The Study Of Meteorological Environmental Factors And Predicting Models Of Algal Bloom In Lake Tai Based On The Grading Standards

The Lake Tai Basin across Shanghai,Jiangsu,Zhejiang and Anhui province,which is densely populated, Agriculture and industry developed as one of the most economically developed regions in our country.In recent years,Many of lakes outbreak of algal blooms frequently in our country, its outbreak levels,degree of the disaster rise substantially.Researching on the relationship between environmental factors and algal blooms outbreak and its change trend in Lake Tai.it can provide theoretical and technical support for determining the major environmental factors that influence algal blooms and simulating the dynamic change of algal biomass,thus it enhances the algal bloom forecasting and response capabilities.Therefore.This article focuses on environmental factors such as meteorology,hydrology and water quality.which have the multi-driving effect on algal bloom.quantifying the correlation between algal biomass and between various environmental factors,identifying the significant impact factors driving algal blooms.Building the effective predicting models of algal bloom,Analyzing the trends of algal blooms,providing the scientific basis and technical support for controlling and warning algal blooms.The main research results are as follows:Statistics Lake Tai the inter-annual and intra-annual variability of the area of algal blooms in recent years,it find that the inter-annual variability of algal blooms from2007to2012,the algal blooms which have higher levels and occurrence frequently appear in2007and2010mainly;the intra-annual variability is that the algal blooms mainly occur in May,July to October.Analysis of the ranges,trends and rules of various meteorological elements before and after the algal blooms.By studying the influence of meteorological factors on the algal blooms,it finds:Algal blooms are influenced and restricted by multiple meteorological factors.In average,high temperature,low pressure,long hours of sunshine.less rainfall are conducive to the occurrence of algal blooms;and the different levels of algal blooms are accompanied by different ranges of meteorological factors.Focusing on the water monitoring points Lake Tai.Using three kinds of statistical methods such as correlation analysis,principal component analysis and gray correlation analysis,Studying the degree of correlation between algal density and environmental factors suchas meteorology,hydrology,water quality, the size of correlation degree in Shazhunan water intake is: potassium permanganate>PH> total phosphorus> water temperature> temperature> pressure> wind> relative humidity> dissolved oxygen> ammonia> sunshine> total nitrogen> precipitation; the size of correlation degree in Xidong water intake is:water temperature> potassium permanganate>total phosphorus>PH>temperature>pressure>relative humidity> wind>ammonia>dissolved oxygen>total nitrogen>precipitation>sunshine.Concluding that there are six significant environmental factors affect the algae density:temperature,pressure,water temperature,PH,potassium permanganate and total phosphorus.Using the six significant environmental factors that concludeby above results as independent variables,the algal density and the corresponding bloom level as the dependent variable,then building multivariate statistical regression equation for the algal density,and Using the six significant environmental factors as the network input,algal density and the corresponding bloom level as network output,then it establishes BP network models.Analysis of the forecast error results of the two models,it finds that the predicting effect of BP network model is better than the regression model;in different monitoring points,the same model has different predicting effect,the predicting effect of both models used in Shazhunan monitoring point are better than Xidong monitoring point.