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.

Geological conditions and key rock mechanics issues in the Western Route of South-to-North Water Transfer Project

In terms of special geological conditions of the Western Route of South-to-North Water Transfer Project, the classification method for surrounding rocks is discussed by combining with the construction method of tunnel boring machine （TBM）. The classification standard of surrounding rocks is put forward on the basis of physical simulations and engineering practices. Damage, deformation and evolution of surrounding rocks induced by TBM excavation are discussed. Meanwhile, the long-term deformation mechanisms and stability of surrounding rocks are also studied. On this basis, a three-dimensional constitutive model for interbedded sandstone slate and a fiat shell-joint element-foundation system for calculating internal forces of segment lining are established. The deformation features of surrounding rocks of deep and steep interbedded sandstone slate and their influences on internal forces of segment lining are presented. Finally, the design methods of segment lining constructed in deep and steep flysch are proposed.

Eco-environmental benefit assessment of China's South-North Water Transfer Scheme——the middle route project

This paper assess the eco-environmental benefits that may come from the middle route project of China's South-North Water Transfer Scheme(SNWT) with principles and methods of eco-economics and planning reports of SNWT's middle route project. Some benefits were calculated in monetary units. To make sure that the results can be comparable with normal monetary indices, concrete assessment objects and the parameters are prudently selected according to the major characteristics of the project and its water import region. Primary assessment revealed that in different project construction stages, the benefit could be more than 13 07 billion RMB Yuan in 2010 and 19 79 billion RMB Yuan in 2030, respectively. The monetary value tends to increase with social-economic development. To realize these potential benefits, however, calls for more endeavors.

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.

Forecasting Loss of Ecosystem Service Value Using a BP Network: A Case Study of the Impact of the South-to-north Water Transfer Project on the Ecological Environmental in Xiangfan, Hubei Province, China

Objective To recognize and assess the impact of the South-to-north Water Transfer Project (SNWTP) on the ecological environment of Xiangfan, Hubei Province, situated in the water-out area, and develop sound scientific countermeasures. Methods A three-layer BP network was built to simulate topology and process of the eco-economy system of Xiangfan. Historical data of ecological environmental factors and socio-economic factors as inputs, and corresponding historical data of ecosystem service value (ESV) and GDP as target outputs, were presented to train and test the network. When predicted input data after 2001 were presented to trained network as generalization sets, ESVs and GDPs of 2002, 2003, 2004... till 2050 were simulated as output in succession. Results Up to 2050, the area would have suffered an accumulative total ESV loss of RMB 104.9 billion, which accounted for 37.36% of the present ESV. The coinstantaneous GDP would change asynchronously with ESV, it would go through an up-to-down process and finally lose RMB89.3 billion, which accounted for 18.71% of 2001. Conclusions The simulation indicates that ESV loss means damage to the capability of socio-economic sustainable development, and suggests that artificial neural networks (ANNs) provide a feasible and effective method and have an important potential in ESV modeling.

Price Analysis of Water Supply for South-to-North Water Transfer Project

The factors influencing the water supply price of a hydraulic project include natural conditions and economic policies. This paper thoroughly demonstrates the water price of South-to-North Water Transfer Project from the viewpoint of economic policies. It is considered that if the project is assigned as a profitable one and built depending on commercial loan from bank completely or mostly, the water price will be too high to be undertaken by users,and if the project places the public good at first while considering the economic benefit, its investment mainly relies on the state (national or local governments) appropriation and self-raised funds and a little from the bank loan on favorable terms, the price determined according to the principle of satisfying the cost and reasonable profit will be relatively lower and can be undertaken by the users in the North China where water shortage is serious. The problem of higher water price of agricultural irrigation to the north of the Yellow River can be tackled by taking measures such as "compensating agriculture by industry" according to foreign practical experiences and relevant suggestions.

LONG AND DEEP DIVERSION TUNNELS OF 1^(ST) STAGE PROJECT IN WEST ROUTE OF SOUTH-NORTH WATER TRANSFER PROJECT

West Route of South-North Water Transfer Project,situated in southeastern Qinghai-Tibet Plateau,is a giant project,which will deliver 17 billion m3 of water from the main stream and tributaries upstream of the Yangtze River to the upper reaches of the Yellow River. It is to be constructed in 3 stages, of which the 1st stage project includes delivering 4 billion m3 of water by gravity from two tributaries of Yalong River and three tributaries of Dadu River. The project consists of 5 dams,7 tunnels and a channel in series,with the dam height of 63～123 m and water transfer length of 260.3 km,of which the tunnels measure 244.1 km. The special climatic,environmental and geologic conditions make the project much more complicated in construction,especially 3 tunnels with the length longer than 50 km each create challenges to the technical requirements of engineering survey,design and construction.

Evolution trend of the water quality in Dongping Lake after South-North Water Transfer Project in China

To investigate the evolution trend of water quality in Dongping Lake after South-North Water Transfer Project operation as well as to ensure the safe usage of the water receiving areas, water samples were collected and determined before and after water delivery in different hydrological seasons. Then, comprehensive pollution index method, comprehensive nutrition state index method and health risk assessment model were utilized to evaluate the quality, nutrition, and health risk of Dongping Lake water. Results showed that the quality of Dongping Lake water still met level Ⅲ (light pollution) no matter before or after water delivery. The nutrition state was improved from light eutropher before water delivery to mesotropher after water delivery. The health risk level was reduced from high-medium before water delivery to medium level after water delivery. In summary, the operation of the eastern route of South-North Water Transfer Project is beneficial for water environment improvement of Dongping Lake.

Simulation of Transport Channel in China's Middle Route South-to-North Water Transfer Project

The unsteady flow in the Middle Route South-to-North Water Transfer Channel was simulated numerically using an implicit solution procedure for the Saint Venant equations. An equivalent roughness was used to simulate the effect of many transfer structures on the water levels in the main channel. Various gate operating and control methods were analyzed to study the response to disturbances produced by varying the flow rates through the Tianjin outlet. The results show that when the inflow at the head changes in the same way as the sum of the flow rates through all the outlets, the transition time and the fluctuation of the water levels using the timed gate operation method are less than when using the simultaneous gate operation method, but the variations of the gate openings and flow rates through each control gate are much larger. The flow disturbances produced by the Tianjin outlet can be rectified within several channel sections and the transition time can be greatly shortened by allowing the water levels immediately upstream of the control gates to vary within proscribed ranges, rather than being held constant.

Computing payment for ecosystem services in watersheds: An analysis of the Middle Route Project of South-to-North Water Diversion in China

Payment for ecosystem services （PES） has attracted considerable attention as an economic incentive for promoting natural resource management recently. As emphasis has been placed on using the incentive-based mechanism by the central government, rapid progress on PES research and practice has been achieved. However PES still faces many difficulties. A key issue is the lack of a fully-fledged theory and method to clearly define the design scope, accounting and feasibility of PES criteria. An improved watershed criteria model was developed in light of research on PES practices in China, investigations on the water source area for the Middle Route Project of South-to-North Water Diversion and ecosystem services outflows theory. The basic principle of assessment is the direct and opportunity cost for ecological conservation and environmental protection in the water source area deduct nationally-financed PES and internal effect. Then the scope and the criteria methods were determined, and internal effect was put forward to define benefits brought from water source area. Finally, Shiyan City, which is the main water source area for the Project of Water Diversion, was analyzed by this model and its payment was calculated. The results showed that： （1） during 2003–2050, the total direct cost and opportunity cost would reach up to 262.70 billion and 256.33 billion Chinese Yuan （CNY, 2000 constant prices）, i.e., 50.61% and 49.38% of total cost, respectively; （2） Shiyan City would gain 0.23, 0.06 and 0.03 CNY/m3 in 2014–2020, 2021–2030, and 2031–2050, respectively.

Potential Ecological Benefits of the Middle Route for the South-North Water Diversion Project

This paper presents a study of the middle route of the South-North Water Diversion Project. The middle route runs through the Northern China plain, where the water shortages are the most severe. There is not only a shortage of water for human usage, but also a shortage of ecological water. Although the current plan for the middle route is strictly focused on supplying water for residential and industrial use, the water can also potentially be used for ecological purposes. This paper evaluates the potential ecological benefits that can be brought to the fragile ecology in northern China by the middle route, in addition to the water supplied to residences and industry. The study describes ecological benefits of the middle route project, such as mitigation of groundwater extraction in the region and positive influences on the climate, the ecological uses of the middle route project itself, such as creating artificial niches along the channel and directly using the channel for ecological purposes, and the ecological uses of the water along the middle route such as diversion of the water into dyer channels that have suffered from drought conditions for decades.

Coupling interaction between biodiversity and aquatic habitat area in Western Route Project vicinity

The Western Route of the South-to-North Water Transfer Project will divert water from the upper Yangtze River and its tributaries, the Dadu River and Yalong River, to the upper Yellow River. The project may ease the water shortage in the Yellow River Basin. However, it may also have some effects on the ecosystem in the upper Yangtze River Basin. Benthic invertebrates play an important role in the river ecosystem, particularly in the circulation of materials and nutrition. Benthic invertebrates are widely used to quickly assess river ecosystems because of their rapid response to changes in the water environment. The diversity of benthic invertebrates is closely associated with the aquatic habitat area. This study examined this interaction by sampling the benthic invertebrates in an expanding area. The conclusions are that the diversity of benthic invertebrates begins to decrease when the aquatic habitat area is reduced to 45% of the original area, and decreases dramatically when the aquatic habitat area is reduced to 10% of the original area. The aquatic habitat area should be kept at more than 45% of the original area in order to maintain the significant diversity of benthic invertebrates.

On conservation and development of architecture and environment in the construction of large-scale national infrastructure——Exemplified by the Jiangsu Section of the Eastern Route South-to-North Water Diversion Project

The water-diverting route project’s characteristics,natural landscapes,and histories and humanism of the Jiangsu Section of the Eastern Route South-to-North Water Diversion Project were systemically analyzed through proposing and studying the canal culture routes,the water resources heritage corridors,the landscape and recreation corridors,and the town economic corridors.The station areas along the water-diverting route were scientifically zoned and graded through quantitative and qualitative synthetic methods.Both planning compendiums and construction controlling methods were proposed based on the project grades of points,lines,and areas.Conservation and development of architecture and environment in the large-scale national infrastructure construction were explored systemically.Theories and methods of developing harmonious water-supplying functions,ecological functions,landscape effects,and cultural effects of large-scale water resources were examined.

2-D NUMERICAL SIMULATION OF FLOODING EFFECTS CAUSED BY SOUTH-TO-NORTH WATER TRANSFER PROJECT

Since the General Channel designed for the South-to-North Water Transfer Project in China has to cross many rivers and streams flowing from west to east, there are potentially serious effects additional flooding on the western side of the project alignment. Therefore, a 2-D numerical model for forecasting basin flood disasters was established and verified using historical flood data. The model was applied to researching the interaction between the proposed Project and flooding events for 5 streams in the Anyang River reach as a representative case study. Simulated results indicate that the model could correctly forecast the flood, submerged area and depths, and water surface elevations along the left side of the channel. The discharge capacity and location of hydraulic structures in the transfer canal alignment were analyzed. Then adjustments to the dimensions and positioning of proposed hydraulic structures were recommended at intersections, especially the addition of a channel to transfer flood water from one stream to another, which can effectively limit the sluice and protect the Anyang City from flooding.

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。

南水北调东线一期工程受水区生态环境效益演变

研究南水北调东线一期工程通水以来受水区生态环境效益的演变态势,对南水北调后续工程高质量建设、加快构建国家水网以及促进工程综合效益发挥有决策参考作用。以定性定量相结合的方式分析东线一期工程在优化水资源配置、保障饮水安全、复苏河湖生态环境和畅通南北经济循环等方面的作用,进而结合层次分析法,从直接效益和间接效益2个方面,筛选构建东线一期工程受水区生态环境效益评价指标体系,主要包括工程年供水量、水质改善度、生态补水量、地下水压采量、地下水水位、水域面积、绿地面积和涵养水源等,并采用VlseKriterijumska Optimizacija I Kompromisno Resenje(VIKOR)多准则妥协解排序方法对南水北调东线一期工程通水以来即2013-2022年受水区生态环境效益演变态势进行分析。结果表明:南水北调东线一期工程通水的10年以来,受水区的生态环境整体复苏效果明显,近3年排序值保持在0.8以上;受降水偏枯进而影响地下水开采量和地下水水位等因素影响,2019年间接生态环境效益下降29.2%,之后迅速恢复并保持稳定。在分析直接效益和间接效益演变的基础上,从工程提质增效、提高工程水质状况以及完善体制机制建设等方面提出东线一期工程进一步促进受水区生态环境持续改善的策略和建议,以期为东线工程及受水区生态环境保护及高质量发展相关研究、决策制定等提供参考。

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。

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。

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。

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。