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Filling the white space on maps of European runoff trends: estimates from a multi-model ensemble

Stahl, K.; Tallaksen, L.M.; Hannaford, J.; van Lanen, H.A.J.. 2012 Filling the white space on maps of European runoff trends: estimates from a multi-model ensemble. Hydrology and Earth System Sciences, 16 (7). 2035-2047. 10.5194/hess-16-2035-2012

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Abstract/Summary

An overall appraisal of runoff changes at the European scale has been hindered by "white space" on maps of observed trends due to a paucity of readily-available streamflow data. This study tested whether this white space can be filled using estimates of trends derived from model simulations of European runoff. The simulations stem from an ensemble of eight global hydrological models that were forced with the same climate input for the period 1963–2000. The derived trends were validated for 293 grid cells across the European domain with observation-based trend estimates. The ensemble mean overall provided the best representation of trends in the observations. Maps of trends in annual runoff based on the ensemble mean demonstrated a pronounced continental dipole pattern of positive trends in western and northern Europe and negative trends in southern and parts of eastern Europe, which has not previously been demonstrated and discussed in comparable detail. Overall, positive trends in annual streamflow appear to reflect the marked wetting trends of the winter months, whereas negative annual trends result primarily from a widespread decrease in streamflow in spring and summer months, consistent with a decrease in summer low flow in large parts of Europe. High flow appears to have increased in rain-dominated hydrological regimes, whereas an inconsistent or decreasing signal was found in snow-dominated regimes. The different models agreed on the predominant continental-scale pattern of trends, but in some areas disagreed on the magnitude and even the direction of trends, particularly in transition zones between regions with increasing and decreasing runoff trends, in complex terrain with a high spatial variability, and in snow-dominated regimes. Model estimates appeared most reliable in reproducing observed trends in annual runoff, winter runoff, and 7-day high flow. Modelled trends in runoff during the summer months, spring (for snow influenced regions) and autumn, and trends in summer low flow were more variable – both among models and in the spatial patterns of agreement between models and the observations. The use of models to display changes in these hydrological characteristics should therefore be viewed with caution due to higher uncertainty.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.5194/hess-16-2035-2012
Programmes: CEH Topics & Objectives 2009 - 2012 > Water > WA Topic 1 - Variability and Change in Water Systems > WA - 1.2 - Quantify variability and departures from natural historical variability in water quality ...
CEH Topics & Objectives 2009 - 2012 > Water > WA Topic 3 - Science for Water Management > WA - 3.2 - Assessment of available water resources in a changing world ...
CEH Topics & Objectives 2009 - 2012 > Water > WA Topic 1 - Variability and Change in Water Systems > WA - 1.4 - Management and dissemination of freshwaters data
CEH Sections: Boorman
ISSN: 1027-5606
Additional Information. Not used in RCUK Gateway to Research.: This is an open-access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
NORA Subject Terms: Meteorology and Climatology
Hydrology
Date made live: 23 Jul 2012 10:52
URI: http://nora.nerc.ac.uk/id/eprint/18843

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