Coastal Plain Landscapes

Objectives

1) Identify landscape (ie. land use, soils, geology) and geochemical variables predictive of the occurrence and distribution of pesticides and nutrients in streams and benthic community structure, and use these variables to develop landscape indicators for headwater streams of the Mid-Atlantic Coastal Plain.

2) Characterize the status of benthic communities and the quality of shallow ground water discharging to headwater streams of the Mid-Atlantic Coastal Plain.

3) Apply experience and results from this study to the design and implementation of similar studies in the Upper Midwest and other areas of the Nation.

see Pitchford and others (2000), Ator and others (2003)

Statement of Problem

Stream chemistry and aquatic ecology are related to landscape conditions in contributing watersheds. The development and calibration of empirical models to predict stream water quality and ecology on the basis of landscape indicators can be useful and cost-effective for environmental monitoring and assessments.

Strategy and Approach

A base survey of small first-order streams (typically draining less than 10 km2) was established in the Mid-Atlantic Coastal Plain (New Jersey through North Carolina). A stratified random sample with unequal probability selection was used to select streams for sampling from among the more than 10,000 first-order streams in the study area (Pitchford and others, 2000, Ator and others, 2003). Twenty-five streams were selected along a gradient of watershed land cover within each of seven hydrogeologic subregions that were delineated on the basis of physiography and the bulk texture of surficial sediments (Ator and others, in press). A complete random sample of 175 alternate streams was also selected for use in cases where primary streams were unusable.

Field reconnaissance and stream replacement yielded a final network of 174 streams. Each stream was sampled for base-flow water quality (including concentrations of selected pesticides, pesticide metabolites, nutrients, and major ions) and ecology (including benthic community composition and riparian habitat) between late February and early June, 2000. Other Coastal Plain streams were also sampled during the same period to provide supporting information for data from the base survey.

Contributing watersheds for each sampled stream were delineated and available land cover, soil, elevation, and other geographic data were compiled and summarized for each watershed. Multiple regression and other empirical statistical approaches are being used to develop models relating measured stream conditions to landscape variables in contributing watersheds.