江苏如东人工岛建设对周边水动力及泥沙冲淤的影响

Influence of Construction of Artificial Island in Rudong,Jiangsu,upon Hydrodynamics,Erosion and Siltation in Surrounding Water Areas

在南黄海辐射沙洲这样一个水动力和泥沙环境都相当复杂的区域建设浅水人工岛,不仅要考虑人工岛本身的稳定型问题,还要深入地认识浅水人工岛建设引起的流场和泥沙冲淤是否造成目前潮流动力场和"水道—沙洲"系统格局的较大变异、自然演变的趋势性过程是否因人工岛建设而加速或逆转。通过整体潮流泥沙物理模型研究了西太阳沙人工岛工程对滩槽演变趋势的影响和工程区滩冲槽淤的短期波动,探讨了如东人工岛工程建设后,岛周围水动力和泥砂冲淤的变化规律,提出了相应的防冲措施。结果表明,拟建人工岛工程建设引起的水流动力变化主要在西太阳沙附近的浅水区,并局限在1.5倍人工岛直径范围内,对邻近水道深槽区的潮流动力没有影响。人工岛工程没有改变西太阳沙周边各水道潮流动力场格局,没有引致水道间潮流动力此消彼长的变化、未改变控制西太阳沙"水道-沙洲"系统演变的动力泥沙环境,西太阳沙核心部位的稳定主要取决于西太阳沙北侧潮流动力增强的自然演变过程。就人工岛建设而言,东北岛壁前沿有效的防冲护底措施对沙洲核心部位稳定和减少北水道深槽淤积泥沙来源均有积极意义。

To build a shoal water artificial island in Fushe Sand Cay in South Yellow Sea where the hydrodynamic and sediment environment is considerably complex, we should not only consider carefully the stability of the artificial island itself but also made in-depth studies to investigate if the flow field and deposit of sedimentation resulted from the construction of the artificial island would change greatly the present tidal current hydrodynamic field and the systematic situation of ＂waterway-sand cay＂ and if the trend pattern of natural evolution would be accelerated or reversed owing to the construction of the artificial island. Integral physical modeling of tidal curren, ts and sedimentation was made to investigate the influence of the construction of Xitaiyand Sand Shoal Artificial Island upon the trend of evolution of the furrow and the short-term fluctuation of the erosion and siltation in the construction area as well as the pattern of change of the hydrodynamics ,erosion anti sedimentation around the artificial island after the completion of Rudong Artificial Island. Corresponding measures against erosion have been proposed. The results of the model tests show that the hydrodynamic change of the water current resulted from the proposed artificial islang occurred mainly in the shoal water area close to Xitaiyang Sand Shoal and within a range of 1.5 diameterof the artificial island ,imposing no influence on the tidal current hydrodynamics in the deep trough of the nearby waterways. The construction of the artificial island has not changed the pattern of the tidal hydrodynamic field in the waterways around Xitaiyand Sand Shoal and has neither resulted in the increase of the tidal hydrodynamics in this waterway but decrease in another nor changed the hydrodynamic sediment environment which controls the evo lution of the ＂waterway sand cay＂system at Xitaiyang Sand Shoal. The stability of the core of Xitaiyang Sand Shoal rests mainly with the natural evolution process that makes the tidal hydrodynamics increase in the north of Xi taiyand Sand Shoal. So far as the construction of the artificial island is concerned, effective measures to protect the apron against erosion in front of the northeast walls of the artificial island will play the positive role in stabilizing the core of the sand cay and cutting down the source of sediment to deposit in the deep trough of the northern wa terway.