| The water resource is one of the most important resources for human beings.Urban surface water can directly or indirectly affect human survival and urban sustainable economic development.The surface water resource in Hangzhou have problems such as uneven spatial and temporal distribution,poor storage capacity,and a large part of its total being difficult to use.With the rapid development of the city's economy and the improvement of people's living standards,urban rivers have been seriously polluted,and the lakes are at high level of eutrophication,leading to an increasing intension between economic development and environmental protection.As the issue of water shortages is inevitable in the long run,the protection of water resource becomes extremely important.Hangzhou has a long history of water resource management.In 2000,Hangzhou Environmental Protection Bureau proposed the"10th Five-Year Plan for Environmental Protection and the 2015 Environmental Plan of Hangzhou City",which systematically carried out a comprehensive environmental pollution improvement operation and strived to make the quality of water meet the standard in the function division of water environment.With the implementation of the project in improving the quality of the city's water environment,the assessment of the overall quality for water environment becomes particularly important.There are many methods for evaluating the quality of surface water at home and abroad.Although the theory behind those methods is relatively mature,they still need to be explored further in practical applications.This paper is aimed at investigating the comprehensive water environment management campaign in Hangzhou,and evaluates the quality of surface water environment before and after the campaign in the past 15 years.I test eight indicators including dissolved oxygen,permanganate index,biochemical oxygen demand,ammonia nitrogen,total phosphorus,fluoride and fecal coliforms in 35 spots along main stream and tributary of Qiantang River,canal(Hangzhou section),Tiaoxi and urban inland river from 2000 to 2015.I then choose several commonly used and mature evaluation methods such as single factor evaluation method and grey correlation evaluation method to assess those indicators.In addition,I employ the Spearman rank correlation coefficient method to do the trend analysis of factors.I analyze the results of the monitoring spots from 2000 to 2015,the trend of each indicators over time,and search for the main influential indicators.Based on the evaluation of the quality of the main surface water and water environment in Hangzhou in these 15 years,I found as follows:(1)Using the single factor evaluation method to assess the water environment quality in Hangzhou during the past 15 years,I found that the environmental quality of the Qiantang River,the canal,the Tiaoxi River and the urban river is getting better,and most of the sections meet the water quality requirements.(2)After analyzing and comparing the main surface water environment in Hangzhou,I found that mong all the water systems under investigation,the water quality of the Tiaoxi River system is the best,followed by the Qiantang River.The water quality of the canal and the urban river is relatively poor,very likely to be affected by the urban area of Hangzhou,which makes the the water flow slow and the self-purification ability weak.(3)Based on the Spearman rank correlation coefficient method in evaluating the eight indicators of each section in these 15 years,I found that all the seven indicators showed significant or insignificant declines except for the fecal coliforms,indicating that their impact on the water environment were weakened.However,as the variation of the concentration of fecal coliforms is difficult to detect,future research is needed to address this issue. |
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