How will climate change modify river flow regimes in Europe?

C Schneider,M C Acreman,M Flörke,C L R Laizé

doi:10.5194/hess-17-325-2013

Abstract

Abstract. Worldwide, flow regimes are being modified by various anthropogenic impacts and climate change induces an additional risk. Rising temperatures, declining snow cover and changing precipitation patterns will interact differently at different locations. Consequently, in distinct climate zones, unequal consequences can be expected in matters of water stress, flood risk, water quality, and food security. In particular, river ecosystems and their vital ecosystem services will be compromised as their species richness and composition have evolved over long time under natural flow conditions. This study aims at evaluating the exclusive impacts of climate change on river flow regimes in Europe. Various flow characteristics are taken into consideration and diverse dynamics are identified for each distinct climate zone in Europe. In order to simulate present-day natural flow regimes and future flow regimes under climate change, the global hydrology model WaterGAP3 is applied. All calculations for current and future conditions (2050s) are carried out on a 5' × 5' European grid. To address uncertainty, bias-corrected climate forcing data of three different global climate models are used to drive WaterGAP3. Finally, the hydrological alterations of different flow characteristics are quantified by the Indicators of Hydrological Alteration approach. Results of our analysis indicate that on the European scale, climate change can be expected to modify flow regimes remarkably. This is especially the case in the Mediterranean (due to drier conditions with reduced precipitation across the year) and in the boreal climate zone (due to reduced snowmelt, increased precipitation, and strong temperature rises). In the temperate climate zone, impacts increase from oceanic to continental. Regarding single flow characteristics, strongest impacts on timing were found for the boreal climate zone. This applies for both high and low flows. Flow magnitudes, in turn, will be predominantly altered in the Mediterranean but also in the Northern climates. At the end of this study, typical future flow regimes under climate change are illustrated for each climate zone.

Highlights

In the last century, natural flow regimes have been heavily modified by different anthropogenic impacts (Malmqvist and Rundle, 2002)
This paper aims at evaluating the sole impact of climate change on river flow regimes in Europe, analysing the dynamics separately for each climate zone
This study aimed at evaluating the future impact of climate change on river flow regimes in Europe and identifying the dynamics separately for each climate zone

Summary

Introduction

Natural flow regimes have been heavily modified by different anthropogenic impacts (Malmqvist and Rundle, 2002). Water demands of an exponential growing world population leads to reduced river discharge due to withdrawals for irrigation, electricity production, manufacturing, domestic purposes and others. Population growth and society’s increasing demands on resources have caused immense land-use changes. Urbanization and deforestation result in large sealed areas that alter flow magnitudes and timing through lower evapotranspiration rates and faster runoff (Sahin and Hall, 1996). Many rivers have been artificially modified by construction works such as channelization, embanking, straightening, widening or deepening with further impacts on flow and flow velocity

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