This article discusses how multiple environmental factors often interact to amplify the effects of severe storms, droughts, and other extreme water-related events.
Last year, a combination of unprecedented local rainfall intensities and storm surges from Hurricanes Harvey, Irma, and Maria flooded Houston, large parts of Florida, and numerous island nations in the Caribbean. Such hydrologic compound events—when the combination of two or more hazard events or climate variables leads to an extreme impact—have a multiplier effect on the risk to society, the environment, and infrastructure [Zscheischler et al., 2018].
Hydrologic extremes, such as floods and droughts, are among the world’s most dangerous and costly natural hazards. Between 1980 and 2013, flood losses tallied more than $1 trillion and caused more than 220,000 recorded fatalities globally. In 2017 alone, major flood disasters in the United States, Caribbean, and Southeast Asia killed more than 1,000 people, caused damages on the order of hundreds of billions of U.S. dollars, and harmed or destroyed the livelihoods of millions of people.