The Role Antecedent Conditions and Large Precipitation Events Play for Major Flooding Episodes on the Prairie Pothole Region of the Dakotas/Northern Great Plains

In South Dakota's James River watershed, flooding persisted for a record-breaking 534 days straight in 2019–2020. In particular, from April 10, 2019, to September 30, 2020, the James River in Stratford, South Dakota, experienced flooding at stream gage 06472000. The James River near Stratford, South Dakota, frequently reaches flood stage; in fact, it has done so eight times since 1995. However, the duration of the flood from 2019 to 2020 is unusual.

The unique topographic features of the northern Great Plains' prairie pothole regions, the soil moisture setting, the snowpack and snowmelt conditions, rainfall events, and the release from reservoirs located north of Stratford on the James River all combined to determine how long the flood would last. As several sites north of Stratford, South Dakota have experienced a substantial rise in flooding and reservoir inflow since the early 1990s, this flooding event is not an isolated event. In addition to examining the circumstances and potential causes of these occurrences, this presentation will consider how climate change may be affecting the northern Great Plains prairie pothole regions including the flooding response to large precipitation events.