2025 CSDMS meeting-123
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Equilibrium Geometry of Sand-Bed Rivers: Insights from Morphodynamic Controls and SRLP
Nilay Iscen,
University of Minnesota Minneapolis Minnesota, United States. iscen001@umn.edu
Andrew Wickert, University of Minnesota Minneapolis Minnesota, United States. awickert@umn.edu
The sand-bed river long-profile evolution model (SRLP) is a complete mechanistic model, describing both transient and steady-state long-profile evolution of a transport-limited sand-bed river with self-forming channel width adjustments by linking sediment transport and river morphodynamics. SRLP allows for planform adjustments as a function of excess shear stress, which is directly related to the critical stress of the bank material (following Parker, 1978, and Dunne and Jerolmack, 2018), thereby linearizing the sediment-transport response to changing river discharge. This one-dimensional, physics-based model captures the internal dynamics of this inherently complicated system, quantifies the changes in the river's bed elevation, cross section, and channel slope, and ultimately provides the critical information about how the river is responding to both natural and anthropogenic disturbances. Our work so far has explored the variability in topographic responses of both steady-state and transient sand-bed channel long-profiles to the changes in sediment and water supply and base level by utilizing SRLP. We also further build on this understanding of how sand-riverbed mobility and the physical factors controlling it couples to the channel form is a key mechanistic link for predicting river response to those external perturbations. Therefore, we now consider how the equilibrium geometry of sand-bed rivers varies as a function of physical controls such as grain size, bed roughness, and bank strength, all of which modify the effective stress available for sediment transport. Then we evaluate the path to steady‐state long-profiles using numerical morphodynamic experiments by SRLP.
