Project background: Interconnected river system network is one of the important measures to restore and constantly improve the function of water ecosystem. Since 2015, in order to continue to guide and support the local government to actively carry out the interconnected river system network, the Ministry of Water Resources was in urgent need of research on key technologies of ecological connectivity planning for water system connecting rivers and lakes focusing on restoration and protection of water ecological environment and taking into account the water resources allocation and flood prevention and disaster reduction.
Main content: By investigating and analyzing the progress and typical cases of ecological connectivity planning of water system connecting rivers and lakes at home and abroad, the key technologies was studied from the aspects of basic theory of ecological connectivity planning of water system connecting rivers and lakes, ecological investigation and analysis technologies, water quantity-water quality-ecology coupling analysis model of water system connecting rivers and lakes, optimization technology of overall layout scheme, engineering technology system for ecological connectivity planning and post-evaluation of planning effect and applied in the demonstration sites in Pearl River Basin, Jiangsu Province and Shandong Province and the technical guidelines for ecological connectivity planning of water system connecting rivers and lakes were compiled on the basis of research, demonstration and application of key technologies. Through the innovative research on investigation and analysis, basic theory, investigation technology, analysis model, overall layout, engineering system and effect evaluation, the key technology system of ecological connectivity planning of water system connecting rivers and lakes has been formed and practical experience has been summarized through demonstration and application and finally technical guidelines have been formed to facilitate further popularization and application.
Scale and Distribution of demonstration and popularization: Based on water quantity-water quality-ecology coupling analysis model of water system connecting rivers and lakes, the regulation scheme is formulated for 298 rivers in the lower reaches of the river network in the Pearl River Delta, including Zhongshun Dawei area, backbone rivers, river tributaries and plain drainage ditches, and the joint regulation demonstration of sluice and pump group in Zhongshun Dawei is carried out; for 90.7km2 main urban area in Yangzhou City, the connectivity degree before and after the implementation of connectivity planning and the hydrodynamic characteristics of plain river network before and after the connection are evaluated and the ecological connectivity engineering measures and non-engineering measures are put forward; based on the characteristics of Jinan City, the investigation technology, planning evaluation technology and engineering technology for vertical connectivity are put forward.
Main scientific and technological innovations and contributions: The meaning of ecological connectivity of water system connecting rivers and lakes has been put forward, the concept of four-dimensional and three-flow connectivity of water system connecting rivers and lakes has been constructed, the water quantity-water quality-ecology coupling analysis model of water system connecting rivers and lakes has been developed, and a technical platform for water system connectivity planning including analysis subsystem of water system connectivity, case database subsystem of water system connectivity and water quantity-water quality-ecology coupling analysis model subsystem has been constructed, with graph theory connectivity quantitative evaluation module and landscape analysis module and integrating water quantity-water quality-ecology coupling analysis model, which has realized the research, development and construction of visual interactive main system for four-dimensional three-flow dynamic programming technology.
Achievement and scientific and technological output: 14 papers have been published, including 4 SCI papers, 2 EI papers; 2 monographs have been published; 3 national utility model patents have been granted and 1 invention patent has been applied and 3 software copyrights and 1 technology extension certificate have been obtained; 1 technical guidelines for ecological connectivity planning of water system connecting rivers and lakes has been compiled. The achievements have reached the leading level at home and abroad.
Economic benefits: Through the research and demonstration on key technologies of ecological connectivity planning for water system connecting rivers and lakes, the post-evaluation technology for connectivity planning and connectivity engineering technology of water system connecting rivers and lakes have been formed, providing technical support for the formulation and implementation of the plans and engineering measures for water system connecting rivers and lakes and having certain economic benefits.
Social benefits: Through the research and demonstration on key technologies of ecological connectivity planning for water system connecting rivers and lakes, the technical guidelines for connectivity planning of water system connecting rivers and lakes, selection technique guidelines for river and lake connectivity in the typical areas in the river basins and guiding technical guidelines for ecological regulation in Xijiang River mainstream have been formed, providing strong technical support for the related work of river and lake system connectivity in China and conducive to improving the living environment of the demonstration area and having significant social benefits.
Environmental benefits: Aiming at the problem of hindered vertical connection between river network in plain areas and tidal river network, the indicator with throughput, flow velocity and pollutant concentration of the water body to reflect the connectivity of “material flow” has been proposed; the hydraulic connectivity scheme in the network area has been evaluated through the established one-dimensional water quantity and quality model of river network and the scheme of simultaneous regulation by boundary sluice and check sluice and directional water diversion or drainage has been put forward, effectively increasing the net water diversion quantity and rapidly reducing the overall concentration of pollutants in the river network.
Ecological benefits: Maintaining the ecological connectivity of water system connecting rivers and lakes can maintain the fluidity and continuity of rivers and water bodies, bring into play the water regulating capacity of lakes and ecological benefits of wetlands, realize the health of water system connecting rivers and lakes and sustainable development and utilization of water bodies and enhance the stability of regional natural ecological and environmental systems. At the same time, through the ecological connectivity of water system connecting rivers and lakes, it can realize the water resources allocation of regulation in flood season-dry season and multi-source complement and improve the flood storage and discharge capacity of rivers and lakes and other functional requirements.
