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ARS Home » Northeast Area » University Park, Pennsylvania » Pasture Systems & Watershed Management Research » Research » Research Project #430520

Research Project: Characterizing Hydrological Processes Linking Agricultural Phosphorus Sources with Surface and Ground Waters Using Near-Surface Geophysics

Location: Pasture Systems & Watershed Management Research

Project Number: 8070-13000-014-10-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Apr 1, 2016
End Date: Oct 31, 2018

Objective:
This research project seeks to improve phosphorus (P) management in ditch-drained agroecosystems by combining near-surface geophysics with conservative tracers to characterize subsurface hydrologic flow pathways that link legacy soil P sources with surface waters. In this project, we will: (1) pair time-lapse electrical resistivity imaging (ERI) with conservative salt tracers to examine the spatial extent, structure and connectivity of subsurface hydrologic flow paths involved in P transport to drainage ditches; (2) leverage results from the geophysical studies to improve the representation of subsurface flow pathways in P site assessment tools and watershed simulation models.

Approach:
This project will continue a highly successful collaboration between the Near Surface Geophysics group at Rutgers University (Newark, NJ) and the USDA-ARS Pasture Systems and Watershed Management Research Unit (University Park, PA), which began in 2014. The shared research goal established by the project team is to apply near-surface geophysical technologies to assess subsurface P transport mechanisms in ditch-drained agroecosystems on the Delmarva Peninsula. Working in collaboration with colleagues from University of Delaware, University of Maryland Eastern Shore, and Virginia Tech, the research team will situate its field campaign on an intensely drained study site located in the heart of Maryland’s Lower Eastern Shore. At the study site, the team will conduct a series of field experiments using time-lapse ERI in conjunction with conservative salt tracers to identify and characterize subsurface flow pathways that connect P sources in agricultural fields to surface waters in small drainage ditches. Results from these experiments will be used to improve the representation of subsurface P transport pathways in watershed simulation models and P risk assessment tools that are commonly used to guide nutrient management across the Delmarva Peninsula.