Floodwater utilization of the Three Gorges Project

Floods are both risks and resources. Floodwater utilization is an important part of flood management. Considering the rising shortage of water resources, serious water pollution, and undersupply of electric power, it’s imperative to strengthen flood management. In light of the hydrological characteristics of the Three Gorges Project (TGP) on the Yangtze River in P. R. China, we investigated the necessity and feasibility of TGP floodwater utilization, proprosed dynamic control of limited water level during flood season of the reservoir and basin-wide integrated floodwater management as strategies, and identified problems that might occur in practice.

Climate Characteristics in Three Gorges Reservoir Area after Water Storage and Its Impact on the Production Potential

Based on the meteorological data from 33 stations of Three Gorges Reservoir from 1960 to 2008,climate yield of rice,corn and winter wheat and the changes of climatic potential productivity after water storage in Three Gorges Reservoir were calculated by the dynamic statistic model of crop growth.The results showed that the temperature in Three Gorges Reservoir was fluctuant decreased before late 1980s,and warmed rapidly after the late 1980s.The precipitation had little change before the late 1990s and had a slight decrease after the late 1990s.Sunshine hours were more in 1960s and 1970s,and then it changed little after 1980s.After water storage,the temperature increased in Three Gorges Reservoir as a whole.The precipitation decreased in the south of Three Gorges Reservoir,while it increased in the northwest of Three Gorges Reservoir.The sunshine hours were reduced except that in the vicinity of Dianjiang.After water storage,climatic potential productivity of rice decreased in the northwest and the northeast,while it increased in the south of Three Gorges Reservoir.The climatic potential productivity of corn decreased in the northeast and the southwest,but increased in the rest of Three Gorges Reservoir.The climatic potential productivity of winter wheat increased almost in total.

Variation Characteristics of Water Environmental Capacity in Poyang Lake under the Scheduling of Three Gorges Reservoir

[Objective] The aim was to study the variation characteristics of water environmental capacity in Poyang Lake under the scheduling of Three Gorges Reservoir.[Method] Choosing chemical oxygen demand (COD),total nitrogen (TN) and total phosphorus (TP) as the control indexes of pollutants in Poyang Lake,the variation characteristics of water environmental capacity in Poyang Lake under the scheduling of Three Gorges Reservoir were analyzed based on the water environment mathematical models of organic compounds and nutrients.[Result] After the operation of Three Gorges Project,high water level in Poyang Lake lasted for a long time in flood season when Three Gorges Reservoir increased discharge volume,while water level went down obviously with the accelerating of recession flow when reservoir decreased discharge volume to store water,so Three Gorges Project had obvious effects on the hydrological regime of Poyang Lake.In 2009,when Three Gorges Reservoir stored water,the water environmental capacity of COD,TN and TP in Poyang Lake in October decreased by 14.0%,15.4% and 15.4% compared with those before operation,while they increased by 3.64%,4.88% and 4.88% in August when reservoir discharged water to prevent flood.[Conclusion] The study could provide scientific foundation for the water pollution control and water environment management of lakes.

The construction management system and practice of Three Gorges Project

Three Gorges Project (TGP),the largest water resources and hydropower project in the world with huge scale and complex techniques,has great comprehensive benefits mainly in flood control,power generation and navigation improvement.Through 17-year construction and practice,the project has been successfully completed.Some valuable experience from the successful construction of TGP has been gained for the management system and mechanism of hydropower project construction in China.Its construction management mode produces important influences on the management system of domestic capital construction.With combination of the construction management practice of TGP,the characteristics of management system and mechanism are summarized,and the suggestions on current hydropower development system and construction management mode are put forward.

Gravity change and its mechanism after the first water impoundment in Three Gorges Project

In this paper we have analyzed precise gravity survey and gravity effects resulted from water loading, crustal deformation, ground water level change and precipitation before and after the water impoundment in the Three Gorges Reservoir. We found that： ① In dam area of the reservoir, gravity effect resulted from water load increase is the most significant, maximum gravity change is 200×10^-8 m/s^2, but this effect is limited in amplitude and range. Gravity change can be observed about 5 km offshore. The gravity change caused by ground water level change is regional; and the impact of precipitation on it should not be neglected. ② At head area of the reservoir, the maximum gravity change is near Xiangxi. Monitoring the variation of gravity field and further study should continue in the future.

Impact of the Three Gorges Dam on Regulation and Storage Capacity of Poyang Lake

The regulation and storage capacity of Poyang Lake is infl uenced by the fl ow from the main stream of the Yangtze River and the fi ve rivers in the Poyang Lake basin.After the operation of the Three Gorges Dam(TGD),hydrological changes in the main stream of the Yangtze River impact water exchange between the Yangtze River and Poyang Lake.Based on the analysis of measured data and factors infl uencing outfl ow at Hukou station,a new empirical formula describing outfl ow at Hukou station and critical water level for lake storage capacity is established.The change in monthly storage capacity of Poyang Lake before and after the construction of the TGD is analyzed quantitatively.The results show that the fl ows from the main stream of the Yangtze River and the fi ve rivers in the Poyang Lake basin affect outfl ow and water storage capacity by changing the water level difference between Xingzi and Hukou stations and by changing the water level at Hukou station.But the Yangtze River and the fi ve rivers in the Poyang Lake basin differ in process and degree.If the water level at Hukou station remains consistent,when the fl ow from the fi ver rivers increases by 1,000 m3/s,the outfl ow at Hukou station increases by 304 m3/s.When the fl ow from the main stream of the Yangtze River increases by 1,000 m3/s,the outfl ow at Hukou station decreases by 724 m3/s.In addition,the operation of the TGD affects the water storage capacity of Poyang Lake.The water volume of Poyang Lake decreases by 49.4%in September,but increases by 47.7%in May.

北京市南水北调配套工程调蓄工程勘察关键技术

北京市南水北调配套工程调蓄工程是北京市“26213”供水格局的重要组成部分,工程分布于北京市西、北、南不同地区,场地建设环境条件复杂,地层结构分布及组合多样,水文地质条件复杂,工程建设面临诸多地质问题及难题。工程勘察成果全面、涉及面广、涵盖工程勘察综合类的全专业领域,完成专业全面的技术成果文件与研究报告60余册,发表学术论文50余篇,取得七大方面技术创新、30余个技术创新点。勘察总体工作思路、技术路线、研发的创新技术、利用的先进手段等方面具有实践推广价值,特别是对城市复杂地质环境条件下建设城市供水调蓄工程具有借鉴作用。

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。

基于支持向量机的蓄水工程土地利用分类与动态变化

为进一步恢复和重建蓄水工程建成前后土地利用变化的历史过程,更好掌握和预报土地利用转移方向,本文利用支持向量机理论开展了土地利用类型解译的适应性研究,通过梳理土地利用动态变化,剖析了蓄水工程建成前后土地利用结构的自适应调节能力和演变方向。结果表明:(1)依靠自学习和自适应等优势能力,支持向量机解译土地利用分类的总体精度高达91.7%、Kappa系数为0.90;除耕地生产者精度相对较低外,水体、林地等其他土地类型具有较高的分类识别能力。(2)利用谷歌地球引擎(GEE)平台梳理土地利用类型演变过程发现,受“三北防护林”工程二阶段(2001—2020年)等项目实施影响,建设用地、林地面积出现较大增幅,其中,林地面积较2000年实施初期增加了近5倍。(3)工程建设运行后林地和建设用地近2/3面积保持了原貌,水体和未利用土地受水利和城建工程影响,原貌类型超过65%以上面积变成了其他类型;“三北防护林”工程加快了林地面积的增加和草地植被覆盖度的提高,低覆盖度草地转移到中、高覆盖度草地的面积净增幅达48.0%、50.2%。

冲刷及整治工程叠加作用下武汉河段滩槽调整特征与成因

大型水库的修建引起了坝下游的滩槽调整,进而对河势、航运、防洪及生态等产生显著影响。为探究滩槽调整的驱动机制,采用1952—2022年水沙和1959—2021年地形观测资料,以长江武汉河段为例,分析了床沙组成、来水来沙及整治工程等因素的影响。研究表明:①武汉河段枯水河槽冲刷量占全河槽冲刷量的90.4%,断面趋向窄深化,河相系数减小。不同江心洲及汊道冲淤出现差异性调整,2001—2021年,铁板洲和白沙洲洲体面积分别减少了63.1%和61.5%,潜洲和天兴洲洲体面积分别增大了212.3%和14.5%;2013年后,铁板洲左右汊均冲,天兴洲汊道左淤右冲。②来沙量锐减,河床以0.125 mm≤d<0.25 mm的细沙居多,抗冲性较弱,是冲刷加剧的先决条件;三峡水库的削峰补枯作用加剧了枯水倾向汊河的冲刷幅度;整治工程改变了滩槽冲淤的横向分布,是江心洲差异性调整的主导因素,也是天兴洲保持左淤右冲的重要原因。③三峡水库蓄水前,洲滩之间演变联动性强;三峡水库蓄水后,来沙减少和中水期时间延长导致洲滩冲刷萎缩,洲滩之间演变联动性变弱;整治工程实施后,工程保持了心滩稳定且其缓流滞沙效应提高了抗冲性,心滩淤长的同时限制了边滩发育,叠加来沙进一步减少,边滩之间、心滩之间演变联动性进一步变弱,边滩与心滩之间演变联动性再次增强。

三峡工程运行背景下洞庭湖近25年来水生态环境的动态研究

三峡工程自2003年运行以来,对长江中下游水环境的影响备受关注。本研究基于25年来对洞庭湖11个点位的监测结果,分析了三峡工程运行背景下洞庭湖水情、水环境质量的时空变化特征,明确了洞庭湖水环境演变的主控因素。结果显示,1996—2015年,长江三口年均水量和输沙量分别为(1.83~10.46)×10^(10) m^(3)、(1.07~147)×10^(6) t,三峡工程运行后的入湖水量和输沙量分别降低了27%和87%;湖体主要水质指标总氮(total nitrogen,TN)浓度在1999—2022年显著上升,而总磷(total phosphorus,TP)浓度则明显下降,全湖处于中营养水平,而东洞庭湖则处于轻度富营养化水平;浮游藻类密度变化范围为(9.00~272.03)×10^(4) ind./L,且逐年上升,藻的优势类群逐渐由硅藻、隐藻向绿藻和蓝藻演替。整体来看,水文调节是维持洞庭湖营养平衡和水环境安全的关键要素。此外,加强农业面源污染控制,推进全面清洁生产,通过生境改善和生态修复来有效拦截入湖口及上游河流污染物是洞庭湖环湖经济带管理部门进行洞庭湖综合治理与水质提升的主要抓手。

三峡水库水面蒸发年内滞后效应分析

水面蒸发在季节变化上相比净辐射等气象要素的相位延迟反映了水体储热对水面蒸发的影响,量化这一对气象要素波动的滞后响应对理解和估算深水水库(湖泊)蒸发非常重要。三峡水库等河道型深水水库的水位和面积具有显著周期性变动,使得其水面蒸发的响应模式更为复杂,而目前对其认识非常薄弱。本文利用2013年8月—2020年7月三峡水库巴东站水面蒸发场和陆面蒸发场的蒸发和气象观测数据,分析了水面蒸发的季节变化及其年内滞后效应。结果表明:水面蒸发场蒸发量在年内的8和12月呈现双峰变化,与只有8月单峰值的陆面蒸发场蒸发量显著不同。水面蒸发场蒸发量相对净辐射、平均气温和水面温度分别存在4、3和2个月的滞后,而陆面蒸发场蒸发量相对滞后时间均在1个月以内;水面与陆面蒸发场相比,水温、蒸发量和水面与大气饱和差之间的滞后时间分别为1、3和4个月,而平均气温和净辐射之间不存在滞后。本文揭示出三峡水库巴东段水面蒸发年内滞后效应主要受到水库水温引起的水面与大气饱和差在季节上滞后的影响,需通过深入分析水温的时空变化来明确整个三峡水库的水面蒸发特征。

南水北调前后北京平原区地下水和地面沉降演变特征

超量开采地下水引发的地面沉降已成为制约北京区域社会经济可持续发展的重要因素之一。2014年12月,南水北调中线工程正式通水,每年向北京输水超过10×10^(8)m^(3),改变了北京供水格局,也为地下水压采、涵养及控制地面沉降创造了条件。本文利用多种监测数据,分析南水进京前后,北京平原区地下水和地面沉降的变化;研究不同水位变化模式下不同岩性及深度土层的变形特征;计算土层不同变形阶段的弹性和非弹性储水率;并对黏性土层产生较大残余变形和滞后变形的原因进行了探讨。结果表明:①2015~2020年,平原区大部分地区第一至第四含水层组地下水位逐渐上升,地面沉降呈减缓的趋势。②第二和第三压缩层组是沉降主要贡献层,除平各庄和榆垡站外,其余各站第三压缩层组沉降占比逐渐增大,沉降主控层有向深部转移的规律。③平原区北部和东部,第二和第三压缩层组对应的地下水位由降转升。在水位下降阶段,土层呈塑性和蠕变变形;水位上升阶段,土层以塑性变形为主,部分时间出现弹性变形,具有黏弹塑性。平原区南部,地下水位始终持续下降,土层变形始终呈塑性和蠕变变形。含水砂层则主要呈弹性变形。④土层变形的不同阶段,弹性和非弹性储水率并不是恒定的,随着地下水位下降,储水率呈减小的趋势。⑤黏性土层存在较大残余变形和变形滞后的原因,一是非弹性储水率大于弹性储水率,二是黏性土层的弱渗透性。

三峡工程建设及其运行调度对秭归库首地区气象及生态环境的影响

三峡工程作为世界上最大型水利工程自2003年蓄水至今已有20年,但其对局地气候、生态等的影响仍不清楚,评估其对库区生态环境、气象及水资源动态的影响是保证三峡工程安全平稳运行的重要基础。本文通过秭归典型区水土保持监测站长期观测结果,从地面常规气象、典型径流场监测及老鹰沟小流域监测探讨三峡工程建成及其运行调度对库首地区生态环境的影响。结果表明,三峡工程三次蓄水后扩大了水域面积及库容量,导致年极端最高气温、平均气温和年平均最高气温均先下降后上升,且三次蓄水后的第二年降雨量均有所增加,提高了最低气温及地面温度,在一定程度上提高了宜居性;农业工程措施如间作白三叶草、黄花菜植物篱笆可以有效降低坡耕地径流量及径流泥沙量,降低农田有机质和氮磷等养分流失,对于减少面源污染、维持土地生产力具有积极作用;由于农业生产排放,老鹰沟小流域氮素平均含量为16.45 mg/L,氮素超标严重,应进一步强化环境管理,保护三峡库区水环境健康。综上所述,三峡工程的建设及其运行调度降低了局地年度气温波动幅度,对当地气候具有长期影响,合理农业工程措施有助于降低水土流失,仍需进一步完善环保措施,维持三峡库区生态平衡。

三峡工程蓄水运用20年综合效益发挥与展望

三峡工程自2003年蓄水发电至今已运行20 a,初步设计主要功能全部实现,并适应运行条件变化和发展需求持续优化运行方式,防洪、发电、航运、水资源利用等综合效益全面发挥。截至2023年底,三峡工程累计拦洪运用66次,拦蓄洪水超2 088亿m^(3),确保了荆江河段防洪安全,极大减轻了长江中下游防洪压力;累计发出清洁电能超16 600亿kW·h,相当于节约标准煤5.1亿t,减少二氧化碳排放13.3亿t;极大改善了库区与长江中游航道条件,累计通过货运量超20亿t,有力促进了长江航运快速发展;枯水期累计向下游补水约3 400亿m^(3),有效保障了长江中下游供水安全;生态调度成效显著,四大家鱼资源量明显恢复。为了应对频发的极端水文事件带来的风险和挑战,确保三峡工程长期安全运行和持续发挥巨大综合效益,从推进气象水文预报技术研究与应用、三峡水库调度运行方案优化、创新成果转化运用、智慧化管理等方面提出了下一步工作展望。

高洪水期运行水位对三峡水库泥沙淤积的影响

三峡水库泥沙问题直接关系到水库库容的长效保持。选取典型高洪水期,基于数值模型探究入库水沙量级、水沙异步及运行水位对三峡库区沙峰输移和淤积排沙的影响。结果表明:入库洪峰的增大抑制了涪陵沙峰比的衰减,并导致更多泥沙输运至坝前,使得坝前沙峰降幅受运行水位的抬升更为显著;变动回水区较常年回水区更易受到入库水沙异步影响,且随着来沙系数的增大,由低水位抬升时淤积占比更高;水库排沙比受入库水沙异步影响有限,且随着入库洪峰、沙峰的增大,排沙比增加的同时对运行水位抬升导致的衰减更为敏感。研究成果初步揭示了入库水沙异步及运行水位对库区沙峰运动与淤积的影响,可为三峡水库汛期优化沙峰排沙调度提供参考。

引江补汉工程控制枢纽品字型双层闸门水力控制技术

石花控制闸是引江补汉工程的控制枢纽,采用品字型双层闸门布置解决了引江补汉工程高水头、超长有压输水水力控制关键技术难题。为了探究石花控制闸品字型双层闸门水力控制技术,采用数值计算和水工模型试验的方法开展研究:①采用一维、三维耦合数学模型计算控制闸启闭引起的系统水力过渡过程,为工程设计提供边界条件;②采用物理模型试验分析控制闸体型的合理性。结果表明:系统沿线最大、最小压力均满足相关规程要求;控制闸内水流流态、压力分布等指标正常,控制闸体型合理。石花控制闸总体设计方案合理,布置方式和研究方法可为其他类似工程提供参考。

农村供水工程中生物慢滤净水工艺数字孪生实践

在新形势下,国家大力推进数字孪生技术在农村供水工程管理中的应用。我国西南丘陵山区农民居住较为分散,水源多样,生物慢滤技术因其构造简单、对水质适应性强而被广泛应用,但在日常运行过程中存在维护不及时、无法准确判断出水是否达标等问题,对供水安全构成威胁。生物慢滤技术实施数字孪生建设,通过在关键节点安装监控设备,监测供水过程的浊度、滤速和水质等参数,监测数据由无线遥感终端汇集至数据分析系统,对超出阈值的实时数据发出报警,通知管水员实地检查。三峡库区秭归县水田坝乡工程实践结果表明,农村供水工程进行智慧化改造能够改变人工现地管理传统方式,减轻了管水员的工作压力,供水水质得到保障。从实践的效果来看,生物慢滤净水工艺数字孪生是农村供水工程智慧化供水的一次有益尝试。

东平湖调蓄南水北调东线来水的可行性

为充分发挥东平湖水库综合效益,提高水库水安全保障韧性,按照“以时间换空间”的思路,提出利用东平湖富余库容调蓄南水北调东线来水的方案。结果表明:东平湖1956-2016年月平均富余调节库容1.17亿m^(3),在大汶河来水偏枯、东平湖水位较低年份利用东平湖富余库容调蓄南水北调东线来水是可行的;对比分析基准方案和2种方案实施后对湖周用水保证率、东平湖需水量、入黄水量、工程安全的影响后,得到东平湖库容调蓄的最优方案。该方案不占用大汶河水指标,同时最大增加了南水北调东线调蓄库容3.62亿m^(3),提高了调度灵活性,为南水北调东线二期供水效益提升提供了新思路。

数字孪生三峡建设与展望

作为水利部数字孪生工程建设的先行先试对象之一,数字孪生三峡建设取得了显著成效。通过水利信息化基础设施、数字孪生平台及智能业务应用体系整合与建设,建立了物理实体工程与数字孪生工程及其影响河段虚实交互映像,有效提升了长江流域调度和三峡工程综合管理能力。文章阐述了数字孪生三峡的建设目标、总体框架、建设内容及初步成果,分析了数字孪生三峡先行先试建设的特色与亮点,并结合新阶段水利高质量发展的要求,对数字孪生三峡下一步建设提出了展望。