Projected Changes in Peak Discharge Across the Continental United States

The understanding of the physical drivers responsible for extreme flooding can provide basic information for water resources management and mitigation of damages and fatalities caused by these events. Here, we focus on thousands of long-term streamgages across the continental United States and develop a statistical framework to attribute the year-to-year changes in seasonal and annual maximum daily discharge. We find that simple models in which basin-averaged precipitation and temperature are used as predictors can describe well the changes in flood extremes. Moreover, we use the insights gained from the analysis of the historical records to assess what the projected changes in discharge during the 21st century could be. We find that flood peaks are projected to increase (decrease) significantly in wetter (drier) areas of the contiguous United States. This is true even when flood changes are not detected in the more recent decades, highlighting the current needs for incorporating climate change in the future infrastructure designs and management of the water resources.