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Have trends changed over time? A study of UK peak flow data and sensitivity to observation period

Griffin, Adam; Vesuviano, Gianni; Stewart, Lisa. 2019 Have trends changed over time? A study of UK peak flow data and sensitivity to observation period. Natural Hazards and Earth System Sciences Discussions. https://doi.org/10.5194/nhess-2019-107

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Abstract/Summary

Classical statistical methods for flood frequency estimation assume stationarity in the gauged data. However, recent focus on climate change and, within UK hydrology, severe floods in 2009 and 2015 have raised the profile of statistical analyses that include trends. This paper considers how parameter estimates for the Generalised Logistic distribution (standard for UK annual maximum flows) vary through time, using the UK Benchmark Network (UKBN2) to separate the effects of land-use change from climate change. We focus on the sensitivity of parameter estimates to adding data, through fixed-width moving window and fixed-start extending window approaches, and on whether parameter trends are more prominent in specific geographical regions. Under stationary assumptions, the addition of new data tends to further the convergence of parameters to some “final” value. However, addition of a single new data point can vastly change non-stationary parameter estimates. Little spatial correlation is seen in the magnitude of trends in peak flow data, potentially due to the spatial clustering of catchments in the UKBN2. In many places, the ratio between the 50-year and 100-year flood is decreasing, whereas the ratio between the 2-year and 30-year flood is increasing, presenting as a “flattening” of the flood frequency curve.

Item Type: Publication - Article
Digital Object Identifier (DOI): https://doi.org/10.5194/nhess-2019-107
CEH Sections/Science Areas: Hydro-climate Risks (Science Area 2017-)
ISSN: 1561-8633
Additional Information. Not used in RCUK Gateway to Research.: Open access paper - full text available via Official URL link.
NORA Subject Terms: Hydrology
Mathematics
Date made live: 17 Apr 2019 13:35 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/522762

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