating.

Stream temperature, hydrologic, climatic, and channel morphological data were collected on two, approximately 800 m stream reaches on Little Creek and Scotts Creek located in mixed coast redwood and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests of Santa Cruz County, California. Spatially and temporally explicit stream temperature measurements were collected using distributed temperature sensing (fig. 1). A fluorescent dye tracer was used to gather information on summer streamflow including the quantification of residence time and hyporheic exchange. A heat budget approach, adopted from a study by Moore et al. (2005), was used to quantify individual heat flux components and to examine the processes of stream heating and cooling. Downstream temperature change over varying distances through each study site were statistically compared against averaged heat budget components over this respective distance. Average daily maximum stream temperatures were statistically compared against measured physical channel characteristics at each 25 m location throughout the study reaches.

Parent Publication

• Coast redwood science symposium—2016: Past successes and future direction

Citation

Louen, Justin M.; Surfleet, Christopher G. 2017. Hydrologic influences on stream temperatures for Little Creek and Scotts Creek, Santa Cruz County, California. In: Standiford, Richard B.; Valachovic, Yana, tech cords. Coast redwood science symposium—2016: Past successes and future direction. Proceedings of a workshop. Gen. Tech. Rep. PSW-GTR-258. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 131-133.