Maintaining healthy rivers and lakes through water diversion from Yangtze River to Taihu Lake in Taihu Basin

On the basis of the Taihu water resources assessment, an analysis of the importance and rationality of the water diversion from the Yangtz,e River to Taihu Lake in solving the water problem and establishing a harmonious eco-environment in the Taihu Basin is performed. The water quantity and water quality conjunctive dispatching ＇decisi＂ofi-makifig support system, which ensures flood control, water supply and eco-aimed dispatching, is built by combining the water diversion with flood control dispatching and strengthening water resources monitoring and forecasting. With the practice and effect assessment, measures such as setting the -integrated basin management format, further developing water diversion and improving the hydraulic engineering projects system and water monitoring system are proposed in order to maintain healthy rivers and guarantee the development of the economy and society in the Taihu Basin.

Sediment transport following water transfer from Yangtze River to Taihu Basin

To meet the increasing ：need of fresh water and to improve the water quality of Taihu Lake, water transfer from the Yangtze River was initiated in 2002. This study was performed to investigate the sediment distribution along the river course following water transfer. A rainfall-runoff model was first built to calculate the runoff of the Taihu Basin in 2003. Then, the flow patterns of river networks were simulated using a one-dimensional river network hydrodynamic model. Based on the boundary conditions of the flow in tributaries of the Wangyu River and the water level in Taihu Lake, a one-dimensional hydrodynamic and sediment transport numerical model of the Wangyu River was built to analyze the influences of the inflow rate of the water transfer and the suspended sediment concentration （SSC） of inflow on the sediment transport. The results show that the water transfer inflow rate and SSC of inflow have significant effects on the sediment distribution. The higher the inflow rate or SSC of inflow is, the higher the SSC value is at certain cross-sections along the ：river course of water transfer. Higher inflow rate and SSC of inflow contribute to higher sediment deposition per kilometer and sediment thickness. It is also concluded that a sharp decrease of the inflow velocity at the entrance of the Wangyu River on the river course of water transfer induces intense sedimentation at the cross-section near the Changshu hydro-junction. With an increasing distance from the Changshu hydro-junction, the sediment deposition and sedimentation thickness decrease gradually along the river course.

Unraveling the mechanisms underlying lake expansion from 2001 to 2020 and its impact on the ecological environment in a typical alpine basin on the Tibetan Plateau

Yanhu Lake basin(YHB)is a typical alpine lake on the northeastern Tibetan Plateau(TP).Its continuous expansion in recent years poses serious threats to downstream major projects.As a result,studies of the mechanisms underlying lake expansion are urgently needed.The elasticity method within the Budyko framework was used to calculate the water balance in the Yanhu Lake basin(YHB)and the neighboring Tuotuo River basin(TRB).Results show intensification of hydrological cycles and positive trends in the lake area,river runoff,precipitation,and potential evapotranspiration.Lake expansion was significant between 2001 and 2020 and accelerated between 2015 and 2020.Precipitation increase was the key factor underlying the hydrological changes,followed by glacier meltwater and groundwater.The overflow of Yanhu Lake was inevitable because it was connected to three other lakes and the water balance of all four lakes was positive.The high salinity lake water diverted downstream will greatly impact the water quality of the source area of the Yangtze River and the stability of the permafrost base of the traffic corridor.

Relationship Between Changes of River-lake Networks and Water Levels in Typical Regions of Taihu Lake Basin,China

The typical regions of the Taihu Lake Basin,China,were selected to analyze the variation characteristics of river-lake networks under intensive human activities.The characteristics of the fractal dimension of river networks and lakes for different periods were investigated and the influences of river system evolution on water level changes were further explored through the comparison of their fractal characters.The results are as follows:1) River network development of the study area is becoming more monotonous and more simple;the number of lakes is reducing significantly,and the water surface ratio has dropped significantly since the 1980s.2) The box dimension of the river networks in all the cities of the study area decreased slowly from the 1960s to the 1980s,while the decrease was significant from the 1980s to the 2000s.The variations of lake correlation dimension are similar to those of the river network box dimensions.This is unfavorable for the storage capacity of the river networks and lakes.3) The Hurst exponents of water levels were all between 0.5 and 1.0 from the 1960s to the 1980s,while decreased in the 2000s,indicating the decline in persistence and increase in the complexity of water level series.The paper draws a conclusion that the relationship between the fractal dimension of river-lake networks and the Hurst exponents of the water level series can reveal the impacts of river system changes on flood disasters to some extent:the disappearance of river networks and lakes will increase the possibility of flood occurrence.

Impact of Taihu Lake on City Ozone in the Yangtze River Delta

The lake-breeze at Taihu Lake generates a different specific heat capacity between the water body and the surrounding land. Taihu Lake has a significant impact on the atmospheric conditions and the air quality in the Yangtze River Delta. This phenomenon is referred to as the Taihu Lake effect. In this study, two simulations were conducted to determine the impact of the Taihu Lake effect in the reference experiment （R-E） and sensitivity experiments （NO_TH）. The control simulations demonstrated that the meteorological field and the spatial distribution of ozone （03） concentrations over Taihu lake obviously changed once the land-use type of water body was substituted by cropland. The surface temperature of Taihu Lake was reduced under the impact of Taihu Lake, and a huge temperature difference caused a strong lake-breeze effect. The results also showed that the difference in the average concentrations of 03 between the R-E and NO_TH experiments reached 12 ppbv in most areas of Taihu Lake, all day, on 20 May 2014. During daytime （0800-1600 LST, LST=UTC＋8）, the influence of the Taihu Lake effect on 03 in the Suzhou region was not significant. However, the influence of the Taihu Lake effect on 03 in the Suzhou region was obvious during nighttime （1800-2400 LST）. The larger changes in the physical and chemical processes were horizontal and vertical advections under the influence of the Taihu Lake effect in Taihu Lake.

A numerical study on water diversion ratio of the Changjiang(Yangtze)estuary in dry season

We studied the flood, ebb and tidal averaged along (net) water diversion ratio (WDR) during dry season in the Changjiang (Yangtze) estuary, China, along with the effects of northerly wind, river discharge, tide and their interactions on WDR using the improved version of three-dimensional numerical model ECOM. Using data for annual mean wind speed and river discharge during January, we determined that the flood, ebb, net WDR values in the North Branch of the estuary were 3.48%, 1.68%,-4.06% during spring tide, and 4.82%, 2.34%,-2.79% during neap tide, respectively. Negative net WDR values denote the transport of water from the North Branch into the South Branch. Using the same data, the corresponding ratios were 50.09%, 50.92%, 54.97%, and 52.33%, 50.15%, 43.86% in the North Channel and 38.56%, 44.78%, 103.96%, and 36.92%, 43.17%, 60.97% in the North Passage, respectively. When northerly wind speed increased, landward Ekman transport was enhanced in the North Branch, increasing the flood WDR, while the ebb WDR declined and the net WDR exhibited a significant decrease. Similarly, in the North Channel, the flood WDR is increased, the ebb WDR reduced, and the net WDR showed a marked decrease. In the North Passage, the flood WDR also increased while the ebb and net WDR declined. As the river discharge increased, the flood and ebb WDR of the North Branch increased slightly and the net WDR increased markedly. In the North Channel the flood and ebb WDR changed very slightly, while the net WDR declined during spring tides and increased during neap tides. The WDR in the North Passage changed slightly during flood and ebb tides while the net WDR showed a marked increase. The WDR values of different bifurcations and the responses to northerly wind, river discharge, and tide are discussed in comparison with variations in river topography, horizontal wind-induced circulation, and tidal-induced residual current.

Wet-Dry Runoff Correlation in Western Route of South-to-North Water Diversion Project,China

The Western Route of the South-to-North Water Diversion Project is an important trans-basin diversion project to transfer water from the upstream Yangtze River and its tributaries （water-exporting area）, to the upstream of the Yellow River （water- importing area）. The long-term hydrologieal data from 14 stream gauging stations in the Western Route area and techniques including the pre-whitening approach, non-parametric test, Bayes, law, variance analysis extrapolation, and Wavelet Analysis are applied to identify the streamflow eharacteristics and trends, streamflow time series cross-correlations, wetness-dryness encountering probability, and periodicities that occurred over the last 50 years. The results show that the water-exporting area, water- importing area, and the streteh downstream of the water-exporting have synehronization in high-low flow relationship, whereas they display non- synchronization in long-term evolution. This corresponds to the complicated and variable climate of the plateau region. There is no obvious increasing or decreasing trend in runoff at any gauging station. The best hydrological eompensation probability for rivers where water is diverted is about 25% to lO%, and those rivers influenced significantly by diversion are the Jinsha and Yalong rivers. Proper planning and design of compensation reservoirs for the water-exporting area and stretch downstream of the water- exporting area can increase the hydrological compensation possibility from water-exporting area to the water-importing area, and reduce the impact on the stretch of river downstream of the water- exporting area.

Elevation of basal lacustrine sediments along the mid-lower reaches of the Yangtze River and its implications for the reconstruction of Holocene water levels

The middle and lower reaches of the Yangtze River,a primary region for freshwater lakes in China,have undergone significant transformations throughout the Holocene.These changes,driven by factors such as sea-level rise,climate change,and human activities,have led to the progressive elevation of water levels in this area.As a result,a floodplain has emerged,characterized by the formation of numerous shallow lakes along the river course.However,the pattern of water-level changes in the main channel of the Yangtze River during the Holocene remains unclear.This gap in knowledge poses challenges for understanding sediment transport dynamics,the interactions between the river and its adjacent lakes,and the prevention and control of flood disasters in the Yangtze River basin.To shed light on these issues,our study compiled data on the surface elevation and water depth of 81 lakes in the mid-lower reaches of the Yangtze River basin.Additionally,we analyzed historical water-level records from the 1900s to the 1970s at eight gauging stations from Shashi to Jiangyin along the river’s main stream.Our findings reveal that,particularly along the Jingjiang section,the basal elevation of most lakes is lower than the Yangtze River’s water level during the dry season.Conversely,the water level of the main stream exceeds that of both the floodplain and the lakes enclosed by the Jingjiang embankment.In the tidal reach,especially within the Taihu Lake basin,the basal elevation of lakes typically falls below sea level.Meanwhile,lakes located along the section from Chenglingji to Wuhu exhibit basal elevations that correspond with the Yangtze River’s annual average and dry season water levels.Given the widespread presence of lakes along the middle and lower reaches of the Yangtze River,our study introduces a new proxy for reconstructing the mean water level of the mid-lower Yangtze River in the Holocene.By analyzing sediments from Nanyi Lake and Chenyao Lake in the lower Yangtze River,we attempted to reconstruct the water level of the Yangtze River’s main channel since 8 ka BP.

Engineering Strategies on Flood Control in Middle Reach of Yangtze River, China

Flood disaster has been a serious hidden danger since the ancient time. The essential cause for the fact that floods have not been eliminated for hundreds of years is that time honored strategies do not suit the cases of flood prevention. In the view of geological environmental analyses of flood formation and from the synthesis of experiences gained in flood control in the past hundreds of years, sluggish draining of flood, silt sedimentation in channel and building levee blindly constitute the main cause of intractable flood for a long time in the middle reach of the Yangtze River. Draining away silt and water is the only way to stamping out flood disaster. Opening up artificial waterways for flood diversion, draining away the silt of channel into the polders, and storing the flood water are important engineering measures for the flood control and damage reduction.

Distinguishing different subclasses of water bodies for long-term and large-scale statistics of lakes:a case study of the Yangtze River basin from 2008 to 2018

Long-term and large-scale lake statistics are meaningful for the study of environment change,but many of the existing methods are labourintensive and time-consuming.To overcome this problem,a novel method for long-term and large-scale lake extraction by shape-factorsand machine-learning-based water body classification is proposed.An experiment was conducted to extract the lakes in the Yangtze River basin(YRB)from 2008 to 2018 with the Joint Research Centre’s Global Surface Water Dataset(JRC GSW)data and OSM data.The results show:1)The proposed method is automatically and successfully executed.2)The number of river–lake complexes is between 3008 and 4697,representing 3.56%–5.70%of the total water bodies.3)The areas of the lakes and rivers in the YRB were obtained,and the accuracy of water classification in each year was stable between 90.2%and 93.6%.Comparing the back propagation neural network,random forest,and support vector machine models,we found that the three machine learning models have similar classification accuracy for the scenario.4)Fragmented and incomplete small rivers in the JRC GSW data,unchecked training samples,and overlapped shape factors are the three error sources.Future work will focus on addressing these three error sources.

水网布局下黄河流域应对极端枯水的关键科学问题

变化环境下极端气象水文事件频发,长江、黄河面临同枯风险。在国家水网建设背景下,为提高长江、黄河同枯的极端不利情景下黄河流域水资源安全保障能力,本文分析了长江、黄河两大流域水资源安全面临的现实问题,识别了变化环境下大型流域枯水遭遇—水危机形成—跨流域调水潜力—多线路成网互济—极端枯水下水资源安全保障中亟需破解的关键科学问题,构建了水网布局下黄河流域应对极端枯水的总体研究框架,提出该领域重点研究方向包括:变化环境下长江、黄河极端枯水遭遇规律与空间变异机制,水危机风险多链路传导与复合影响定量评估,极端枯水下跨流域调水挖潜增供,长江和黄河跨流域联合调配与多线路互济精细化调控、极端枯水下流域水资源韧性提升优化调控等。

不同营养水平调水对贡湖湾湖区水质及浮游藻类影响的模拟研究

为探究“引江济太”工程调水给受水湖区水体带来的生态效应,采用水生微宇宙模型进行为期11 d的室内模拟实验,以太湖贡湖湾湖区为受水水体,引入3组设定好的不同营养盐水平(贫营养水平O、中营养水平M、富营养水平E)的望虞河河水,研究在不同营养盐水平调水影响下,受水水体水生态环境的动态响应过程。结果表明:整个实验过程中,中营养和贫营养调水组的水体TN、NO_(3)^(-)-N、NH4_(+)-N、TP、SRP、TOC含量下降明显,富营养调水组影响效果较中营养和贫营养调水组差;调水提高了受水水体生态系统的多样性和均匀度水平,硅藻等非蓝藻细胞密度增加,蓝藻细胞生长受到竞争胁迫,中营养和贫营养调水的影响作用效果好于富营养水平。RDA分析结果表明,受水水体的pH、DO、SiO_(3)^(2-)-Si、TDS、NO_(3)^(-)-N、SRP是本实验水体影响藻类群落结构的主要环境驱动因子。

不同调水方式对巢湖水质影响模拟

引调水工程是目前用来改善湖泊水质的重要手段,然而引调水的调水路线、来水水量以及来水水质对湖泊水质改善效果都至关重要。本文以“引江济巢”工程为例,针对巢湖的浅水湖泊特征,考虑引调水入湖后不仅对水量和水质有直接改善作用,还可能因为湖区水动力条件改变及内源释放影响水质,通过构建二维水动力水质模型,模拟不同调水路线、水量下湖区水动力条件,进一步考虑不同来水水质和底泥释放对水质改善的影响。结果显示,调水对流场的扰动在丰水年较弱、枯水年较强,流量对湖区水质影响随流量增大而增强,来水水质的优劣是决定湖区水体水质是否改善的关键。整体而言,西湖区受调水影响较小,东湖区能够对全湖水质变化起到指示作用。调水方案应基于湖泊实际水量与水质状态综合考虑调水流量与水质制定。

基于耳石微化学的长江禁捕前后鄱阳湖都昌水域刀鲚群体动态变化研究

为了解长江禁捕对鄱阳湖都昌南部水域刀鲚(Coilia nasus)资源的影响,利用电子探针微区分析(EPMA)分别对该水域禁捕前(2014年)和禁捕后(2019年)刀鲚的洄游生态学特征开展了研究。结果显示,所有刀鲚个体耳石自核心至边缘均依次具有锶钙比(Sr/Ca×1000)<3、3~7以及<3的生境履历特征,表现为典型的溯河洄游履历。禁捕后刀鲚数量(17尾)明显多于禁捕前(2尾),体长[(28.1±2.3)cm]也长于禁捕前[(21.3±4.7)cm],且长于禁捕前的已有报道。此外,刀鲚耳石边缘低值区呈现多样化特征[2014年(125.0±63.6)μm、80~170μm,2019年(173.5±73.6)μm、20~290μm],表现出多个上溯群体在该水域混栖的现象。结合该水域多数个体性腺尚未成熟,且都昌南部水域(大矶山至和合乡水域)是刀鲚群体自江湖通道出入鄱阳湖中部和南部湖区及通湖河流(如饶河、信江等)的必经之路,得出都昌水域主要行使刀鲚洄游通道的生态功能,亟须加强保护。

长江-涨渡湖水系沉积物微塑料分布与赋存特征

探究微塑料在涨渡湖水系的分布和赋存特征,可为湖泊沉积物微塑料老化及生物毒性风险评估提供基础数据。在阻隔湖泊涨渡湖、七湖、陶家大湖、邻近长江干支流和连通水道设置11个采样点,通过采集表层沉积物,分析了长江-涨渡湖水系沉积物微塑料丰度、尺寸、形状和种类组成。结果显示,长江-涨渡湖水系所有采样点沉积物中均有微塑料存在,其干物质中微塑料平均丰度为2602.25 n/kg,其中涨渡湖的微塑料丰度最高,为5687.69 n/kg。微塑料尺寸主要分布在[20,50]μm,占微塑料总颗粒数的59.04%;尺寸大于100μm时,微塑料丰度随尺寸的增大而减小;薄膜状微塑料最多,占微塑料总颗粒数的56.06%;微塑料种类主要为聚氯乙烯、聚对苯二甲酸乙二醇酯、氟橡胶和氯化聚乙烯。研究结果有助于了解湖泊微塑料赋存现状及提升水生态环境质量。

1955-2021年期间长江中游枝城至螺山河段与三口洪道水沙输移变化规律

长江与洞庭湖之间存在复杂的江湖水沙交换关系,水沙变化引起江湖冲淤变化,从而对长江中游区域防洪、水资源利用、航运及水生态环境等产生较大影响。本文利用实测资料较为系统地分析了荆江与洞庭湖水沙输移变化规律,结果表明:1955-2021年期间枝城、沙市、螺山站年径流量变化趋势不明显,监利站年径流量增幅为17.4%,三口分流洪道与七里山站均以减少为主;1955-1989年期间枝城与沙市站年输沙量变化趋势不明显,监利站明显增加,三口分流洪道与七里山站明显减少,1990-2021年期间各站均显著减少,其中三峡工程运用后荆江河段(枝城站)、三口分流洪道、洞庭湖出湖及城螺河段年输沙量分别减少90.1%、90.2%、22.5%及76.6%;受水库下泄径流过程改变的影响,荆江河段、荆江三口分流洪道、洞庭湖出湖与城螺河段年内径流过程均呈不同程度的坦化,枯水期平均流量均显著增加,消落期平均流量稍有增加,汛期出现一定程度的减少,蓄水期稍有减少,下泄径流过程坦化以及2006、2011年特枯水年分别引起荆江三口年均分流量减少41.2亿和32.4亿m~3。随着三峡上游水库群陆续建成运用,荆江河段、三口分流洪道、洞庭湖出湖及城螺河段径流量将进一步坦化,由于干流河床泥沙补给逐渐减少,输沙量将进一步减少,预计长江与洞庭湖水沙输移变化规律将基本保持现有变化格局。

引江济淮工程(河南段)水资源调配系统设计与开发

为强化引江济淮工程(河南段)水资源统一调配,基于Spring Boot和Vue前后端分离开发的模式,利用天地图API、WebGL、Echarts等技术设计研发引江济淮工程(河南段)水资源调配系统。从设计思路、功能界面、关键技术3个角度论述系统设计思路和实现过程,从而实现地理信息服务、供需水预测、水资源优化配置、水资源优化调度等功能,实现水量分配可视化、运行调度智能化和跨流域调水管控一体化。系统测试结果表明:引江济淮工程(河南段)水资源调配系统的建立提高了受水区水资源精细化管理的水平,解决了引江济淮工程(河南段)跨流域调水的配置难题,为受水区水资源高效利用提供有效的技术支撑。

基于耳石微化学特征的鄱阳湖刀鲚永修群体的关键栖息地识别

随着长江禁渔国策的持续实施,长江干流和沿线通江湖泊中刀鲚资源及其关键栖息地将有可能得到恢复。为了确证长江禁渔后的2020年在鄱阳湖永修瓢头水域所采集到21尾刀鲚的洄游履历和资源类型,本研究采用电子探针微区分析技术(EPMA)对其耳石元素锶(Sr)和钙(Ca)的微化学特征进行了测定和分析。结果显示,所有个体耳石的Sr/Ca值变化较为复杂。自耳石核心至边缘Sr/Ca值分别出现了对应淡水生境的低值(<3)和对应河口半咸水或海水生境的中高值(>3),最后边缘部分再次出现了对应洄游返回淡水生境的低Sr/Ca值(<3)。Sr含量面分析图中也呈现出了对应淡水—河口半咸水—海水—淡水的蓝色—黄绿色、红色—蓝色变化的图谱;证明上述个体均具有明显的江海洄游特征,为典型溯河洄游型刀鲚。鄱阳湖永修瓢头水域是一处尚未曾正式报道过的洄游型刀鲚分布区。根据性成熟度和摄食情况可将瓢头水域刀鲚分为产卵场群体和非产卵群体两类。通过与鄱阳湖其他水域刀鲚情况的比较分析可以推定,两类刀鲚可能起源于鄱阳湖内两个不同区域的产卵场。对于产卵场群体而言,瓢头水域可能更主要起到产卵场的作用;而对于非产卵群体来说,瓢头水域更多地起到洄游通道的作用。本研究可为了解长江禁渔对刀鲚资源和关键栖息地的恢复效果提供最新的基础信息。

基于补偿水头差的沿江口门引排流量计算方法研究

长江支流口门多建有节制闸,利用涨落潮过程自行引排水,而引排水流态的复杂性使得引排流量过程难以精准确定。以太湖流域杨林塘口门为例,通过分析引排水调度方式及流态特征,发现涨潮时开启中孔闸门引水,内河侧流态复杂且附近水位差别大,而落潮时开启全部闸门排水,外江侧流态复杂且附近水位有所差别。为此,提出了一种基于补偿水头差的沿江口门引排流量计算方法。该方法通过设置系列补偿水头差修正堰流公式中的水位,统计了计算流量与实测流量偏差值,进而建立了流量偏差值与补偿水头差的相关关系,最终确定适宜的补偿水头差,从而建立适宜沿江口门引排流量计算公式。结果表明:利用该方法预测的引水流量误差减小40%~50%,排水流量误差减小3%~6%。相关经验可供工程设计人员及闸管单位运行管理人员借鉴。

新孟河运南支河闸控方案下河湖水动力影响探讨

通过构建太湖流域北部一维、二维耦合的河湖水动力数学模型,模拟并分析了新孟河延伸拓浚工程运南段主要无闸控支河设控前后对引水沿线河道和滆湖水动力的影响。结果表明,新孟河运南段支河口门设控下,引水后运南段河道水位、流速将明显上升,经北干河东侧入滆湖流量有所增加,但支河闸控有利于北干河西侧分流比升高,支河口门东侧闸控将导致滆湖北部水体交换能力降低、水动力有所减弱,滆湖东侧出湖河道流量受新孟河运南段支河闸控的影响较小。为提高新孟河工程引水效益,探讨提出了支河闸控方案在引水期、非引水期和应急排水期等时期的实施建议,为新孟河工程运行及优化调度提供一定的参考。