A Nonparametic Trend Test Study Of Water Qulity Change

Environmental issues have drawn widespread attention, and the influencing factors that cause climate change can be divided into natural factors and human factors. Nonparametric test methods, which calls Partial Hirsch-Slack(PHS test), can distinguish whether the environmental problems are caused by natural factors or by man-made factors, PHS test can analyze the impact of human activities on the environmental problems without the influence of natural factors. Based on the Mann- Kendall(MK) test and seasonal Kendall test, this paper studys the improved seasonal Kendall(HS) test and Partial Hirsch- Slack(PHS) test, and the HS test and PHS test is revised in this paper.Through Monte Carlo experiment, we can simulate the different frequency and different time length of data, study the testing power of the HS test and PHS test, and use the Monte Carlo experiment to simulate the significance level of HS test and PHS test. All of them can prove the superiority of the HS test and PHS test. Nonparametric test of HS test and PHS test, ignoring the size of the data, only pays attention to the order of the relative value or data,which can avoid the impact of missing data values and outliers. What’s more, both HS test and PHS can performe well,When presence of depandent data exists.After studing the HS test and the PHS test, this paper collected weekly data that that are high-frequency data from 2004 to 2013,and these data refer to water quality change trend of three monitoring stations in the Yellow River, including Gansu Lanzhou xincheng bridge, Shanxi Yuncheng Hejin bridge, Shandong Jinan Luoshui. Test the change trend of water quality evaluation index:PH、DO、CODMn、NH3-N. PHS test test the change trend of water quality evaluation index considering environmental factors by means of choosing sunshine time, average temperature, and average wind speed as covariate respectivly. The HS test directly test the change trend of an evaluation index without covariate.The study results show: the PHS test is proved to have good applicability.by comparing the results of the HS test and PHS test,...