A climatology of peak stream discharge in relation to rapid ablation events in the Chesapeake Basin, 1950-2009

Extreme snow ablation can greatly impact the hydroclimatology of a region; affecting streamflow, soil moisture, and groundwater supplies. Little is known, however, about the climatology of such large ablation events throughout the U.S., in addition to both the global and synoptic scale forcing mechanisms behind such events. This study seeks to fill that gap by exploring such extreme ablation events occurring in the Chesapeake watershed.

By creating a ranked database of stream discharge events for the three major rivers in this basin, the James, the Potomac and the Susquehanna, top discharge events associated with large ablation occurrences were explored to determine the synoptic forcing mechanisms behind such events. Stream discharge data were obtained through the USGS streamflow gauge sites, and were then sorted and ranked by season and by river. Ranked streamflow events were then compared to gridded snow depth data to relate the top five percent of stream discharge events to extreme ablation events in preceding days.

Atmospheric forcings leading up to, and during, identified events were further classified by air mass synoptic types, with the goal of identifying pathways by which global-scale anomalies can influence this major basin. The Chesapeake basin was used as a test-bed, from which further basin analyses can be expanded upon. Understanding the synoptic forcings leading to such extreme ablation events, as well as how such events affect the hydroclimatology of a region, will increase our ability to efficiently and effectively adapt to complex environments under future climate change.