01 July 2019

Recent trends in the frequency and duration of global floods

The Atlantic Multidecadal Oscillation, North Atlantic Oscillation, and Pacific Decadal Oscillation were the main atmospheric teleconnections explaining the trend in frequency and duration of the global floods.

Science

This comprehensive study is the very first global study of actual flood events, which identifies temporal changes in the frequencies, and characteristics of probability distribution of flood durations to understand the changing organization of the local to global dynamical systems. Using the global active archive of flood events (with 31 years of data from 1985 to 2015), we addressed the following questions in a hypothesis-testing framework. (1) How has the annual frequency of floods changed at the global scale and various latitudinal belts during the last three decades? (2) How has the probability distribution of flood duration (represented by the moments and extreme values) changed at the global scale and various latitudinal belts during the last 3 decades? (3) Are the changes (if any) in the flood frequency and the probability distribution of flood durations due to the changes in a specific flood class, i.e., short, moderate, or long duration? (4) Can the changes (if any) in the flood frequency and the probability distribution of flood durations be related to the variability in the atmospheric teleconnections and low-frequency climate oscillations? (5) Which countries are most vulnerable to short-moderate-, and long-duration floods?

Impact

Our analysis and vulnerability profile for different countries can be helpful to inform and improve the flood warning systems tailored to the various types and resource management practices during the post-disaster responses. Furthermore, with increasing globalization, countries are now interdependent through supply chain networks to achieve streamlined production and overall cost reductions. A country-level understanding of the exposure to different types of floods can help more accurately predict the vulnerable nodes that might cause a systemic network failure. It can also provide the necessary analysis for pricing and portfolio risk management for the agencies that ensure and hedge against the flood losses.

Summary

A global assessment of flood events using the Dartmouth Flood Observatory (DFO) database is performed here to explore the planetary nature of the frequency and duration of floods (short, moderate, and long). This comprehensive study is the very first global study of “actual flood events” which identifies temporal changes in frequencies and characteristics of probability distribution of flood durations to understand the changing organization of the local to global dynamical systems. We also presented a simple overview of the vulnerability profile for different countries using the damages database.

Contact
Naresh Devineni
City University of New York (City College)
Publications
Najibi, N, and N Devineni.  2018.  "Recent Trends in the Frequency and Duration of Global Floods."  Earth System Dynamics 9(2): 757-783.  https://doi.org/10.5194/esd-9-757-2018.