Last updated August 17, 2017

Increased Flooding Risk

Heavy precipitation is contributing to increased flooding around the world. Flooding is worsened by regional climate trends such as increases in heavy rain and snow, early snowmelt, and increased seasonal precipitation. Flooding is also affected by non-climatic factors such as land development, deforestation, levee placement and local topography, making it challenging to determine an overarching climate signal in flood trends.

US trends

Streamflow levels are increasing alongside the increased frequency of heavy precipitation events across most of the US. In the largest rivers of the US, including the Ohio, Missouri, and Mississippi, the number of days with high stream flow (the top 25 percent of readings) has risen over the past 30 years (1987-2016).[1]