Evolution Of Yellow River Mouth And Effect On Stability Of Estuary Lateral Bay Artificial Island

The modern Yellow River mouth is an important shallow water oil and gasregion，namely Sheng Li Ken Dong oil and gas region, for exploitation on land YellowRiver diversion in1996by human and also construction of many artificial islands.Therefore, in the paper, basing on the measured data and experimental data study andanalysis on the erosion and deposition, the structure of the shallow strata andpreliminarily discuss on the engineering stability of esturay lateral bay artificial islandin modern Yellow River mouth.Through remote sensing image MSS754, TM432false color composite images,extraction many periods in the main river channel of water and coastline (low tide line)by visual interpretation, and with hydrological data etc. mainly study on the evolutionof river channel, coastline changes, and inshore erosion and deposition since1996.The conclusions show: Now large-scale diversion of Yellow River channel entirelycontrolled by human, river channel in Single and straight stage at the beginning andmore years of use, but downstream of artificial river channel, river channel in thenatural state, still swings frequently but in small-scale, diversion2times(divided into3stages). In new Yellow River mouth region the coastline extension and expansionrapidly in1996-2005, eroded backward in2005-2007, expansion rapidly on both sidesof spit and on top but from extension forward slowly to finally eroded backward in2007-2011, but in old Yellow River mouth region the coastline continuously erodedbackward in1996-2011, in total back approximately7.19km. Regarding estuarylateral bay artificial island as the boundary eroding on the south side and depositingon the north side.With use of historical documents and data mainly analyzing on evolution ofdeposition environment since1855and the structure of the shallow strata in old Yellow River mouth region, new Yellow River mouth region and estuary bay region.The conclusions show:(1) In old Yellow River mouth region from bottom to topmainly followed by shallow marine sedimentary facies, prodelta sedimentary facies,delta front remote dam sedimentary facies, estuarine sand bar sedimentary facies;(2)In new Yellow River mouth region from bottom to top mainly followed by shallowmarine sedimentary facies, prodelta sedimentary facies, delta front remote damsedimentary facies, delta lateral margin sedimentary facies, estuarine sand barsedimentary facies, river sedimentary facies;(3) In estuary bay region from bottom totop mainly followed by shallow marine sedimentary facies, prodelta sedimentaryfacies, delta front remote dam sedimentary facies, delta lateral margin sedimentaryfacies. In new and old Yellow River mouth region, easily developing weak layers inlower strata, sediment particles coarser and weigher in upper strata but finer andlighter in lower strata, which shows the inverse graded bedding structure, but inestuary bay region finer in both lower and upper strata.By processing drilling and shallow profile data, especially main analysis on thevertical variation feature of moisture content, liquidity index, compressibility factoretc. important engineering parameters in0-40m. The conclusions show: In lateralartificial island region the main material components of shadow strata is silty clay,especially in strata formed since1855sediment particles finer, higher moisturecontent and higher liquidity index and higher compressibility factor than in muchlower strata. Besides, in upper strata there are weaker layers that own much highermoisture content and much higher liquidity index and much higher compressibilityfactor than in adjacent low and up strata. Lastly, according to the differences ofengineering and mechanical strength in0-40m divided into6large strata, engineeringSuitability of all strata are not good, moreover, most of very bad.Through study and analysis on feature of erosion and deposition above, withestuary lateral bay artificial island engineering specific analyze on region engineeringstability. The conclusions show: In new Yellow River mouth coastline expansion onboth sides of spit, the top of delta spit flattened and no extension seaward because oferosion by NE waves, and old Yellow River mouth spit constantly erosion to smaller, which leads to estuary lateral bay artificial island finally in open sea, which may facemore stronger ocean dynamics, and whose stability will be threatened. Besides, innorth side of estuary lateral bay artificial island, in new Yellow River mouth region,the strata subside rapidly, but in old Yellow River mouth region and lateral bayartificial island region slowly, which leads to arise the uneven subsidence, which willthreaten engineering foundation stability in lateral bay artificial island region.