On the Variability of Flood Attributes and Damages at the Global Scale

Thursday, December 12, 2019 - 17:15
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We analyzed the frequency and duration of floods obtained from the Dartmouth Flood Observatory (DFO) at the global flood scale to explore evidence of trends during 1985-present at global and latitudinal scales. Three classes of flood duration (i.e., short: 1-7, moderate: 8-20, and long: 21 days and above) are also considered for this analysis. The non-parametric Mann-Kendall trend analysis is used to evaluate three hypotheses addressing potential monotonic trends in the frequency of flood, moments of the duration, and the frequency of specific flood duration types. We also evaluated if trends could be related to large-scale atmospheric teleconnections using a Generalized Linear Model framework. Results show that flood frequency and the tails of the flood duration (long duration) have increased both at the global and the latitudinal scales. However, much of the trend in frequency and duration of the floods can be placed within the long-term climate variability context since Atlantic Multidecadal Oscillation, North Atlantic Oscillation, and Pacific Decadal Oscillation were the main atmospheric teleconnections explaining this trend. There is a significant increasing trend in the annual median of flood durations globally and each latitudinal belt, and this trend is not related to these teleconnections. We also present the scaling of flood damages using duration of floods for each country. This study provides insights for understanding the frequency and persistence in hydrologic extremes and how they relate to changes in the climate, organization of global and local dynamical systems and country scale socioeconomic factors.

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