On June 7th, 2017 at 2.30 pm, "Morphodynamics of Gravel-Bed Rivers" seminar will take place at DEIB Seminar Room "Alessandra Alario" (building 21), as new appointment of HIL Seminars.
It is estimated that roughly half of the sediment eroded from the continents originates: in high relief mountainous areas, which comprise only ~10% of the Earth’s surface. The rivers draining these areas are thus tasked with carrying large volumes of sediment, but typically only when discharges are much higher than average. Measuring sediment loads at these discharges is challenging, even in the best of circumstances, thus it is useful to have alternative methods for estimating sediment transport rates. In this talk I will discuss some of the research done by my group to improve methods for modeling bed load transport rates when it is impractical to measure them. Our results pertain mostly to gravel-bed rivers. I will also discuss simple but physically based relations between bed load transport and channel geometry derived from field measurements in many gravel-bed rivers in North America. We find that the range of flows under which channels transport large volumes of bed load yet remain stable is relatively narrow. One of the biggest challenges we face in modeling the morphodynamics of gravel-bed rivers is in coupling the various relations for flow and sediment transport with the relations that characterize bank instability and channel widening.
Biography: John Pitlick is a Professor in the Geography Department, University of Colorado-Boulder. His research focuses on linkages between surface-water hydrology and geomorphology in high-gradient rivers. The main objective of this work is to develop a more complete understanding of the coupling between rivers and their surrounding landscapes. Field work is an important component of this research; the overall approach is to integrate field data with modeling to quantify the effects of sediment transport on the natural functioning of rivers. Several projects done in collaboration with aquatic ecologists have focused on the role of fluvial-hydraulic processes in altering habitats for fish and benthic organisms. He has worked throughout the state of Colorado, the Pacific Northwest, the northern Rocky Mountains and the French Alps. He is also co-director of the Graduate Program in Hydrologic Sciences at CU-Boulder.