Flume experiment on flow division ratio of bifurcated Jiaomen outlet in the Zhujiang River
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摘要: 作为珠江主要的泄洪排沙口门,珠江蕉门主要承泄西北江的径流和泥沙,与虎门通过横向汊道凫洲水道连通,其分水分沙的比例对粤港澳大湾区防洪及通航安全至关重要。针对凫洲水道分流比问题,本文基于蕉门分汊河口的形态特点及地貌特征,设计系列水槽实验,探究凫洲水道分流比、分流比影响因子及其变化趋势等。结果表明:在保证宽度比、深度比和流量比均相似的情况下,该水槽实验可较高精度地模拟蕉门分汊河口分流比。凫洲水道分流比受到蕉门与虎门共同影响:虎门与蕉门的相对流速比越大,凫洲水道分流比越大,其主汊地位越明显。在现有的地貌特征条件下,凫洲水道主支汊转变的阈值是虎门与蕉门相对流速比,约为0.35。研究成果可为蕉门整治、保障其行洪通航安全等提供参考依据。Abstract: The Jiaomen outlet is the main flood and sediment discharge of the Zhujiang River. It is connected with Humen outlet through a lateral branch, namely the Fuzhou Channel. The flow and sediment division ratio of the bifurcated Jiaomen outlet are important for flood control and navigation safety of the Guangdong-Hong Kong-Macao Greater Bay Area. Focusing on the flow division ratio of the Fuzhou Channel, this study designed a series of scaled physical experiments to explore the relationship between flow division ratio of the Fuzhou Channel and the flow of Jiaomen outlet and adjacent Humen outlet. The dimension of the physical model is based on morphological characteristics in the vicinity of the Jiaomen outlet nowadays. Results of the experiment are in good agreement with the filed measurements under two different flow conditions, demonstrating a reliable model performance. Subsequently, series of experiments have been carried out by varying upstream discharges of Humen and Jiaomen. Experimental results indicate that the division ratio of the Fuzhou Channel depicts a positive relationship with the flow velocity ratio between Humen and Jiaomen. Thus, the flow division ratio of the Fuzhou Channel depends on both Humen and Jiaomen. The experimental results further suggest that, under present geomorphic situation, if the upstream velocity ratio between Humen and Jiaomen decreases to 0.35, the Fuzhou Channel would shift from the main branch to secondary. The research results can provide a reference for the artificial regulation of Jiaomen outlet and its flood and navigation safety.
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Key words:
- Jiaomen outlet /
- Fuzhou Channel /
- bifurcated estuary /
- flow division ratio /
- flume experiment
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表 1 伶仃洋东四口门水沙分配表
Tab. 1 Distribution of water and sediment discharge of the east four outlets in the Lingding Bay
口门 径流量/
(108 m3·a−1)径流量在四大口门中的
占比/%悬沙输沙量/(104 t·a−1) 输沙量在四大口门中的
占比/%虎门 578 34.6 995 27.2 蕉门 541 32.4 1323 36.1 洪奇门 200 12.0 489 13.3 横门 351 21.0 857 23.4 总计 1670 100 3664 100 表 2 实验工况设计表
Tab. 2 Parameter setting of experiments
工况 V1/(cm·s−1) V2/(cm·s−1) V1/V2 1 4 20 0.2 2 8 20 0.4 3 10 20 0.5 4 12 20 0.6 5(基准实验) 16 20 0.8 6(基准实验) 20 20 1.0 7 24 20 1.2 8 24 18.5 1.3 9 24 14 1.7 10 24 12 2.0 11 24 10 2.4 表 3 实验流速比与分流比结果
Tab. 3 Measured flow division ratio under various velocity ratios
工况 设计流速比 实测流速比 断面5分流比 1 0.20 0.202 0.45 2 0.40 0.427 0.54 3 0.50 0.591 0.58 4 0.60 0.646 0.61 5(基准实验) 0.80 0.749 0.62 6(基准实验) 1.00 1.032 0.75 7 1.20 1.221 0.77 8 1.30 1.288 0.80 9 1.80 1.773 0.91 10 2.00 1.940 0.98 11 2.40 2.341 0.99 -
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