Trend Analysis and Detection of Change Points in Monthly, Seasonal and Annual Flow: A Case Study of Fars Province, Iran

Increasing or decreasing of the flow rate has the direct impact on surface water resources and the management of them in each region. According to this، in the present study، monthly، Mann-Kendall non-parametric and sen’s methods were used to declare positive or negative flow trend، and also Pettitt test was implemented for detection of its change points and abrupt shifts in 12 gauging stations in Fars province during 1972-2011. Furthermore، TFPW approach was used in order to decline the effects of autocorrelation and serial correlation on the Mann-Kendall test. The results of Mann-Kendall test and sen’s method illustrated the decreasing trend for all stations. Also the results of Pettitt test revealed that in four of twenty stations، change points had occurred between 1998 and 1999. Pol khan station (That is located at the end of Kor river)، with decreasing 15. 942 (m3/s) in the mean annual stream flow between two periods (per change point in comparison the post-change point)، and also statistical Mann Kendall (z=-0. 251) and slope (-0. 513)، has the most dramatic change and decreasing trend.