Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/30/2010
Publication Date: 5/15/2011
Publication URL: http://handle.nal.usda.gov/10113/59935
Citation: Gormally, K., McIntosh, M., Mucciardi, A., Mccarty, G.W. 2011. GPR detection and 3D mapping of lateral macropores II. Riparian Application. Journal of Environmental Quality. http://doi:10.2136/sssaj2010.0342. Interpretive Summary: The nutrient buffering capacity of riparian wetlands is commonly assumed to depend on the width of the riparian corridor. Yet recent research suggests that nitrogen fate can also vary depending on preferential groundwater flow, soil biogeochemistry, and the extent and type of riparian vegetation. Networks of lateral macropores can form preferential pathways, rapidly transmitting contaminated water from adjacent agricultural fields and resulting in higher than expected nitrogen loads in stream channels. In this study we test and validate our GPR-based mapping procedure in a Mid-Atlantic riparian wetland with known preferential flow activity. The results indicate that GPR is an effective technology for in situ network mapping without disturbing environmentally sensitive wetland ecosystems.
Technical Abstract: The morphology and prevalence of 1-10 cm diameter macropores in forested riparian wetland buffers is largely unknown despite their importance as a source of preferential nutrient delivery to stream channels. Here, we validated in situ procedures for detecting and mapping the three-dimensional structure of near-surface (15-65 cm deep) lateral macropore networks using non-invasive ground-penetrating radar (GPR) technology at a Mid-Atlantic riparian wetland field study site. Soil core samples used to ground truth the procedures showed that the detection predictions were 92% accurate and tracer dye transmission through the site corroborated the morphology predictions. The results indicate that GPR is an effective technology for in situ network mapping without disturbing environmentally sensitive wetland ecosystems.