University of Oulu

Ashraf, F. B., Haghighi, A. T., Riml, J., Mathias Kondolf, G., Kløve, B., & Marttila, H. (2022). A method for assessment of sub-daily flow alterations using wavelet analysis for regulated rivers. Water Resources Research, 58, e2021WR030421.

A method for assessment of sub-daily flow alterations using wavelet analysis for regulated rivers

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Author: Ashraf, Faisal Bin1; Torabi Haghighi, Ali1; Riml, Joakim2;
Organizations: 1Water Energy and Environmental Engineering Research Unit, University of Oulu, Oulu, Finland
2Department of Sustainable Development, Environmental Science and Engineering, KTH Royal Institute of Technology, Stockholm, Sweden
3Department of Landscape Architecture and Environmental Planning, University of California, Berkeley, CA, USA
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 4.6 MB)
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Language: English
Published: American Geophysical Union, 2022
Publish Date: 2022-05-24


New tools are needed to evaluate the impacts of short-term hydropower regulation practices on downstream river systems and to progress towards sustainable river-flow management. As hydropower is increasingly being used to balance the energy load deficit caused by other less flexible sources, sub-daily flow conditions across many regulated river (RR) systems are changing. To address this, we used wavelet analyses to quantify the discharge variability in RRs and categorized the level of variability based on the conditions in natural free-flowing rivers. The presented framework used the definition of fluvial connectivity (Grill et al., 2019) to identify free-flowing rivers used in the study. We tested the developed framework in 12 different RRs in Finland and found higher overall averaged subdaily variations, with up to 20 times larger variability than natural conditions. A large, highly regulated Finnish river system was found to have the highest sub-daily variations in winter, while smaller RRs with lower levels of regulation the highest variations in summer. The proposed framework offers a novel tool for sustainable river management and can be easily applied to various rivers and regions globally. It had flexibility to analyze sub-daily variations in desired seasonal or other ecologically sensitive periods.

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Series: Water resources research
ISSN: 0043-1397
ISSN-E: 1944-7973
ISSN-L: 0043-1397
Volume: 58
Article number: e2021WR030421
DOI: 10.1029/2021WR030421
Type of Publication: A1 Journal article – refereed
Field of Science: 218 Environmental engineering
212 Civil and construction engineering
Funding: This study was funded by Maj-and Tor Nessling Foundation (grant no. 201800109). The BioWater project supported the writing, Nordic Center of Excellence, funded by NordForsk (Project Number 82263) and Ecoriver and HYDRO RDI projects funded by the Academy of Finland (grant numbers 323810 and 337523) and Kvantum Institute spearhead project. We utilised the ‘WaveletComp’ package available for the R programming language to do the wavelet transform.
Academy of Finland Grant Number: 323810
Detailed Information: 323810 (Academy of Finland Funding decision)
337523 (Academy of Finland Funding decision)
Copyright information: © 2021. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.