The Study Of Coastline Evolution For Muddy Coast At The South Bank Of The Aojiang River

Headland bay is an important coastal landform and its coast is always separated by natural headland and forms the specific shoreline outline because of sediment deposition under the action of hydrodynamic. Many scholars studied the shoreline outline among headland bays by parabolic and hyperbolic model and the studied shoreline is mainly the sandy beach resulted from wave action. While there are seldom studies on muddy coast among headline resulted from wave and tidy along Zhejiang province.This paper takes Cangnan County, Wenzhou City, Zhejiang Province, South coast of Aojiang River as a research area and the coast of South Bank of Aojiang River evolves by natural factors and human factors and this article just studies the south coast of Aojiang river from the natural factors.According to the simulation results of Aojiang River south coast, parabolic model can be used to simulate muddy shoreline among headline bay and much better than hyperbolic model. Aojiang river south coast is overall balance in1989under the wave action and it is conformed to the result of shape elements formular comuputing, which uses flat coastal morphological parameters static equilibrium shape parabolic relationship determination, combined with a balanced Cape Coast Bay-type form factor formula to compute.In the process of establishing the parabolic model,C2correction equation is obtained. At the basis of plane form of Oliveira analysis among headlined, fit multiple C2value data, and C2correction equation is obtained. Take flat shape parameters of a number of domestic bays into modified equation to vertify, the accuracy of C2can reach99.99%, and distortion C2value can be accurately amended. Established standard parabolic model is applied to research standard of muddy coast. The erosion of shoreline can not be determined when simulating shoreline falls the landside of natural shoreline and it is only be considered unstable or dynamic equilibrium. The shoreline is accreted or not depends on the variation trends of natural coast outline.The wave action and tidy action should be considered at the same time when simulate muddy coast line by parabolic model and get the shoreline variation trends of the following year. In1989, the south coast of Aojiang River is been sedimentation overall and coast line continues expanding to sea. In1990, the south coast of Aojiang River is unstable overall and sedimentation is much greater. In2006, the south coast of Aojiang river is balance overall.The reasons why the south coast of Aojiang River deposited suffered by wave, tide and etc. Waves rush to the beach berm and will come back to sea with large amounts of silt material and deposit gradually. The tidy flow rate is less than the carrying sand flow rate near the south coast of Aojiang River, and the sands will deposit in the bay. The sediment is mainly the terrigenous material carried by Yangzi River, about30%of deposition inputted to the sea near Zhejiang and the south coast line of Aojiang River slows down and appears signs of balance.