Study On Prediction Of The Environment Impact Of Fishing Port Engineering To Dongwuyang Internal Bay

The internal bay is a piece of land surrounded by the sea on three sides and the other side is the sea.The internal bay is in the shape of a circular arc Bay and U shaped. Usually we regard the two corresponding cape bay near the mouth of the Bay and outside the line as the dividing line.The internal bay generally locates in the shallow sea and improves the ecological function in the sea area.It is rich in biological diversity and many marine protected areas have more distribution.Although it has good natural environment in the bay area, but the environment is also highly sensitive and easy to be influenced by other factors. Because of the special geographical position, the sea water is exchanged slowly and the sediment is by the wind wave disturbance relatively small and easy accumulation.In recent years, human activities are more frequently in the internal bay and the number of ocean engineering increase quickly. These ocean engineering will cause great influence on the bay hydrodynamic environment and sediment movement. Besides,they also have inestimable influence on the ecological function in the Bay. So it is very necessary to study the impact of human activities on the environment in the internal bay.HD and MT model in MIKE21 verification were used to study the Dongwuyang, calculating and analyzing the change of Dongwuyang tidal current field and sediment field in presence of the Xiandong and Guanmen fishing port project individually and simultaneously.Which set single building Xiandong fishing port as scene one(fishing port is located in the west coast of Dongwuyang.) and set single building Guanmen fishing port as scene two(fishing port is located in the bay mouth of Dongwuyang and west side of Dongan island.).Two fishing port engineering exist at the same time as the scene three. Verified by the measured data analysis shows that the tide level calculation results and measured values are in good agreement. The two trends are basically the same, tide duration and ebb duration had little difference.The relative error of Huyuao’s velocity is 6.3%~19.9% and the direction is 0.5%~7.8%. The relative error of Xiandong’s velocity is 4.4%~18.7% and the direction is 0.6%~7.1%. The suspended sediment concentration in the model is close to the measured value, almost all in the same order of magnitude. Comprehensive comparison results show that the model can better reaction Dongwuyang practical power flow field and sediment distribution characteristics and is has a certain degree of credibility.Through the analysis of three different conditions hydrodynamic field variation. The results show that single construction Xiandong fishing port, the Dongwuyang internal bay amplitude of flow velocity area minimum; the construction of a single Guanmen fishing port, the amplitude of flow velocity has the largest area, than to build a single Xiandong fishing port flow area of the speed increase 1.6km2; when two fishing port existing at the same time, increase flow area is greater than that of single construction Xiandong harbor area smaller than that of the single building Guanmen fishing area. The mainly reason is in Dongan island and Guanmen fishing port on the west side of the existing closed channel, flow rate was higher than in surrounding areas greater. The Guanmen fishing port breakwater construction and changes around the coastline. So the waterways surrounding hydrodynamic environment more and high velocity water northward transport more kinetic energy. But due to the Xiandong fishing port in the blocking effect, water cannot continue northward transport. So if Xiandong fishing port and Guanmen fishing port exist at the same time, it will have a cumulative effect in increase the velocity of flow.Based on the comparison of the tidal volume of three kinds of different scenes in the Dongwuyang internal Bay area, the water flux of the west side of the Dongwuyang is decreased to 17.6% than the water flux under the natural condition and the amplitude of reduce is much larger than the east mouth of the Dongwuyang internal bay. As the fishing port engineering construction is located in the west of Dongwuyang and the water flux of the mouth of the Bay on the west side is more direct. comparing three different scenes,the Dongwuyang West Bay saliva flux and found that the construction of a single guanmen fishing port of the largest water flux, contaminations in the scene two can quickly exhausted and improve the ability of water self purification.The saliva flux changed a little in the east of Dongwuyang internal bay and has less impact on the eastern coast.Comparing with three different scenes, the change of sediment scouring and deposition in the sea floor shows that the area of the strong erosion area of the scene two is the largest, reaching 1.86 km2. The reason is the high speed water from Guanmen channel transport to northward smoothly, thus leading to strong erosion area extends northward.The strong erosion area of scene three is 0.93 km2.Because the guanmen fishing port breakwater construction to change the characteristics of the shoreline and the flow velocity outside of breakwater increases which making Guanmen waterways within the water flows through the Guanmen fishing port becomes more smooth. But exists the Xiandong fishing port at the same time, the strong erosion area to extend northward. This is also the two fishing port exist at the same time of sediment erosion and deposition produce a result of the cumulative effect. The area of the scene one is the smallest, which is 0.75km2.There are 26 kinds of algae and 21 species of zooplankton in the area which from the Guanme waterway to Xiandong fishing port the fairy. Guanmen fishing port engineering construction of the Guanmen channel waters near the water slightly turbulent, will cause the deposition at the bottom of the suspended sediment and lead to the water turbid. It will affect the growth of algae and zooplankton and reduce the production of cage culture area and kelp seaweed culture area. large yellow croaker spawn regional distribution will be changed.