Coweeta Hillslope Project

PROJECT TITLE: Clean Water from Complex Natural Systems: Soil and Hydrological Controls

SPONSOR: Institute for Critical Technology and Applied Science

PROJECT DURATION: 1 May 2014 to 30 December 2018

PRINCIPAL INVESTIGATORS: Brian Strahm, Kevin McGuire, Jennifer Knoepp (USFS), Stephen Schoenholtz

GRADUATE STUDENTS: Ray Lee, Ph.D. student

PROJECT SUMMARY: Excess reactive nitrogen (N) in the environment is a major component of global change. Nitrogen loading is a critical problem impacting surface waters at scales ranging from headwaters to coastal waterways, with nitrate being of particular concern. Reactivity within, and rates of transport through the soil system control nitrate export to surface waters. When and where reactive processes versus transport control overall export is unclear and limits our ability to predict nitrate loading under future climate and land use scenarios. Current research has not successfully differentiated these two drivers effectively because different disciplines typically focus on one perspective or the other. An interdisciplinary approach that simultaneously quantifies soil and hydrologic controls of nitrate export is required to solve this problem. A field- scale physical model offers an opportunity to constrain major sources of variability and evaluate processes controlling nitrate export. Use of a one-of-a-kind, field-scale physical model on a hillslope at the USDA Forest Service Coweeta Hydrologic Laboratory and NSF Long-term Ecological Research site will enable high-resolution characterization of N reactivity, while simultaneously supporting accurate quantification of nitrate transport. This holistic understanding of fate and transport of nitrate in the environment is broadly applicable wherever issues of global change and land-use raise concerns about the ability of complex natural systems to provide clean water to sustain ecosystem services and communities.

PUBLICATIONS:
Lee, R.M. McGuire, K.J., Strahm, B.D., Knoepp, J.D., Jackson, C.R, and Stewart, R.D., 2019. Revisiting the Hewlett and Hibbert (1963) soil drainage experiment and modeling the effects of decadal pedogenic processes and leaky boundary conditions, Water Resources Research (revision submitted)

PRESENTATIONS:
McGuire, K.J., Lee, R.M., Strahm, B.D., Knoepp, J.D., Stewart R.D., Jackson, C.R., Scott, D.T. 2019. Revisiting the Hewlett and Hibbert hillslope drainage experiment and tracking downslope nitrate transport, Gordon Research Conference on Catchment Science: Interactions of Hydrology, Biology and Geochemistry, June 23-27, Andover, NH.
Lee, R.M., Strahm, B.D., McGuire, K.J., Knoepp, J.D. 2019. Decoupled water and nitrate transport downslope and across the terrestrial-aquatic interface, 139-2, presented at 2018-2019 International Soils Meeting, San Diego, CA, 6-9 Jan.
Strahm, B.D., Lee, R.M., McGuire, K.J., Knoepp, J.D. 2018. Decoupled water and nitrate transport downslope and across the terrestrial-aquatic interface, B24A-02, presented at 2018 Fall Meeting, AGU, Washington D.C., 10-14 Dec.
Lee, R., McGuire, K., Strahm, B., Knoepp, J., 2017. Modeling reactive nitrogen cycling on a forested hillslope using 15NO3 and D2O tracers, ASA-CSSA-SSSA International Annual Meetings, Oct. 22-25, Tampa FL.
Lee, R., McGuire, K., Strahm, B.D., Knoepp, J., 2016. Modeling reactive nitrate cycling on a forested hillslope using 15NO3 and D2O tracers, ASA-CSSA-SSSA International Annual Meetings, Nov. 6-9, Phoenix, AZ.
Lee, R.M., K.J. McGuire, and B. D. Strahm. 2015. Modeling relative roles of biogeochemical cycling and hydrologic transport on nutrient export at a forested hillslope, Poster presentation, Gordon Research Conference on Catchment Science: Interactions of Hydrology, Biology, and Geochemistry, June 14-19, Andover, NH.