Delineating Riparian Vegetation Using Remotely Sensed Data: A Variable Width Model from the Boise Foothills
Dr. Trevor Caughlin and Dr. Anna Bergstrom
Riparian vegetation is critically important for dryland ecosystem functions including maintaining water temperatures for resident fish populations, enhancing carbon sequestration, stabilizing stream banks and flow, and supplying and retaining nutrients within water systems. Development of management and conservation strategies for these vital areas is dependent on mapping the extent of the characteristic riparian vegetation. The primary step in modeling hydrological ecosystem dynamics includes defining the riparian buffer through fixed-width or variable-width approaches. Fixed-width buffers do not accurately capture smaller, unique riparian areas because they only account for the watercourse, ignoring inputs such as stream order or geomorphology. A variable-width buffer reflects spatial variability in riparian vegetation by accounting for landscape complexities, such as fine-scale variation in topography that complicate proper estimations of riparian zones. Using a 1-m spatial resolution digital elevation model (DEM) derived from aerial lidar, we mapped the stream network of the southwestern section and lower elevations of the Dry Creek Experimental Watershed in Idaho, USA. This watershed encompasses a topographically complex/diverse ecosystem gradient, from sagebrush steppe to evergreen forest. Then, we generated random points along the predicted stream network to digitize (n = 1,500) and ground truth (n = 150) riparian vegetation. We developed a regression model to predict riparian vegetation width using the collected digitized and ground truth measurements, and additional covariates (i.e., slope, aspect, elevation, vegetation). Our results provide a way to accurately map riparian buffers in sagebrush steppe ecosystems through a novel variable-width approach and allow for additional research on the geomorphological, hydrological, and ecological characteristics of riparian areas within drylands.
Vaage, Claire; Caughlin, Trevor; and Bergstrom, Anna, "Delineating Riparian Vegetation Using Remotely Sensed Data: A Variable Width Model from the Boise Foothills" (2022). 2022 Undergraduate Research Showcase. 88.