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Jamie Hannaford  - - - 
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Terry Marsh

49 shared publications

Centre for Ecology and Hydrology, Wallingford, OX10 8BB, UK

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Publication Record
Distribution of Articles published per year 
(2006 - 2015)
Total number of journals
published in
 
3
 
Publications
Article 0 Reads 14 Citations Climate-driven changes in UK river flows: A review of the evidence J. Hannaford Published: 01 February 2015
Progress in Physical Geography: Earth and Environment, doi: 10.1177/0309133314536755
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There is a burgeoning international literature on hydro-climatic trend detection, motivated by the need to detect and interpret any emerging changes in river flows associated with anthropogenic climate change. The UK has a particularly strong evidence base in this area thanks to a well-developed monitoring programme and a wealth of studies published over the last 20 years. This paper reviews this research, with a view to assessing the evidence for climate change influences on UK river flow, including floods and droughts. This assessment is of international relevance given the scale of the research effort in the UK, a densely monitored and data-rich environment, but one with significant human disturbances to river flow regimes, as in many parts of the world. The review finds that changes can be detected in river flow regimes, some of which agree with future change projections, while others are in apparent contradiction. Observed changes generally cannot be attributed to climate change, largely due to the fact that river flow records are limited in length and the identification of short-term trends is confounded by natural variability. A UK ‘Benchmark’ network of near-natural catchments is an internationally significant example of an initiative to enable climate variability to be discerned from direct human disturbances (e.g. abstractions, dam construction). Generally, however, the problem of attribution has been tackled rather indirectly in the UK, as elsewhere, and more efforts are required to attribute change in a more rigorous manner.
Article 1 Read 12 Citations An appraisal of the performance of data-infilling methods for application to daily mean river flow records in the UK Catherine L. Harvey, Harry Dixon, Jamie Hannaford Published: 01 July 2012
Hydrology Research, doi: 10.2166/nh.2012.110
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River flow records are fundamental for the sustainable management of water resources and even very short gaps can severely compromise their utility. Suitably-flagged flow estimates, derived via judicious infilling, are potentially highly beneficial to data users. The UK National River Flow Archive provides stewardship of, and access to, UK river flow records. While many datasets held on the archive are complete, gaps remain across a wide range of flow records. A comprehensive assessment of existing techniques for infilling these gaps is currently lacking. This paper therefore assesses 15 simple infilling techniques (including regression, scaling and equipercentile approaches), each relying upon data transfer from hydrologically-similar donor stations, to generate estimates of flow at 26 representative gauging stations. Results reveal the overall superiority of equipercentile and multiple regression techniques compared to the poorer capability of catchment area scaling. Donor station choice has a strong influence on technique performance. Modifying datasets to improve homogeneity, by seasonally grouping flows or excluding certain periods, offers improved performance. These findings provide a foundation upon which guidance on infilling river flow records can be based in future, allowing hydrometric practitioners and data end-users alike to adopt a consistent and auditable approach towards infilling.
Article 0 Reads 28 Citations An assessment of trends in UK runoff and low flows using a network of undisturbed catchments Jamie Hannaford, Terry Marsh Published: 01 January 2006
International Journal of Climatology, doi: 10.1002/joc.1303
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In many parts of the world attempts to discern climatic‐driven changes in river flow patterns are hindered by the combined impact of other, more direct anthropogenic disturbances such as ion and impoundments. This study capitalises on a newly defined ‘benchmark’ network of natural catchments in the UK to discern natural variability in flow regimes. Trend tests were applied to time series of runoff and indicators of low‐flow magnitude and duration for two study periods to assess the sensitivity of trends to the frame of reference over which tests were conducted. Notwithstanding the volatility of the recent past, the results demonstrate a general stability in runoff and low flows since the early 1960s. The strongest signal to emerge from the study is a positive runoff trend for catchments in Scotland, which was resilient to the effect of the study periods. There was also some indication of increasing runoff in maritime western areas of England and Wales. These increases in maritime areas are likely to reflect the dominance of westerly airflows in the recent past, associated with an increase in the North Atlantic Oscillation (NAO) Index. For low flows, there were no compelling trends—significant positive trends over the 1973–2002 period are influenced by a sequence of notably dry years at the start of the period and were not observed over a 40‐year time‐frame. There are some indications of a tendency towards decreasing low flows in some eastern catchments, but this is supported by few significant results. The results of this study provide a baseline against which to assess longer‐term change from historical flow time series and to monitor future change in the benchmark network. Copyright © 2006 Royal Meteorological Society