USGS Grant Number:
Year Established: 2007 Start Date: 2008-04-01 End Date: 2011-03-31
Total Federal Funds: $129,042 Total Non-Federal Funds: $131,041
Principal Investigators: Philippe Vidon, Nancy Baker, Jeffrey Frey
Abstract: Understanding the processes controlling the delivery of nitrogen, phosphorus and carbon to streams in artificially drained landscapes of the Midwest is of critical importance to developing comprehensive nutrient management strategies at the watershed scale. Most nutrient and carbon losses in artificially drained landscapes of the Midwest occur during precipitation events through tile drain flow and overland flow. In addition, recent research has identified preferential flow through soil macropores as an important export mechanism contributing to tile drain flow. There is nevertheless a lack of empirical data documenting the relative importance of overland flow (OLF), matrix flow (MF) and preferential flow through soil macropores (PF) on nitrogen, phosphorus and dissolved organic carbon (DOC) losses to streams. For this project, a team of USGS scientists has teamed up with the PI (Vidon) to measure the relative importance of OLF, MF and PF during 6-8 storms over a two-year period in an artificially drained Midwestern watershed, and to identify the changes in the nature of in-stream nitrogen (nitrate, ammonium, total Kjeldahl nitrogen (TKN)), phosphorus (soluble reactive phosphorus (SRP), total phosphorus (TP)), and DOC (aromaticity) during storms. The work will take place in a small first order watershed, which is continuously monitored by the U.S. Geological Survey as part of the National Water Quality Assessment Program (NAWQA) for the White River, Great, and Little Miami River Basins. Water quality data will be collected in precipitation and at 2-4 hour intervals during storms in overland flow, tile flow and the stream. The PIs will used a two phase (tile + stream) multi-tracer (chloride, cation, oxygen-18) approach to independently estimate the relative importance of tile drain flow, overland flow, precipitation and seepage in the stream, and the relative importance of matrix flow and preferential flow through soil macropores in tile flow. In addition, the team of PIs will assess the impact of till vs. no-till practices on N, P and DOC (NPC) losses to streams during storms by monitoring water quality in two tile drains that drain fields with till and no-till. The potential of DOC and DOC specific UV absorbance (SUVA) as potential hydrologic tracers to identify water sources in a watershed context will also be evaluated. By providing a direct quantification of the relative importance of each water delivery pathway to NPC transport to streams for a variety of storms and crop development conditions, this project will provide an increased understanding of the processes controlling NPC delivery to streams, and provide tools to better target best management practices (BMP) to minimize the impact of agriculture on raw rural water quality in the Midwest. The proposed project will also address each of the three main objectives of the section 104G of the Water Resources Research Act of 1984 (RFP FY 2007 page 3): 1) it will promote the collaboration between USGS (Frey, Baker) and university (Vidon) scientists on significant national water resources issues; 2) results of this research will be disseminated to a broad audience through the organization of workshops where results are presented to interested citizen groups; 3) finally, this project will assist in the training of water scientists by involving graduate and undergraduate students in research and by supporting the research of Dr. Vidon (early career scientist, PhD 2004).