Long-term Trends in Temperature and Precipitation in the Langat River Basin, Malaysia

This paper analyzed the long-term trends in extreme precipitation as well as temperature at eleven meteorological stations in the Langat River Basin using Mann-Kendall, Theil-Sen’s Slope, and Spearman Rank Correlation methods during all available records. Before applying the Mann-Kendall and Theil-Sen’s Slope methods, the trend free pre-whitening method was applied to eliminate the influence of serial correlation from the time series. The Trend Analyses indicate that when there are increasing and decreasing trend in precipitation and temperature, only increasing trends are significant at 5% level. The Theil-Sen's Slope method identified that the rate of incrementing precipitation variables (Maximum, Minimum, and annual precipitation) is greater than that on temperature. It was found that Mann-Kendall method is more stringent in detection of trend than Spearman Rank Correlation method. The spearman Rank Correlation method can be used to confirm the significant trends detected by the Mann-Kendall method.

کلیدواژه ها:

trend analysis ، Mann-Kendall ، Theil-Sen's Slope ، Spearman Rank Correlation ، Langat River Basin