Impacts of Climate Change on the Hydrological Regime of the Danube River and Its Tributaries Using an Ensemble of Climate Scenarios

Judith Stagl,Fred Hattermann

doi:10.3390/w7116139

Abstract

Information about the potential impacts of climate change on river runoff is needed to prepare efficient adaptation strategies. This study presents scenario projections for the future hydrological runoff regime in the Danube River Basin. The eco-hydrological watershed model Soil and Water Integrated Model (SWIM) was applied for the entire Danube River catchment, considering 1224 subbasins. After calibration and validation of the model, a set of high-resolution climate projections (bias-corrected and non-bias-corrected) served as meteorological drivers with which future daily river discharge under different climate warming scenario conditions was simulated. Despite existing uncertainties, robust trends could be identified. In the next 30 years, the seasonal stream-flow regime of the Danube and its tributaries is projected to change considerably. Our results show a general trend towards a decrease in summer runoff for the whole Danube basin and, additionally, in autumn runoff for the Middle and Lower Danube basin, aggravating the existing low flow periods. For the winter and early spring seasons, mainly January–March, an increase in river runoff is projected. Greater uncertainties show up in particular for winter runoff in the Dinaric Alps and the Lower Danube basin. The existing trends become very distinct until the end of the 21st century, especially for snow-influenced river regimes.

Highlights

River runoff is highly sensitive to climate, especially to changes in precipitation, snow regime and evapotranspiration [1,2]
Our modeling results clearly show an earlier runoff peak and a shift from summer to spring due to a changed snow regime. This is in line with the climate impacts reported in Mauser et al [15], who projected for the Upper Danube River basin a higher water availability in winter and lower water availability in summer
With a regional hydrological model and a broad ensemble of climate scenarios, we estimated the impacts of climate change on runoff seasonality in the Danube River catchment

Summary

Introduction

River runoff is highly sensitive to climate, especially to changes in precipitation, snow regime and evapotranspiration [1,2]. Climate change will affect the hydrologic regime and river flow characteristics through changes in precipitation and evapotranspiration, as well as in the snow regime. The future development of the river runoff conditions, as a consequence of climate change, is of great interest for stakeholders and decision makers in the riparian states. Information about potential impacts is needed for consolidated impact assessments and for long-term planning and adaptation (i.e., National Communications of the United Nations Framework Convention on Climate Change). In Europe, discussions arose around how changes in water resources and river runoff can be considered in river basin management plans, as they are required by the European Water Framework.

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Discussion

Conclusion