Investigating streamflow variability and hydroclimatic teleconnections: a comparison of regulated and unregulated streamflow stations

Abstract

This study evaluates the relationship between flow variability of unregulated and regulated streamflow stations and global climate indicators. Mann–Kendall and change-point analysis is applied to investigate the gradual and abrupt changes in streamflow data, followed by the investigation of multi-scale fluctuations in streamflow data using Continuous Wavelet Analysis. Linkages between streamflow and global climate indicators are examined using Cross-Wavelet and Wavelet Coherence Analysis. Results showed contrasting trend values for unregulated and regulated streamflow stations. Surprisingly, all unregulated stations experienced a significant abrupt shift in change point contrary to the regulated streamflow. Further, for unregulated stations, streamflow variability and hydroclimatic teleconnections were observed at a lower scale, indicating that variations in streamflow are more frequent and generally occur on an intra-annual to inter-annual scale. Contrary to this, regulated stations observed the streamflow variability and hydroclimatic teleconnections at a larger scale (8–10 years), indicating that all the fluctuations are smoothed out. Thus, unregulated stations cannot be used as a proxy for regulated stations in any given basin. Indeed, for better water resource planning and management, both regulated and unregulated streamflow should be investigated. HIGHLIGHTS Distinct characteristics of unregulated and regulated streamflow variability and hydroclimatic teleconnections.; Intra-annual and annual variability, i.e., 0.5 and 1 year, are prominent in unregulated in contrast with the appearance of intra-decadal scale in the regulated streamflow stations.; Hydroclimatic teleconnections of unregulated stations are prevalent up to inter-annual scale, whereas they existed up to intra-decadal scale for regulated stations.;

Keywords

• climate indices
• hydroclimatic teleconnections
• regulated and unregulated stations
• streamflow variability
• wavelet analysis