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Title: DETERMINATION OF SUBSURFACE FLOW CHARACTERISTICS FOR THE INSTALLATION OF GROUNDWATER SAMPLERS

Author
item Dulaney, Wayne
item Gish, Timothy
item Daughtry, Craig
item DOOLITTLE, J - USDA/NRCS, RADNOR, PA
item KUNG, K - UNIVERSITY OF WISCONSIN

Submitted to: International Conference on Precision Agriculture Abstracts & Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/1/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Although it is generally claimed that site-specific or precision farming production practices benefit soil and water quality while increasing or maintaining farm profitability, little research has been conducted to support this assertion. In order to assess the environmental and economic consequences of precision farming, a 30 hectare (ha) experimental field site located in Beltsville, Maryland has been characterized and instrumented in order to determine surface and subsurface field-scale fluxes of agricultural chemicals from four, four ha watersheds each managed using different production practices. New and emerging technologies such as electro-magnetic induction (EM) and ground-penetrating radar (GPR) were used to produce contour maps showing the extent, orientation, and depth of subsurface clay layers that channel groundwater flow. Maps of these flow pathways were used to identify optimal sites for the installation of various hydrologic instruments, including 256 real-time soil moisture sensors. Data from these soil moisture sensors confirmed that GPR profile images can be successfully used to locate buried clay lenses and identify subsurface convergent flow pathways.

Technical Abstract: It is generally asserted that the adoption of site-specific production techniques benefits soil and water quality while increasing or maintaining farm profitability. To evaluate this assumption, a 30 hectare (ha) research site located in Beltsville, Maryland has been characterized and instrumented to determine field-scale fluxes of agricultural chemicals from four, four ha watersheds each managed under different production practices. Electromagnetic induction (EM-38) data was linked to the geo-statistical analysis of over 40 km of ground-penetrating radar (GPR) data to produce contour maps showing the extent, orientation, and depth of subsurface layers governing groundwater movement as well as their spatial correlation. These maps were used to identify optimal sites for the installation of various hydrologic instruments, including 256 real-time soil moisture sensors. Soil moisture data confirmed the usefulness of GPR profile images to locate buried lenses and identify subsurface convergent flow pathways.