Variability of seasonal floods in the Upper Danube River basin

Abstract

Abstract:The objective of this study is to analyse the spatial variability of seasonal flood occurrences in the Upper Danube region for the period 1961-2010. The analysis focuses on the understanding of the factors that control the spatial variability of winter and summer floods in 88 basins with different physiographic conditions. The evaluation is based on circular statistics, which compare the changes in the mean date and in the seasonal flood concentration index within a year or predefined season.The results indicate that summer half-year and winter half-year floods are dominant in the Alps and northern Danube tributaries, respectively. A comparison of the relative magnitude of flood events indicates that summer half-year floods are on average more than 50% larger than floods in winter. The evaluation of flood occurrence showed that the values of seasonal flood concentration index (median 0.75) in comparison to the annual floods (median 0.58) shows higher temporal concentration of floods. The flood seasonality of winter events is dominant in the Alps; however, along the northern fringe (i.e. the Isar, Iller and Inn River) the timing of winter half-year floods is diverse. The seasonal concentration of summer floods tends to increase with increasing mean elevation of the basins. The occurrence of the three largest summer floods is more stable, i.e. they tend to occur around the same time for the majority of analysed basins. The results show that fixing the summer and winter seasons to specific months does not always allow a clear distinction of the main flood generation processes. Therefore, criteria to define flood typologies that are more robust are needed for regions such as the Upper Danube, with large climate and topographical variability between the lowland and high elevations, particularly for the assessment of the effect of increasing air temperature on snowmelt runoff and associated floods.

Using High-Density LiDAR Data and 2D Streamflow Hydraulic Modeling to Improve Urban Flood Hazard Maps: A HEC-RAS Multi-Scenario Approach

“…In the last decades, with climate change and global warming, the associated natural disasters have reached more disastrous and catastrophic scales [1][2][3][4][5][6]. Many natural disaster patterns have diversified and modified under the pressure of climate change [7][8][9].…”

Spatial Patterns and Characteristics of Flood Seasonality in Europe

“…Second, most of the previous studies on flood seasonality focused on the mean date of the AMF occurrence and/or the temporal concentration of the floods around their mean date (e.g. Parajka et al (2009) or Jeneiová et al (2016) for both Austria and Slovakia), while the detailed characteristics of monthly flood seasonality distributions has rarely been studied in Europe. However, if unimodal, bimodal or skewed seasonality distributions exist, the 20 mean date of the AMF can be misleading and mask important insights into the flood generating mechanisms (Ye et al, 2017).…”

Detection of trends in magnitude and frequency of flood peaks across Europe

“…Examples of recent studies include but are not limited to: Hannaford and Buys (2012) for the UK, Murphy et al (2013) for Ireland, Giuntoli et al (2012) in France, Arheimer and Lindström (2015) in Sweden, Blöschl et al (2011) and Jeneiová et al (2016) in Austria, Brázdil et al (2006Brázdil et al ( , 2012, Kundzewicz et al (2013) and Pekárová et al (2016) in Central Europe, and Bard et al (2012) for the Alpine mountain region. Such analyses provide insight into regional patterns of flood changes within selected catchment, national or regional boundaries.…”