The 1-D continuous wavelet transform of Morlet was used to investigate the characteristics of water quality at Longdong monitoring station, upper Yangtze River of Panzhihua. The consistence of CODMn and NH_3-N were chosen as main monitoring indicators, produced by Longdong monitoring station by weekly monitoring from 2004 to 2010. The result shows that consistence of CODMn changes between -8 and 8 with roughly 42 weeks mainly cycle, 10 weeks and 21 weeks for the second cycle. Consistence of NH_3-N changes between -0.3 and 0.3, and the largest value appears on 5th week of 2004, a larger value at 35th, 70th and 110th weeks. Except the mentioned weeks above consistence of NH_3-N changes smoothly. There is a small fluctuation from 1 to 15 weeks at the curve of NH_3-N consistence wavelet coefficient variance, and a relatively large fluctuation in 15-50 weeks, while after that that curve showing a rising trend. Overall, CODMn changes by rainfall while NH_3-N by agricultural production habits. In wet season, soil erosion was strengthened with much more mud and sand draining to the river, resulting in a declining of water quality.
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