Temperature and Relative Humidity Gradients of Intermittent and Perennial Tributaries in Northern California

ABSTRACT TEMPERATURE AND RELATIVE HUMIDITY GRADIENTS OF INTERMITTENT AND PERENNIAL TRIBUTARIES IN NORTHERN CALIFORNIA by Eric Hillman Tharsing Willard Master of Science in Geosciences Hydrology/Hydrogeology Option California State University, Chico Summer 2009 Perennial and intermittent tributary streams are extensive components of the stream networks across landscapes. Riparian zones surrounding streams are important components of the bio-scape. Four tributary streams (Two perennial and Two intermittent) were sampled, in the Southern Cascade region of California using methods developed to infer effects of harvesting on microclimatic gradients from stream to upland. These methods were modified to observe the effects of flow on temperature and relative humidity gradients. The objectives of this study are: (1) to characterize flow of perennial and intermittent tributary streams of Big Chico Creek using temperature and stage methods; (2) identify differences in temperature and relative humidity at intermittent ix and perennial sites during different flow conditions; (3) describe effects of perennial and intermittent stream classes on temperature and relative humidity gradients and (4) compare changes in gradients from stream to upland between stream classes. Five temperature and relative humidity loggers were installed along transects running from stream to upland positions at each stream. Linear regressions of relative changes along transects were used to quantify gradients. One and two-way ANOVA were used to determine statistical differences in gradients and relative changes along transects respectively. This was done between stream classes, transects, and transects and Stations for appropriate time periods. Results point to distinct temperature and relative humidity gradients for perennial and intermittent streams (0.0195 and 0.0102 C/m), during daytime dry conditions, while the intermittent stream is dry and the perennial is still flowing. For the same time period significant differences exist between stream Stations and all other Stations (7.5m to 45m) along the perennial transect, while intermittent statistical differences don’t exist until near upland Stations (30m to 60m). The study indicates that perennial and intermittent streams have distinctive temperature and relative humidity conditions above the stream during the peak daytime, when the intermittent ceases to flow and the perennial continues to flow. Additional site specific data are needed for various site conditions in order to determine if generalizations can be made about these stream classes.