黄浦江河口水沙输运机制研究

Water and sediment transport mechanism in the Huangpu River Estuary,Shanghai

受潮汐影响的弯道泥沙输运表现出与径流弯道不一样的现象.本文运用通量分解机制法,以黄浦江河口大潮期间实测水文资料为基础,对黄浦江河口受潮汐影响的弯曲河道水沙输运进行机制分析.结果表明,黄浦江河口水沙输运受弯道环流影响可分为纵向输运和横向输运.纵向水体潮周期净输运因径流作用指向口外,泥沙潮周期净输运因潮泵输运大于平流输运指向口内.潮周期横向水体净输运和泥沙净输运均指向凸岸,其中横向水体输运以欧拉输运为主,横向泥沙属于以平流项为主.通过比较水量输运的纵横比和泥沙输运的纵横比可得黄浦江河口大潮期间水量潮周期横向净输运大于纵向,泥沙是纵向大于横向.说明潮泵输运在黄浦江河口大潮期间起主导作用.

Sediment transports in a bend channel affected by the tide are different from those dominated by the riverine flow.This paper used the flux decomposition mechanism method to examine the water and sediment transports in the Huangpu River Estuary,basing on the field observations in the 2002 flood season.The results showed that the water and sediment transports in the Huangpu River Estuary consisted of longitudinal and transversetransportsinduced by the secondary flow.The net water transport averaged over a tidal cycle points to the ebb direction,and the net sediment transport points to upstream dominated by the tidal pumping effect.The net transport of both water and sediment across the channel over a tidal cycle direct to the convex bank,in which an Euler transport predominated in water transport,and an advection transport controled sediment transport.Compared the longitudinal with the transverse water and sediment transport fluxes,we found that the cross-channel net water transports were bigger than along-channel fluxes over a flood tidal cycle while cross-channel sediment transport fluxes were smaller than along-channel fluxes,which implied that the tidal pumping played the major role in the net transports of sediment in the flood season.