Trend Analysis Using Mann-kendall And Sen’s Slope Estimator Test for Annual And Monthly Rainfall for Sinjar District, Iraq
Fawaz Kh. Aswad, Ali A. Yousif, Sayran A. Ibrahim
Abstract
The time series rainfall data of 70 years (1940 – 2010) of Sinjar District used to identify the trend and slope magnitude of this series. To analyze the trend, the non-parametric test (Mann-Kendall test) andSen’s slope estimator were used. For developing a functional relationship between variables, a linear trend of rainfall data for the studied area evaluated using the linear regression. The annual trend analysis showed decreasing trend because the value of Mann- Kendall’s tau and the magnitude of Sen’s slope estimator were both negative and was found to be - 0.06501 and -0.7283, respectively. Also for the slope of the linear regression was negative and equal to −0.916 mm/year, which represents the rate of decreasing in trend for yearly annual rainfall. In addition, the results showed that the trend analysis of monthly rainfall has a varied trend of rainfall in the rainy months. Finally, the results showed a positive trend (increasing) for the months of October and April and negative trend (decreasing) for the other months.