Understanding of extreme snow melt runoff events: a case study of the Chesapeake Basin

Snow ablation events in the Chesapeake region directly affect streamflow in the basin; changes in flow can lead to severe flooding if not planned for adequately. Motivated by recent trends in Northern Hemisphere spring snow cover, we explore the potential for more intense, earlier snowmelts, and the impact of such events of the hydroclimatology of the Chesapeake Basin, a region encompassing some 165,759 kmē. This study investigates the processes that lead to rapid ablation events in this region, with the eventual goal of exploring how the frequency of such events might change under future climate scenarios. This knowledge will allow forecasters and water resource managers the ability to predict large melts, and allow communities to prepare for the potential flooding. Gridded daily snow depth data at 1° X 1° spatial resolution from 1950-2009 was used for this analysis. Ablation events were identified using streamflow data from major tributaries of the Chesapeake, using a discharge rate greater than 4247m³s⁻1 corresponding to a 3 cm change in depth. Three types of ablation events were identified: snow ablation only, rain on snow, and ablation to rain. A case study of each ablation category will be discussed in depth, along with the dominant atmospheric conditions associated with each event. Preliminary results indicate snow ablation correlates well with flooding events within the basin. Constructing a database of past ablation events will provide a better understanding of climate conditions that lead to these events, and their impact on the region.