Quantitative linkages between watershed conditions and mainstem channel characteristics in Lagunitas Creek, Northern California

Abstract

The Lagunitas Creek watershed provides critical habitat to endangered and threatened fish populations. Although much research has been conducted on the relationship between sediment particle size and habitat quality, it is not well known how watershed conditions may affect the bed texture variability along mainstem channels. I explore the relationship between watershed conditions and channel bed texture through a geomorphic landscape unit (GLU) framework which analyzes the spatial distribution of rock type, land cover, and surface gradients for selected sub water sheds. I found that channel slopes do not appear to correlate with variations in bed texture, but it is not immediately apparent that differences in subwatersheds can explain this variability. Individual subwatershed attributes—instead of combined GLUs—may be more appropriate for predicting bed texture. I suggest an adjusted GLU approach that is more sensitive to variability within each attribute category.