More frequent flooding? Changes in flood frequency in Switzerland since 1850

Schmocker-Fackel, Petra; Naef, Félix

doi:10.1016/j.jhydrol.2009.09.022

Cited by 121 publications

(74 citation statements)

References 23 publications

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“…Changes in river flood regimes are traditionally analyzed using statistical approaches and observed data (e.g., Lindström and Alexandersson, 2004;Stahl et al, 2010;Schmocker-Fackel and Naef, 2010) or process-based numerical modeling and a scenario approach (e.g., Dankers and Feyen, 2008;Arheimer et al, 2012;Bergström et al, 2012). Both these strategies have potential advantages but also many challenges, as discussed by Hall et al (2014).…”

Section: Introductionmentioning

confidence: 99%

Climate impact on floods: changes in high flows in Sweden in the past and the future (1911–2100)

Arheimer

Lindström

2015

Hydrol. Earth Syst. Sci.

132

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Abstract. There is an ongoing discussion whether floods occur more frequently today than in the past, and whether they will increase in number and magnitude in the future. To explore this issue in Sweden, we merged observed time series for the past century from 69 gauging sites throughout the country (450 000 km 2 ) with high-resolution dynamic model projections of the upcoming century. The results show that the changes in annual maximum daily flows in Sweden oscillate between dry and wet periods but exhibit no significant trend over the past 100 years. Temperature was found to be the strongest climate driver of changes in river high flows, which are related primarily to snowmelt in Sweden. Annual daily high flows may decrease by on average −1 % per decade in the future, mainly due to lower peaks from snowmelt in the spring (−2 % per decade) as a result of higher temperatures and a shorter snow season. In contrast, autumn flows may increase by +3 % per decade due to more intense rainfall. This indicates a shift in floodgenerating processes in the future, with greater influence of rain-fed floods. Changes in climate may have a more significant impact on some specific rivers than on the average for the whole country. Our results suggest that the temporal pattern in future daily high flow in some catchments will shift in time, with spring floods in the northern-central part of Sweden occurring about 1 month earlier than today. High flows in the southern part of the country may become more frequent. Moreover, the current boundary between snow-driven floods in northern-central Sweden and rain-driven floods in the south may move toward higher latitudes due to less snow accumulation in the south and at low altitudes. The findings also indicate a tendency in observations toward the modeled projections for timing of daily high flows over the last 25 years. Uncertainties related to both the observed data and the complex model chain of climate impact assessments in hydrology are discussed.

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Section: Introductionmentioning

confidence: 99%

Climate impact on floods: changes in high flows in Sweden in the past and the future (1911–2100)

Arheimer

Lindström

2015

Hydrol. Earth Syst. Sci.

132

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“…This is primarily because, in comparison with North America where many catchments can justifiably be called "pristine", a true natural network is much more difficult to establish in Europe due to the higher population density, an associated lack of natural landscape and a long history of water infrastructure development. However, the large number of trend studies that have been carried out on regional or national scales testifies to the usefulness of at least parts of the national networks including, for example, France (Renard et al, 2008), southern Germany (KLIWA, 2003, Switzerland (Birsan et al, 2005;Schmocker-Fackel et al, 2010), Slovakia (Majercakova et al, 1997;Skoda, 2005, 2009), the Czech Republic (Fiala, 2008;Fiala et al, 2010) and Spain (Beguería et al, 2003;Morán-Tejeda et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Streamflow trends in Europe: evidence from a dataset of near-natural catchments

Stahl

Hisdal

Hannaford

et al. 2010

Hydrol. Earth Syst. Sci.

407

295

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Abstract. Streamflow observations from near-natural catchments are of paramount importance for detection and attribution studies, evaluation of large-scale model simulations, and assessment of water management, adaptation and policy options. This study investigates streamflow trends in a newly-assembled, consolidated dataset of near-natural streamflow records from 441 small catchments in 15 countries across Europe. The period 1962The period -2004 provided the best spatial coverage, but analyses were also carried out for longer time periods (with fewer stations), starting in 1932, 1942 and 1952. Trends were calculated by the slopes of the Kendall-Theil robust line for standardized annual and monthly streamflow, as well as for summer low flow magnitude and timing. A regionally coherent picture of annual streamflow trends emerged, with negative trends in southern and eastern regions, and generally positive trends elsewhere. Trends in monthly streamflow for 1962-2004 elucidated potential causes for these changes, as well as for changes in hydrological regimes across Europe. Positive trends were found in the winter months in most catchments. A marked shift towards negative trends was observed in April, gradually spreading across Europe to reach a maximum extentCorrespondence to: K. Stahl (kerstin.stahl@hydrology.uni-freiburg.de) in August. Low flows have decreased in most regions where the lowest mean monthly flow occurs in summer, but vary for catchments which have flow minima in winter and secondary low flows in summer. The study largely confirms findings from national and regional scale trend analyses, but clearly adds to these by confirming that these tendencies are part of coherent patterns of change, which cover a much larger region. The broad, continental-scale patterns of change are mostly congruent with the hydrological responses expected from future climatic changes, as projected by climate models. The patterns observed could hence provide a valuable benchmark for a number of different studies and model simulations.

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“…Therefore, the question arises whether the Swiss authorities have to adjust the procedure for determining design floods in Switzerland, too (KOHS, 2007;Schädler et al, 2007). Or is the increasing frequency of flood events in the last decades just a small sample of a longer series, where periods with few and frequent floods alternate as an analysis by Schmocker-Fackel and Naef (2010) suggests? How will our hydrological systems change in general, if the climate system changes significantly?…”

Section: Introductionmentioning

confidence: 99%

How does climate change affect mesoscale catchments in Switzerland? – a framework for a comprehensive assessment

et al. 2010

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Abstract. Within the framework of this study we identify mesoscale catchments in Switzerland that exhibit sensitivity towards a change in climate with a focus on alterations of the water balance and peak flow conditions. For this study, the hydrological modelling system PREVAH is used, which is a semi-distributed and conceptual yet process-oriented model forced with hourly meteorological input on basis of a spatial resolution of 500×500 m 2 . We calibrate the model where measured discharge records are available and transfer the calibrated model parameters to ungauged catchments through regionalisation, to arrive at a comprehensive set of model parameters for the entire area of Switzerland. To assess future changes, we apply an extensive set of 16 Regional Climate Models (RCMs) to the catchments. The RCM data are downscaled to a dense network of meteorological stations for the period from 2021 to 2050 using the Delta Change Approach. This downscaling method incorporates a bias correction of the RCM output and provides change rates and values for precipitation and temperature.In the present paper we describe the application of a calibration and regionalisation procedure developed previously for Northern Alpine catchments to Southern catchments. The necessity to differentiate between a Northern and a Southern Alpine region, with their distinct climatologic and physiogeographic features, has proved true as the calibrated parameter sets show systematic differences between those regions, e.g. for the runoff forming parameters percolation rate (PERC) or storage time for quick runoff (KOH). For the Southern Alpine area, we calibrated two thirds of the available catchments, i.e. 23 out of 36, successfully for standard and flood conditions according to a combined model score of a linear and logarithmic Nash-Sutcliffe-Efficiency (NSE, NSE ln ) and a mean annual volumetric deviation (VD a ). TheCorrespondence to: N. Köplin (nina.koeplin@giub.unibe.ch) rate of successfully calibrated catchments is rather small in comparison with the results for the Northern Alpine catchments, where 140 out of 159 calibrations have been successful, and the distribution of the Southern catchments is more irregular. However, as the median NSE and NSE ln as well as the range of VD a show an overall good model fit, a successful regionalisation may be expected. Next steps are the regionalisation of the Southern Alpine model parameters and the application of climate scenarios to the complete set of catchments, i.e. about 200 Swiss mesoscale catchments with an average area of 150 km 2 . Thus we can identify process-based relationships between climate sensitivity and catchment characteristics and provide quantitative information on future water balance and peak flow conditions of Swiss mesoscale catchments.

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More frequent flooding? Changes in flood frequency in Switzerland since 1850

Cited by 121 publications

References 23 publications

Climate impact on floods: changes in high flows in Sweden in the past and the future (1911–2100)

Climate impact on floods: changes in high flows in Sweden in the past and the future (1911–2100)

Streamflow trends in Europe: evidence from a dataset of near-natural catchments

How does climate change affect mesoscale catchments in Switzerland? – a framework for a comprehensive assessment

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