An innovative approach for locating and evaluating subsurface pathways for nitrogen loss.

Area of Science:

• Environmental Science
• Hydrology
• Soil Science

Background:

• Watershed-scale chemical flux to ecosystems is poorly understood, hindering effective contamination mitigation strategies.
• Characterizing processes like evapotranspiration, runoff, plant uptake, and subsurface flow is essential.
• Conventional sampling methods fail to adequately measure preferential flow of water and solutes in subsurface environments.

Purpose of the Study:

• To develop and test a novel sampling strategy for accurately identifying subsurface preferential flow pathways.
• To understand how agricultural watershed management practices influence chemical transport.
• To characterize chemical flux from agricultural watersheds to adjacent ecosystems.

Main Methods:

• Utilized ground-penetrating radar (GPR) for subsurface structure mapping.
• Integrated near real-time soil moisture data, surface topography, and remotely sensed imagery.
• Employed a geographic information system (GIS) to analyze spatial data and identify flow pathways.
• Confirmed identified pathways using yield monitor data and remote sensing imagery.

Main Results:

• Successfully identified spatial locations of preferential flow pathways for chemicals exiting agricultural watersheds.
• Demonstrated the efficacy of the integrated GPR, GIS, and remote sensing approach for characterizing subsurface flow.
• Provided initial insights into the movement of chemicals from agricultural lands to riparian and stream ecosystems.

Conclusions:

• The developed sampling strategy effectively identifies subsurface preferential flow pathways, crucial for understanding chemical transport.
• This approach offers a significant advancement over conventional methods for characterizing complex subsurface hydrology.
• Accurate identification of these pathways is vital for formulating effective strategies to mitigate chemical contamination in downstream ecosystems.