Change point analysis of discharge time series in some hydrometric stations in Golestan Province

Change point analysis technique is an important method to detect potential change in time series. Therefore, the main objective of this research is to determine and analysis of change points in the annual discharge of Golestan Province over 20 hydrometric stations in a 34-years period.

Time and magnitude of change points have been defined and the results have been analysed along with variations of temperature and precipitation through the study area. According to the results, a significant positive correlation is exist between discharge and precipitation (p<0.001). While, the correlation between discharge and temperature had a negative non-significant correlation.

The results showed that the dominance of change points are decreasing over the study area along with some increasing and no change cases. The number of significant decreasing points were significantly higher than increasing changes and the major changes had occurred in the 1994, 1995, and 1998 years in 4, 5, and 3 stations, respectively (the decreasing points happened over 1994-1998-time span). The highest observed changes was related to Lazoureh station in 1980 and 2011 years which the values of changes in discharge were 3.01 and 0.9 cubic meter per seconds, respectively. Discussion and

It can be concluded that, the number and amount of changes in water discharge can be determined by the change point analysis technique. Understanding the trends decrease or increase in watershed rainfall and discharge have an important role in water resources management and water-related issues.