Impact of hydropower reservoirs on floods: evidence from large river basins in Austria

ABSTRACT

In this study the impact of hydropower reservoirs on floods is systematically assessed for eight heavily modified river basins in Austria. Since little discharge data from prior to the construction is available, unaffected annual peak discharges downstream of the reservoirs were estimated by transposing the peak runoff of an unaffected catchment, considering the spatial proximity, the catchment area and the temporarily corresponding precipitation conditions. Comparing the observed and estimated discharge, results show significant reductions not only at gauges directly affected by the reservoir but also farther downstream at receiving rivers. The propagation of the flood peak reduction downstream is also related to catchment area and reservoir characteristics. Extreme events with return periods greater than 30 years show a noteworthy flood peak reduction of over 33% on average. These findings show that reservoirs primarily constructed for hydropower generation also contribute significantly to flood control and flood mitigation.

KEYWORDS:

• flood peak reduction
• hydropower storage reservoirs
• flood control
• downstream impact
• flood risk
• flood mitigation

Editor A. Castellarin Associate Editor B. Dewals

Editor A. Castellarin Associate Editor B. Dewals

Acknowledgements

Discussions with Dr Klaus Hebenstreit and Dr Willibald Kerschbaumsteiner helped in understanding the operational procedures of storage hydropower plants in Austria. This is highly acknowledged. We also acknowledge the work of DI Katharina Lebiedzinski in the context of this paper. We also greatly appreciate the comments and suggestions from two anonymous reviewers, which helped to improve this work.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The study was performed using openly available primary input data. All intermediate and final data that were generated in this study are available in the Supplementary Material and upon request to the corresponding author.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/02626667.2022.2130332

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was funded by the Earth System Sciences (ESS) research programme of the Austrian Academy of Sciences (ÖAW) within the project “Integrated Flood Risk Management in Mountain Areas: Assessing Sectoral Interdependencies, Conflicts and Options for Policy Coordination” (PoCo-FLOOD).