Numerical Simulation of Water Level Under Interaction Between Runoff and Estuarine Dynamics in Tidal Reach of the Yangtze River

The Yangtze Estuary, the largest estuary in China, is under an obvious interaction between runoff and astronomical tide. The research on the interaction is very important for the exploitation and utilization of water resources in this area. A horizontal 2D hydrodynamic numerical model is established and verified in the present study with the modeling rmage from Datong to the Yangtze Estuary. Based on the comparison of high water levels under the interaction between different runoff and estuarine dynamics, some conclusions are drawn. By revealing the general laws about the relationship between the astronomical tide and flood, the flood level is forecasted to lay a foundation for further research on storm surge in the Yangtze Estuary.

Water Quality Evaluation in Tidal River Reaches of Liaohe River Estuary, China Using a Revised QUAL2K Model

Rivers in the Liaohe River Estuary area have been seriously polluted by discharges of wastewater containing petroleum pol- lutants and nutrients. In this paper, The Enhanced Stream Water Quality Model （QUAL2K） and its revised model as well as One-dimensional Tide Mean Model （1D model） were applied to predict and assess the water quality of the tidal fiver reach of the Liaohe River Estuary. Dissolved oxygen （DO）, biochemical oxygen demand （BODs）, ammonia nitrogen （NH3-N） and total phosphorus （TP） were chosen as water quality indices in the two model simulations. The modelled results show that the major reasons for degraded rivers remain petroleum and non-point source pollution. Tidal water also has a critical effect on the variation of water quality. The sensitivity analysis identifies that flow rate, point load and diffuse load are the most sensitive parameters for the four water quality indices in the revised QUAL2K simulation. Uncertainty analysis based on a Monte Carlo simulation gives the probability distribution of the four wa- ter quality indices at two locations （6.50 km and 44.84 km from the river mouth）. The statistical outcomes indicate that the observed data fall within the 90% confidence intervals at all sites measured, and show that the revised QUAL2K gives better results in simulating the water quality of a tidal fiver.

Tidal Level Response to Sea-Level Rise in the Yangtze Estuary

The rise of tidal level in tidal reaches induced by sea-level rise has a large impact on flood control and water supply for the regions around the estuary. This paper focuses on the variations of tidal level response along the tidal reaches in the Yangtze Estuary, as well as the impacts of upstream discharge on tidal level response, due to the sea-level rise of the East China Sea. Based on the Topex/Poseidon altimeter data obtained during the period 1993-2005, a stochastic dynamic analysis was performed and a forecast model was run to predict the sea-level rise of the East China Sea. Two- dimensional hydrodynamic numerical models downscaling from the East China Sea to estuarine areas were implemented to analyze the rise of tidal level along the tidal reaches. In response to the sea-level rise, the tidal wave characteristics change slightly in nearshore areas outside the estuaries, involving the tidal range and the duration of flood and ebb tide. The results show that the rise of tidal level in the tidal reaches due to the sea-level rise has upstream decreasing trends. The step between the stations of Zhangjiagang and Shiyiwei divides the tidal reaches into two parts, in which the tidal level response declines slightly. The rise of tidal level is 1-2.5 mm/a in the upper part, and 4-6 mm/a in the lower part. The stations of Jiangyin and Yanglin, as an example of the upper part and the lower part respectively, are extracted to analyze the impacts of upstream discharge on tidal level response to the sea-level rise. The relation between the rise of tidal level and the upstream discharge can be fitted well with a quadratic fimction in the upper part. However, the relation is too complicated to be fitted in the lower part because of the tide dominance. For comparison purposes, hourly tidal level observations at the stations of Xuliujing and Yanglin during the period 1993-2009 are adopted. In order to uniform the influence of upstream discharge on tidal level for a certain day each year, the hourly tidal level observations are corrected by the correlation between the increment of tidal level and the increment of daily mean upstream discharge. The rise of annual mean tidal level is evaluated. The resulting rise of tidal level at the stations of Xuliujing and Yanglin is 3.0 mm/a and 6.6 mm/a respectively, close to the rise of 5 mm/a according to the proposed relation between the rise of tidal level and the upstream discharge.

Prediction of Siltation in the Downstream Approach Channel of Tidal Locks

Silt deposition occurs in the downstream approach channel of the tidal lock as in a closed channel or excavated dock basin. It is often difficult to calculate or predict siltation because of complex flow and sediment conditions and many other affecting factors. In this paper, the characteristics of flow movement in the approach channel (including its mouth) of the tidal lock are analyzed, the basic laws of sediment movement and siltation mechanism are investigated, the conditions for three types of siltation (circumfluence siltation, density flow siltation and slow flow siltation) are discussed, and corresponding calculating formulas are proposed. A practical example shows that the difference between measured and calculated results is small, indicating that the present calculating methods could be used in design and management of practical engineering projects.

基于数值模拟的澄通感潮河段水源地预警站设置研究

针对突发性水污染事件可能严重影响水源地取水,而现有研究针对感潮河段水源地预警站的确定方法尚无系统论述的问题,基于长江澄通感潮河段水动力-水质耦合数学模型,在厘清径潮共同作用下该河段污染物扩散输运规律的基础上,初步确定了长青沙和狼山水源地的预警站位置和数量;结合影响水源地的潜在污染源分布特征和污染物累积特征对预警站进行了空间校核,利用预警响应时效性对预警站进行了时间校核,最终确定了两水源地上下游共4个预警站的位置;基于预警站位置水质与水源地位置水质的相关性确定了长青沙和狼山水源地的应急响应方案,并给出了苯酚泄漏的风险响应限值。

感潮河段城市湿地水动力模拟及改善方案研究

湿地具有固碳释氧、涵养水源等作用,改善水体交换能力是湿地研究热点之一,但关于潮汐变动水位条件下湿地水体调控措施的探究相对较少。以长江南京段绿水湾湿地为例,建立平面二维水动力模型,开展感潮河段城市湿地水动力模拟及改善方案研究。计算不同水文条件及闸泵调度方案下湿地流场,分析潮位变动对绿水湾湿地水动力的影响,分析不同闸泵调度措施对水体流动性的改善效果。研究表明,闸泵联合调度可使枯季大部分区域水动力明显增强,但仍存在主槽外坑塘等局部滞水区,需通过湿地植被重构的方式提高水体自净能力。对易暴发藻类的4—5月,闸泵联合调度可较好改善绿水湾内上游区域的水动力条件,对于改善效果并不明显的下游区域建议增设补水点,降低水体富营养化风险。本研究可为绿水湾湿地的设计、建设与管理提供科学依据。

新形势下我国江河入海水通量监测实践与对策建议

针对我国入海河口生态环境问题突出、江河入海污染物总量不明的问题,梳理了我国江河入海水通量监测的历史,分析了我国江河入海水通量评估工作的现状以及“十四五”生态环境监测和海洋环境保护等规划的要求,提出污染物排海总量不明的主要原因是江河入海水通量监测未取得突破,具体表现在江河污染物入海通量未得到有效掌握、江河入海水通量监管体系未得以构建运行、江河入海水通量监测技术未得到建立和规范。结合在辽河口海洋环境在线监测试验基地开展的江河入海流量在线监测系统设计研究、江河入海水通量监测技术研发、江河入海水通量监测技术标准化研究、辽河入海水通量监测试验等工作,建议总结分析我国已开展的江河入海水通量监测试验工作,深入开展江河入海水通量监测顶层设计,加强江河入海水通量监测关键技术方法研究。

感潮河段江滩湿地水体交换模拟与调控措施研究

保障湿地水体交换能力对完善湿地功能,维持湿地生态系统的健康至关重要。南京绿水湾湿地是长江江滩湿地,具备多种湿地特点,动力条件复杂。以绿水湾湿地为研究对象,通过构建二维水动力―水龄耦合数学模型,模拟了现状和不同闸、泵调控措施下各区域的水动力特征及水体交换能力。结果表明:现状工况湿地内部水面覆盖率低,水体交换能力差,大部分区域水体交换时间在7 d以上,甚至是14 d以上;建闸后虽然增加了枯季的水面覆盖率,但明显减弱了湿地内水动力,延长了各区域换水周期,换水周期大于14 d的区域明显增多;补水泵站的运用整体上缩短了大部分区域的换水周期,使得水域流速大于0.010 m/s的区域面积明显增加,换水周期大于14 d的区域面积减少。建闸蓄水后,为预防藻类暴发,需控制湿地内水体的换水周期在14 d内,结合各区域水动力和水体交换特点,提出了闸门生态调度、布置净水能力较强的挺水或沉水植物、增设补水点等调度策略。

基于Delft3D的珠江前航道尸体模型漂移轨迹预测

为预测珠江前航道中尸体的漂移轨迹,帮助当地水警确定溺亡者尸体的具体位置,利用Delft3D构建珠江前航道水动力模型,并使用尸体模型进行了多次现场漂移试验。通过对珠江前航道表层流速进行拟合,建立了尸体模型漂移的预测模型,R^(2)为0.88。研究结果表明,珠江前航道释放的尸体模型受潮汐和径流作用沿河道做往复运动,并呈逐渐漂向下游的趋势;漂移模型验证中尸体模型的漂移速度和方向基本与潮流一致,模拟结果的误差在1 km以内,终点距离误差率小于15%;实例验证中成年女性尸体的模拟结果误差约为300 m;游船所引起的波浪力等外力导致漂移轨迹呈现出南北方向性的偏差,需要进一步提升模拟效果。该漂移模型的推导模式同样适用于其他感潮河段,可使尸体的漂移轨迹变得可测,为尸体打捞工作和警方的案件处理提供了便利和参考。

EFFECT OF FUTURE SEA LEVEL RISE ON DISASTROUS FLOODS IN THE TAIHU LAKE LOWER REACH DEPRESSIONS AND COUNTERMEASURES

Use of numerical simulation of the tidal flow of the Changjiang River Estuary and the HuangpuRiver to forecast flood in the Taihu Lake lower reach drainage system for the case of future sea level riseof 0.4 m and 0.8 m,and floods preventing and reducing methods are discussed in this paper.

Classification of River Reaches on the Little Disturbed East Alligator River, Northern Australia

The East Alligator River drains a 7000 km2 catchment in northern Australia comprised largely of Aboriginal land and has a very low average population density of about 0.15 persons per km2. River reaches were classified according to geomorphic features on both the East Alligator River and its major tributary, Magela Creek, next to which is located the Ranger uranium mine. Sixteen reaches were described for the 241.4 km of the East Alligator River and ten reaches were described for the 118.8 km of Magela Creek. The dominant river types on the East Alligator River were various types of anabranching rivers, sandstone gorges and cuspate tidal meanders. On Magela Creek the dominant river types were wetlands and channel billabongs, island anabranching and sandstone gorges. It is unusual for anabranching rivers and gorges to be so dominant. Current river classification schemes could not accommodate all the various river types and need to be modified so that tidal channels are covered in more detail and so that the classification of anabranching rivers recognises that sand-bed varieties occur in partly confined valley settings.

长江感潮河段径流对潮波变形和传播的影响研究

受径、潮流相互作用,长江感潮河段潮波从河口向上游传播过程中沿程变形过程复杂。基于长江感潮河段实测高、低潮位,潮时资料以及大通站日均流量数据,采用数理统计、Hermit插值和小波分析方法,分析了长江感潮河段潮汐特征值和潮波传播特征值随流量的变化关系。结果表明:高、低潮位及平均水位随流量增大而增大,并且越往下游对流量的敏感度越低;江阴以上河段潮差随流量增大而先减小后增大;径流对分潮振幅的影响在江阴以上河段较明显,半日潮和全日潮振幅随流量增大先减小后增大,1/4日分潮振幅随流量增大而减小,其中半日潮振幅变化幅度最大;平均水位坡度在芜湖-马鞍山段随流量增大而先增大后减小,在马鞍山以下河段与流量呈正相关;潮波振幅衰减率随流量增大而先增大后减小,越靠近入海口,流量阈值越大。研究成果有助于深入认识河口径潮相互作用机制,亦可为河口治理提供参考。

基于SWMM的水位和降雨对感潮河段水质影响分析——以佛山五福围片区为例

为探究水位和降雨对河涌水质的影响,以佛山市五福围片区作为研究区域,建立SWMM水动力-水质模型,模拟分析感潮河段在降雨和水位影响下水质的变化规律。模拟结果显示:水位和降雨对河涌水质有着明显的影响。晴天时,闸站向河涌补水使河涌水位升高,从而水质提升;而随着降雨量增加时,冲刷作用导致水质恶化,但降雨径流平均浓度降低,暴雨时降雨径流平均浓度反而升高;在4条重点河涌中,北合围涌排放入河径流量和污染物负荷排放最高,而冲元涌最低。研究结果对于佛山市五福围片区的河涌水质管理和治理具有一定的启示作用。

码头建设对感潮河段水生态影响研究

评价建设项目对生态环境的影响非常重要,本文依据《环境影响评价技术导则生态影响》(HJ 19—2022),以感潮河段珠江三角洲东海水道的码头建设项目为例,阐述了项目建设期和运营期对水生生态环境产生的影响,提出相应的环保管理措施。结果表明,项目位于感潮河段,研究水域没有集中的产卵场,受潮汐影响较小,大部分的水生生物物种为淡水生物;码头项目施工期对水生态系统的影响主要是底栖生物损失和鱼卵仔稚鱼损失;项目建成后运营期产生的污水均得到有效处理,不会对研究水域水生生态环境带来显著影响。

浦阳江流域感潮河段洪水预报研究

浦阳江流域中上游属感潮河段,易受下游洪水顶托影响,导致预报站水位流量关系不稳定,给洪水预报作业带来难度。以诸暨站以上流域范围为研究对象,选用1990—2021年间具有代表性的20场洪水,建立三水源新安江模型,对诸暨站流量进行预报;基于BP神经网络优良的非线性映射能力,建立以湄池水位、时段降雨量、安华水库下泄流量、诸暨站预报流量等为输入因子的诸暨站水位预报模型,以探究该模型在诸暨洪峰水位预报中的适用性。结果证明2019—2021年的场次洪峰水位预报效果较优,场次水位相对误差均保持在2.5%以内。

基于MIKE21的小清河感潮河段水质数值模拟研究

为改善小清河感潮河段水质状况,提高水环境污染防治能力,以小清河感潮河段为研究区,利用MIKE21模型构建水动力水质耦合模型,选择主要超标污染物COD、TN、TP,利用实测水质数据对模型进行率定、验证,并模拟了不同上游来水水质、不同污染物削减条件和不同水文期突发水污染事故共3种情况下感潮河段水质变化,结果表明:经率定、验证后的水动力水质耦合模型适用于小清河感潮河段;当上游来水为Ⅳ类水时,COD、TP基本达标,TN超标,当上游来水为Ⅴ类水时都不达标,应尽量控制上游来水水质达到Ⅳ类标准,并加强流域水体TN污染治理;削减30%的点源、面源污染能够有效减少COD、TP污染,但对TN改善效果不佳;污染水团在平水期迁移过程中对水体的影响持续时间较长、浓度较大,丰水期污染物迁移速度较快,应急处理时间较少。

基于ADCP的感潮型分汊河道径流变化研究

经历汛期高水位后,长江局部河势出现变化,水流贴岸顶冲部位调整,崩岸时有发生。以长江芜湖河段大拐段潜洲为研究对象,通过对比2023年枯水期和丰水期的实测水文资料和地形资料,基于ADCP的水文测验成果,分析感潮型分汊河道的径流变化规律。结果表明,潜洲分汊河道从枯水期进入丰水期后,径流流速提高1.6~2.6倍,流向与断面垂线夹角变小,主汊分流比占比下降,支汊分流比占比提高且冲深加剧。研究结果可为河演分析和护岸工程实施提供依据。

感潮河段疏浚对悬浮物的变化影响模拟探究

西江为珠江流域的重要支流,干流水质状况较好,自思贤滘西滘口至西海水道段均可维持Ⅱ类水质标准,属于感潮河段。同时作为珠江流域重要的通航航道,西江承担着3000 t级船舶的通航任务,通航码头的建设需要对干流河道进行航道疏浚。文章利用二维非稳态模型针对该感潮河段的疏浚进行水动力与水环境悬浮物的影响模拟,分析河道疏浚对西江干流悬浮物浓度的影响程度与范围,以期为感潮河段河道疏浚造成的环境影响预测与饮用水源区保护提供科学技术参考。

长江下游感潮河段水闸引排水能力的计算模型应用——以新孟河界牌水利枢纽为例

针对长江下游感潮河段水闸引排水调度的精细化需求,以新孟河界牌水利枢纽为研究对象,构建潮位预报与引排水流量计算模型。采用多元线性回归分析潮汐特性,结合镇江站与新孟河闸的水位实测资料,建立镇江站潮位动态预报方案。在此基础上,推求新孟河闸的过程水位,并构建闸下水位与引排水流量的函数关系,实现潮周期内引排水流量的精细化计算以满足水利枢纽调度需求。研究成果可为长江下游感潮河段水闸引排水调度提供理论方法和技术支撑。

黄浦江中上游潮位变化及其成因分析

黄浦江中上游潮位变化直接影响城市防洪安全。基于黄浦江中上游代表站1980~2021年高、低潮位及1956~2021年流量数据,研究了黄浦江中上游潮位和来水量的变化,并对成因进行了分析。结果表明:黄浦江中上游高潮位和低潮位都呈上升趋势,2001~2021年多年平均高潮位相比1980~2000年上升16 cm,低潮位上升16 cm;2001~2021年多年平均上游全年来水量相比1956~2000年增加了65亿m 3,其中汛期增加了53%,非汛期增加了65%。黄浦江潮位变化主要受土地利用变化、流域骨干工程和城市防洪工程建设、圩区整治,以及下游潮汐顶托作用的综合影响。