1 research outputs found
Characteristics and process controls of statistical flood moments in Europe - a data based analysis
Many recent studies have sought to characterize
variations of the annual maximum flood discharge series over
time and across space in Europe, including some that have
elucidated different process controls on different statistical
properties of these series. To further support these studies,
we conduct a pan-European assessment of process controls
on key properties of this series, including the mean annual
flood (MAF) and coefficients of variation (CV) and skewness (CS) of flood discharges. These annual maximum flood
discharge series consist of instantaneous peaks and daily
means observed in 2370 catchments in Europe without strong
human modifications covering the period 1960–2010. We explore how the estimated moments MAF, CV and CS vary due
to catchment size, climate and other controls across Europe,
where their averages are 0.17 m3
s
−1 km−2
, 0.52 and 1.28,
respectively.
The results indicate that MAF is largest along the Atlantic
coast, in the high-rainfall areas of the Mediterranean coast
and in mountainous regions, while it is smallest in the sheltered parts of the East European Plain. The CV is largest in
southern and eastern Europe, while it is smallest in the regions subject to strong Atlantic influence. The pattern of the
CS is similar, albeit more erratic, in line with the greater sampling variability of CS. In the Mediterranean, MAF, CV and
CS decrease strongly with catchment area, suggesting that
floods in small catchments are relatively very large, while in
eastern Europe this dependence is much weaker, mainly due
to more synchronized timing of snowmelt over large areas.
The process controls on the flood moments in five predetermined hydroclimatic regions are identified through correlation and multiple linear regression analyses with a range
of covariates, and the interpretation is aided by a seasonality analysis. Precipitation-related covariates are found to be
the main controls of the spatial patterns of MAF in most of
Europe except for regions in which snowmelt contributes to
MAF, where air temperature is more important. The Aridity Index is, by far, the most important control on the spatial
pattern of CV in all of Europe. Overall, the findings suggest
that, at the continental scale, climate variables dominate over
land surface characteristics, such as land use and soil type, in
controlling the spatial patterns of flood moments.
Finally, to provide a performance baseline for more local
studies, we assess the estimation accuracy of regional multiple linear regression models for estimating flood moments in
ungauged basin