عنوان مقاله [English]
In this research Flow -Precipitation fluctuations in 9 Station, analyzed by spectral density functions and Autocorrelation Functions in the frequency and time domain in Dinevar basin. First analyzed fluctuations in the correlogram of each time series. Then Spectral density functions are based on the Fourier series was used to check the time series in the frequency domain. In this regard, the Spectrum value of each flow and rainfall series is calculated and was drawn Graph of each series periodogram. Periodogram of this data had in fluctuated in several frequencies. It was seasonal fluctuations with frequency 0.083, short term fluctuations with frequency 0.25 and midterm fluctuations with frequency 0.167 that Fluctuations return period of 6 months wasn’t observed in Precipitation data. Cross spectral analysis of data showed High match levels in frequencies 0.25 and 0.25. Also the estimated values of delay by cross spectral analysis for seasonal fluctuations in Precipitation (0.083) and the effect of this on seasonal flow fluctuations was estimate nearly 1.5 months. This delay determinate nearly 0.4, 0.5 and 0.14 months for fluctuations with return period less. According to spectral analysis results of Precipitation data in whole stations, after removing the frequency and trends, cycle was observed in frequency 0.01 that these frequencies showed Wet and dry periods in this region.