Progress 09/01/07 to 08/31/11
Outputs
OUTPUTS: Thousands of stream miles in the southern Piedmont region are impaired because of high levels of suspended sediment. It is unclear if the source is upland erosion from agricultural sources or bank erosion of historic sediment deposited in the flood plains between 1830 and 1930 when cotton farming was extensive. The objective of this the first two years of this study was to determine the source of high stream suspended sediment concentrations in a typical southern Piedmont watershed using sediment fingerprinting techniques. Twenty-one potential tracers were tested for their ability to discriminate between sources, conservative behavior, and lack of redundancy. Tracer concentrations were determined in potential sediment sources (forests, pastures, row crop fields, stream banks, and unpaved roads and construction sites), and suspended sediment samples collected from the stream and analyzed using mixing models. Results indicated that 137Cs and 15N were the best tracers to discriminate potential sediment sources in this watershed. The δ15N values showed distinct signatures in all the potential suspended sediment sources, and δ15N was a unique tracer to differentiate stream bank soil from upland subsurface soils, such as soil from construction sites, unpaved roads, ditches, and field gullies. Mixing models showed that about 60% of the stream suspended sediment originated from eroding stream banks, 23 to 30% from upland subsoil sources (e.g., construction sites and unpaved roads), and about 10 to 15% from pastures. In the last year of the study we investigated sub basins within a larger watershed we previously examined. The objective was to examine spatial variation in the origin of the suspended sediments and to test a streamlined fingerprinting approach which would reduce the cost. Samples were collected from three tributaries, the outlet of the main stem, and at the middle of the main stem. Two methods to collect suspended sediment samples were compared: a mobile continuous flow centrifuge and automated samplers. A relatively small initial tracer suite consisting of 15N, 13C, TN, and TC was employed in tracer selection. The pool was tested for discriminatory power in another watershed in the region and found to provide similarly positive results indicating its possible applicability as an inexpensive regional tracer suite. Tracer concentrations were obtained through a single mass spectrometry analysis requiring less than one gram of sediment. Results using a multivariate mixing model showed that banks contributed the majority of sediment throughout all locations sampled and that in tributaries it was an even more dominant source. To reduce costs and streamline the process, we used a single analysis that included total carbon, total nitrogen, and nitrogen-15. These tracers avoid the large sample volume and expensive analysis associated with cesium-137. In addition, we used automated samplers to collect samples during storms instead of the mobile truck-mounted centrifuge. Costs of the management approach were approximately $7,550 compared to $46,600 for the research approach for our watershed. PARTICIPANTS: We cooperated with scientists at the USDA National Sedimentation Lab and the Hydrology and Remote Sensing Lab on this project. The Sedimentation Lab performed rapid geomorphic assessments on our stream reaches and the Hydrology Lab did the analysis of our samples for cesium-137. TARGET AUDIENCES: One of the target audiences for our study is state environmental agencies. To reach this group, we organized a symposium on sediment fingerprinting and rapid geomorphic assessment at the 2010 Land Grant and Sea Grant National Water Conference, February 21-25, in Hilton Head, SC. This symposium included Dr. Des Walling, an internationally recognized expert on sediment fingerprinting, and speakers from state and federal agencies, as well as universities. We have submitted a journal article based on the symposium on how to turn fingerprinting from a research tool to an operational tool used by state agencies. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Our project was selected by the NIFA Committee for Shared Leadership as one to highlight at the 2011 Land Grant and Sea Grant National Water Conference, January 31 and February 1, 2011 in Washington, DC. In September, 2011, our project received the Outstanding Research Award from the USDA NIFA Southern Region Water Program. The results of our study may be applicable to other watersheds in the Piedmont depending on the extent of urbanization occurring in these watersheds. Better understanding of the sources of fine sediment has practical implications on the type of sediment control measures to be adopted. Investment of resources in improving water quality should consider the factors causing stream bank erosion and erosion from unpaved roads and construction sites to water quality impairment. The use of the streamlined approach should allow for the adoption of sediment fingerprinting as an operational tool for state agencies in the Southern Piedmont wishing to utilize it in TMDL/BMP evaluations. As a result of the sediment fingerprinting and rapid geomorphic assessment symposium, we are working with the symposium presenters to develop two papers assessing what is needed to take these techniques from the research to management tools where they can be used by state agencies dealing with sediment-impaired streams.
Publications
- Radcliffe, D.E. R. Mukundan, R. McKinley, and L.M. Risse. 2011. Sediment fingerprinting: A new approach for muddy streams. Regional poster of excellence. National Conference Proceedings. Available at http://www.usawaterquality.org/conferences/2011/regional/Proj_Excel.h tml
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Progress 09/01/09 to 08/31/10
Outputs
OUTPUTS: In the third year of this project, we initiated a new sampling strategy to test the results of the data from last year and to try a new tracer. We sampled two tributaries to see how well delta N-15 would work in identifying upland subsoil sources (mainly unpaved roads since there are very few construction sites left in the watershed). We also tested the use of fatty acid methyl ester (FAME) analysis as a tracer. In addition, we performed a rapid geomorphic assessment of the stage of channel evolution in these tributaries. We found that the tributaries were in an earlier stage of channel evolution (less stable) than the main stem. We also found that N-15 combined with total carbon could identify the three major sources of sediment in two tributaries: banks, upland subsoils, and pastures. End-member analysis using these tracers indicated that banks were the major source of sediment in these tributaries (over 80% of the load) and this supported the RGA results that the streams were in a stage of channel evolution where bank erosion was common. FAME analysis also identified the three sources but end-member analysis with these tracers indicated that forests were the major source of sediment and we do not believe this is correct. We organized a symposium on sediment fingerprinting and rapid geomorphic assessment at the 2010 Land Grant and Sea Grant National Water Conference, February 21-25, in Hilton Head, SC. This symposium included Dr. Des Walling, an internationally recognized expert on sediment fingerprinting, and speakers from state and federal agencies, as well as universities. We received approval for a no-cost extension of this project until 8/31/2011. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Our project has been selected by the NIFA Committee for Shared Leadership as one to highlight at the 2011 Land Grant and Sea Grant National Water Conference, January 31 and February 1, 2011 in Washington, DC. Our current efforts are aimed at reducing the costs for sediment fingerprinting so that state agencies can use this method. The major costs are due to analysis of cesium-137 (>$100/sample) and use of the truck-mounted centrifuge ($20,000 for the centrifuge and pump). We are testing to see if delta N-15 and carbon can be used to identify the sources ($20/sample) and automated stream samplers can be used to collect sediment during storms (large samples are not required for carbon or delta N-15). If this approach works, it could dramatically change the way states approach sediment-impaired streams. As a result of the sediment fingerprinting and rapid geomorphic assessment symposium, we are working with the symposium presenters to develop two papers assessing what is needed to take these techniques from the research to management tools where they can be used by state agencies dealing with sediment-impaired streams.
Publications
- Mukundan, R., Radcliffe, D.E., Ritchie, J.C., Risse, L.M., and McKinley, R.A. 2010. Sediment fingerprinting to determine the source or suspended sediment in a Southern Piedmont stream. J. Environ. Qual. 39:1328-1337.
- Mukundan, R., Radcliffe, D.E., and Ritchie, J.C. 2010. Channel stability assessment through rapid channel morphology and sediment yield analysis. Hydrologic Processes. DOI: 10.1002/hyp.7890.
- Mukundan, R., D.E. Radcliffe, J. Ritchie, M. Risse, and R. McKinley. 2010. Sediment fingerprinting and RGA in a Southern Piedmont Stream. Abstract and presentation. 2010 Land Grant and Sea Grant National Water Conference, February 21-25, in Hilton Head, SC. Available at http://www.usawaterquality.org/conferences/2010/MondayPDF/Symposium%2 05_1pm-5/Mukundan.pdf
- McKinley, R. and D.E. Radcliffe. 2010. Correlating sub-basin sediment fingerprints to land use in the North Fork Broad River Basin. Soil Science Society of America International Annual Meeting. Oct 31 - Nov 4, 2010. Long Beach, CA. Available at http://a-c-s.confex.com/crops/2010am/webprogram/Paper59170.html
- Mukundan, R., Radcliffe, D.E., and Risse, L.M. 2009. Spatial resolution of soil data and channel erosion effects on SWAT model predictions of flow and sediment. J. Soil Water Conserv. 65:92-104.
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Progress 09/01/08 to 08/31/09
Outputs
OUTPUTS: In the second year of this project, we were very successful in obtaining samples from the winter/spring season of 2008 and 2009. Twenty one potential tracers were tested and two were found to be suitable: cesium 137 (Cs-137) and a heavy isotope of nitrogen (delta N-15). Tracer concentrations were determined in potential sediment sources (forests, pastures, row crop fields, stream banks, and unpaved roads/construction sites) and suspended sediment samples collected from the stream and analyzed using two methods: mixing models and end-member analysis. Results indicated that about 60% of the sediment originated from eroding stream banks, 23-30% from upland subsurface sources such as construction sites and unpaved roads and about 10-15% from pastures. In the fall, rainfall has been very heavy and we have been able to start collecting storm samples again. We have initiated a new sampling strategy to test the results of the data from last winter and spring and to try a new tracer. We are sampling tributaries that we expect to be high in upland subsoil surfaces to see how well delta N-15 will work in identifying these sources (mainly unpaved roads since there are very few construction sites left in the watershed). We are also testing the use of fatty acid methyl ester (FAME) analysis of source and suspended sediment samples. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
This is the first study that has found a way to distinguish bank sediment from upland suboil sources (construction and unpaved road) and banks. Our research has also shown the utility of a mobile centrifuge and pump for sampling during storms. We have organized a symposium on sediment fingerprinting and rapid geomorphic assessment of the 2010 Land Grant and Sea Grant National Water Conference, February 21-25, in Hilton Head, SC. This symposium will include Des Walling, an internationally recognized expert on sediment fingerprinting, and speakers from state and federal agencies, as well as universities.
Publications
- Mukundan, R., Radcliffe, D.E., Simon, A., and Klimentz, L. 2009. Rapid geomorphic assessment and sediment tracking, North Fork Broad River, Georgia. 2009. 2009 USDA-CSREES National Water Quality Conference Abstracts. Available online at: http://www.usawaterquality.org/conferences/2009/Abstracts/Wshed-oral/ Mukundan09.pdf
- Mukundan, R., Radcliffe, D.E., Ritchie, J. and McKinley, R. 2009. Sediment fingerprinting to determine the source of suspended sediment in a Southern Piedmont Stream. Soil Science Society of America 2009 abstract. Available online at: http://a-c-s.confex.com/crops/2009am/webprogram/Paper52628.html
- Mukundan, R., Radcliffe, D.E., and Risse, M. 2009. Soil database resolution effect on SWAT model predictions of sediment in a Southern Piedmont watershed. J. Soil Water Conserv. (in press).
- Mukundan, R. and Radcliffe, D.E. 2009. Channel stability assessment through rapid channel morphology and sediment yield analysis. Catena. (pending).
- Mukundan, R., Radcliffe, D.E., Ritchie, J., and McKinley, R. 2009. Sediment fingerprinting to determine the source or suspended sediment in a Southern Piedmont stream. J. Environ. Qual. (pending).
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Progress 09/01/07 to 08/31/08
Outputs
OUTPUTS: Geomorphic assessment indicates that the stream channels in the study watershed are relatively unstable. Preliminary sediment fingerprinting results point towards stream banks as the primary source of suspended sediment in the streams. The project introduces a new approach to sediment TMDL practitioners by incorporating geomorphic analysis of fluvial systems, sediment fingerprinting, use of long term sediment loads rather that concentrations (that varies over space and time) for setting targets and determining viable load reduction scenarios. PARTICIPANTS: Cooperators from the National Sedimentation Lab (USDA-ARS) and the Hydrology and Remote Sensing Lab (USDA-ARS) provided a 2-day seminar/field visit on sediment fingerprinting and geomorphic assessment for the water resources faculty and students at the University of Georgia. TARGET AUDIENCES: The target audience is stakeholders within the watershed and extension specialists and agents throughout the southern piedmont region. Also, students and other researchers. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The project was the research highlight of the Spring 2008 issue of Southscapes - a magazine published semi-annually by the College of Agricultural and Environmental Sciences, University of Georgia (http://srwqis.tamu.edu/). Preliminary results on geomorphic assessment of stream channels and sediment fingerprinting will be presented at the National Water Conference 2009 at St. Louis, MO.
Publications
- Mukundan, R., Radcliffe, D.E., Risse, L.M., Miller, W.P. and Ritchie, J.C. 2008. Sediment Fingerprinting in a Southern Piedmont Watershed - Preliminary Results. Proceedings of the 2008 National Water Conference, Sparks, Nevada Feb 3-7, 2008.
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