Graduate Student Seed Grant Projects
Fate and transport of fine particulates in a first order agricultural stream
Growth in agriculture, resource extraction, and urbanization in the last century have resulted in increased inputs of fine sediments to freshwater systems to the extent that sediment is now the second-most common cause of stream impairments nationwide. The current approach to sediment management focuses on reducing total sediment inputs to streams from surrounding land areas. This approach does not consider those details of sedimentation (e.g., particle sizes, movement within the stream channel, suspended vs. bedded forms) that directly influence sediment impacts on aquatic life and the ecosystem services provided by water resources.
To improve our understanding of alluvial sediment fate and transport, we labeled sediments with rare earth elements (REE) lanthanum (La) or ytterbium (Yb) and injected them into the channel at the initiation of each of two artificial flood events (one REE per event). Fine sediment deposition in the channel and flood plain, transport of suspended particles, sediment breakthrough rates, resuspension and transport during subsequent flood events, and particle size distributions at each sample location were quantified. Combined, these data illustrate the potential for REE tracers to reveal sediment fate and transport patterns. Information gained from these studies can lead to improved water quality models and estimates of the effectiveness of best management practices and expected lag times between management actions and water quality improvements.