Momentum-Impulse Model of Fine Sand Clogging Depth in Gravel Streambeds for Turbulent Open-Channel Flow

Abstract

Amomentum-impulse model that accounts for the critical impulse of a particle bridge that is balanced with a fluid pulse resulting from turbulent pumping is presented and applied for predicting the clogging depth of fine sand in gravel streambeds overlain by turbulent open-channel flow. The model was tested against the literature-derived database of clogging depth with conditions defined by hydraulic flume experiments characterized by fine sand infiltrating into gravel substrates, with hydraulically-rough open-channel flow ranging from subcritical to critical conditions. Results show the efficacy of the momentum-impulse model and support the hypothesis that particle bridging and intragravel flow due to fluid pumping control the clogging depth. Model results show improvement over previous empirical modeling of the clogging depth phenomena due to the reduction of unknown parameters from four coefficients to one coefficient and an increase in model predictability as quantified using k-fold validation and model comparison. A set of curves developed from simulations of the validated momentum-impulse model is provided, which will be useful for stream-restoration practitioners interested in estimating embeddedness. In addition, the clogging profile is shown using clogging depth predicted with the momentum-impulse model, which is an additional application of this work.