عنوان مقاله [English]
Temperature is main factors of climate and their variation may lead to change the climate of every region. Due to the direct effects of environmental temperature on water resources. Investigation of temperature trend in different temporal and spatial scales, forms a large part of climatology and water resources management researches. In this study the trend changing of temperature of the karun basin at the three scale namely, monthly, seasonally and annually were investigated using the trend-free pre-whitening mann-kendall (TFPW-MK). The used data includes discharge data of 38 meteorological stations in the period of 29 years (1986-2014). In this study, the slope of the linear trend of data estimated using the theil-sen approach (TSA) and then using trend-free pre-whitening (TFPW) approach the effect of coefficient of self-correlation of data was eliminated. Finally, the trend changing of temperature was examined using Man-Kendall.
The results showed that the trend of more than 64 percent of the stations on annual basis are incremental and the increasing trend rates of 13 of the stations are significant at 10% level. On seasonal scale the trend of more than 67 percent of the stations to spring, summer and winter seasons are incremental.On monthly scale, the results showed that the trend of more than 50 percent of the stations on monthly scale are incremental and the increasing trend rates of 26 percent of this stations are significant at 10% level. The results of this study showed that the monthly and annual streamflow of most stations have increasing trend.