OREGON STATE UNIVERSITY

Local and Downstream Effects of Contemporary Forest Harvesting on Streamflow and Sediment Yield

Zégre, N. P.
Nov-19-2008

This dissertation is a collection of three manuscripts that serve to fill the knowledge gaps and advance methods of detecting the effects of contemporary forest harvesting in experimental catchment studies. The objective of this research was to develop change detection models using time-series records to detect and quantify the effects of forest harvesting on streamflow and sediment yield. To accomplish this, it was necessary to characterize streamflow and sediment processes at a temporal scale capable of describing daily, monthly, and seasonal dynamics following forest harvesting; increase sample sizes used to construct regression-based change detection models; and develop alternative methods to the paired-catchment approach in order to discern changes in streamflow and sediment using highly variable time-series data. The paired-catchment approach was used to detect and quantify relative changes in streamflow and sediment yield in 5 harvested catchments. The ability to detect statistically significant changes at certain time-steps was a function of accounting for all sources of variability in change detection models. In this study, we aimed to develop robust change detection models using time-series data to increase sample size and decrease false/missed detections of true treatment effects.

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