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.

Characteristics and Effects of Inorganic Nitrogen in East Water-source and Inflow Rivers of Chaohu Lake

[Objective] To study the characteristics and effects of inorganic nitrogen in east water-source and inflow rivers of Chaohu Lake. [Method] The speciation and distribution characteristics of dissolvable inorganic nitrogen （DIN） in east water-source and inflow rivers of Chaohu Lake were investigated, and their effects on water qual- ity were examined. [Result] The concentrations of NH3-N and NO2--N were the high in flood season, and low in non-flood season, while the concentration of NO3--N pre- sented the opposite trend; the concentration of NO3--N was the highest in Shuangqiao estuary, where the pollution was the worst. DIN in Zhegao estuary and Xiaozhegao estuary was mainly caused by domestic sewage and industrial wastewaters; surface runoff and pollution from ships contribute the most to the DIN content in Shuangqiao estuary. [Conclusion] This study provided basic data and theoretical basis for the control and management of eutrophication in Chaohu Lake.

Estimating minimum ecological water required of the western route first stage project of China＇s south-to-north water transfer scheme for water exporting rivers

It is well known that there is abundant water resources in basin of the Yangtze River, the first largest river in China, which is mainly located in Southern China. However, water resources is very scarce in the basin of the Yellow River, which is mainly located in Northern China. So the western route project of south-north water transfer scheme （WRP-SNWTS） aims to transfer water from the Yangtze River to the Yellow River. The area of WRP-SNWT, located in the upper reaches of the Yangtze River and the main areas of Sichuan and the marginal areas of the Qinghai-Tibet Plateau, has sufficient water resources but fragile ecology and environment. Therefore, it is necessary for WRP-SNWT to analyze the ecology water required. Based on the planning principles of from low elevation to high elevation, from small to large, from short to long and from easy to difficulty, the WRP-SNWT will be constructed through three stage projects. The western route first stage project of the south-north water transfer scheme （WRFST-SNWTS） is planned to transfer 4×10^9m^3/a from six tributaries of the Yalong river and from Dadu river to Jiaqu of Yellow River.. Daqu river and Niqu river are the branches of Xianshui river. Sequ river, Duke river, Make river and Ake river are the branches of Dadu river, which account for 65-70% of the total river run-off. It need more research and the rest run-off can satisfy channel ecology water required. According to analysis ecological water required which mainly satisfy for aquicolous biology in water-exporting region, such as low air temperature. Fish and aquicolous biology main living from May to August, and rivers are iced up from December to March of next year, ecology water required mainly for fish and aquicolous biology. The flow criterion of Tennant method is modified. The ecology water required of WRFSP-SNWTS is estimated by the flow data of Zhuwo gauging station, Zhuba gauging station, Chuosijia gauging station and Zumuzu gauging station. The result show that the ecology water required calculated by modified Tennant less 1 l percent than that of Tennant. This estimating result can supply more water resources for transferring to Yellow River. Meanwhile, this can supply gist for research transferring water of WRFSP-SNWTS.

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.

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.

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。

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。

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。

协同推进南水北调后续工程和长江经济带高质量发展

推动长江经济带高质量发展,是以习近平同志为核心的党中央作出的重大决策,是关系党和国家事业发展全局的重大战略。南水北调东、中、西三条线均以长江为水源,是跨流域跨区域配置水资源的骨干工程,是国家水网的主骨架和大动脉,在保障国家经济安全、粮食安全、生态安全等方面具有基础性、战略性作用。两者联系紧密,互促共生。文章通过对长江经济带高质量发展内涵的分析,以及在国家水安全保障、长江经济带高质量发展对南水北调高质量发展的具体要求梳理的基础上,对共同推进南水北调和长江经济带高质量发展提出了初步的认识和思考。

水网格局下流域生态流量保障调度研究——以永定河流域为例

水利部2022年起部署实施母亲河复苏行动,以生态流量和水量为保障目标,生态流量管理模式也转向以水量、流量和过程等多样化生态保障为目标的新模式。生态用水需求的多样化,对流域生态用水总量、水利工程调蓄能力提出了更高要求。在保证永定河流域防洪、供水安全前提下,充分发挥跨流域调水对流域生态流量的补偿作用,提出了水网格局下江河流域生态流量保障调度框架,包括生态流量保障目标确定、考虑跨流域调水的生态流量保障调度方案制定、考虑跨流域调水的生态流量保障调度方案执行3个方面,以永定河为例,分析了流域生态流量保障调度实践及效果,提出以贯通“调算—优化—优选”全过程的生态调度决策方法,构建以生态效益最优、补水效率最高、补水费用最小为调度目标的多目标生态流量优化调度模型,可为我国北方水资源短缺流域开展生态流量保障调度提供参考。

长江流域水源涵养服务价值及其空间转移评估

水源涵养服务价值在不同区域之间的转移是流域上下游之间进行横向生态补偿需要考虑的关键内容。然而,水源涵养服务价值的转移依赖于流域的水文循环路径和河流的水量输送。现有的生态系统服务价值转移量评估方法缺乏对水源涵养服务转移中水文特征的描述,评估结果的合理性有待加强。针对此问题,从转移方向和转移路径2个方面改进断裂点-场强模型,通过引入河流方向系数判断流域上下游以及干支流地区之间的水力联系,在水源涵养服务转移评估中考虑河流的水文特征,并在长江流域应用,提高评估结果的合理性与可用性。结果表明,2020年长江流域水源涵养量为11 538.45亿m3,水源涵养服务的价值量为11 953.83亿元。相比现有模型的评估结果,研究改进的断裂点-场强模型突出了水源涵养服务价值从流域上游向下游转移的特征、增加了转移强度和范围。长江流域水源涵养服务价值的转出量由大到小依次为:四川>江西>湖南>贵州>湖北>安徽>重庆>云南>浙江>青海>陕西>广西>西藏>河南;各省份水源涵养服务价值的转入量由大到小依次为:云南>安徽>湖北>重庆>江苏>湖南>四川>上海>西藏。

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。

流域景观格局演变对河流水质的影响——以巢湖流域南淝河为例

景观格局由景观组成、地理特征和景观配置等方面共同组成,流域景观格局演变是河流水质时空变化的重要驱动因素。为探讨景观格局演变对城市地区典型河流水质的定量影响与作用机制,本研究基于巢湖流域南淝河2013年与2023年水质数据和土地利用数据,采用单因素ANOVA检验、层次聚类法探究水质时空变化,通过Bioenv分析、VPA分析等多元统计方法探究在不同时空尺度下景观格局中的各个部分对水质综合营养状态指数(TLI)的解释率以及影响TLI的关键因子。结果表明:2023年南淝河水质优于2013年,总氮、总磷和TLI在2013年显著高于2023年,但不同年份水质的季节差异并不一致。不同时期的调查结果均发现,非汛期景观格局对TLI的解释率高于汛期,1000 m河岸带缓冲区和子流域尺度下景观格局对TLI影响较大。景观组成、地理特征对TLI的独立解释率大于景观配置;景观配置对TLI的影响主要集中在与景观组成、地理特征的联合作用中。在景观组成中,建设用地面积占比、园地面积占比与TLI呈显著正相关,水域面积占比与TLI呈显著负相关。在地理特征中,面积高程积分、地形湿度指数与TLI呈显著负相关。研究认为,未来南淝河流域要限制“源”景观的无序扩张,不可忽视地理特征对河流水质的优化作用,并从景观配置中的“复杂度、破碎度和连通性”等方面着手对城市进行合理规划以辅助改善水质。

长江苏州段水质变化及七浦塘引水对阳澄湖水质影响分析

根据2019—2022年长江苏州段水质各指标数据,分析变化趋势。结果表明,全年7月份的水质质量最差,超标主要项目为氨氮和溶解氧;夏季的水质较其他季节稍差,超标主要项目为溶解氧;2022年水质较前几年好转,Ⅱ类水断面占比上升,不达标月份减少,测次达标率集中在90%以上。溶解氧、总磷、总氮呈明显的季节性变化规律,溶解氧和总氮的含量冬春较高,夏秋较低;总磷变化规律则相反,冬春较低,夏秋较高。七浦塘引水工程对周边地区水质改善明显,七浦塘与阳澄湖引水期溶解氧、氨氮和总磷均显著优于排水期。

广东省河湖库水域系统时空变化特征及驱动力分析

为研究广东省河湖库水域系统历史变迁发展规律,对其1980—2021年时空变化、景观格局、土地利用转移特征进行分析,并结合相关性系数分析水域变化的驱动因素。结果表明:(1)1980—2021年河流面积持续缩减而水库面积不断增长,二者变化趋势均于1995年发生突变;(2)水域景观格局表现出破碎化、复杂化、离散化的趋势;(3)近40 a内水域周边50 m土地利用的变化主要为河流向水库的转化,同时1995—2021年有大面积的河湖库水域转为城乡、工矿、居民用地;(4)年平均气温、常住人口密度以及经济产值是水域面积及景观格局变化的主要驱动因子。该研究成果明确了广东省河湖库水域的变化特征,可为针对性的水域保护政策制定提供一定的依据。

“引江济太”影响下太湖贡湖湾湖流时空变化

“引江济太”作为流域骨干调水工程,对贡湖湾湖流的影响一直受到较多关注。2022年夏季(8月25日9月5日)和2023年冬季(1月18日2月28日),在贡湖湾布设9个站点,开展“引江济太”和风场共同影响下的贡湖湾湖流运动特征研究。通过监测氯离子浓度分布来分析“引江济太”作用下江水入贡湖湾后输移规律,并建立数值模型,基于示踪粒子验证模型的可靠性。夏季和冬季贡湖湾垂向平均流速均呈现出河口区和交界断面区高、中间过渡区低的特点,河口区湖流主要受“引江济太”影响,中间过渡区、交界断面区湖流主要受风场影响。贡湖垂向平均流场可分为顺时针、逆时针、中间进两岸出、中间出两岸进4种类型。“引江济太”一定程度上会加快贡湖部分水域的流速,贡湖中轴线处流速的改善作用最为明显。