A Framework for Exploring Joint Effects of Conditional Factors on Compound Floods Water Resources Research

This study highlights the features of vine copula for examining compound events involving underlying conditions that amply the compounding effects. To illustrate, we study compound floods inTexas (TX), USA. These compound floods consist of combinations of precipitation and surface runoff with the El Ni ~no-Southern Oscillation (ENSO) and rising temperatures as underlying conditions. Although the individual variable of precipitation and runoff may not itself be extreme, large exceedances can lead toflooding situations when combined. The presence of underlying conditions (e.g., El Ni ~no and/or rising temperatures) can exacerbate the associated flood impacts. We use observational data during May–August for each climate division of TX. A three-dimensional vine copula is used first to quantify the ENSO effect onprecipitation and runoff through conditioning sets of vine copula. We further examine the interplay of a warming signal and El Ni ~no to reveal their mutual effects on compound floods by placing these two factors