Lateral Mixing of the North and West Branches of Susquehanna River at Hummels Wharf, PA

Elaine Langone Center, Terrace Room

The mixing zone of the north and west branches of the Susquehanna River at a site downstream from the merging point (Sunbury, PA) was studied to understand how these two streams and the rain events, associated with their corresponding watersheds are affecting this lateral mixing. Continuous data sampling from the Shady Nook site was used to collect multiple transects from August 2009 to August 2013 to identify the transition zone between the west and north branches. The specific conductivity of the water yielded the strongest correlation to the two branches’ mixing zone and provided accurately tracking of the lateral shifting during both wet and dry conditions. Based on this correlation, predictions can be made to explain movement of pollutants and their mixing. Precipitation and discharge data was examined to study the influence of rain events on the location of the mixing zone. Results have shown that as the discharge of the mainstem increases, the mixing zone shifts lateral away from the Shady Nook shoreline until it reaches a threshold discharge of 12300 ft3/s, and then the mixing zone shifts backward as the discharge increases beyond this threshold discharge.