Study On Water Supply Potential And Efficient Utilization Of External Water Transfer In The Middle Route Of South-to-North Water Transfer Project

Water resources in China are unevenly distributed in time and space.In order to alleviate water shortages in water-scarce areas,The Middle Route of the South-to-North Water Transfer Project has been completed.In recent years,the runoff characteristics of the Danjiangkou Reservoir which is the water source area of project have undergone significant changes,and there are significant differences between the runoff series used in the planning of the project.With the completion of the connection between the canal of the mid-line project and the storage reservoirs along the canal,research on the storage capacity of the reservoirs along the mid-line project has important practical significance for expanding the water supply potential of the mid-line project.At the same time,the inter-regional development in the Beijing-Tianjin-Hebei region is unbalanced,which may result in the actual distribution of external water transfer may not meet the actual development needs of the region.Therefore,it is critical to determine appropriate proportion of the external water transfer rights.This paper studies the water supply potential and efficient use of externally diverted water from the Middle Route Project of South-to-North Water Diversion,and concludes as follows:1.Using the Mann-Kendall(MK)test,Markov process and run-length analysis to study annual characteristics,trends and changes of runoff in Danjiangkou reservoir from 1956 to 2017.The annual runoff series of the reservoir decreased by 5.05 billion m3 per year after entering the 21st century,and continuous dry conditions are likely to occur during the autumn flood season,which is not conducive to reservoir water storage and water transfer.2.The water supply dispatching map can be optimized by limiting the discharge flow and the hedging rules,respectively,which can increase the annual average northward water transfer by 120 million m3 and 260 million m3 respectively.Construct a joint dispatching model of the middle line and the reservoir along the line,the average annual water filling capacity of the reservoirs along the main line in Henan Province and Hebei Province is 270 million m3 and 180 million m3 respectively.3.Establishing the distribution model of external water transfer rights in the Beijing-Tianjin-Hebei region to calculate the most suitable proportion of external water distribution in the three regions.The model calculates that the water distribution in Beijing is higher than the actual value,and the water distribution in Hebei Province is less than the actual value.The proportion of water distribution is highest when focusing on high efficiency targets.