How will climate change modify river flow regimes in Europe?

Abstract

Worldwide, flow regimes are being modified by various anthropogenic impacts and climate change induces an additional risk. Rising evapotranspiration rates, 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 natural and modified flow regimes, 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, 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 European scale, climate change can be expected to modify flow regimes significantly. This is especially the case in the Mediterranean climate zone (due to drier conditions with reduced precipitation across the year) and in the continental climate zone (due to reduced snowmelt and drier summers). Regarding single flow characteristics, strongest impacts on timing were found for the boreal climate zone. This applies for both, high and low flows. While low flow magnitudes are likely to be stronger influenced in the Mediterranean climate, high flow magnitudes will be mainly altered in snow climates with warmer summers. At the end of this study, typical future flow regimes under climate change are illustrated for each climate zone including a validation on robustness

Impacts of climate change on European hydrology at 1.5, 2 and 3 degrees mean global warming above preindustrial level

“…Van Vliet et al 2015, Forzieri et al 2014, Schneider et al 2013, however with the focus of assessing climate change impacts at fixed periods, for example midor end century. Recent studies have begun to assess climate change (Vautard et al 2014) and associated water impacts in Europe and beyond (Roudier et al 2016) at specific levels of global warming.…”

Impacts of Climate Change on Riverine Ecosystems: Alterations of Ecologically Relevant Flow Dynamics in the Danube River and Its Major Tributaries

“…The "Indicators of Hydrologic Alteration" approach given by Richter et al [13] includes a "Range of Variability" analysis which allows effective comparison of the pre-and post-impact conditions, but does not pose any ecologically grounded quantitative limit values. Although some authors propose thresholds for a set of selected indicators of hydrological alterations (e.g., [3,6,25]), simple rules for thresholds are likely to be misleading as the biological impact of flow alterations also relies on other ecological factors like habitat quantity and quality [52].…”

Projected Change—River Flow and Urban Drainage

“…Another Europe-wide hydrological impact study was undertaken by Schneider et al (2013) who applied the global hydrological model WaterGAP3 on a 50′ × 50′ European grid. Climate change impacts were based on three GCMs after bias correction.…”