Title: Landscape and Watershed Ecosystem Evaluation and Management for Sustainability

Cooperators: D.D. Bosch, A.W. Thomas, and L.R. Lowrance

Problem:
While great strides have been made to reduce pollution from point and nonpoint sources in the United States, environmental pollution still remains a significant problem. The U.S. Department of Agriculture has taken an aggressive stance to develop resource management strategies for minimizing any agricultural contributions to the problem. A combination of shallow ground water, extensive application of agrichemicals, climate, and soil properties makes the Atlantic Coastal Plain region a prime candidate for contamination of ground and surface water resources.

Approach:
Nonpoint source agricultural pollution within Coastal Plain landscapes and watersheds is being characterized through field and watershed studies. The results of these studies are being used to relate controlling geophysical, climatic, and management features to pollution levels. Once these relationships are understood, management alternatives for area agriculture will be developed. We are also developing methods to enhance practical use of watershed models, expand the use of geographical information systems, and incorporate climatic variation and other uncertainties into the agri-management decision process.

Results:
Approximately 10% of the precipitation falling on area watersheds is lost as surface runoff while shallow subsurface flow estimates range from 3 to 20%. Evaporation and plant transpiration make up the largest component, 60-70%, of the water budget. Surface runoff contains fairly high concentrations of pesticides (0-90 µ l^-1 ) but these concentrations are substantially reduced (~ 0) by riparian buffers surrounding upland fields. Subsurface runoff contains very low levels of pesticides and moderate concentrations of nutrients from applied fertilizers (0-15 mg l^-1 of nitrate nitrogen, and 0-15 mg l^-1 of chloride). Results indicate riparian buffers are an extremely effective management practice for Coastal Plain watersheds.