Electricity vs Ecosystems – understanding and predicting hydropower impact on Swedish river flow

B Arheimer,G Lindström

doi:10.5194/piahs-364-313-2014

B Arheimer, G Lindström

Open Access

https://doi.org/10.5194/piahs-364-313-2014

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Abstract

Abstract. The most radical anthropogenic impact on water systems in Sweden originates from the years 1900–1970, when the electricity network was developed in the country and almost all rivers were regulated. The construction of dams and changes in water flow caused problems for ecosystems. Therefore, when implementing the EU Water Framework Directive (WFD) hydro-morphological indicators and targets were developed for rivers and lakes to achieve good ecological potential. The hydrological regime is one such indicator. To understand the change in flow regime we quantified the hydropower impact on river flow across Sweden by using the S-HYPE model and observations. The results show that the average redistribution of water during a year due to regulation is 19 % for the total discharge from Sweden. A distinct impact was found in seasonal flow patterns and flow duration curves. Moreover, we quantified the model skills in predicting hydropower impact on flow. The median NSE for simulating change in flow regime was 0.71 for eight dams studied. Results from the spatially distributed model are available for 37 000 sub-basins across the country, and will be used by the Swedish water authorities for reporting hydro-morphological indicators to the EU and for guiding the allocation of river restoration measures.

Highlights

There is a growing interest among hydrological scientists in how society and water systems are coevolving (Wagener et al 2010, Sivapalan et al 2012, Montanari et al 2013) as it is important to find a balance between water for humans and water for nature (Falkenmark and Rockström 2004) and efficient methods for integrated water management (Rahaman and Varis 2005).Dysenius and Nilsson (1994) found out that 77% of the river discharge from the northern part of the world is affected by fragmentation of the river channels by dams and water regulation
The most radical anthropogenic impact on water systems in Sweden remains from the years 1900–1970, when the electricity network was developed in the country, exploiting the potential energy of surface water
According to the model results for the whole of Sweden, hydropower has a significant impact on the seasonal distribution of flow, as water is stored during the high flow of the snow-melt and released during winter when electricity is needed most (Fig. 2). This is according to expectations, since the purpose of regulation is to store water from one time period to another

Summary

Introduction

There is a growing interest among hydrological scientists in how society and water systems are coevolving (Wagener et al 2010, Sivapalan et al 2012, Montanari et al 2013) as it is important to find a balance between water for humans and water for nature (Falkenmark and Rockström 2004) and efficient methods for integrated water management (Rahaman and Varis 2005).Dysenius and Nilsson (1994) found out that 77% of the river discharge from the northern part of the world is affected by fragmentation of the river channels by dams and water regulation. The impact of regulation for hydropower production was estimated using the S-HYPE model with routines to predict river regulation and naturalized flow, respectively.

Results

Conclusion