| 摘要: |
| 用物理模型实验和数学模型计算相结合的方法，研究了均匀缓坡岸滩上，规则波及不规则波浪作用下形成的沿岸流及其对岸边排放污染物输移扩散的影响。针对渤海湾的地形和主要波浪方向，研究了渤海湾主要排污口附近单纯波浪以及波浪、潮流共同作用下近岸海域内流动速度分布与相应污染物输移扩散规律。结果表明，在渤海湾近岸海域(一定范围内)，污染物输移扩散受到波浪作用的影响，表现为平行岸线方向。波浪作用使得远离污染物排放口的滩涂受污染的影响增大。 |
| 关键词: 渤海湾，波浪，近岸流，污染物输移扩散 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金重点资助项目，59839330号；国家自然科学基金资助项目，19772031号 |
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| THE STUDY OF POLLUTANT TRANSPORT ON THE ACTION OF WAVES IN THE NEAR-SHORE AREA OF BOHAI BAY |
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SUN Tao, TAO Jian-Hua
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Department of Mechanics,Tianjin University
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| Abstract: |
| Bohai bay is a typical example of shallow water，mild slope beach with weak water exchange ability in the west of Bohai Sea in China．Accompanying the rapid economic development in the Bohai sea coastal regions has be en a serious deterioration of water quality，mainly due to influx of wastewater from Beijing，Tianjin and Hebei province．The ecological environment has been altered and red tides(HAB)now appear frequently．The transport of pollutant is complex in the near-shore area because of the effect of many dynamic factors．In this paper，the state of contamination in the near-shore area of Bohai bay，especially the effect of wave-induced current，the influence of waves on pollutant transport in the near-shore area of Bohai bay is studied by physical experiment and numerical simulation．
The experimental and numerical study on pollutant transport on the action of the regular and irregular waves is investigated for two mild beaches with different slope s in a wave basin．The numerical model is combined with a wave propagation model，a wave-breaking model，a wave-induced current model and a pollutant transport mode1．The numerical wave propagation model is established based on the high-order approximation of parabolic mild slope equation and it can be used to simulate the wave refraction，diffraction and breaking in the near-shore area combined with wave breaking mode1．The wave-induced current model is based on the concept of the radiation stress．
The experiments of long-shore current were conducted in the wave basin，which is 42.6m long，24.0m wide and 1.0m deep．The plane beach was rotated at 30。 with respect to the wave marker to increase the length of the beach and make the wave propagate obliquely to the shoreline．Long-shore current induced by the regular and irregular waves with different wave factors is investigated over two mild beaches with different slopes．The agreement between numerical and experimental results is good．The results proved that the pollutant transport in the area outside of the surf-zone is not significantly affected by the effect of wave, and pollutant transport will be parallel approximately to shoreline on the action of wave in the surf-zone.
The effect of waves on pollutant transport near the main sewage outfalls in the Bohai bay were studied by analyzing the distributions of velocities and the pollutant transport under pure wave，pure tide and the combined action of wave and tide． It is concluded that the pollutant transport is influenced significantly by the wave action at certain areas of near-shore zone with mild slope beach．The contaminated area on the combined action of wave and tide is similar to the results on the effect of pure wave．The effect of wave is that contamination is far from outfall in the near-shore zone．The effect of tide current is to extend the contaminated area across to the shoreline．
The direction of pollutant transport is parallel approximately to the shoreline and changes according to wave direction．Compared to the results from regular wave and single-directional irregular wave，cross-shore distributions of current induced by multi-directional irregular waves are more gentle and the pollutant transport on the action of single-directional irregular waves are similar to the results of regular waves．Due to the effect of the waves，the mudflat will be contaminated even away from sewage outfalls．It is thus important，when designing wastewater outfall locations，to place the outfall location outside the surf-zone by considering the action of waves on mild slope beaches such as Bohai bay. |
| Key words: Bohai bay,Water waves,Near-shore curent,Pollutant transport |
