Research On The Controlling Function Of Laizhou Shoal To The Sedimentary Dynamic Patterns Of East Of Laizhou Bay

Laizhou shoal locates in inshore of Diao Longzui, southeast bank of Laizhou Bay,it’s asand spit underwater shoal up to16km.The shoal impacts the hydrodynamic environment,transport of sediments, erosion and silt of seabed and evolution of the beach of east of LaizhouBay profoundly. In recent years, due to constructions of reservoirs at upper reaches of riversinpouring into northeastern of Diao Longzui and small scale shoal dredging， the erosion anddeposition balance nearby Laizhou shoal is broken,causing a series of dynamic landscapechanges in eastern LaizhouBay, resulting in a great impact on the local mariculture and coastalconstructions. Research on the controlling function of Laizhou shoal to the sedimentary dynamicpatterns of east of Laizhou Bay can provide decision support and basis of project construction,environmental protection and management, resource management and comprehensive utilizationin the study area for the government.This thesis use quasi-harmonic analysis method to analyze characteristics of the tidal andthe trend of the study area; use particle size analysis method to analyze the composition anddistribution characteristics of the surface sediments of the study area, especially analyze thesurface sediment distribution characteristics and influencing factors of Laizhou shoal; usedepth comparison method to analyze characteristics of topography evolution of the study area;use CERC formula to calculate rate of alongshore transport of sand of northen coast of Laizhoushoal，and qualitatively analysis erosion and deposition of different shorelines according to theresults of rate of along shore transport of sand; use the hydrodynamic module and sedimenttransport module of Mike21software to simulate characteristics of the tidal current field,the wave field and the erosion and deposition fo seabed of the study area. On this basis, thecontrolling function of Laizhou shoal to the sedimentary dynamic patterns of east of LaizhouBay is studyed, the results show that:Tidal of the study area is irregular semidiurnal tide, tidal current of the study area isirregular half-daytrend, reciprocating current dominants the tidal current，residual current ofthe study area vary from1.4cm/s to5.3cm/s.Dominated surface sediments of the study area is sandy silt, from the shore to the sea,as the depth increases, particle size of surface sediments becomes gradually fined, mediandiameter, averageparticle size and sorting coefficient are symmetric in Laizhou shoal, from top of the shoal to both sides,the particle size becomes smaller, the separation gets worse.The study area is in the micro-silting as a whole, Qi Mu Island erosion amount is less than2cm, Longkou Bay is basically in the erosion and deposition equilibrium Jiehekou to Shihuzuinearshore maximum scour is about10cm, stone tiger mouth to three mountainIsland inshore deposition amount is less than12cm, Diao Long mouth nearshore erosion is about4cm, the Laizhoushallows northeastern side of the maximum deposition thickness of about2.5cm, shoal southwestside of the maximum scour the amount is up to5cm, the northwest side of maximum depositionup is9.5cm thick, Pacific Bay is basically in the erosion and deposition equilibrium.Laizhou Shoal barrier fluctuation trend in the shallows at the top of the flow rate larger in the shallows on both sides and the formation of a roughly symmetrical rotation is in the opposite direction of circulation, the flow rate of the circulation center is small; broken in the wave of the shoal beach top at Shoal South side of the tide and wave and hydrodynamic conditions are weak, and shallows south side of the waters formed a good cover; partial N-SW blocked in the shallowsto the longitudinal sediment flow in the shallow roots uninstall accumulation in the wave formation of the Big Wave pushing to the NW direction along the shallows handling, continue to shape the modern Laizhou shallows across the shallows to less S to continue handling the amountof sediment. The south side of the shoal waters sediment transport is not obvious, basically in theerosion and deposition equilibrium.