Investigating the Impact of Large Scale Climatic Phenomena, ENSO and PDO, on Streamfolw Time series using Correlation Analysis and Wavelet Transform

Today, there is concern that climate change and climate variability may affect human society and enforce them to undergo much harm in their life. Questions come up that "how has long term climate varied in the past". More of past studies, on the field of detection, focused on statistical methods. But these methods cannot interpret periodic behaviors. Continuous Wavelet Transform (CWT) reveals some aspects that other spectral analyses (Fourier analysis) miss. The basic objective of the continuous wavelet transform is to achieve a complete time-scale representation of localized and transient phenomena occurring at different time scales. In this research we have investigated discharge trends and periodicity as the two main aspects of runoff variability for Karoon River. To understand of relation between streamflow oscillations and climatic phenomena correlation analysis was used. At the next step, CWT was implemented as a powerful way to characterize period, time position andduration of oscillations in streamflow data series. Wavelet spectrum showed bands of intermittent fluctuations from interannual variability (3-6year) that could be related to ENSO phenomenon