根据国家水安全保障的战略需求，分析与探讨国家水网的总体布局，明确河湖水系连通工作的战略需求，深入分析河湖水系连通对水资源、防洪、生态、环境、社会和经济的影响，剖析国家水网建设中需要注意的主要问题，辨析南水北调工程在国家水网建设中的功能和作用。结果表明，建设国家水网是提高我国水安全的有效措施，但河湖水系连通工程涉及经济社会方方面面，有必要站在全局的高度，从提高水资源保证率、减轻洪涝灾害、改善生态环境等诸多方面，分析河湖水系连通工程的得与失、利与弊，结合近期与远期、供水区和受水区的经济社会发展趋势，全面剖析河[JP+1]湖水系连通工程的效益与风险，建设好利国利民、功在千秋的国家水网，切实提高我国的水安全。通过多学科交叉的系统研究，全面分析河湖水系连通和国家水网建设工作中的重点和难点，为加快构建国家水网提供参考和支撑。

With the rapid development of economics and society,especially with the implementation of “reform and opening up” to the outside world,the industry and urbanization developed very quickly in China.The rapid development of industry resulted in the considerable need for water resources,and the great changes of water cycle among supply,uses,assumption and drainage.It further resulted in the great challenge on water supply,as well as the exacerbation of water quality and deterioration of aquatic ecosystems.On the other hand,rapid urbanization affected the relationship between rivers and lakes,and resulted in fragmentation of rivers and shrinkage even disappearance of lakes.In order to improve the water security,it is quite necessary to construct the national water networks with the capability of adjustment between abundant and dry periods,as well as complementary between western and eastern China.Considering the strategic needs of national water security,the overall layout of national water network was investigated,and the strategic needs of river-lake system connectivity were analyzed.Possible effects of river-lake system connectivity on water resources,flood control,ecological system,environment,society and economics were comprehensively analyzed through multidisciplinary ways.The function and roles of South-North Water Transfer Project in the construction of national water network were also identified.Great efforts have been made to comprehensively analyze the key issues and difficulties in river-lake system connectivity through multidisciplinary and systematic research,so as to provide reference and scientific support for the construction of national water network. From the analysis on the connectivity of river-lake system,it was found that the connection of river-lake system and the construction of national water networks are the most important national strategy to improve water security in China.Major functions and roles of the national water networks mainly focused on the improvement of water resources allocation and water supply,improvement of water quality and aquatic ecosystem,as well as the improvement of capability to mitigate floods and droughts.The objective of connection for rivers and lakes should respect the law of naturalized hydrological cycle and evolution of rivers and lakes,and consider the functions of water resources,environment,and ecology.Through the construction of reservoirs,dams/weirs,pumping stations and channels,national water networks will be constructed at the national,regional and urban scales.The water networks will be characterized with reasonable layout,different functions,storage and drainage,regulation and control,adjustment between abundant and dry periods,mutually supplement among different sources,flows clearly,and excellent environment.