The principal objective of the proposed work is to document the effects of urbanization on Valley Creek Watershed in a rapidly developing area of suburban Philadelphia. Valley Creek, a tributary of the Schuylkill River, runs through Valley Forge National Historical Park. The limestone-fed stream supports a native brown trout population. In addition to the common effects of development such as increased surface runoff and sediment loading, the watershed has experienced point-source pollution problems from hazardous waste sites and aquifer dewatering from quarrying operations and pumping for municipal water supply.
A historical review will determine the changes in the stream caused by development over the last 200 years. The study will then turn to the effect of continuing urbanization. Development-induced geeomorphologic changes are stream flows, channel morphology, bed composition, and suspended sediment concentration. The degree and pattern of heterogeneity of hydraulic conductivity of the fractured rock aquifer will be examined at multiple scales from existing hydrogeologic data and with a 3D groundwater model material to representing contaminant transport in fractured rock We will then evaluate the effect of aquifer heterogeneity and 3D flow pathways on stream subsurface exchange rates, contaminant transports, and chemical loadings to the fish and other biota. Tracer-injection experiments will be used to directly assess stream-subsurface exchange in Valley Creek.
We propose to investigate several aspects of the interaction between environmental quality and biota. First, we will collect sediment distribution data to assess impacts of changes in channel characteristics on community structure of macroinvertebrates and fish. Second, we will compare sediment PCB levels and supply rates with PCB levels found in organisms. Third, we will use stable isotope d15 N values to assess positioning of species in the food web in order to measure biomagnification. Fourth, we will measure general stress levels in the organisms using heat shock proteins (hsp 70) and relate this to PCB levels as an independent indicator of environmental impacts on organisms. This work leads to a comprehensive picture of how urbanization-induced changes affect invertebrate and fish communities.
Political controversies in this watershed have left a history of the political struggles that develop during urbanization that can be used to gain understanding of the political forces during urbanization. The social science research will be based on the use of three sociological perspectives: (1) The Advocacy Coalition Framework; (2) network analysis; and (3) discourse analysis. These sociological perspectives define a watershed politics that results from the formation of different advocacy coalitions, each with a specific network structure and belief system. The vision definition will give a comprehensive view of the process of urbanization, as well as the influence by social, economic, and political factors.
