| Title |
Long-Term Trend Analyses of Water Qualities in Nakdong River Based on Non-Parametric Statistical Methods |
| Authors |
김주화 ( Kim Ju Hwa ) ; 박석순 ( Park Seog Sun ) |
| Keywords |
Trend analysis; Water quality; Non-parametric statistics; Nakdong River; Mann-Kendall Test; LOWESS |
| Abstract |
The long-term trend analyses of water qualities were performed for 49 monitoring stations located in Nakdong River. Water quality parameters used in this study are the monthly data of BOD(Biological Oxygen Demand), TN(Total Nitrogen) and TP(Total Phosphorus) measured from 1990 to 1999. The long-term trends were analyzed by Seasonal Mann-Kendall Test and Locally WEighted Scatter plot Smoother(LOWESS). Nakdong river was divided into four subbasins, including upstream waershed, midstream watershed, western downstream watershed and eastern downstream watershed. The results of Seasongal Mann-Kendall Test indicated that there would be no trends of BOD in upstream waershed, western and eastern downstream watershed. Trends of BOD were downward in midstream watershed. For TN and TP, there were upward trends in all of watersheds. But LOWESS curves suggested that BOD, TN and TP concentrations generally increased between 1990 and 1996, then resumed decreasing. |