华南休闲海滩沙坝触发的裂流风险及特征研究

张尧; 刘旭楠; 刘强; 王斌; 洪晓; 周水华; 张娟; 孟潇洁; 李锐; 陶金波; 王岗

doi:10.3969/j.issn.0253-4193.2020.09.002

华南休闲海滩沙坝触发的裂流风险及特征研究

doi: 10.3969/j.issn.0253-4193.2020.09.002

张尧^1,,
刘旭楠¹,
刘强¹,
王斌^1, ,,
洪晓^{1, 2},
周水华²,
张娟²,
孟潇洁³,
李锐⁴,
陶金波⁴,
王岗⁵

1.
自然资源部海洋减灾中心，北京 100194
2.
国家海洋局南海预报中心，广东广州 510260
3.
中国海洋大学工程学院，山东青岛 266100
4.
国家海洋局北海预报中心，山东青岛， 266061
5.
河海大学港口海岸与近海工程学院，江苏南京 210098

基金项目: 国家自然科学基金（51609043）；自然资源部海洋减灾中心业务项目（2018AB005）。

详细信息

作者简介:
张尧(1988—)，男，江苏省宿迁市人，博士，副研究员，从事计算水动力及海洋灾害研究。E-mail：yzhang@nmhms.org.cn

通讯作者:
王斌。E-mail：soawb@hotmail.com

中图分类号: P731.23
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- 文章访问数: 252
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- 被引次数: 0
出版历程
- 收稿日期: 2019-06-14
- 修回日期: 2019-10-16
- 网络出版日期: 2021-04-21
- 刊出日期: 2020-09-25

Study on the risk and characteristics of rip currents over sandbars at South China’s recreational beaches

1.
National Marine Hazard Mitigation Service, Ministry of Natural Resources, Beijing 100194, China
2.
South China Sea Prediction Center, State Oceanic Administration, Guangzhou 510260, China
3.
Engineering College, Ocean University of China, Qingdao 266100, China
4.
North China Sea Marine Forecasting Center, State Oceanic Administration, Qingdao 266061, China
5.
College of Harbor, Coastal and Offshore Engineering, Hohai University, Nanjing 210098, China

摘要

摘要: 为应对频发的致命性海滩溺水事故，自然资源部开展了我国首次滨海旅游区裂流灾害技术调查，在华南地区发现大量滨海休闲海滩存在浅滩沙坝和裂流现象。作为全国调查的部分成果，本文应用多种方法研究了广东省3个热门海滩沙坝触发的裂流机理、特征和演变规律。地形动力计算和卫星影像显示了沙坝形态、岸线形状以及裂流的高度动态性，尤其在青澳湾裂流呈现非常规的反季节变化，冬季风险较高而夏季风险较低。在相位解析水动力数值模拟中，裂流表现出对沙坝形态、浪高、浪向的高度敏感性。沙坝间较宽间隙会产生尺寸较大的裂流区，但比起窄沟槽不一定伴随更强的流速。当大部分水流集中从邻近的较宽通道回流入海时，部分窄沟槽几乎没有裂流产生。裂流流速与浪高成正比与入射角成反比。数值模拟结果表明，当入射角达到10°～30°时，沿岸流会取代离岸流占主导地位。现场调查也验证了在低潮时，较浅的水深会放大水流和波浪的地形效应，导致裂流风险加剧。本文研究结果可为滨海旅游区裂流灾害的工程减缓措施和公共警示提供有益参考。未来将会持续开展针对特定岸线的长期观测，以为裂流预警报和风险管控积累足够的统计数据。
- 裂流 /
- 沙坝 /
- 波浪 /
- 海滩形态 /
- 数值模拟 /
- 灾害风险
Abstract: In responding to deadly drowning accidents, China's first operational attempt on the rip current hazard prevention for coastal tourism was carried out by the National Marine Hazard Mitigation Service (NMHMS). A great number of recreational beaches in South China are found developing littoral sand bars and rip currents. Present paper, which is part of the nation-wide work, investigate the mechanism, characteristics, and evolution sandbar-induced rip current at three most visited beaches employing multi-techniques as complementary tools. The alongshore sandbar morphology, shorelines, and rip currents are highly dynamic with seasonal variations evidenced by the morphodynamic calculation and the satellite image interpretation. Unconventional contrary seasonal evolution of the rip current is identified at Qing’ao Bay with higher risk in cooler seasons. The rip current shows high sensitivity to the sandbar group pattern, the wave height, and the incident direction according to the phase-resolving hydrodynamic modelling. The wider rip channel between sandbars generated larger rip size compared to narrower gaps, but is not necessarily accompanied by stronger flow velocity. The rip current might be totally absent in small channels when majority of water flows out through neighboring broader pathways. The flow velocity is demonstrated proportional to the wave height and inversely proportional to the incident angle. Alongshore currents dominated over rip currents as the wave incident angle reached 10°−30° in the numerical simulation. It is verified in the field observation that the rip current is most hazardous at low tide when shallower water depth intensifies the topographic effect on waves and currents. The study result provides useful reference for the engineering mitigation and public warning of beach rip hazard. In near future, long time observation for specific sections of shoreline would be conducted to accumulate enough statistics for the rip current prediction and risk governance.
- rip current /
- sandbar /
- wave /
- morphodynamics /
- numerical modelling /
- marine hazard

HTML全文

图 1 华南3个研究目标海滩位置和形态示意图

Fig. 1 Location and profiles of the 3 investigated beaches in the South China

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图 2 十里银滩的波浪月平均数据

Fig. 2 Monthly wave statistics at the 10-mile Beach

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图 3 十里银滩的谷歌地图卫星影像（红色线段为100 m）

a. 2016年11月6日；b. 2017年8月21日

Fig. 3 Google Earth satellite images at the 10-mile Beach (the red line represents 100 m)

a. November 6, 2016; b. August 21, 2017

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图 4 西涌海滩的波浪月平均数据

Fig. 4 Monthly wave statistics at the Xichong Beach

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图 5 西涌海滩的谷歌地图卫星影像（红色线段为100米）

a. 2013年12月30日；b. 2014年9月18日；c. 2015年8月25日；d. 2016年7月16日

Fig. 5 Google Earth satellite images at the Xichong Beach (the red line represents 100 m)

a. December 30, 2013; b. September 18, 2014; c. August 25, 2015; d. July 16, 2016

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图 6 青澳湾的波浪月平均数据

Fig. 6 Monthly wave statistics at the Qing’ao Bay

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图 7 青澳湾的谷歌地图卫星影像（红色线段为100 m）

a. 2010年8月5日；b. 2013年11月27日；c. 2015年8月23日；d. 2016年12月18日

Fig. 7 Google Earth satelite images at the Qing’ao Bay (the red line represents 100 m)

a. August 5, 2010; b. November 27, 2013; c. August 23, 2015; d. December 18, 2016

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图 8 十里银滩沙坝和裂流通道（a）及裂流头（b）航拍照片

Fig. 8 Aerial photo of sandbars and rip channels (a), and rip head (b) at the 10-mile Beach

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图 9 2018年7月12日海陵岛十里银滩裂流彩染示踪试验视频截图（数模案例的2号通道）

Fig. 9 Video snapshots of the dye-tracer in the rip current at channel 2 of the 10-mile Beach of Hailing Island on July 12, 2018

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图 10 数值模拟的十里银滩水深地形及沙坝裂流通道分布（a）和5组有效波高和平均流速的计算结果（b−f）

b. 入射波高1.4 m，入射角0°；c. 入射波高1.2 m，入射角0°；d. 入射波高0.7 m，入射角0°；e. 入射波高0.7 m，入射角11.25°；f. 入射波高0.7 m，入射角33.75°

Fig. 10 Bathymetry with sand bars and 4 rip channels in the simulated area at 10-mile Beach (a), and computed results of significant wave heights and averaged velocities for 5 cases (b−f)

b. H_incident=1.4 m, θ = 0°; c. H_incident=1.2 m, θ = 0°; d.H_incident=0.7 m, θ = 0°; e. H_incident=0.7 m, θ = 11.25°; f. H_incident=0.7 m, θ = 33.75°

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表 1 基于地形动力学指标分析的滨海旅游海滩裂流风险等级表

Tab. 1 Beach characteristics and rip risk level based on morphodynamic values

海滩组别	沙粒沉降参数	潮浪参数	海滩类型	裂流风险
反射型	$ {{\varOmega }} $<2	RTR<3	完全反射型（R）	低
	$ {{\varOmega }} $<2	RTR>7	低潮台地型（LTT）	低
	$ {{\varOmega }} $<2	3≤RTR≤7	低潮台地裂流型（LTTR）	中
中间状态型	2≤$ {\varOmega} $≤5	RTR<3	沿岸沙坝型（B）	高
中间状态型	2≤$ {\varOmega} $≤5	3≤RTR≤7	低潮冲流沙坝裂流型（LTBR）	高
消散型	$ {\varOmega} $>5	RTR<3	沙坝消散型（BD）	中
消散型	$ {\varOmega} $>5	3≤RTR≤7	无沙坝消散型（NBD）	低
超消散型	$ {\varOmega} $>2	RTR>7	平缓超消散型（UD）	低

下载: 导出CSV

表 2 十里银滩月平均裂流风险等级的地形动力模型计算结果

Tab. 2 Monthly rip current risk at the 10-mile Beach calculated by the morphodynamic model

月份	RTR	$ {{\varOmega }} $	海滩类型	风险等级
1	1.9	10.9	BD	中
2	1.8	11.0	BD	中
3	2.1	11.4	BD	中
4	2.4	10.1	BD	中
5	2.3	10.3	BD	中
6	1.4	13.2	BD	中
7	1.7	13.0	BD	中
8	1.6	10.9	BD	中
9	2.4	9.5	BD	中
10	1.9	10.9	BD	中
11	1.6	12.2	BD	中
12	1.5	12.1	BD	中

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表 3 西涌海滩月平均裂流风险等级的地形动力模型计算结果

Tab. 3 Monthly rip current risk at the Xichong Beach calculated by the morphodynamic model

月份	RTR	$ {{\varOmega }} $	海滩类型	风险等级
1	1.1	3.0	B	高
2	1.1	3.1	B	高
3	1.1	3.2	B	高
4	1.3	2.8	B	高
5	1.6	2.4	B	高
6	1.1	3.4	B	高
7	1.0	3.7	B	高
8	1.0	3.5	B	高
9	1.3	2.7	B	高
10	1.1	3.1	B	高
11	0.9	3.4	B	高
12	0.9	3.3	B	高

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表 4 青澳湾月平均裂流风险等级的地形动力模型计算结果

Tab. 4 Monthly rip current risk at the Qing’ao Bay calculated by the morphodynamic model

月份	RTR	$ {{\varOmega }} $	海滩类型	风险等级
1	1.8	21.1	BD	中
2	2.1	19.0	BD	中
3	2.3	16.5	BD	中
4	2.7	14.3	BD	中
5	3.2	11.9	NBD	低
6	3.2	11.8	NBD	低
7	3.1	11.3	NBD	低
8	3.0	10.9	NBD	低
9	2.6	13.9	BD	中
10	1.9	21.4	BD	中
11	1.9	21.4	BD	中
12	1.9	21.4	BD	中

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表 5 不同模拟工况下的入射波浪条件

Tab. 5 Incident wave conditions for the numerical simulation

模拟工况	入射波高/m	波向	周期/s	相对岸线的入射角度/（°）
1	1.4	SE−SSE	4.9	0
2	1.2	SE−SSE	4.9	0
3	0.7	SE−SSE	4.9	0
4	0.7	SSE	4.9	11.25
5	0.7	S	4.9	33.75

下载: 导出CSV

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