Quality Evaluation And Prediction Of Lakewater Based On Grey Fuzzy Model

Lakes provide a good living environment for lives on earth,but recently,water quality of lake was polluted severely,and it had aroused people's attention.Making objective evaluation and prediction of the lake water quality was good for the further understanding of the water quality status,and future trends.It was the precondition of lakes comprehensive treatment,and had the vital significance to the protection of lakes.The Guanting Reservoir belonged to the generalized lakes,located in the northwest of Beijing,was the important water source of Beijing and Hebei regions.The study of its water quality was of great importance.To analyze and evaluate Guanting Reservoir's water quality,this paper adopted the method of fuzzy mathematics to set up the water quality comprehensive evaluation model.According to the water quality monitoring data of 2011 to 2014,it could be divided into normal river flow period,wet period,and dry season period to improve the evaluation precision.It showed that the main pollutants of the reservoir was NH3-N.The results of using this method were more reasonable than the single factor evaluation.In the aspect of water quality prediction,the paper used the theory of grey mathematics to establish the gray prediction model.Selecting 2010 to 2014 monitoring data of Yanhecheng,it could also be divided into normal river flow period,wet period,and dry season period respectively.Using this model to predict the water quality indicators of 2015 and 2016,such as DO,CODMn,NH3-N,and the accuracy of the model was checked.It directly affected the forecast results,due to the characteristics of water quality monitoring data was not enough complete.Compared with the real water quality of 2015,the error of the model to predicting CODMn was a little big.The main reason was probably that water quality index of the sample data changed dramatically.But overall,the index prediction accuracy of model to the other could also be accepted.