| The Yangtze River Estuary waters have many ship harbors and waterway engineering,which provides great convenience for the economic construction of the coastal city especially Shanghai.Besides that,it's also the only sea channel in the Valley provinces.However,the Yangtze River Estuary waters is a disaster-prone region,the strong wind waves will be directly ringing to all kinds of marine engineering and the safety of people's life and property,while the patency of the Yangtze River Estuary is always related to the local shipping economy,and then affect the economic development of Yangtze River Delta region.The waters near the Yangtze River Estuary are shallow,the beach trough staggered and the hydrodynamic environment is complex.In the processing of spreading the waves from the offshore to the Yangtze River Estuary and adjacent waters,the influence of complex topography and depth will cause in a series of near-shore changes such as refraction,diffraction,fragmentation and reflection.As the medium strong tidal estuary,the waves are disturbed by the tide and tidal currents.In addition,with the expansion of the scale of marine engineering,especially under the condition of cold air and Typhoon weather.The single-station wave information obtained from the site observation is difficult to meet the design requirements.The wave field and element distribution of the Yangtze River Estuary can be simulated well under the condition of guaranteeing precision,using the wave forecasting model SWAN.This paper aims to construct a wave numerical model suitable for the Yangtze River Estuary based on the WRF wind field and wave data.Through the grid nesting of the Yangtze River Estuary in the East China Sea.In the case of the model simulation precision,it simulates the channel engineering and the situation under different astronomical tides.Under the condition of different wind direction,the more the wave from the offshore to the near shore broadcast to the waterway,the more effective wave height gradually decreased.The channel on both sides of the effective wave height's difference is obviously.Different astronomical tide causes the effective wave height difference.Obviously,the wave direction but the difference is not big.Under the effect of eastward wind,the effective wave height decreases obviously with the channel influence,and the effective wave height difference is obvious in the same latitude.The wave direction is shifted slightly northward from the external wave to the apparent change,in the north side of the waterway is almost parallel to the engineering edges,and the waves are distributed along the edge of the channel south.Under the influence of different astronomical tides,the effective wave height at the entrance of waterway is slightly larger than the NEAP in the tide.The difference between the two is not very large in the channel,but the distribution of wave propagation is greatly influenced by the neap of the effective waves in the channel.The distribution difference of effective wave height on the right side of nine sections of sand is also obvious.When the southwestward wind is acting,the effective wave height varies obviously in the roadway.Affected by the North side project,the effective wave height distribution is obvious.The waves are almost along the path parallel to the waterway engineering into the fairway,in the passage of the spread of the project,the edge of the south side of the distribution of waves along the direction of the project,near the shore of a slight southward offset.The inner wave direction is identical to the incoming waves,and the marginal waves in the north side are distributed along the project,and slightly northward.The effective wave height is slightly larger than the neap when the tide enters the fairway,and the effective wave height in the waterway is obviously distributed.The distribution of effective wave height in the right half of waterway engineering is basically the same,and the influence range is larger.The distributions of the left half segment were significantly different during neap.The distribution of waves is roughly the same.For the Yangtze River Estuary under the cold air process,the condition of not joining the flow field and the water level,adding only the water level condition,adding only the flow field condition and the comprehensive water level and the flow field in condition 4 is simulated.In the first case,the case of the water level and the flow field,the effective wave height varies considerably under the influence of wind speed,and the wave cycles and wave direction are smaller in the case of sudden change of wind velocity.In the second case,the result of the model is generally higher than the measured value in the case of water level,which indicates that the water level has a great influence on the effective wave height,and the wave height and cycle are periodically changed.In the third case,only the flow field is considered in the early stage of cold air,the flow field increases the efficiency of the wave.In the medium term,the flow field makes the effective wave high slightly lower.In the fourth case,when the water level and the flow field are synthetically considered,the result of the model calculation is higher than the measured value when the water level is considered in the middle of the cold air.While considering the flow field model is less than the actual measurement,these two conditions are balanced;but because the water level has a relatively large influence on the wave height,the wave height is the same as the changing regularity of the wave height and the cycle when the water level and the flow field influence are considered.According to the parameters of different recurrence period,the peak wave height and wave height frequency distribution in the offshore waters of the Yangtze River Estuary are calculated.The rose charts of different waves are calculated and the hazard grading maps of the Yangtze River Estuary are drawn up based on the formula of risk assessment. |
PDF Full Text Request