by S.W. Ator, J.M. Denver, and T.C. Hancock
Data from the Mid-Atlantic Coastal Plain (New Jersey through North Carolina) were analyzed to evaluate the importance of variable surficial hydrogeology to shallow ground-water quality. This work was facilitated by newly available regionally consistent mapping of the variable texture and depositional history of surficial sediments. A surficial hydrogeologic framework was developed to provide a template for understanding the major physical processes controlling chemical transport in the shallow hydrologic system. Seven distinct hydrogeologic subareas were delineated from physiography and the bulk texture of surficial sediments, the primary natural factors affecting the flow and chemistry of shallow ground water and small streams. Data collected from 533 wells in unconfined aquifers from 1987 through 1997 were analyzed along with land-use, soils, and other variables to evaluate the effectiveness of the framework at describing regional ground-water quality. The results emphasize the importance of surficial hydrogeology in the design and results of future water-monitoring studies.
Regional patterns in ground-water chemistry within the Coastal Plain are related to surficial hydrogeology as described by the framework. Concentrations of most major ions and nutrients are higher in the Coastal Lowlands (a poorly-drained area of abundant organic matter and little dissolved oxygen) than in another subarea of similar land use but coarser, more weathered sediments and better drainage. Ground-water chemistry is particularly variable within subareas of mixed textures, which are important to local ground-water quality but are indistinguishable at the regional scale.
Ator, S.W., Denver, J.M., and Hancock, T.C., 2000, Relating Surficial Hydrogeology to Shallow Ground-Water Quality in the Mid-Atlantic Coastal Plain [abs.], National Water Quality Monitoring Conference, April 25-27, 2000, Austin, Tex.
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