1.中水珠江规划勘测设计有限公司;2.河海大学水灾害防御全国重点实验室
TV87
国家自然科学基金面上项目(42471049)；广州市南沙区水务局重大科技项目(2022-263)
1.China Water Resources Pearl River Planning,Surveying Designing Co,Ltd;2.The National Key Laboratory of Water Disaster Prevention,Hohai University
珠江三角洲联围地区经济高度发达，但受极端天气、海平面上升及泄洪格局变化综合影响，防洪潮形势严峻。以广州市南沙区为典型联围研究对象，剖析上游西江、北江泄洪格局演变及外海潮位变化对防洪潮的影响，分别提出防洪能力提升的工程方案和防潮能力提升的工程方案，构建河网一维非恒定流数学模型进行方案分析论证。结果表明：（1）1990年后北江三水站分流比显著增加（均值由15.5%升至21.8%），叠加河道下切与洪水归槽效应，加剧南沙区外江防洪压力；外海潮位以3.6 mm/a速率持续上升，南沙区附近测站200年一遇设计潮位抬升0.58~0.66 m，导致现有堤防防潮能力被动降低。（2）提出思贤滘分流比调控防洪工程方案，将50年一遇以上洪水条件下的三水站分流比调控至22.6%，有利于缓解南沙区外江防洪压力。（3）提出南沙区纯堤防防潮工程方案和联围筑闸防潮工程方案，对比分析后推荐联围筑闸方案，对珠江三角洲主要水道节点防洪水位、分流比影响不大。研究成果可为珠江三角洲典型联围地区防洪潮工程优化提供参考。
The Pearl River Delta’s embankment area boasts a highly developed economy. However, under the combined impacts of extreme weather, rising sea levels, and changes in flood discharge patterns, flood and tide control challenges have become severe. Taking Nansha District in Guangzhou as a typical study area of the embankment area, this study analyzes the effects of evolving flood discharge patterns in the upstream Xijiang and Beijiang Rivers, as well as changes in sea tide levels, on flood and tide control. Engineering schemes to enhance both flood control capacity and tide control capacity are proposed, and a one-dimensional unsteady flow mathematical model of the river network is constructed to analyze and validate these schemes. The results indicate that: (1) After 1990, the diversion ratio at Sanshui Station on the Beijiang River increased significantly (with an average rise from 15.5% to 21.8%). This increase, coupled with river channel incision and the flood reallocation effect, has intensified the flood control pressure on the outer river of Nansha District. In addition, sea tide levels have been continuously rising at a rate of 3.6 mm/a, resulting in a 200-year return period design tide level elevation of 0.58–0.66 m at the monitoring station near Nansha District, which passively reduces the tide control capacity of existing embankments. (2) A flood control engineering scheme based on regulating the diversion ratio at Sixianjiao is proposed, adjusting the Sanshui Station diversion ratio to 22.6% under flood conditions exceeding a 50-year return period. This adjustment is conducive to alleviating the flood control pressure on the outer river of Nansha District. (3) Two tide control schemes for Nansha District are proposed—a pure embankment tide control scheme and a joint embankment enclosure sluice construction tide control scheme. Comparative analysis recommends the joint embankment enclosure sluice construction scheme, as it exerts minimal impact on the flood levels and diversion ratios at the major waterway nodes of the Pearl River Delta. These findings can serve as a valuable reference for optimizing flood and tide control engineering in typical embankment areas of the Pearl River Delta.
