| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | March 15, 2012 |
| Latest Amendment Date: | August 13, 2013 |
| Award Number: | 1151294 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Holly Barnard
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | May 1, 2012 |
| End Date: | April 30, 2018 (Estimated) |
| Total Intended Award Amount: | $413,291.00 |
| Total Awarded Amount to Date: | $413,291.00 |
| Funds Obligated to Date: |
FY 2013 = $327,582.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
201 SIKES HALL CLEMSON SC US 29634-0001 (864)656-2424 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
SC US 29634-0001 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): |
Hydrologic Sciences, Geobiology & Low-Temp Geochem |
| Primary Program Source: |
01001314DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
CAREER: ADVANCING THE MECHANISTIC UNDERSTANDING OF FIELD-SCALE PREFERENTIAL FLOW AND TRANSPORT PROCESSES IN SOILS USING GEOPHYSICS
Stephen Moysey
Clemson University
Preferential flow and transport processes cause water and contaminants to be isolated within distinct flow paths that can by-pass a large portion of a soil. Despite the universal occurrence of this phenomenon and its fundamental control on water and solute movement in the subsurface, there are few tools available to investigate the mechanisms leading to preferential flow at the field scale. As a result, there is a gap in knowledge regarding how interactions between different mechanisms causing preferential flow can alter observed flow behaviors, particularly as soil and rainfall conditions undergo seasonal changes throughout the year. This project will address the knowledge gap by testing the hypotheses that: (1) mechanisms controlling preferential flow and transport shift throughout the year due to seasonal dependence on antecedent water content and hydrologic forcing, and (2) ground penetrating radar (GPR) and electrical resistivity data can be used to detect preferential flow behaviors and discriminate the mechanistic causes of these observations. This research will be carried out by performing transient infiltration and steady-state tracer tests in two large (>32m3 volume) hydrogeophysical grid lysimeters under different water content and rainfall characteristics. The bottom face of each lysimeter is designed to collect distributed discharge of water and solutes from a grid of 1m x 1m outflow cells. One of the lysimeters will be constructed in the lab and filled with synthetic soil heterogeneities representative of conditions causing preferential flow. The design of this lysimeter will allow for evaluation of active preferential flow mechanisms based on patterns of the outflows. The second lysimeter will be located on a hillslope in the Clemson Experimental Forest. This lysimeter will represent natural soil conditions and capture seasonal effects of changing antecedent water content and variable rainfall characteristics. In each experiment, the lysimeters will be continuously monitored using time-lapse 3D GPR surveys and electrical resistivity measurements. The hydrologic and geophysical data from the lysimeter experiments will be analyzed using data reduction techniques that allow for quantitative comparison of the results for each set of control variables. As a result, the project will provide unique, quantitative insights into how the details of transient preferential flow and transport processes evolve in response to changing environmental conditions.
Understanding preferential flow processes is of fundamental importance to society as it affects many critical issues in watersheds, including flooding, contaminant fate and transport, agriculture, infrastructure stability, and ecosystem health. For example, the contribution of preferential flow processes to ecosystem services to be worth is estimated to be over US$304 billion per year. The integration of novel geophysical imaging techniques with infiltration and transport studies will provide unique insights into the dynamics of preferential flow at the field scale ? including an improved understanding of seasonal controls on these processes. There is an urgent need for understanding these basic processes to enable prediction and informed adaptation to shifts in watershed behavior as climate change causes perturbations in traditional soil behaviors. The high-resolution data obtained in this study will allow for testing and refinement of existing conceptual models for representing preferential flow in soils under varying hydrologic conditions. The educational aspects of this project will help to introduce and prepare a new generation of hydrologists ? spanning middle school girls to working professionals ? to extract information from an increasingly overwhelming mass of available data that ranges from hydrologic repositories to high-resolution geophysical images. Specific educational activities include the involvement of undergraduate students in the project through the Creative Inquiry pedagogy at Clemson, a hands-on educational module on water resources to be delivered to eighth grade girls through Clemson?s Project WISE summer camp, and an annual continuing education workshop for professionals to increase the awareness and understanding of geophysical applications in hydrology. In all three of these activities, there will be an emphasis on using a new generation of methods for sensing the environment and mining of large data sets to advance our fundamental understanding of hydrologic processes at real field sites.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Preferential flow through soils contributes to important societal issues ranging from enhancing the contamination of groundwater by pollutants to controlling the generation of storm runoff that produces flooding. It has been estimated that the contribution of soil preferential flow processes to ecosystem services is worth over US$304 billion per year! Understanding when preferential flow occurs within soils is, however, very difficult because the details of when, where, and how these flows occur is poorly understood. This project investigated the use of non-invasive geophysical sensing techniques for improving our understanding of these processes. Through the research, we were able to develop new technologies that improve our ability to detect and monitor preferential flows in soil; these technologies include the creation of an advanced facility for non-invasive monitoring of soils, which boasts a one of a kind robotic radar imaging system that we designed and built on the project, and a new mathematical approach to better focus electrical resistivity images to accurately capture hydrologic processes. While these methodologies are appropriate for understanding preferential flow at field scales, we also used an x-ray CT scanner to create 3D movies of flow processes at the pore scale, where features like soil cracks can have a drastic impact on the flow of water and transport of contaminants. We used these pore- to field-scale imaging technologies to demonstrate that complex flow behaviors can result in soils under different conditions. Through the research we have begun to unravel the detailed mechanisms controlling these flow behaviors, which is a key step in improving the predictability of such processes in real world settings. The project has thus far directly led to the production of 9 manuscripts and 17 conference presentations documenting the results of the research. A large number of graduate (5) and undergraduate students (8) were supported by the project and many more participated in the research. Several students also participated in the development of novel educational activities, like game-based learning activities and virtual reality visualizations for the earth sciences, which have been used in both university classes and public outreach. For example, the research team participated in the creation and delivery of experiential learning modules for middle school girls attending Clemson’s Project WISE STEM camp; these activities conveyed the importance and challenges of water issues faced by the girls’ peers around the world. Another key outreach aspect of the project was an effort to translate common hydrogeophysical tools used in research, such as ground-penetrating radar imaging and Python programming, into practical tools for practitioners working in the environmental consulting industry. To this end, workshops were prepared and delivered to working professionals participating in Clemson’s annual Hydrogeology Symposium. Overall this CAREER award was highly effective in aiding the PI to achieve an integrated approach to high quality research and education. The success of this project in building a strong approach to an academic career is further exemplified by the fact that two of the project participants have gone on to obtain tenure-track faculty positions and another is currently completing a post-doc prior to pursuing a faculty position.
Last Modified: 07/29/2018
Modified by: Stephen M Moysey
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