Research On Optimal Promotion Of Water Resources Carrying Capacity Under Uncertainty In Shiyang River Basin

Shiyang River Basin is the third biggest inland river basin of Hexi corridor,Gansu province.The main administrative regions in the basin include Wuwei city and Jinchang city.The basin has relatively high population density,prosperous economy,and large water requirement.Besides,the Shiyang River Basin is faced with problems of low water production ability,high water exploitation and utilization degree,irrational regional water resources allocation,and serious water resources waste.These problems have further caused serious ecological deterioration and water shortage problems.In general,the scale of socioeconomic development has exceeded the limit of water resources carrying capacity(WRCC)of the Shiyang River Basin.Therefore,it has practical significance to carry out researches on the analysis and evaluation of WRCC,and rational utilization and optimal allocation of water resources.Meanwhile,water resources system is a complex and open system with many uncertainties such as randomness,fuzziness,greyness,etc.Firstly,this study aims to analyze the existing problems in the concept of WRCC.Secondly,optimal water resources allocation models of Wuwei city and Jinchang city under uncertainty will be established to improve WRCC.And post-optimality analysis is to be conducted to provide suggestions for decision makers when planning the schemes for improving WRCC.The main contents and conclusions of this study are as follows:(1)Because of the inherent chaotic and vague property of WRCC,there hasn't been a unified definition.In addition,with the development of science and technology,researchers have further understanding about WRCC.In this paper,a new connotation of WRCC concept was put forward.Based on the new connotation,the metabolism idea in biology was introduced into regional WRCC.And water resources metabolism theory was obtained,which could be described as the organic process of water resources flowing into regional socioeconomic system,and outputting production,service and contaminant.Based on the theory and the principle of sustainable development,considering the state of regional water resources and socioeconomic system,a comprehensive evaluation index system was established to analyze and evaluate the regional WRCC and sustainable development.Results showed that the WRCC of Wuwei city has reached the limit and couldn't carry the further socioeconomic development.(2)In the research of WRCC in agriculture oriented regions,the upper level decision makers(local government)want more economic benefit,while the lower level decision makers(peasants)want more crop yield.So the conflict among different water use levels should be fully considered.Considering the uncertainties and two-level problems in agricultural water management,a two-level fuzzy programming model based on fuzzy maximum method was established.The objective function of the upper level is to maximize the economic benefits and the objective function of the lower level is to maximize the crop yield.Under some necessary constraints,such as food security constraint,an optimization model under uncertainty was applied to improve agricultural WRCC.Results showed that the optimized WRCC is increased to some extent.(3)In the research of WRCC in industry oriented regions,economic benefit and social benefit should be both taken into account.Therefore,considering the multi-objective problems in industrial water resources management,and the uncertainties of water quantity and water quality,a stochastic fractional multi-objective programming model was established.The economic objective is to maximize the economic benefit,and social objective is to maximize the occupied population.The model was applied to improve the industrial WRCC.Results showed that the optimized economic benefit and occupied population increase correspondingly.(4)Water resources utilization efficiency(WRUE)has a significant effect on WRCC.So spatial and temporal analysis of WRUEs of Wuwei city and Jinchang city was conducted by using DEA method and Malmquist index to reflect the WRCC from another aspect.At the spatial scale,WRUEs among different areas were analyzed.At the time scale,the inter-annual dynamic change and trend of WRUE were analyzed based on Malmquist index.Besides,the post-optimality analysis of the optimal schemes for WRCC was conducted by adopting DEA method.Based on the above analysis,a new perspective could be provided for decision makers when selecting rational schemes.