| As a basic material essential for human survival and the normal functioning of the economy and society,the demand for water resources is increasing,but the reduction of water resources has led to a serious impact in some areas.In recent years the water resources of the Yellow River water have tended to decrease and the spatial and temporal distribution has been uneven from year to year.In order to avoid this problem posing a threat to people’s lives and property,the state has introduced a water rights trading system to resolve regional water conflicts.Research on water rights trading in China started late and there has been relatively little research on it,especially on large scale trading activities across regions and multiple basins,and there has been little research on the risks to water supply caused by upstream water conditions.Therefore,the water rights trading research carried out in this paper provides important theoretical value and practical guidance for the future work of water rights trading in China.The 16 municipalities in Henan Province in the water receiving area of the South-North Water Transfer Central Line and the water extraction area along the Yellow River water source were used as the study area,with the aim of improving the efficiency of water allocation,taking into account the changes in water availability from different water sources,and starting from the supply and demand issues in the study area,combined two external water sources with local water sources,a multi-source joint probability distribution model was constructed to analyze the risk of water scarcity in the study area’s water purchasing cities.The above model was used as one of the objective functions and combined with the economic efficiency function of the study area to construct a GA-Copula based multi-objective water rights trading scheme preference model,and the actual water use in the study area in 2015 was used as the base data to carry out the study,and combined with the incoming water from different water supply sources,the water rights trading preference scheme under various encounter scenarios was developed separately to provide a reference for the water rights trading work in Henan Province.The main studies are as follows:(1)Based on the data collected,the local water sequence,the Yellow River water sequence and the South-North water sequence of each city were fitted to different marginal distributions and the most suitable marginal distribution was optimized.Substituting the preferred marginal distribution function into the commonly used The joint probability distribution models were constructed using the preferred Copula function and marginal distribution function,and the optimal joint distribution was determined using the Akaike information criterion(AIC),Bayesian Information Criterion(BIC),Root Mean Square Error(RMSE)as well as the Ordinary Least Squares(OLS)evaluation to determine the optimal joint distribution,the fittest was performed using the K-S test and the graphical evaluation method.The joint probability distributions and contour(surface)plots of the two-dimensional Copula function for the preferred two-water city and the three-dimensional Copula function for the threewater city are plotted.The results show that the joint probability values increase as the volume of water from either source increases,and secondly,for the same joint distribution probability values,they can correspond to different combinations of water supply source events.(2)Based on the mathematical formulae for the probability of encounters with multiple water sources,and the data from the joint probability distribution model,nine encounter probabilities for dual water source cities and 27 encounter probabilities for triple water source cities were obtained.The analysis of the obtained encounter probabilities shows that there are various combinations of encounters among local water sources,Yellow River water sources and South-North water sources,and the probability of asynchronous encounters is greater than that of synchronous encounters,indicating that there is a complementary spatial correlation between different water sources in multi-water supply cities.(3)A GA-Copula based multi-objective water rights trading optimization model is constructed for the characteristics of multiple water sources in the study area.The model takes the economic benefits of the study area and the water supply risks of the purchasing city as the objective function,and realizes the mutual feedback between multiple water sources in the process of computational optimization.Using an improved NSGA-II genetic algorithm(Non-dominated Sorting Genetic Algorithms)generates Pareto solution sets,and using utility functions for different subjects of interest and "YCRT"(The Young Conflict Resolution Theory)theory to optimize solution sets,derives the best trading solution.The results show that with the multi-year average water supply from the South-North water transfer source and the Yellow River source,combined with the 2015 accounting level,the model can be used to optimize the allocation of water resources for water rights trading,the study area can achieve significant economic benefits,and the water supply risk of the purchasing city is significantly reduced,with the economic benefits of the study area increased by 12.5%and the water supply risk of the purchasing city reduced by 5%.(4)The annual runoff from the Huayuankou hydrological station,the runoff from the Danjiangkou reservoir and the variation of the local water sources in the study area were plotted on the basis of the data collected from various water sources in the study area for many years,an analysis of the incoming water pattern was also carried out to obtain the variation of different water sources and to classify the abundance and depletion scenarios,whereby three typical encounter scenarios were selected.The tradable water rights of the study area under different encounters with local,Yellow River and South-North water sources were calculated and used as input to multiobjective water rights trading optimal model based on the GA-Copula function to calculate and develop water rights trading schemes for each of the three typical encounter scenarios,and to compare the economic benefits of the study area and the water supply risks of the purchasing city before and after trading. |
PDF Full Text Request