The changing nature of flooding across the central United States

In the twentieth and twenty-first centuries, flooding has taken a devastating societal and economic toll on the central United States, contributing to dozens of fatalities and causing billions of dollars in damage(1,2). As a warmer atmosphere can hold more moisture (the Clausius-Clapeyron relation), a pronounced increase in intense rainfall events is included in models of future climate(3). Therefore, it is crucial to examine whether the magnitude and/or frequency of flood events is remaining constant or has been changing over recent decades. If either or both of these attributes have changed over time, it is imperative that we understand the underlying mechanisms that are responsible. Here, we show that while observational records (774 stream gauge stations) from the central United States present limited evidence of significant changes in the magnitude of floodpeaks, strong evidence points to an increasing frequency of flooding. These changes in flood hydrology result from changes in both seasonal rainfall and temperature across this region.