Date of Award
Master of Science (MS)
Laura K. Lautz
beaver dam analogue, channel morphology, stream restoration, unoccupied aerial vehicles
Physical Sciences and Mathematics
Beaver dam analogues (BDAs) are a stream restoration technique that is rapidly gaining popularity in the western United States. These low-cost stream-spanning structures, designed after natural beaver dams, are being installed to confer the ecologic, hydrologic and geomorphic benefits of beaver dams in streams that are too degraded to provide suitable beaver habitat. BDAs can slow streamflow, reduce the erosive power of the stream and promote aggradation, making them attractive restoration tools in incised channels. Despite increasing enthusiasm for BDAs, few studies to date have evaluated the impacts of these structures on channel morphology. Here, we examine the geomorphic changes that occurred within the first year of restoration efforts in south-central Wyoming using high-resolution visible light orthophotos and elevation data collected with unoccupied aerial vehicles (UAVs). By leveraging the advantages of rapidly acquired images captured by low-cost UAV surveys with recent advancements in Structure from Motion photogrammetry, we constructed centimeter-scale digital elevation models (DEMs) of the restoration reach and an upstream reference reach. Through DEM differencing, we identified areas of enhanced erosion and deposition around the BDAs, suggesting that BDA installation initiated a unique geomorphic response beyond the scale of natural channel variability. However, we measured net erosion in both reaches which is counter to the desired restoration outcome of net aggradation around the BDAs. This net loss of sediment is inconsistent with studies of natural beaver dams, underscoring the differences between BDAs and the dams that inspired their construction, but is in agreement with theoretical channel evolution models of beaver-related stream restoration. To better understand the impacts of BDAs on channel morphology and restoration efforts throughout the Mountain West, it is imperative that we consistently assess the effects of beaver-inspired restoration projects across a range of hydrologic and geomorphic settings and that we continue this monitoring for years to decades.
Davis, Julianne, "Evaluating the geomorphic channel response to beaver dam analogue installation using unoccupied aerial vehicles" (2020). Theses - ALL. 426.