Available at: https://digitalcommons.calpoly.edu/theses/711
Date of Award
MS in Forestry Sciences
Natural Resources Management
Brian C. Dietterick
Six geomorphic study reaches were established in 2002 along a forested mountain stream (gradients range from 0.02 to 0.05) on Cal Poly's Swanton Pacific Ranch in Santa Cruz County, California. These study reaches are a component of paired and nested watershed studies in the approximately 500 hectare Little Creek watershed. The overall goal of this study was to monitor water quality and channel conditions before, during, and after a selective harvest of redwood. A selective harvest occurred in the North Fork of Little Creek in Summer 2008. In August 2009, approximately 90% of the Little Creek Watershed was burned in the Lockheed Fire. Channel change was evaluated by measuring ground profiles using traditional survey methods. Cross section and longitudinal profiles are surveyed annually every summer in the six study reaches. Change is assessed through evaluation of cross sections and longitudinal profiles, analysis of bed elevation and cross-sectional area change data, and analysis of residual pool characteristics and longitudinal profile variability. Changes in the channel during this time have been relatively small and are typically associated with movement or introduction of coarse woody debris to the stream channel. However, during the study period no large stream flow events occurred (return interval at the closest USGS gauging station does not exceed 5 years). Historically, large debris flow events have occurred in this watershed, with well documented events in 1955 and 1998. The survey data is an important tool for understanding change detection in channel characteristics before and after harvesting, and following fire disturbance.