On April 28 and 29, 2020, NHRI organized a meeting of performance evaluation on 3 special projects of the national key research and development program, Integration and Application of Water Security Technology in the Yangtze River Delta led by the Institute.  The 3 special projects are Research and Development of Multi-scale Hierarchical Intelligent Models for Plain River Network Hydrodynamics, Integration and Demonstration of River Smooth Flow and Water Quality Improvement Technology in Typical Cities and Joint Operation Technology and Application of Water Resources of Complex Rivers and Lakes in the Yangtze River Delta. All the 3 special projects successfully passed the performance evaluation by the expert group. More than 40 people including invited experts, program leader, and special project administrators, leaders and technical backbones attended the meeting.

Technologies, like multi-scale hierarchical and two-direction nesting, multi-source data assimilation, parameters intelligent identification, refined simulation of river network in urbanized areas and heterogeneous model configuration, have been developed and improved by the special project, Research and Development of Multi-scale Hierarchical Intelligent Models for Plain River Network Hydrodynamics. Meanwhile, based on cloud platform, a multi-scale hierarchical intelligent simulation system for the Yangtze River Delta plain water network hydrodynamics has been independently developed, realizing multi-scenario business customization services for river basins-regions, cities and polders. The research results have been successfully applied in the joint operation of river basin-regional flood control, intelligent operation of urban-polder flood control projects, and comprehensive regulation of water environment in urban river network. In addition, the model has obvious advantages in multi-scale nested simulation. The resolution of river network in the Tai Lake region is up to 4, that of city 6, and that of polder 8, which are flexible and convenient. The user report of Jiangsu Provincial Flood and Drought Disaster Prevention Command Center shows that the overall system function, simulation accuracy, and calculation efficiency have reached the same level as the internationally leading Infoworks ICM software, the modeling speed has been increased by more than 20% compared with similar software, such as MIKE 11, and the simulation time saved by more than 10%. The software product test report provided by Software Testing Center of Jiangsu Province shows that the water level simulation accuracy of the urban river network in the Tai Lake region can be controlled within 50px.

The multi-engineering, multi-objective water resources operation collaborative criteria and optimal operation method for the complex water system in the Tai Lake Basin have been proposed by the special project, Integration and Demonstration of River Smooth Flow and Water Quality Improvement Technology in Typical Cities. And a joint operation technology for water resources has been developed based on multi-objective collaboration, a multi-objective collaborative operation model for water resources constructed, a water resources joint operation decision support system in the Tai Lake Basin integrated, and the optimal scheme for joint operation technology of water projects system proposed to ensure the water security of the Tai Lake Basin. Research results are innovative in the theory and technology of water resources joint operation and multi-objective collaborative decision, and have been demonstrated and applied in the joint operation of water resources in complex rivers and lakes in the Yangtze River Delta. Water supply guarantee rate (the guarantee rate of the minimum allowable water diversion level and the target rate of water quality comprehensive evaluation index in the Tai Lake) of important water sources has been increased by more than 10% in the dry season. These research results have obtained good social, economic and ecological benefits.

With the focus of the outstanding problems of urban river network water environment improvement in the Yangtze River Delta, the mechanism of river network hydrodynamics on water quality indicators has been revealed, suitable flow velocity and sensitive factors for maintaining the transparency of a river proposed, and the water transparency simulation method and quantitative relationship between water fluidity index and water quality index in urban river network established by the special project, Joint Operation Technology and Application of Water Resources of Complex Rivers and Lakes in the Yangtze River Delta. At the same time, the release rule of organic pollutants in river sediment has been revealed, the appropriate formula of biological exciter and process parameters of dosing in sediment pollutant reduction process proposed, groove circulation and biofiltration devices developed to promote the circulation of polluted water, solving the treatment problem of semi-closed water body in plain river network area. The intelligent optimization and automatic intervention technology for water quality improvement operation schemes has been developed, the urban river network cloud platform and model cloud platform built based on the Internet of Things, and a multi-target real-time monitoring, accurate simulation, intelligent mutual feedback joint control and debugging system integrated. In addition, the key technologies such as water system pattern and water allocation, multi-source complementary water source guarantee, precise control of river network water level and in-situ restoration of stagnant water have been developed, and a technical system for smooth flow and water quality improvement of plain urban river network established, solving the problem of water environment improvement in plain river network area. Meanwhile, 5 demonstration areas for smooth flow and water quality improvement in cities such as Hangzhou, Changshu, and Shanghai have been built, with research findings promoted and applied in more than 10 cities in China. The water level difference of artificial reconstruction is more than 500px, and the replacement frequency can reach 3-5 times a week. Flowing water has been kept for 100% of these demonstration areas. A third-party monitoring report shows that the water mobility of the assessment section in demonstration areas has been increased by more than 10%, and the water quality steadily improved by more than one category. Thus urban river network water ecological environment has been significantly improved, city's overall value and comprehensive competitiveness enhanced, and the economic, social and environmental benefits increased remarkably.

The expert group unanimously agreed that the above-mentioned special projects passed the performance evaluation. NHRI Office of the National Key Special Projects announced the results of expert scoring, and emphasized that the evaluation materials should be modified and improved, and the evaluation data completed and archived according to the key special project management requirements and the expert evaluation opinions within a specified time.