Tamarisk and fluvial geomorphic form in Dinosaur National Monument, Colorado and Utah

Effective tamarisk (Tamarix romosissima) control strategies must incorporate sound understanding of hydrogeomorphic controls on the invasive shrub's distribution. In this case study of the regulated upper Green River and the unregulated Yampa River, fine-grained sediment availability dominates tamarisk's large-scale distribution. Local shear stress and flood reworking influence establishment on specific deposits. Tamarisk germinate in a narrower elevation range on the Green River, where most tamarisk occupy deposits that formed since flow regulation began and are rarely inundated. Managed flooding could comprise a passive control method for tamarisk. Our strategy to predict where managed floods will effectively complement mechanical removal was to compare tamarisk's distribution along a wild and a regulated river. We describe a methodology to compare analogous hydrologic, hydraulic, and geomorphic locations, and apply these comparisons to develop spatially discrete recommendations for tamarisk's removal. Removal in these locations would complement higher-magnitude floods proposed on the regulated upper Green River.