Hydrologic Characteristics of Summer Stream Temperatures in Little Creek and Scotts Creek at the Swanton Pacific Ranch
Stream temperature impacts have resulted in increased restrictions on land management such as timber harvest and have created considerable uncertainty for future planning and management of redwood forestlands. Challenges remain in the assessment of downstream cumulative effects given the complexity...
| Main Author: | |
|---|---|
| Format: | Others |
| Published: |
DigitalCommons@CalPoly
2016
|
| Online Access: | https://digitalcommons.calpoly.edu/theses/1659 https://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=2834&context=theses |
| Summary: | Stream temperature impacts have resulted in increased restrictions on land management such as timber harvest and have created considerable uncertainty for future planning and management of redwood forestlands. Challenges remain in the assessment of downstream cumulative effects given the complexity of stream temperature dynamics. The goal of this research is to identify the risk of downstream temperature heating based on the summer low flow residence times, stream morphological characteristics, stream water storage, and heat budget exchanges. 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 forests of Santa Cruz County, California. Spatially and temporally explicit stream temperature measurements were collected using distributed temperature sensing. 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 was used to quantify individual heat flux components and to examine the processes of stream heating and cooling. Comparisons of observed and modeled temperatures between the two sites and the relative influences of individual heat budget components indicated that the magnitude and spatial frequency of subsurface-surface water interactions, along with incoming net radiation, played a substantial role in how heat was transferred through each system. Solar radiation exposure from stream shading and modeled groundwater inflows were important explanatory variables in the magnitude and spatial distribution of stream temperatures for the two streams located in the same watershed subjected to similar meteorological conditions. The measurement and evaluation of a stream’s hydrologic characteristics, stream shading, and aspect ratio were statistically significant measurements (α |
|---|