Impact of the eastern water diversion from the south to the north project on the saltwater intrusion in the Changjiang Estuary in China

The south to the north project (WDP) on the saltwater intrusion in the Changjiang Estuary is studied by the improved three-dimensionai (3D) numerical model.The net unit width flux in the Changjiang Estuary as well as the sectional salt flux is calculated in the North Branch (NB),the South Branch (SB),the North Channel (NC),the South Channel (SC),the North Passage (NP) and the South Passage (SP),respectively.The net seaward water flux in the SB is reduced,and the net water flux spilling over from the NB to the SB is enhanced after the eastern WDP.Under the mean river discharge condition in the dry season,the net salt flux spilling over from the NB to the SB is increased by 2.09 t/s and 0.52 t/s during the spring and neap tides,respectively,due to the eastern WDP.The saltwater intrusion in the Changjiang Estuary is enhanced by the eastern WDP.Compared with that during the spring tide,the net water diversion ratio during the neap tide in the NC is smaller,and thus the enhancement of the saltwater intrusion by the eastern WDP is smaller in the NC,and larger in the NP and the SP.The tidally averaged surface salinity at the water intakes of the Dongfengxisha Reservoir,the Chenhang Reservoir and the Qingcaosha Reservoir rises both during the spring and neap tides.

Critical chain construction with multi-resource constraints based on portfolio technology in South-to-North Water Diversion Project

Recently, the critical chain study has become a hot issue in the project management research field. The construction of the critical chain with multi-resource constraints is a new research subject. According to the system analysis theory and project portfolio theory, this paper discusses the creation of project portfolios based on the similarity principle and gives the definition of priority in multi-resource allocation based on quantitative analysis. A model with multi-resource constraints, which can be applied to the critical chain construction of the A-bid section in the South-to-North Water Diversion Project, was proposed. Contrast analysis with the comprehensive treatment construction method and aggressive treatment construction method was carried out. This paper also makes suggestions for further research directions and subjects, which will be useful in improving the theories in relevant research fields.

Reliability model of organization management chain of South-to-North Water Diversion Project during construction period

In order to analyze the indispensability of the organization management chain of the South-to-North Water Diversion Project （SNWDP）, two basic forms （series connection state and mixed state of both series connection and parallel connection） of the organization management chain can be abstracted. The indispensability of each form has been studied and is described in this paper. Through analysis of the reliability of the two basic forms, reliability models of the organization management chain in the series connection state and the mixed state of both series connection and parallel connection have been set up.

Land Cover Changes and Drivers in the Water Source Area of the Middle Route of the South-to-North Water Diversion Project in China from 2000 to 2015

The Middle Route of the South-to-North Water Diversion Project(MR-SNWDP)in China,with construction beginning in 2003,diverts water from Danjiangkou Reservoir to North China for residential,agriculture and industrial use.The water source area of the MR-SNWDP is the region that is most sensitive to and most affected by the construction of this water diversion project.In this study,we used Landsat Thematic Mapper(TM)and HJ-1 A/B images from 2000 to 2015 by an object-based approach with a hierarchical classification method for mapping land cover in the water source area.The changes in land cover were illuminated by transfer matrixes,single dynamic degree,slope zones and fractional vegetation cover(FVC).The results indicated that the area of cropland decreased by 31%and was replaced mainly by shrub over the past 15 years,whereas forest and settlements showed continuous increases of 29.2% and 77.7%,respectively.The changes in cropland were obvious in all slope zones and decreased most remarkably(–43.8%)in the slope zone above 25°.Compared to the FVC of forest and shrub,significant improvement was exhibited in the FVC of grassland,with a growth rate of 16.6%.We concluded that local policies,including economic development,water conservation and immigration resulting from the construction of the MR-SNWDP,were the main drivers of land cover changes;notably,they stimulated the substantial and rapid expansion of settlements,doubled the wetlands and drove the transformation from cropland to settlements in immigration areas.

Penalty model for delay of bidding section construction period in South-to-North Water Diversion Eastern Route Project from perspective of programs

According to the multi-project and program management theory, this paper analyzes the program generation principle and establishes a program based on progress goals. On the basis of the present situation of calculation of penalty for delay of the bidding section construction period with the critical path method, we studied the effects of contractor-induced delay of the bidding section construction period in detail, including the effects on the construction period of the bidding section itself, the earliest start times of the next bidding section and other subsequent bidding sections, and the construction period of the program, and then constructed a penalty model for delay of the bidding section construction period from the perspective of programs. Using the penalty model, we conducted a practical analysis of penalty for delay of the construction period of the Baoying station program in the South-to-North Water Diversion Project. The model can help determine the amount of penalty for delay of the construction period in bidding sections scientifically and reasonably,

IMPACTS OF THE SOUTH-TO-NORTH WATER DIVERSION PROJECTS (MIDDLE ROUTE)ON THE WATER ENVIRONMENT OF THE MIDDLE AND LOWER REACHES OF THE HANJIANG RIVER

In this paper, according to the rule of unbalanced sediment transport and the analysis of field data, different water diversion schemes were theoretically studied, including the erosion and sedimentation trend as well as their impacts on the environment of the middle and lower reaches of the Hanjiang River. The results showed that the 95×10 8m 3 water diversion scheme will cause less erosion and water level decrease than the 15×10 8m 3 water diversion scheme. Using a water diversion scheme of 95×10 8m 3, the decrease of water quantity can impact the river hydrodynamic regime substantially and the environments of the middle and lower reaches of the Hanjiang River will be greatly affected. It is therefore necessary to develop new water resources or build projects to meet the need of the environment and the needs for navigation.

Critical discharge at Datong for controlling operation of South-to-North Water Transfer Project in dry seasons

Previous research shows that there is a strong correlation between saltwater intrusion in the Yangtze Estuary and discharge at Datong. In the near future, the discharge of the Yangtze River during dry seasons will decrease due to the construction and operation of large water diversion projects, including the South-to-North Water Transfer Project, which will further exacerbate saltwater intrusion in the estuary. In this paper, a nested 1D river network model and a 2D saltwater numerical model are used to associate saltwater intrusion in the Yangtze Estuary with different values of discharge at Datong. It is concluded that 13 000 m3/s is the critical discharge at Datong for preventing saltwater intrusion and controlling the volume of water transferred by the South-to-North Water Transfer Project. Furthermore, based on the analysis of river discharge from Datong to Xuliujing and in consideration of the influence of all of the water diversion projects, operation schemes are proposed for the Eastern Route of the South-to-North Water Transfer Project for different hydrological years.

南水北调西线工程水源区可调水量“十问”

南水北调西线工程是我国“四横三纵”国家水网主骨架尚待建设的最后一环,而水源区可调水量是西线工程规划论证面临的焦点和难点问题。本文从水资源本底条件与演变趋势,生态环境与经济社会发展需水,调蓄水库与输水工程规模,调水对水源区及其下游水资源开发利用、水生态环境、水力发电、航运等方面影响的角度,提出了与水源区可调水量相关的10个问题;以长江上游分布式水文模型为基础,建立了南水北调西线工程水源区可调水量模拟分析模型,力图系统、定量地回答所提问题。本文的主要研究结论有:在仅考虑满足水源区河道内外生态环境和经济社会需水的前提下,“上线+下线”组合方案多年平均可调水量为1.59×10^(10)m^(3),“完全下线”方案在建设岗托水库进行联调时,多年平均可调水量将达到1.74×10^(10)m^(3);在综合考虑调水对水源区水平衡、水力发电和航运影响及其可接受程度后,南水北调西线水源区可调水量为1.22×10^(10)~1.26×10^(10)m^(3)。长远来看,应谋划西南片区水网与国家水网主骨架、“大动脉”的连接与融合,在减小南水北调西线工程调水影响的同时,提高南水北调西线工程的整体供水能力以及对气候变化等外部条件的适应性。

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。

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。

气候变化对南水北调西线工程的影响及建议

南水北调工程是国家水网的重要组成部分,其西线工程建设是缓解我国西北、华北地区水资源短缺的重要举措。气候变化下西线工程引水区和受水区水资源情势直接关系到工程的规划建设与运行方式。基于历史实测资料和气候模式情景,采用数理统计与水文模拟相结合的途径分析了气候变化对南水北调西线工程引水区和受水区水资源的影响。结果表明:1)1961—2020年西线调水区和受水区气候变化以暖湿化为主要特征,调水区年径流量整体稳定略增,受水区年径流量显著性减少。2)未来中期(2035年)和远期(2050年),调水区和受水区气温继续显著升高,降水多呈非显著增加;未来中期、远期调水区年径流量较基准期(1961—2000年)分别增加1.42%和2.08%,受水区年径流量分别减少1.02%和0.28%。3)未来气候变化下,调水区年径流量相对稳定,能够满足调水需求,受水区年径流量略减,对跨流域调水需求有所增加。为确保南水北调西线工程的长期稳定运行,建议加强气候变化及其影响的不确定性研究,制定科学合理的应对措施,以应对未来可能的水资源短缺的挑战。

南水北调中线总干渠冰盖糙率观测分析

冰盖糙率是确定渠道冰期输水水位和流量关系的基础参数,一直是明渠冰工程研究的重点之一。鉴于当前大型混凝土渠道冰盖糙率研究成果相当匮乏,以南水北调中线总干渠石家庄以北唯一无输水建筑物的唐河节制闸—放水河节制闸渠段为研究区域,依据全线通水以来唯一生成全渠段封冻冰盖的2016年1—2月逐日水位和流量实测数据,采用伯努利能量方程和谢才-曼宁公式推求渠道糙率,定性定量分析封冻前后渠道糙率变化特征。结果表明:①研究渠段畅流期渠道糙率n b为0.0167,封冻期冰盖综合糙率n c为0.0146,冰盖下表面糙率n i为0.0118。②由于水力磨蚀作用,封冻期冰盖糙率随时间呈波动减小的趋势。③渠道一旦生成封冻冰盖,输水能力大幅降低,仅占渠道设计流量的66.7%。该研究给出了大型混凝土渠道封冻冰盖糙率和输水能力降低的确切数值,以期为冰期输水调度和类似工程设计提供科学依据。

局部降温对输水渠道水华抑制的影响分析

南水北调中线工程自通水以来,发挥着巨大的社会和经济效益,已成为京津地区的主力水源。中线工程输水的水质理化指标相对稳定,但局部渠段存在藻类异常增殖现象,有水华爆发的风险。针对出现的藻类异常增殖问题,在通冷风这一改变局部气象条件的工程措施基础上,建立了澎河—沙河渡槽段平面二维水动力和水质模型,研究了通风位置、通风温度和通风时长等因素对输水渠道水温和藻类的影响。研究表明:水温和叶绿素a浓度均与通风位置、通风温度和通风时长有关,通风温度越低、通风时长越长,平均水温和叶绿素a浓度下降幅度越大,平均水温最高可下降约2℃,叶绿素a浓度最大可降低约54.5%,且仅上游和全渠段通风均可有效降低水温和抑制藻类生长,仅下游通风对水温和藻类的影响较小。因此,采取局部降温的方式可以起到一定的降低叶绿素a浓度的作用,综合考虑藻类抑制效果和工程成本,在水华易爆发渠段的上游通冷风是行之有效的工程措施。

综合水价内涵、形成机制及实施路径探析

在我国南水北调工程受水区水价管理问题分析的基础上,考虑我国南水北调受水区推进综合水价改革的现实需求,参考电价和天然气价格形成机制,系统解析了综合水价内涵及形成机制,明确综合水价具有区域水资源一体化管理、各类水源成本统一核算和用户终端水价差异化核定特征,提出综合水价需具备工程一体化、管理一体化、监管制度化的实施基础,通过供给侧一体化定价、用户侧差别化定价和管理侧梯次化推进落实综合水价改革,最后提出了推进综合水价改革的相关建议,为我国综合水价改革提供技术支撑,并服务于相关决策的制定。

多源多特征集成的南水北调工程丹江库区湿地时空格局演变

丹江口水库是中国南水北调工程的关键水源区。随着城镇化发展以及大坝二次建设,库区湿地生态系统变化显著,亟需湿地生态科学监测。以丹江库区为例,依托Google Earth Engine(GEE)平台,首先采用已有土地覆盖数据集生成湿地样本集,其次整合Landsat影像、DEM等数据构建多源特征集合,并基于Jeffries-Matusita(JM)距离进行特征优选,使用随机森林(RF)算法实现了1985~2023年丹江库区湿地制图。结果表明:①本文提出的样本采集流程可有效提高样本质量,为长时序分类样本采集提供参考;②湿地分类特征优选后特征数由37个减为27个,分类总体精度变化不大,优选后的特征应用于丹江库区湿地分类的平均总体精度(OA)以及平均数量和分配分歧指数(QADI)分别为89.53%和0.0802,说明特征优选有效减少信息冗余,提高影像分类效率;③1985~2023年,丹江库区湿地面积呈波动增加趋势,从1985年的17839.85 ha扩大到2023年的28872.48 ha,面积增长38.12%。总体来说,丹江库区湿地生态系统呈现出逐步恢复和优化的良好态势。

南水北调中线受水区水资源利用效率及影响因素

为提升南水北调中线工程受水区水资源利用效率,以工程沿线北京、天津2个直辖市和河南、河北18个省辖市共计20个地域单元为研究区域,基于2015—2021年面板数据,采用Super-SBM模型、GML模型及sys-GMM估计法对受水区水资源利用效率进行测度,对影响因素进行识别。结果表明:全区水资源静态利用效率总体偏低但呈波动上升态势,区域差异较大,呈京津板块>河南板块>河北板块格局,空间上呈现以京津冀、郑州2个都市圈为核心向外围逐渐递减的“核心-外围”结构;全区水资源动态利用效率整体呈波动上升趋势,主要源于技术进步,而技术效率作用有限;经济发展水平、水资源禀赋、科技水平、城镇化进程、人口密度与水资源利用效率显著正相关,水污染程度、产业结构、环境规制与水资源利用效率显著负相关。

南水北调中线受水区全要素水资源绿色效率及节水减排潜力

采用非径向、非角度SBM-DEA模型测算2015—2021年南水北调中线受水区20个城市全要素水资源绿色效率,探究其时空演变规律,并分析各市节水减排潜力。结果表明:受水区全要素水资源绿色效率总体呈现以京津冀、郑州两大都市圈为核心向外围逐渐递减的“核心-外围”空间结构模式以及全要素水资源绿色效率由高到低依次为京津、河南、河北的空间分异规律;2015—2021年受水区全要素水资源绿色效率总体呈波动上升趋势,但仍处于较低水平,仅实现了最优效率的70%~85%;不同城市节水减排潜力差异显著,空间上呈现“南高北低、西高东低”的分布格局。

南水北调中线水源区植被指数时空变化分析

通过单线性回归(SLOPE)和地理加权回归(GWR)法,用植被指数(NDVI)研究南水北调中线水源区的植被分布变化趋势及机制,为保障水量和水质提供理论支撑。结果表明,2000—2019年水源区NDVI和入库流量呈现同步增长,植被逐渐变好,2007年以前NDVI增长幅度大,2008—2011年处于波动阶段,2012年以后增长幅度减小;NDVI变化最明显的是研究区东北部、西部和丹江口库区周边,这些区域地势相对低平、人口集中,中山和高山区NDVI变化不大;高程、坡度、人口数和城镇化是影响水源区NDVI分布的主要因素,降水、气温和产业比重是次要因素;各因素影响的强度和方向在空间上有异质性,自然地理因素对NDVI影响的最显著范围为高程1090 m以下、年均降水量980 mm以上的区域,人文地理因素影响的显著范围区是人口密度大、城镇化率高的地区。

基于水网视角的水资源与关联要素适配性评价

为研究水资源与关联要素的空间错配问题,基于水网视角,根据适配理论和水资源多维属性理论,提出了包含资源层、社会层、经济层和生态层的水资源与关联要素适配性评价方法,并应用于南水北调中线一期工程影响区。结果表明:该方法可较为合理、系统地揭示水资源与关联要素的适配特征;2016—2020年南水北调中线一期工程影响区水资源与关联要素空间分布相对合理,整体基尼系数为0.388,资源层和社会层水资源与关联要素空间适配性较好,基尼系数分别为0.283和0.284,而经济层和生态层水资源与关联要素错配问题严重,基尼系数为0.501和0.486;南水北调中线一期工程通水后,水资源与关联要素的空间适配性在资源层、社会层、经济层有不同程度改善,在生态层变化不大。

基于生态补偿的南水北调后续工程水价研究

制定科学合理的跨流域调水工程水价是开展水源区生态补偿的重要途径之一。在现有水价的基础上,新增生态补偿作为水价的重要组成部分,运用机会成本法测算南水北调东线工程水源区生态补偿标准,并引入社会发展阶段系数和政府支付能力系数对其进行修正,构建计入生态补偿的南水北调后续工程水价定价模型。以南水北调东线一期工程胶东干线为例,得到2016、2020年水源区的理论生态补偿标准分别为116.121、199.992亿元,在现行价格基础上水价需分别提高0.93、4.51元/m^(3)。结果表明,生态补偿会耗费大量资金,只有当工程调水能力达到规划设计规模时,持续性调水才能逐步降低供水成本,否则水价会超出受水区的承受范围,工程效益也难以发挥。