The influence of decadal-scale variability on trends in long European streamflow records

Hannaford, J. ORCID: https://orcid.org/0000-0002-5256-3310; Buys, G.; Stahl, K.; Tallaksen, L.M.. 2013 The influence of decadal-scale variability on trends in long European streamflow records. Hydrology and Earth System Sciences, 17 (7). 2717-2733. https://doi.org/10.5194/hess-17-2717-2013

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Abstract/Summary

This study seeks to provide a long-term context for the growing number of trend analyses which have been applied to river flows in Europe. Most studies apply trend tests to fixed periods, in relatively short (generally 1960s–present) records. This study adopts an alternative "multi-temporal" approach, whereby trends are fitted to every possible combination of start and end years in a record. The method is applied to 132 catchments with long (1932–2004) hydrometric records from northern and central Europe, which were chosen as they are minimally anthropogenically influenced and have good quality data. The catchments are first clustered into five regions, which are broadly homogenous in terms of interdecadal variability of annual mean flow. The multi-temporal trend approach was then applied to regional time series of different hydrological indicators (annual, monthly and high and low flows). The results reveal that the magnitude and even direction of short-term trends are heavily influenced by interdecadal variability. Some short-term trends revealed in previous studies are shown to be unrepresentative of long-term change. For example, previous studies have identified post-1960 river flow decreases in southern and eastern Europe: in parts of eastern Europe, these trends are resilient to study period, extending back to the 1930s; in southern France, longer records show evidence of positive trends which reverse from the 1960s. Recent (post-1960) positive trends in northern Europe are also not present in longer records, due to decadal variations influenced by the North Atlantic Oscillation. The results provide a long-term reference for comparison with published and future studies. The multi-temporal approach advocated here is recommended for use in future trend assessments, to help contextualise short-term trends. Future work should also attempt to explain the decadal-scale variations that drive short-term trends, and thus develop more sophisticated methods for trend detection that take account of interdecadal variability and its drivers.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.5194/hess-17-2717-2013
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 ...
UKCEH and CEH Sections/Science Areas:	Billett (to November 2013) Boorman (to September 2014)
ISSN:	1027-5606
Additional Information. Not used in RCUK Gateway to Research.:	Open Access paper - Official URL provides full text
NORA Subject Terms:	Hydrology Meteorology and Climatology
Related URLs:	Discussion paper
Date made live:	11 Sep 2013 14:27 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/503096

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