Security Evaluation And Optimal Allocation Of Water Resources In The Upper Hanjiang River Basin

With the increasing economic and social demand for water resources,the problems in water security have become a shortcoming that restricts sustainable economic development in China.The upper Hanjiang river basin(UHRB)is an essential water source for China's Middle Route of South-to-North Water Project Diversion.As the water demand within the basin keeps increasing,along with the water supply pressure for inter-basin water transfer,the security of water resources in the UHRB is facing potential risks.This thesis explores the water resources security situation and its optimization scheme in the UHRB.Taking into consideration the "three red lines" water resources policy,research has been carried out on the security evaluation and optimal allocation of water resources in the UHRB,final the main work and research results are as follows:(1)From the perspective of the actual situation of water resources security in the UHRB,an index system for water resources security evaluation was established for the four major cities within the basin by selecting indicators from the three aspects of water resources,economic society,and ecological environment.Then the principal component analysis was performed to reduce the dimensionality of the original index system for optimization.Based on the optimized index system,the entropy weight method was used to evaluate the water resources security of the four cities,and the factors influencing the water resources security of each city were analyzed.The evaluation results show that under the guidance of the water resources policy,water resources security in the UHRB has been beneficially improved and is now generally at a better level.However,to a certain extent,it is still affected by alternating water resource abundance and depletion.(2)For the purpose of exploring the future evolution trend of water resources security in the UHRB,based on the principle of system dynamics(SD),the future water demand of the four cities within the basin was analyzed.The SD model of water demand in the UHRB was constructed and simulated using the Vensim PLE software.According to planned water supply capacity together with the control of total water consumption red line,the water supply for the four cities in 2025 and 2030 was analyzed.Forecasting the evolution trends of water resources security in terms of the supply-demand balance,the degree of carrying capacity was introduced to evaluate the water resources security of the UHRB.The evaluation results show that the water resources security in the UHRB shows spatial heterogeneity;in 2025 and 2030,Hanzhong City,Ankang City,and Shangluo City will be over-carrying to different degrees,while Shiyan City is in a critical state.(3)The complex adaptive system was adopted to analyze the basic framework of the water resources allocation system in the UHRB,coupling with the SD model,the multiobjective optimal water resources allocation model was constructed with the consideration.The NSGA-II algorithm was executed to solve the model,and the Pareto optimal solution sets for 2025 and 2030 were obtained.From the different focus on objectives,six schemes were selected from Pareto optimal solution sets of 2025 and 2030 for decision-makers,respectively.The degree of carrying capacity was recalculated to evaluate the water resources security after optimal allocation.The results show that the overall water resources security level of both single city and river basin was improved.As the planned water supply capacity lags behind the control of total water consumption red line,Ankang and Shangluo cities are still over-carrying,and it is an urgent need to strengthen the construction of water supply projects for the two cities.