Study: mild floods are declining, but intense floods are on the rise | John Abraham

Milder floods that refill reservoirs are decreasing as severe floods become more commonIt is well known that humans are causing the Earth to warm. We also know that a warmer atmosphere has more water vapor. Just like the air is more humid when it is warm, and less humid when cold. The more humid air leads to more intense precipitation and potentially more flooding. But how much change we will see is an open scientific question.This question is made complex by the fact that flooding isn’t just about rain. It reflects a dependence on evaporation, rain, the ability of land and water management to handle water surges, and other factors. Fortunately, a very recent study out of Science Advances has helped advance our understanding of the confluence of global warming, intense rain and flooding. if the catchment or region capturing the precipitation is smaller, but the precipitation event intensity remains the same, the potential for losses is less. In large catchments, the peak streamflow is more likely to be influenced by the catchment wetness conditions preceding the storm event. What this study does is to show, using just data and no model projections, that flood risk is indeed increasing but at the rare to very-rare flood end. The milder floods that are more of a nuisance than a threat to property and lives, are actually decreasing. This is worse news than before though, as it is these milder floods that make up the bulk of the refill to our water supply reservoirs. Continue reading...