Publication Date:
2013-03-05
Description:
The flood seasonality of catchments in Switzerland is likely to change under climate change due to anticipated alterations of precipitation as well as snow accumulation and melt. Information on this change is crucial for flood protection policies, for example, or regional flood frequency analysis. We analysed projected changes in mean annual and maximum floods of a 22 yr period for 189 catchments in Switzerland and two scenario periods in the 21st century based on an ensemble of climate scenarios. The flood seasonality was analysed with directional statistics that allow assessing both changes in the mean date a flood occurs as well as changes in the strength of the seasonality. We found that the simulated change in flood seasonality is a function of the change in flow regime type. If snow accumulation and melt is important in a catchment during the control period, then the anticipated change in flood seasonality is most pronounced. Decreasing summer precipitation in the scenarios additionally affects the flood seasonality (mean date of flood occurrence) and leads to a decreasing strength of seasonality, i.e. a higher temporal variability in most cases. The magnitudes of mean annual floods and more clearly of maximum floods (in a 22 yr period) are expected to increase in the future, due to changes in flood generating processes and scaled extreme precipitation. Southern alpine catchments show a different signal, though: The simulated mean annual floods decrease in the far future, i.e. at the end of the 21st century. Copyright © 2013 John Wiley & Sons, Ltd.
Print ISSN:
0885-6087
Electronic ISSN:
1099-1085
Topics:
Architecture, Civil Engineering, Surveying
,
Geography
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