A Novel Framework for Simulating Particle Deposition with Moving Bedforms

Previous modeling studies of hyporheic exchange induced by moving bedforms have used a Lagrangian frame of reference, typically a simulation domain that moves with an individual bedform. However, that approach is not suitable for simulating the exchange and accumulation of fine particles at a specific location by the migration of a series of bedforms, which commonly occurs in sand-bed streams. Here we present a novel simulation framework that represents mobile bedforms with a moving-interface domain and determines the resulting hyporheic transport using particle tracking. Simulation results successfully reproduce observations of clay deposition in sand beds, and the resulting development of a low-conductivity layer near the scour zone. Increased bedform celerity and filtration both lead to shallower depth of clay deposition, and a more compact deposition layer. While increased filtration causes more clay to deposit, increased celerity reduces deposition by flattening hyporheic exchange flowpaths.