This project seeks to predict how gravel braided rivers will respond to changes in sediment supply, which may be expected as a result of climate change. It seeks to better predict the response of braided rivers to changes in flooding regimes and sediment supply by combining unprecedented high-resolution data from braided rivers in Scotland and New Zealand with a new simulation model that will allow predictive experimentation over tens to hundreds of years. The project addresses a deficiency in current predictive river modeling capability by developing a model many researchers have called for over the past two decades. We have a pilot version of this model working and we will extend, refine, and rigorously test this model before making it available to the broader research and river management communities. The insight gained from our planned experiments, as well as our plan to make the new modeling tool available, may open up new avenues of experimentation and discovery.
Braided rivers are those in which the flow is divided into multiple parallel channels that split and come back together around large bars (sediment deposits) repeatedly like the intertwined strands of a rope. Braided rivers represent some of the most energetic and rapidly evolving environments and are frequently hotspots for biodiversity and serve as vital habitat for salmon as well as other highly valued species. Braided rivers were historically much more common, but engineering and river management have worked to discourage braiding. Increasingly, efforts to restore rivers are recognizing the importance of sometimes promoting braiding. It is likely that climate-change-induced shifts in flooding and the amount of sediment (e.g., gravel and sand) supplied from upstream could push many rivers back to a braided state. Despite the importance of braided rivers, our ability to predict their behavior and understand their function is immature at best. This project aims to advance both. Aside from the scientific value of the research, the project can help provide guidance to river managers and restoration practitioners charged with working with and/or restoring braided rivers. These professionals are seek reasonable quantitative predictions for managing braided rivers. The project broadens the participation of underrepresented groups through initiatives involving research opportunities for undergraduates and new experiences for K-12 students. The project leverages a variety of existing resources (e.g., field data, computational resources, outreach programs, web portals) by pursuing collaborations with funded efforts of other organizations, some supported by NSF. Finally, the modeling approaches developed as part of this research could help advance simulation modeling efforts in other fields interested in forecasting climate change impacts and/or environmental management.
