SWS May 2025 Webinar: Long-term resilience of Surface Height on Floodplains

Floodplains associated with altered rivers and streams of the central United States are often subjected to surface height loss over decades of time as channels down-cut. In southern Illinois, ground heights on floodplains without bedrock control fell by 0.2 to 0.9 cm per year over the last twenty years. These falling surface heights on floodplains are partly due to the downcutting of altered river channels, which further increases the unit stream power for the transport of sediment and water over the floodplain toward the incising channel. Overall, on floodplain wetlands, ground surfaces gain or lose height over time depending on the balance of processes between plant production and decomposition, and sediment deposition and erosion. Actions to slow channel incision could help to reduce surface height loss and maintain higher levels of surface accretion. The challenge for managers is to develop strategies to reduce impacts on developed infrastructure by limiting channel downcutting through channel restoration, supporting natural vegetation processes, and promoting the resilience of surface elevation, infrastructure, and roadways.

Baldcypress swamps, Texas arroyos, worldwide monsoonal wetlands