Evaluation Of Water Circulation Health Of Typical County In North China Plain

With the integrated effect of climate change and human activities,the regional water cycle structure,driving force and process have largely changed.A series of water problems such as frequent water disasters,water shortages,water environmental pollution,and water ecological degradation have influenced the healthy development of cities and towns.The reason of these problems is the incoordination between the natural and social water-cycle,which is the "illness" feedback of the "natural-society" dual water cycle.Therefore,based on the above situation,it is critical to diagnose the regional water-cycle health and solve the related water problems.This research selected Guantao County,a typical county in North China with severe human disturbance and limited water resources as the study area.Based on the analysis on regional water cycle characteristics,the comprehensive index method and grey correlation analysis method were selected to diagnose the regional water-cycle health and the corresponding evolution process in the past 9 years.The main results are as follows:(1)Based on the conception illustration of the dual water-cycle,the related structure and the influence factors of nature and society were analyzed,considering the development difference between the county town and city.The water-cycle path,driving force and flux in county town was interpreted.As the climate zone is same,in the county town,the water-cycle driving force is weaker,the water users are more diverse,and the flux of same subprocess is smaller,compared with the city.(2)Based on the analysis of county water-cycle characteristics and key paths,a total of 19 indicators in 5 dimensions were selected from the cycle sub-process of "takesupply-use-discharge-return" to construct an evaluation system,Combining with the characteristics of water-cycle in Guantao County,the weight of each index was determined by AHP,and relevant standards and data were consulted to determine the threshold system of indicators.(3)The comprehensive index method and grey relational analysis method were selected to evaluate the water-cycle health of Guantao County.The index evaluation results of the comprehensive index method show that the diversity of standby water sources,the proportion of river lengths that meet the water quality standards,and the rainwater reuse rate have the lowest health scores.They are in a severely ill state.The penetration rate of tap water,the guarantee rate of ecological water use,and the rate of centralized treatment of waste and sewage have the highest scores,and they are very healthy.Based on the dimensional-level evaluation of the two methods,the water supply and water use dimensions perform best,basically maintaining above a healthy state;the worst is the water source dimension and the reuse dimension.The water source dimension is fluctuant and unstable;the reuse dimension has been in a subhealthy state for a long time.The comprehensive evaluation results of the two methods are relatively consistent.which is rising in fluctuation and slowly tending to health state,the sensitive index of the whole water cycle process is the variation of groundwater depth,which indicates the urgency and necessity of the strict management of groundwater in Guantao area.(4)The evolution trends of the two calculation methods at the dimensional level and the target level are consistent,but there are certain differences in the health levels of individual years.Considered the calculation principles of the two methods,the comprehensive index method is more inclined to quantitative analysis.After quantitative analysis,the grade is determined qualitatively,while the gray relational analysis is qualitative analysis to determine the health grade,without considering the changes in the system.The two methods have their own focus,which ultimately leads to differences in results.The research results further expand the research scope of the regional dual water cycle evaluation,and provide decision-making basis and reference for the healthy and sustainable development of water resources in the study area.At the same time,the evaluation results can also provide ideas for the fine and comprehensive management of water resources at county level under the same development mode in the North China Plain.