Sediment Transport At The New Outlet Of Yellow River And Changes Of Erosion And Accumulation

Yellow River (Huanghe) breach and diversion of the river course happenedfrequently through the whole historical period under the integrated impacts of natureand human factors. Since an artificial diversion has carried out in 1996, peopleintervention stabilized the present channel and protecting delta environments. Duringthe changed of the water and sand, discharge riverine and oceanic dynamics in theYellow River estuary have changed greatly. The new particular characteristics haveshowed in the delivery and distribution of river sediment discharge, the coastalconfiguration of Yellow River delta. The coastline changes, spatial-temporal changesin sediment density current at the new outlet and the erosion and accumulation ofsubaqueous delta of the old and new Yellow River mouth have been analyzed in thispaper, based on the synchronous hydrological observation data, remote sensinginterpretation, bathymetric charts and so on, and the technology remote sensing imageprocessing, spatial analysis of GIS and mechanical calculation of sedimenthyperpycnal plumes were used.The results show that the speed of accumulation is more quickly in the first stagesdue to the effect of topography in the river estuary, water and sediment discharge.Then river mouth area has almost maintains the dynamic balance after the man-madewater transfer in 1999. But in recent years the new mouth area suffered continuallyfrom sediment washing out and serious beach erosion. Till 2000, the net accumulationof sediment in river estuary is 10.28 hundred million tons which is less than the riversediment discharge. The spatial distribution of sediments deposition at the mouth isuneven, because the river channel leaned to north at the new outlet and the tidalcurrents impacts at both sides, A majority of sediments deposit at deltaic front and asmall quantity of sediments transport to the side, sediments to the north is more thanthat to the south.Hyperpycnal plumes have happened frequently at the new mouth. Rapiddeposition of river sediments discharge at the mouth, transported by gravity-drivenunderflows, has significant impact on the subaqueous delta sedimentary system andthe configuration of esturine spit. The relationship between the appearance anddevelopment of hyperpycnal plumes and the period of tide, and the change of currentspeed all have shown new particular characteristics.