Numerical Simulation Of Tidal Current And Sediment Movement In The Ruyi Island Of Haikou City

In this paper,based on FVCOM to build the Haikou Ruyi Island's three-dimensional tide current and the three-dimensional bed load and suspended sediment total sediment mathematical model,the three dimensional tidal current field and three dimensional silt field in the area are calculated before and after the project.After the project,two schemes of scheme one and scheme two are calculated respectively.and detailed analysis of the distribution of the situation in the region of the three-dimensional flow field and three-dimensional sediment concentration field,and the change of annual siltation in the sea area near the project before and after the engineering.Finally,according to the calculated three dimensional tidal current field,three dimensional sediment content field and annual deposition distribution situation,the merits and demerits of scheme one and scheme two are analyzed,the main conclusions are as follows:1.The eastern side of the Qiongzhou Strait is the irregular semi-diurnal tidal area of the South China Sea,and the west is the normal diurnal tide area of the Beibu Gulf.The Qiongzhou Strait is located at the junction of the two tidal waves.Tidal characteristics such as tidal range change rapidly along the Qiongzhou Strait.Ruyi Island is located in the Qiongzhou Strait Pu Qianwan area.To the west,it is a pocket type Beibu Gulf.From the South China Sea,the tide moving north along the Beibu Gulf converges and accumulates in the Beibu Gulf,and then drains from west to east from the Qiongzhou Strait.The velocity of tidal current from west to east is larger in this area.2.At Baisha shoal.Due to the sudden increase of the cross section,the velocity of the deep channel through which the current flows through the Qiongzhou Strait began to decrease,and the coarse sand coming from the Beibu Gulf slowly desilted with the decrease of the velocity,and the Baisha shoal was formed over time.The tidal current from west to east is affected by the topography of Baisha shoal.The main stream is divided into two parts:one is moving along the deep trough outside the bay,the other is moving along the front bay in the bay.It can be seen from the calculation results that the velocity of tidal current from west to east is obviously larger,and the average velocity is about 1m/s.The anti-L-type breakwater at the middle bay of the scheme one has obvious effect on the tidal current and a better cover effect on the East Bay,resulting in the formation of a eddy current behind the East Bay.Because of the short breakwater,the scheme two has little effect on the water flow,and the eddy current behind the East Bay is nearly half smaller than that of the scheme one.3.The results show that sediment concentration in Ruyi Island is obvious,the sediment content in Puqian Bay,south of Ruyi Island,is generally small,the average sediment content is about 0.01mg/dm3,and the velocity of deep trough in the middle of Qiongzhou Strait is larger outside the Bay.The bed surface]ayer of Qiongzhou Strait is coarse sand,the sediment starts more,and the sediment content in the water is larger.In the vertical direction,the sediment content increases gradually from the surface to the middle and then to the bottom.4.By calculating the scheme one and scheme two's distribution situation of annual siltation in the sea area near Ruyi Island respectively,it can be seen clearly that the Sediment erosion and deposition situation of the scheme one is more stable than that of the scheme two,and the erosion area of the island head is less,the degree of the island body breaking is smaller,the harbor entrance silt area is smaller,less hindrance to navigation.