1a.Objectives (from AD-416)
The objective of this cooperative research is to develop computer model components, which can be coupled to CONCEPTS, for predicting the onset and continual development of river meandering.
1b.Approach (from AD-416)
A linear model of the flow in the interior of sinous streams will be enhanced to include: (1) the near-bank domain, (2) transport of graded sediments, and (3) the formation of alternate bars and point bars including simulation of changes in transverse bed profile. The stresses exerted by the flow on the streambank as simulated by the above model will be used by the process-based streambank erosion algorithms of the channel evolution model CONCEPTS to predict streambank erosion and to adjust bank profiles. The predictive capabilities of the resulting model regarding hydraulics, non-uniform sediment transport, streambank erosion, and channel migration will be validated on selected laboratory experiments, field data of single bends of sand- and gravel-bed streams, and selected multiple-bend streams segments of Tahoe Basin streams.
Components were developed to enable the ARS channel evolution computer model CONCEPTS to simulate lateral channel migration using technology from the RVR-MEANDER toolbox developed by the University of Illinois. Extensive testing of the new model for idealized river geometries and for the Mackinaw River, IL, shows that the new model more realistically predicts complex planform patterns observed in nature than the standard empirical migration methods based on calibrated migration coefficients in use today. Further, it was found that floodplain-soil complexity can greatly contribute to planform complexity of meandering rivers. The simulations performed allowed for highlighting three key parameters that characterize the effect of floodplain heterogeneity on channel planform complexity, respectively quantifying the local randomness of soil resistance, the cross-valley increase of soil resistance, and the spatial scale of soil heterogeneity. This project was monitored by meetings, phone and e-mail communications between the ADODR and principal investigator.