Simulated Forecast And Assessment Of Water Resources Carrying Capacity In Xi'an City

Water,the important material and strategic resource for the regional socio-economic development,is a cornerstone for supporting the ecological environment.Xi'an is the core city of Guanzhong Plain urban agglomeration.However,with the rapid development of social economy in recent years,urban water demand has increased year by year,and Xi'an belongs to one of the inland water-deficient cities,which brings severe challenges to urban development.Water resources carrying capacity(WRCC)is a concept which is used to measure the carrying capacity of regional water resources to social and economic scale.We introduce it into this study and combine it with the theory of sustainable development to comprehensively consider the combined effects of water resources,socio-economic and environment.Based on the analytic hierarchy process,the evaluation index system of water resources carrying capacity was established.Based on the analysis of natural resources conditions,socio-economic development and water resources development and utilization status of the study area,a system dynamics model was established,and the simulation results were normalized and input into the evaluation system to study the development trend of WRCC in Xi'an.Finally,combined with the results,it puts forward corresponding suggestions for improving the WRCC in Xi'an.The main results of this study are as follows:(1)Briefly introduced the basic concept of WRCC and its influencing factors,analyzed the connotation of sustainable exploit of water resources,and established the evaluation index system of WRCC of Xi'an based on the establishment of evaluation index system,and using the analytic hierarchy process to empower each indicator in the system.The indicator system is divided into four subsystems,totaling 16 indicators.The evaluation indicators cover water resources,society,economy,water environment and other aspects,and it can comprehensively reflect the WRCC of Xi'an.(2)The design of the model starts from the balance of water supply and demand and the pollution situation of water environment.Based on the system dynamics,the model of WRCC is established.By analyzing the logical relationship between each subsystem and each variable,it is reasonable to model.The design equations of each relationship are assigned and the parameters are assigned.The model structure is divided into 6 subsystems,totaling 138 variables.After the model was built,it through the dimensional consistency and system structure of the modeling software VENSIM.The historical data of some variables are validated from 2005 to 2016.The results show that most of the parameter errors are within 10%of this acceptable range,the model has a good performance.(3)According to the current socio-economic development status of Xi'an and the needs of future development,four different simulation scenarios are proposed based on the conventional model to predict the trend of WRCC from 2016 to 2020.The results show that the current development pattern cannot meet the requirements of sustainable development of WRCC;under the high-speed economic scheme,its economic growth is optimal among several models,but the demand for water resources and sewage discharge will also significantly increase.The industrial water consumption has increased sharply to 6.19×10~8tons,and the index of WRCC has rapidly dropped to 0.21 in 2020.Under the readjusted industrial structure scheme,the economic growth is inferior to the high-speed economic scheme but superior to the business as usual mode,and the index of WRCC is 0.46,which was moderate in several scenarios;under the resource-environment protected scheme,the status of WRCC has been greatly improved,but the model has not adjusted the economic related parameters;the index of WRCC under the comprehensive scheme is the most ideal and arrived at 0.61 by 2020.(4)According to the simulation results under different scenarios,from the perspectives of water,sewage discharge control and water-saving measures in different industries,proposing feasible solutions applicable to the study area,so as to improve the WRCC of Xi'an provides a scientific theoretical basis.