Numerical modeling of bedload and suspended load contributions to morphological evolution of the Seine Estuary(France)  

作　　者：Baptiste Mengual Pierre Le Hir Aurelie Rivier Matthieu Caillaud Florent Grasso 

机构地区：[1]IFREMER,DYNECO/DHYSED Laboratory,Centre de Bretagne,CS 10070,29280,Plouzane,France [2]UMR 7266 LIENSs,CNRS-La Rochelle University,17000,La Rochelle,France [3]IRSN(Institut de Radioprotection et de Sûrete Nucleaire),PRP-ENV/SERIS/LRC Laboratory,50130,Cherbourg-Octeville,France

出　　处：《International Journal of Sediment Research》2021年第6期723-735,共13页国际泥沙研究（英文版）

摘　　要：This numerical modeling study(i)assesses the influence of the sediment erosion process on the sediment dynamics and subsequent morphological changes of a mixed-sediment environment,the macrotidal Seine estuary,when non-cohesive particles are dominant within bed mixtures(non-cohesive regime),and(ii)investigates respective contributions of bedload and suspended load in these dynamics.A three dimensional(3D)process-based morphodynamic model was set up and run under realistic forcings(including tide,waves,wind,and river discharge)during a 1-year period.Applying erosion homogeneously to bed sediment in the non-cohesive regime,i.e.,average erosion parameters in the erosion law(especially the erodibility parameter,E0),leads to higher resuspension of fine sediment due to the presence of coarser fractions within mixtures,compared to the case of an independent treatment of erosion for each sediment class.This results in more pronounced horizontal sediment flux(two-fold increase for sand,þ30%for mud)and erosion/deposition patterns(up to a two-fold increase in erosion over shoals,generally associated with some coarsening of bed sediment).Compared to observed bathymetric changes,more relevant erosion/deposition patterns are derived from the model when independent resuspension fluxes are considered in the non-cohesive regime.These results suggest that this kind of approach may be more relevant when local grain-size distributions become heterogeneous and multimodal for non-cohesive particles.Bedload transport appears to be a non-dominant but significant contributor to the sediment dynamics of the Seine Estuary mouth.The residual bedload flux represents,on average,between 17 and 38%of the suspended sand flux,its contribution generally increasing when bed sediment becomes coarser(can become dominant at specific locations).The average orientation of residual fluxes and erosion/deposition patterns caused by bedload generally follow those resulting from suspended sediment dynamics.Sediment mass budgets cumulated over the simulated

关 键 词：Non-cohesive sand-mud mixtures Erosion Suspended sediment transport Bedload transport MORPHODYNAMICS Seine Estuary 

分 类 号：TV142[水利工程—水力学及河流动力学]