地学前缘 ›› 2023, Vol. 30 ›› Issue (5): 553-566.DOI: 10.13745/j.esf.sf.2023.2.73

• 非主题来稿选登 • 上一篇    

基于数值模拟的琼州海峡东口推移质输运量估算

仝长亮1,2,3(), 朱钰1,3, 吴祥柏4,*(), 莫颖明2, 王雪木3   

  1. 1.海南省海洋地质资源与环境重点实验室, 海南 海口 570206
    2.海南省地质测试研究中心, 海南 海口 570206
    3.海南省海洋地质调查研究院, 海南 海口 570206
    4.江苏科技大学 船舶与海洋工程学院, 江苏 镇江 212100
  • 收稿日期:2022-01-01 修回日期:2023-01-01 出版日期:2023-09-25 发布日期:2023-10-20
  • 通讯作者: 吴祥柏
  • 作者简介:仝长亮(1981—),男,正高级工程师,主要从事海洋地质资源和环境研究工作。E-mail: tongchangliang@163.com
  • 基金资助:
    海南省自然科学基金项目(422RC800);海南省基础与应用基础研究计划(自然科学领域)高层次人才项目(2019RC349);海南省国土环境资源厅海南岛北部海砂调查评价项目(HZ2015-235);海南省地质局西南浅滩海砂开采试点项目(T102972.510)

Estimating bedload transport at the eastern entrance to the Qiongzhou Strait by numerical simulation

TONG Changliang1,2,3(), ZHU Yu1,3, WU Xiangbai4,*(), MO Yingming2, WANG Xuemu3   

  1. 1. Hainan Key Laboratory of Marine Geological Resources and Environment, Haikou 570206, China
    2. Hainan Geology Detection and Research Centre, Haikou 570206, China
    3. Marine Geological Institute of Hainan Province, Haikou 570206, China
    4. School of Naval Architecture and Ocean Engineering, Jiangsu University of Science and Technology, Zhenjiang 212100, China
  • Received:2022-01-01 Revised:2023-01-01 Online:2023-09-25 Published:2023-10-20
  • Contact: WU Xiangbai

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摘要：

琼州海峡东口沉积作用主要受东西向往复流的控制,并呈现涨潮东流、落潮东流、涨潮西流和落潮西流4种形式,独特的沉积动力特征使得海峡东口分布大量潮流沙脊。沉积动力研究对于该区域海砂的开发和海底稳定性评估具有重要意义。海峡东口沉积作用的数值模拟计算表明:在中央水道、海峡北岸和浅滩区,潮流流速相对较大,其垂向平均流速可达0.7~1.0 m/s,其他区域流速为0.3~0.5 m/s;东向流流速较西向流大,但在海峡北岸,粤西沿岸流的存在使得西向流显著大于东向流,该特征在大潮期间尤为明显,小潮期间的流速普遍小于大潮时段,一般大潮流速是小潮的1.5~2.0倍。底质类型显示,研究区以砂砾质沉积为主,主要分布在中央水道、浅滩区和海峡北岸海域,全区平均粒径均值为2.67Φ,总体分选较差。研究区临界起动流速范围为0.12~0.79 m/s,在中央水道至西南浅滩一带临界起动流速在0.6 m/s以上,砂质沉积区起动流速多为0.35~0.45 m/s,而东部陆架的泥质沉积区起动流速基本小于0.22 m/s。Bagnold输运率计算模型结果显示:海峡北岸的输运率最大,其次为中央水道和浅滩区;其分布大小与潮流沙脊的位置和走向具有较好的一致性,潮周期内的净输运趋势在海峡北岸为西向,其他区域多为东向;大小潮的净输运量相差一个数量级,剖面计算得出一个月内通过琼州海峡东口的推移质净通量可达108 kg量级且总体方向为东向。

关键词: 沉积动力, 推移质, 输运量, 潮流模拟, 琼州海峡东口

Abstract:

The widespread tidal ridges at the eastern entrance to the Qiongzhou Strait are mainly controlled by east-west tidal currents of four types, i.e., eastward/westward flood or ebb. According to the numerical simulation, the speed of tidal currents is relatively fast in the central waterway, the north shore and shoals, where the average vertical speed can reach 0.7-1.0 m/s, whilst elsewhere it is about 0.3-0.5 m/s. In general, the eastward current speed is faster than the westward counterpart, but the opposite is true at the north shore due to the western Guangdong coastal current. This characteristic is especially obvious during spring tides where the current speed is generally 1.5-2.0-fold faster compared to during neap tides. The study area is dominated by sandy and gravel deposits distributed mainly in the central waterway, shoals and the north shore, where the average particle size of sediment is 2.67Φ areawide, with poor sorting overall. The critical starting rate of bedload transport ranges between 0.12-0.79 m/s—above 0.6 m/s in the central channel to shoals in the southwest, and generally 0.35-0.45 m/s in sandbanks. However, in muddy areas of the eastern shelf, the starting rate is generally less than 0.22 m/s. Using the Bagnold transport model, the north shore has the highest transport rate, followed by the central waterway and shoals. Within a tidal cycle, sediment is transported westward along the north shore but mostly eastward elsewhere, and the net transport volume between spring and neap tides can differ by an order of magnitude. According to the cross-section calculation, the net amount of bed materials transported through the eastern entrance to the Qiongzhou Strait is on the order of 108 kg per month.

Key words: sedimentary dynamics, bedload, transport volume, tidal current simulation, east entrance of Qiongzhou Strait

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