Application Of Sensitivity Analysis In Surface Water Quality Evaluation

With the development of social economy,human activities have increasingly serious impact on the surface water environment,which leads to deterioration of water quality when it exceeds the self-purification capacity of the water body.The environmental assessment of the surface water is to evaluate the overall environment based on the monitoring value of some environmental indicators.The evaluation results can provide scientific suggestions for decision-makings in water quality prediction,environmental pollution warning,surface water environmental planning and environmental pollution control.At present,there are some shortcomings in the previous methods of water environment assessment,such as the subjective evaluation which is not suitable for the comprehensive system of multi-index dynamic change.Therefore,how to develop and select a suitable evaluation model for surface water environmental assessment system is the key and difficult point in this field.The surface water is characterized with many environmental indexes,fast change and strong fluidity,so this study,based on main evaluation methods,puts forward a set of evaluation models and mechanisms that are suitable for surface water environmental assessment,and resorts to Dev-C++ and MATLAB software development platform to realize them concretely.Details are described as follows:(1)This paper synthesizes the advantages of entropy weight coefficient method and matter element analysis method,and proposes and implements an "entropy weight-matter element comprehensive evaluation model".The process of entropy weight coefficient method is realized by using Dev-C++ software platform,while the process of entropy weight coefficient method and matter element analysis method are realized by MATLAB software platform.In this way,the evaluation model of "entropy weight-matter element" is realized.In order to verify the accuracy and rationality of the proposed model,we apply the model to evaluate the heavy metal pollution in farmland soil around a lead-zinc metal tailings area in Huanjiang,Guangxi.The evaluation results show that the proposed method is scientific and effective,and is easy to realize and operate.(2)In this paper,the sensitivity analysis method is used to analyze the sensitivity of the index weight,aiming to analyze the impact of arbitrary change of index weight on evaluation results in the evaluation system.In order to verify the applicability and feasibility of the sensitivity analysis,this paper also applies this method to the comprehensive evaluation of the environmental health in a pumped storage power station.The variation range of each index weight is analyzed,and the conclusion conforms to the objective reality is obtained.Suggestions for improving the engineering environment of the storage e power station are put forward.(3)With the collected data of surface water monitoring index in New city Reservoir area of Jilin Province,some pretreatments are performed.Firstly,the evaluation model of "entropy weight-matter element" is used to evaluate the grade of four seasons in the new city reservoir,say spring,summer,autumn and winter respectively.Then,the sensitivity analysis of the grade evaluation results of four seasons is carried out,and the conclusions are made according to the evaluation results and their sensitivity analysis.Finally,according to the conclusion,the paper puts forward some targeted improvement measures and scientific suggestions for the four seasons of the new city reservoir.