CAREER: Experimental and Theoretical Investigation of Sediment Supply and Sorting in Meandering Rivers

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A non-technical description of the project's broader significance and importanceMeandering river channels are one of the most iconic features of the landscape and the migration of these large bends in rivers are a direct concern to communities and landowners along the flood plain. The mechanisms of meander formation and migration have long attracted the attention of scientists and engineers. There remain, however, considerable gaps in knowledge of these channels, especially regarding the dynamic interactions among sediment supply, grain-size of river bed sediment, and the river-bed topography. The scientific focus of this CAREER project is to explore these relationships using laboratory flume experiments, analytical theory, and numerical modeling. The results of this research will have applications to pressing societal issues such as flood protection, stream channel maintenance, river restoration, and dam removal. The research will be integrated with an educational and outreach program designed to introduce K-12 students and the public to important issues in river science and management, and to improve the educational experience of undergraduate and graduate engineering students.A technical description of the projectThe scientific objectives of this project are 1) to investigate how channel curvature affects equilibrium patterns of bed topography and surface sorting, 2) to examine how changes in sediment supply affect sorting and bed topography in meandering channels, and 3) to explore the interactions of free and forced bars in meandering channels of mixed grain size sediment and variable sediment supply. A comprehensive suite of flume experiments will be conducted to test several hypotheses. The first experiments will use detailed flow and sediment transport measurements to examine the mechanisms controlling equilibrium conditions at different meander curvatures. The second experiments will focus on questions related to sediment supply effects on bar-pool morphology and the interactions between free and forced bars in curved channels. In conjunction with Italian colleagues, the project will develop a theoretical model for river meandering that incorporates sediment supply and grain sorting. This new model, along with two-dimensional numerical models, will extend knowledge of processes of meandering channels beyond the scales achievable in the laboratory.