Using 2D Modeling to Develop Flood Mitigation Strategies for Philadelphia’s Eastwick Community

In this William Penn Foundation-funded project, Princeton Hydro worked with landscape architects and planners from the University of Pennsylvania, Keystone Conservation Trust, and Audubon Pennsylvania to better understand how to increase coastal, storm, and social resilience in the 15.7 square mile Lower Darby Creek Area. This area is in the coastal plain of Pennsylvania and home to 35,000 residents, the Philadelphia International Airport, and US Interstate-95. It is also home to John Heinz National Wildlife Refuge, America’s first urban refuge, which was established to preserve and restore the natural area known as Tinicum Marsh. 

Eastwick, a low-lying, urbanized neighborhood in Southwest Philadelphia, is a predominantly Black (57.5%) and low-income community (median income $36k) with many of its residents often displaced after hurricanes and large storm events. Storms with large amounts of precipitation, coupled with storm surges as small as 3 feet, present potentially devastating conditions for the surrounding residential and ecological communities on the coastal plain. About 130 Eastwick residences have flooded more than 10 times in the last 20 years due to stronger storms and increased land development upstream of the Darby Creek and Cobbs Creek.

Princeton Hydro’s study focused on the key problem areas in Eastwick: the confluence of Darby Creek and Cobbs Creek; a constriction at Hook Road and 84th Street; and the Clearview Landfill, which is part of the Lower Darby Creek Superfund site. The study sought to answer questions commonly asked by community members related to flooding conditions, with the main question being: What impact does the landfill have on area flooding? Princeton Hydro developed a 2-dimensional hydrologic and hydraulic model to understand how varying restoration techniques, including removal of the Clearview Landfill, expansion of the existing tidal freshwater wetland, removal of bridge infrastructure, and rerouting storm flows, would alter flooding in the Eastwick neighborhood. Modeling scenarios focused on restoring original drainage patterns in the vicinity of John Heinz National Wildlife Refuge, which includes converting the existing impoundment into tidal freshwater wetland. 

Modeled results were discussed with residents and stakeholders at a workshop to solicit resident feedback and confirm model outputs. Results from the modeling and ecological assessments informed a resilience assessment that identified stakeholder values, drivers of change, key findings, primary goals, and strategies to meet the goals. The final report culminated in a plan that can be used as a guidance document that illustrates ways to reduce flooding, increase regional ecological value, and provide storm resiliency.