Climate Variability and Change—Hydrological Impacts (Proceedings of the Fifth FRIEND World
Conference held at Havana, Cuba, November 2006), IAHS Publ. 308, 2006, 496–501.
High and low flow trends in a national network of undisturbed
indicator catchments in the UK
JAMIE HANNAFORD & TERRY J. MARSH
Centre for Ecology and Hydrology, Wallingford, Oxfordshire OX10 8BB,
UK
jaha@ceh.ac.uk
Abstract This paper presents the
results of trend analyses applied to indicators of high and low flows in a
network of undisturbed catchments in the UK, over the 1970–2004 period.
Significant positive trends in high flows were identified across northern and
western areas; these increases are associated with changing atmospheric
circulation patterns associated with the North Atlantic Oscillation (NAO), and
may reflect the impact of multi-decadal oscillations rather than climatic
change. There was no compelling evidence for any pronounced decrease in low
flows, despite the clustering of droughts in recent years. The recent trends
are compared to several longer (>60 year) hydrometric records which show
pronounced temporal fluctuations, but there is little evidence of long-term
trend.
Key words flood(s);
high flows; low flows; Mann-Kendall test; natural catchments; North Atlantic
Oscillation; trends; UK