ARS | Publication request: WATERSHED-SCALE SURFACE AND SUB-SURFACE REMOTE SENSING AT THE OPE3 SITE

Submitted to: Meeting Abstract
Publication Type: Abstract
Publication Acceptance Date: June 15, 2003
Publication Date: October 27, 2003
Citation: Gish, T.J., Walthall, C.L., Daughtry, C.S., McCarty, G.W., Dulaney, W.P. 2003. Watershed-scale surface and sub-surface remote sensing at the OPE3 site. 1st Interagency Conference on Research in the Watershed.

Technical Abstract: The Optimizing Production inputs for Economic and Environmental Enhancement (OPE3) research program focuses on developing strategies for meeting economic crop production goals while mitigating excess chemical loss to neighboring ecosystems. The OPE3 site has four hydrologically-bounded watersheds, about 4 ha each, which feed a wooded wetland and first order stream. Among the OPE3 watershed-scale research projects seeking to meet these goals are investigations focused on methods to quantify spatial variations of water and nutrients via characterization of subsurface flow pathways and analysis of crop response. Subsurface topography of the first continuous clay lens was determined by combining ground-penetrating radar (GPR) data with surface digital elevation maps to identify the spatial location of subsurface convergent flow pathways. Remote sensing provided information on crop nitrogen status and foliage density via spectral vegetation indices (SVI) from an airborne imaging system and confirmed the location of sub-surface flow pathways. The crop nitrogen mapping procedure exploited the relationship between crop nitrogen and leaf chlorophyll with ratios of SVIs that normalize the readings for crop density. Both the spectral and spatial information domains of imagery were used to map LAI at high spatial resolutions (1 to 4 m pixels) and provided a link for mapping the impact of soil water dynamics over several growing seasons. The maturation and fusion of these technologies will permit an assessment of watershed strategies influencing water and chemical flow and their impact on surrounding ecosystems while simultaneously assessing the effectiveness of varied management strategies on crop production.