Suchergebnisse

Abstract. 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 has raised
the profile of statistical analyses that include trends. This paper considers how parameter estimates for the generalised logistic
distribution vary through time in the UK. The UK Benchmark Network (UKBN2)
is used to allow focus on climate change separate from the effects of
land-use 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 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.