Evaluation of Total Sediment Transport Model in the Simulation of Morphodynamics in Two Different Hydrodynamic Settings

Abstract

The bed level change in rivers and estuaries due to several dynamic parameters such as tide, waves, river discharge, and wind is a common problem. The current practice is to predict the changes through numerical modeling and compare it through field measurements. The empirical relations to be adopted for the sediment transport estimation form an integral part of morphodynamic models. In this study, five different total sediment transport formulae have been incorporated in the morphodynamic routine of a circulation model. The hydrodynamic model accounts for tide-induced flows, tide being the dominant forcing in the estuaries considered for the study. The preceding sediment transport formulae for predicting bed level changes (erosion and accretion) are subjected to an assessment, through statistical approaches, to find the most suitable formula for different hydrodynamic settings of a macrotidal estuary (Hooghly) and a microtidal estuary (Cochin). The results are validated with the field measurements and finally the appropriate empirical formula is designated based on a detailed analysis. The AW model outscores in the Brier skill score (BSS) analysis and thus qualifies to be most suited sediment transport model for the macrotidal estuarine dynamics with a score of 0.55, and the AW model is followed by the VR model with a score of 0.52. As per BSS, the EH model falls under the Good model category with a score of 0.48, for the microtidal estuary and thus qualifies to be the better suited sediment transport model among the models considered.