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The Influence of Modelling Choices on Hydropeaking Impact Assessment: A Systematic Comparison of 1D and 2D Approaches

Author(s): Davide Vanzo; Matthias Burgler; Timo Wicki; Robert M. Boes; David F. Vetsch

Linked Author(s): Davide Vanzo

Keywords: No Keywords

Abstract: The frequent and abrupt discharge fluctuations generated by hydropower production, namely hydropeaking (hereinafter HP), lead to significant changes in the downstream river reach hydraulic regime and have several recognized impacts on local ecosystems, affecting fish and macroinvertebrate communities (e. g. [1]), but also vegetation (e. g. [2]). To design efficient mitigation strategies of such ecohydraulic impacts, several national guidelines call for hydropeaking impact assessment. As an example, the Swiss Federal Water Protection Act requires the quantification and mitigation of hydropeaking impacts by the end of 2030 [3]. To this aim, several indicators are suggested, generally related with different biotic and abiotic metrics such as the dewatering rate (or water depth rate of change) and the variation of the wetted area. In praxis, HP impact assessment requires the choice and the setup of a modelling approach for hydrodynamic simulations. As a result, such modelling choices might affect the quantification of the investigated indicators (e. g. [4]). The main goal of this study is to assess the result variability related to the modelling choices on the quantification of some specific HP-related indicators. Doing that, we aim to provide a supporting analysis framework to select suitable modelling approaches and spatial resolutions for robust hydropeaking impact analysis. The HP impact assessment comparison presented here is based on five biotic indicators defined in [3]. Different spatially resolved 1D and 2D models, for a total of 21 configurations, were simulated and analyzed. Finally, the deviations between indicator results were quantified and discussed, in order to she d some light on adequate modelling choices for HP impact assessment.

DOI:

Year: 2018

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