Hydro-morphodynamic numerical modeling indicates risk zones for riverbed clogging

Area of Science:

• Environmental Science
• River Ecology
• Sedimentology

Background:

• Riverbed clogging by fine sediments impairs aquatic habitats by reducing permeability, porosity, and oxygenation.
• Current clogging assessments often lack predictive capabilities, hindering effective habitat restoration in mountain rivers.

Purpose of the Study:

• To evaluate a two-dimensional (2D) numerical model for simulating fine sediment infiltration and mobilization.
• To assess the model's predictive capacity for identifying clogging-prone areas in gravel-bed rivers.

Main Methods:

• A 2D numerical model was developed and calibrated using field data from a controlled morphodynamic gravel-bed channel.
• The model simulated fine sediment dynamics around large wood pieces before and after an artificial flood.
• Model outputs were compared with measured sediment parameters to validate its performance.

Main Results:

• The model accurately reproduced fine sediment distribution in surface and subsurface layers.
• It identified a high-velocity zone with declogging and a slower zone with increased fine sediment accumulation.
• Simulated data revealed how floodplain swales contribute to downstream fine sediment infiltration and clogging.

Conclusions:

• A robust 2D numerical model effectively captures fine sediment dynamics in gravel-bed rivers.
• The model can reliably identify areas susceptible to riverbed clogging.
• This predictive tool is valuable for optimizing habitat restoration strategies in mountain rivers.