Complex picture for likelihood of ENSO-driven flood hazard

Area of Science:

• Climatology
• Hydrology
• Environmental Science

Background:

• El Niño and La Niña events, representing extremes of ENSO climate variability, have a global influence on river flow and flooding.
• Estimating historical precipitation probabilities aids in assessing risks during extreme ENSO events.
• The nonlinear relationship between precipitation and flood magnitude necessitates hydrological data analysis for accurate probability estimation.

Purpose of the Study:

• To estimate historical flood probabilities using hydrological data analysis.
• To investigate the complexity of flood hazard likelihood during ENSO events.
• To compare hydrological analysis findings with precipitation-based estimates.

Main Methods:

• Utilized the ERA-20CM-R river flow reconstruction dataset for the twentieth century.
• Analyzed hydrological data to estimate historical probabilities of extreme river flow.
• Compared results with precipitation data to identify discrepancies.

Main Results:

• The likelihood of altered flood hazard during ENSO events is more complex than commonly understood.
• Flood risk probabilities exhibit significant global variation.
• Substantial uncertainties exist within the data, and hydrological analysis shows clear differences compared to precipitation data.

Conclusions:

• Hydrological analysis provides a more nuanced understanding of ENSO's impact on global flood hazards.
• Precipitation-based assessments may oversimplify or misrepresent flood risks during ENSO.
• Further research is needed to address data uncertainties and refine ENSO-flood risk models.