Abstract:

Establishment of water mobile monitoring framework is of great significance to enhance the overall ability of water monitoring in the ThreeGorges Reservoir.Because there are too many waterquality indicators and not all of them are suitable for mobile monitoring,it’s required to select proper waterquality indicators.The scientific screen method of the waterquality indicators is a foundation work.Based on the status of water monitoring in the ThreeGorges Reservoir,this paper analyzed the requirement of the water mobile monitoring.According to the water environments and the characteristics of mobile monitoring,the principle of waterquality indicators screen was formulated,including representativeness principle,scientific principle and feasibility principle.After that,analysis and comparisons of 5 classical statistics methods widely used in indicators selecting,such as the Delphi method,principal component analysis method,genetic algorithm method,gray relevancy method and analysis hierarchy process were conducted in this study.Each of them has its strengths and applicability.First of all,screening the waterquality indicators for mobile monitoring should consider many factors,such as the function areas of the water environment,pollution features,distribution of pollution sources,and geography condition etc.It was also required to judge whether the indicators could be monitored accurately by using the mobile monitoring equipment.Because of the subjectivity features and relative applicability,the Delphi method was selected as the initial screen method.Also,the result needs to be modified in accordance with the principle of indicators screen of waterquality for mobile monitoring.After completing the initial choice,principal component analysis method was considered as the most suitable one for the qualitative screen of waterquality indicators for mobile monitoring.After years of operation,Ecology and Environment Monitoring System of the ThreeGorges Project has accumulated a lot of valuable local monitoring data.Such a data set provide critical support for the principal component analysis method.This makes the result of screen objective and reliable.This combination system of qualitative and quantitative screening optimized for the waterquality indicators selection of mobile monitoring in the ThreeGorges Reservoir just proved the feasibility in theory.Furthermore,taking the Jiangjin Bridge Monitoring Section as an example,Delphi method was used to select the indicators initially.After that,according to the monitoring data of 2010,principal component analysis method was taken to select the most important indicators in this area,including TN,TP,COD,BOD,dissolved oxygen,CODMn,petroleum,NH3N,Hg,Volatile Penol and As.This result proved the feasibility in practice.In order to keep coincidence with the actual situation,field trip and actual waterquality mobile monitoring in the ThreeGorges Reservoir are further needed to verify and revise the screen result of waterquality indicators.The last result will be expected to provide theoretical support for the future practices on water mobile monitoring