Research On The Impact Of Climate Change On The Transferable Water Quantity And Water Supply Risk Of The Middle Route Of South-to-North Water Transfer Project

With the intensification of the greenhouse effect caused by the industrialization and urbanization process,climate change and the hydrological and water resources effects caused by it will become an important factor to be considered in the inter-basin water transfer project.As a major strategic infrastructure to alleviate the serious shortage of water resources in the northern China,the Middle Route Project of the South-to-North Water Diversion runs through the Yangtze River,Huaihe River,Yellow River and Haihe River.The designed annual water transfer scale is 14 billion cubic meters,and the water supply area is 1.45 million square kilometers,benefiting 438 million people.Under the expectation that the water resources will become increasingly tense in the future,the efficient and rational allocation of water resources allocation of the project needs research on the transferable water quantity of the water source under the climate change scenario.In addition,climate change also affects the safety and stability of water supply by affecting the synchronous-asynchronous encounter between the water source area and the water receiving area.The thesis takes the Middle Route Project of the South-to-North Water Diversion and its water-receiving city Zhengzhou as the research object.On the basis of collecting data sources such as meteorology,runoff,soil,land use,water supply and water receiving areas in the water source area,the distributed hydrological model of SWAT was constructed on the basis of collecting data such as meteorology,runoff,DEM,soil,land use,water supply and water use.Statistical data of historical inflow runoff process,regulation rules and evaporation-infiltration of Danjiangkou Reservoir was collected.The transferable water volume of the midline project is calculated by establishing the water quantity scheduling model of the reservoir area.The Coupla function is used to construct a joint distribution model of the transferable water quantity in the water source area and the water resource gap in the water receiving area,and to study the drought encounter and engineering operation risk of the water source area and the water receiving area in the operation of the South-to-North Water Transfer Line.The main contents and conclusions of the thesis are as follows:Based on the regional DEM digital elevation data,land use data,soil data and meteorological data,the SWAT distributed hydrological model of the upper reaches of the Hanjiang River was constructed as the catchment area of the Danjiangkou Reservoir in the water source area of the South-to-North Water Transfer Project.The SWFI-CUP SUFI-2 optimization algorithm was used to analyze the parameters globally,and the top 12 parameters with the highest sensitivity are obtained.The results of runoff simulation show that the monthly simulated flow rate of the model from 2006 to 2010 is consistent with the measured trend.The correlation coefficient R2 is 0.93,the efficiency coefficient NSE is 0.92,and the relative error is 0.93.During the verification period,the simulation accuracy did not decrease much between 2011 and 2013.The efficiency coefficient NSE and the correlation coefficient R2 reached B,which is close to 0.9,and the relative error Re reached 8.8%,indicating that the SWAT model has good applicability in the upper reaches of the Hanjiang River.From the 46 global climate models supported by the fifth assessment report,the four time-space scales of BCC-CSM1.1,CSIRO-Mk3.6.0,MIROC-ESM and NorESM1-M were selected with high accuracy and comprehensive climate scenario simulation.Climate model,a multivariate regression downscaling model based on GCM data nodes in the Hanjiang River Basin.Based on the comparison between the climate simulation results and the measured data of various climate models from 2006 to 2017,the CSIRO-Mk3.6.0 climate model with the highest fitting degree was selected as the data foundation for constructing the future hydrological model and water quantity scheduling model.The runoff process under the four typical concentration paths(RCP2.6,rcp4.5,rcp6.0,rcp8.5)between the upper and lower reaches of the Hanjiang SWAT hydrological model from 2006 to 2100 was simulated.The results show that under the four emission scenarios,the Danjiangkou Reservoir inflow rate is increasing in the 21 st century.The uneven distribution of the year increased from a low-emission scenario to a high-emission scenario.According to the water dispatching regulations of the Danjiangkou Water Control Project,three different scheduling schemes,such as “prioritizing the water supply for the South-to-North Water Transfer Project”,“prioritizing to ensure the socio-economic and ecological water use in the middle and lower reaches of the Han River” and “both considerations”,are considered to establish a water quantity scheduling model.A water volume scheduling model was established to calculate the water volume sequence by calculating the water withdrawal amount of the upstream water supply,the middle water circulation,the water discharge,the water intake,and the water loss.The results show that the water supply from low priority to high priority in the middle route of the South-to-North Water Transfer Project has a ratio of adjustable water to total water supply of about 4%.The calculation of the adjustable water volume in the historical sequence from 1961 to 2001 shows a fluctuation trend of about 20 years.The calculation of the adjustable water volume from 2006 to 2010 under the climate scenario shows that the adjustable water volume in each scenario is increasing in the 21 st century.Under the high emission scenario above RCP2.6,the adjustable water volume increases with the increase of the discharge load,and the adjustable water volume in the RCP2.6 scenario with low greenhouse gas load is higher than the medium emission scenario.Taking Zhengzhou as the research area,based on the economic resource planning and global climate model prediction results from 2006 to 2030,the water shortage of water-receiving cities and the adjustable water volume of the mid-line project under different climate scenarios were analyzed.The results show that the total probability of the three favorable conditions in the water source and Zhengzhou City is close to 47%.The probability of a total unfavorable encounter is about 20%,and the probability of a neutral encounter is close to 33%.The increase in greenhouse gas emission intensity will increase the probability of unfavorable conditions.