Wavelet Analysis of Water Quality Changes in Dianchi Lake during the past 7a

Water pollution is one of the most serious environmental pollution the world faces, and there are very few papers to study the water environmental indicators of time-series. The paper, through using the continuous wavelet time series, analyzed the Dianchi Lake water quality indicators as each indicator has different emergence of the extreme time at different periods of time during the past 7a. Results showed that the Dianchi Lake water quality indicators had different change cycles at different time scales near 7a, with pH being low in spring and summer, high in autumn and winter, DO being high in spring and summer, low in autumn and winter, CODMn being low in autumn and winter, high in spring and summer, and NH3-N being low in spring and summer and high in autumn and winter. Although the overall water quality in Dianchi Lake has been improved, the pollution sometimes still gets worse at certain sections of the Dianchi Lake. Therefore,using the wavelet to study the law of water pollution is not only effective but also applicable to the study of other pollutants time series evolution.