Biosystems and Ag. Engineering Bldg, room 225 and via Zoom
Abstract
Relationships between intense rain, antecedent moisture and flooding trends in Minnesota watersheds since 1950.
Recent flooding research has revealed antecedent moisture conditions (AMCs) preceding intense rain events are important drivers of resulting flood severity. Part 1 of the study looked for trends in intense rain events, AMCs and predicted runoff at 132 precipitation stations in Minnesota from 1950-2021. Of Minnesota watersheds, the Cottonwood River watershed (CRW) showed the highest increases in intense rain, AMCs and predicted runoff, corresponding with observed flooding increases there since 1990. Part 2 looked at the CRW’s rainfall and flow history across 660 delineated flow events, and partitioned the respective roles intense rain and AMC trends played in recent flooding. The analysis suggests that CRW flooding increases were primarily driven by increases in intense rain events (>75mm/day), with wetter AMCs playing a lesser role.