Abstract
Abstract. An understanding of multi-annual behaviour in streamflow allows for better
estimation of the risks associated with hydrological extremes. This can
enable improved preparedness for streamflow-dependant services, such as
freshwater ecology, drinking water supply and agriculture. Recently, efforts have focused on detecting relationships between long-term hydrological behaviour and oscillatory climate systems (such as the North Atlantic Oscillation – NAO). For instance,
the approximate 7 year periodicity of the NAO has been detected in
groundwater-level records in the North Atlantic region, providing potential
improvements to the preparedness for future water resource extremes due to
their repetitive, periodic nature. However, the extent to which these 7-year, NAO-like signals are propagated to streamflow, and the catchment processes
that modulate this propagation, are currently unknown. Here, we show
statistically significant evidence that these 7-year periodicities are
present in streamflow (and associated catchment rainfall), by applying
multi-resolution analysis to a large data set of streamflow and associated
catchment rainfall across the UK. Our results provide new evidence for
spatial patterns of NAO periodicities in UK rainfall, with areas of greatest
NAO signal found in southwest England, south Wales, Northern Ireland and
central Scotland, and show that NAO-like periodicities account for a greater
proportion of streamflow variability in these areas. Furthermore, we find
that catchments with greater subsurface pathway contribution, as
characterised by the baseflow index (BFI), generally show increased NAO-like signal strength and that subsurface response times (as characterised by
groundwater response time – GRT), of between 4 and 8 years, show a greater
signal presence. Our results provide a foundation of understanding for
the screening and use of streamflow teleconnections for improving the
practice and policy of long-term streamflow resource management.
Subject
General Earth and Planetary Sciences,General Engineering,General Environmental Science
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