Hydrogeologic characterization and modeling of soil water-groundwater-surface water interactions in a forested catchment with a chain of lakes, Pocono Mountains, Pennsylvania.

摘要

The goal of this research project has been to enhance the understanding of soil water-groundwater-surface water interactions and their influence on the buffering of anthropogenic acids and the associated detrimental mobilization of aluminum to surface waters. Many studies have revealed the important control exerted over the latter processes by transient fluxes along different hydrologic flow paths in a catchment. To model the transient fluxes to surface water bodies in a selected catchment containing a chain of lakes, an end-member mixing analysis (EMMA) was completed.; Through characterization of the hydrogeologic system, soil water and groundwater end-members were characterized. That effort demonstrated that water-rock interactions, associated with different residence times and flow paths, produced local and regional groundwaters with distinct solution compositions. Organic and mineral horizon solutions were also described.; The EMMA technique was then utilized to model the hydrology of this catchment because of its efficiency in terms of requiring little district measurement of hydrogeologic fluxes. The application of EMMA to the Lake Shred Catchment was a novel approach on several accounts. The utilization of EMMA to model lacustrine environments had not been previously reported in the literature. Furthermore, the model proved successful for interpreting soil water-groundwater-surface water interactions ongoing in a chain of lakes. Adaptations to the model required by this approach included hierarchical routing of surface water end-members, remixing of lake waters to account for in-lake storage, and consideration of end-members whose compositions evolved dynamically over the course of the study.; Inferences regarding the hydrogeologic system active in the catchment, based upon geologic field investigation and a solution monitoring program, were largely substantiated by the model results. Trends of enhanced alkalinity and elevated pHs from the headwater lake, Deep Lake, through downstream surface water bodies, were explained on the basis of diminished component fluxes of relatively poorly buffered soil solutions and increasing fluxes of regional groundwaters. Furthermore, the effects of drought on the watershed, including diminished circulation of shallow soil waters and groundwaters, successfully explained the evolution of surface waters during the events.