Abstract
Profiling the hydrological response of watershed precipitation and streamflow to large-scale circulation patterns and astronomical factors provides novel information into the scientific management and prediction of regional water resources. Possible contacts of El Niño–Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), sunspot activity to precipitation and streamflow in the upper Yangtze River basin (UYRB) were investigated in this work. Monthly precipitation and streamflow were utilized as well as contemporaneous same-scale teleconnections time series spanning a total of 70 years from 1951 to 2020 in precipitation and 121 years from 1900 to 2020 in streamflow. The principal component analysis (PCA) method was applied so as to characterize the dominant variability patterns over UYRB precipitation time series, with the temporal variability of first two modes explaining more than 80% of total variance. Long-term evolutionary pattern and periodic variation characteristics of precipitation and streamflow are explored by applying continuous wavelet transform (CWT), cross-wavelet transform (XWT) and wavelet coherence (WTC), analyzing multi-scale correlation between hydrological variables and teleconnections in the time-frequency domain. The results manifest that ENSO exhibits multiple interannual period resonance with precipitation and streamflow, while correlations are unstable in time and phase. PDO and sunspot effects on precipitation and streamflow at interannual scales vary with time-frequency domains, yet significant differences are exhibited in their effects at interdecadal scales. PDO exhibits a steady negative correlation with streamflow on interdecadal scales of approximately 10 years, while the effect of sunspot on streamflow exhibits extremely steady positive correlation on longer interdecadal scales of approximately 36 years. Analysis reveals that both PDO and sunspot have significantly stronger effects on streamflow variability than precipitation, which might be associated with the high spatiotemporal variability of precipitation.
Highlights
Global climate change has influenced global and regional hydrological cycles [1].The effect of large-scale climate effects in modulating water cycle events provides the key for anticipating variation of hydrological factors [2]
Multiple timescales of hydrological variable series, such as precipitation and streamflow, are generally manifested as small time-scale variation cycles nested in largescale variation cycles, i.e., multi-level timescale structures and localized variation characteristics exist in precipitation and streamflow variability within the time domain
(1) Continuous wavelet transform results indicate that both precipitation and streamflow series exhibit significant interannual oscillations during the whole study period, with continuous annual periodicity spanning the entire time domain
Summary
Global climate change has influenced global and regional hydrological cycles [1].The effect of large-scale climate effects in modulating water cycle events provides the key for anticipating variation of hydrological factors [2]. Comprehending the variability of hydrological variables such as precipitation and streamflow is fundamental to understanding water cycle dynamics [3,4,5], while such variability has been indicated to be associated with climate change effects and large-scale climate anomalies [3,6]. Relevant information of ENSO and PDO would cause improvements in precipitation and streamflow predictions, thereby mitigating floods and droughts in the Pacific region and elsewhere [19,20]. Since the influences of ENSO and PDO have significant temporal variability [17,21], the value of using climate indices such as ENSO or PDO in water resource predictions depends on understanding of the local relationship between these indices and hydrological factors on time [17]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
