On the Prediction of the Characteristic Times of River Meander Cutoff Sequence: Theoretical Model and Comparison With Laboratory and Field Observations

River meander dynamics inevitably interferes with a number of human activities and productive processes. Therefore, investigating the involved physical processes and modeling their space-time evolution represent a crucial requirement in terms of sustainable river management and restoration planning. In the present study, a deterministic integral-differential equation that governs river-bend growth and death in the absence of natural or anthropic forcing is for the first time derived and solved by resorting to cardinal fluid-mechanical equations such as Navier-Stokes' in the Lamb-Oseen version. The related 1-D model, which accounts for morphology and sedimentology via the meander migration rate and its radius of curvature, proves to be able to grasp the periodic nature of the phenomenon. Additionally, it exhibits an overall very good agreement with field pre-cutoff and post-cutoff observations, as well as with the outcome of an ad hoc-designed laboratory experiment that simulated near-cutoff conditions. Hence, it may represent a fast and easy tool to monitor river bend hydro-geomorphological evolution, particularly when the signs of the incipient instability suggest quantifying the time left to its routine exploitation and to timely plan, where needed, suitable management and restoration interventions.