Progress 10/01/03 to 09/30/12
Outputs
OUTPUTS: Attention had been focused on four water related projects. First, Dr. Birl Lowery and I co-advised a RA to work on a proof of concept pilot project to quantify the minimum sampling area to determine net water recharge and deep chemical leaching in the central sand area of Wisconsin. Second, I helped the UW-Madison STAR Director, Dr. Kathy Sanders, to launch a campus-wide multidisciplinary water incubator pilot program. Third, I helped the Wisconsin Commerce Department to host a Chinese delegation from the Anhui Province, China by organizing a workshop on non-point water pollution control as well as to work closely with the officials from the Wisconsin Commerce Department to develop strategy to pull Wisconsin expertise together to attract the Anhui Province so that they will seek technical helps from Wisconsin to remediate their water pollution problem. Finally, I continued the research to quantify the recent ET increase along the western Great Lakes regions. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
My work had generated two results. First, the Anhui Province has informed the Wisconsin Commerce Department that they will send another delegation to finalize the details of the collaboration between Anhui and Wisconsin to clean up the Chao Lake watershed in Anhui Province. Specifically, the Anhui Agricultural University had submitted a MOU to the UW-Madison Soil Science Department to seek technical help on the control of non-point source agricultural pollution. Second, a group of multidisciplinary faculty had worked together to address the water crisis in central Wisconsin that was caused by the recent ET increase along the western Great Lakes regions.
Publications
- No publications reported this period
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: 1. The Work on "Develop Hybrid Model to Quantify Contaminant Transport through Preferential Pathways" had been revised and accepted for publication. 2. Based on long-term regional precipitation and river discharge, an alternative method was developed to estimate the trend of watershed-scale evapotranspiration rate. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The regional evapotranspiration rate of the Central Wisconsin River Basin had increased one to two inches from 1994 to 2007. During the same period, the regional evapotranspiration rate of the Upper Rock River basin was steady.
Publications
- Kung, K.-J. S., C. S. Helling, T. J. Gish, E. J. Kladivko, T. S. Steenhuis, and D. B. Jaynes. 2007. A Hybrid Approach to Characterize and Predict Contaminant Transport through Preferential Pathways in Fractured Crystalline Rocks. Vadose Zone Hydrology (Accepted)
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: 1. Develop Multimedia-Based Material for Environmental Education: Five video scripts developed earlier were further revised. The effort has been focused on resolving major differences among PIs on how to best present a story to arouse audiences' interest to act and participate. 2. Develop Conceptual Model to Quantify Contaminant Transport through Preferential Pathways: Experimental tracer breakthrough patterns collected by Becker and Shapiro (2000) were used to test a hybrid approach to quantify and predict contaminant transport in porous media. Because the potential gradient (or head difference between the injection well and withdraw well) was not given, different scenarios were assumed in the analysis. As the results were submitted to the Water Resources Research, the editor rejected the approach. Currently, Dr. Becker found and provided the raw data on head difference between the injection well and withdraw well, while Dr. Shapiro needs time to review the raw data before he can approve the release of the raw data. 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
Retardation dictates the fate and transport of sorbing chemicals in porous media. The retardation coefficients could be accurately measured under lab condition. It has been unclear how to scale up the lab-measured retardation coefficients to predict the transport of radioactive cations in porous media with preferential pathways. The hybrid approach could offer insight on the relationship of the lab-measured retardation coefficients and the actual field-scale retardation coefficients of the radioactive cations.
Publications
- No publications reported this period
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: The two prevalent methods to quantify and predict contaminant transport in porous media have been deterministic approach based on solving the convection-dispersion equation and stochastic approach such as Transfer Function Model. The unique strength and weakness of these two methods were examined. How to develop a hybrid approach by avoiding the weakness of each method, while preserving their strengths, was proposed and tested in 2006. The theoretical foundation of the hybrid approach was further refined in 2007. Experiments data of fate and transport of both radioactive cations and conservative tracers in fractured aquifers from literatures were collected to test the applicability of the hybrid method. Preliminary results indicated that the equivalent pore spectrum derived based on the breakthrough patterns of conservative tracers can be used to predict the transport of radioactive cations that experienced retardation because of sorption.
PARTICIPANTS: C. S. Helling: USDA-ARS Sustainable Perennial Crops Lab. (retired) T. J. Gish: USDA-ARS Hydrology & Remote Sensing Lab E. J. Kladivko: Department of Agronomy, Purdue University T. S. Steenhuis: Department of Biological and Environmental Engineering, Cornell University D. B. Jaynes: USDA-ARS National Soil Tilth Lab
TARGET AUDIENCES: The targeted audiences are the soil and environmental scientists.
Impacts
Retardation dictates the fate and transport of sorbing chemicals in porous media. The retardation coefficients could be accurately measured under lab condition. It has been unclear how to scale up the lab-measured retardation coefficients to predict the transport of radioactive cations in porous media with preferential pathways. The hybrid approach could offer insight on the relationship of the lab-measured retardation coefficients and the actual field-scale retardation coefficients of the radioactive cations.
Publications
- Kung, K.-J. S., C. S. Helling, T. J. Gish, E. J. Kladivko, T. S. Steenhuis, and D. B. Jaynes. 2007. A Hybrid Approach to Characterize and Predict Contaminant Transport through Preferential Pathways in Fractured Crystalline Rocks. Water Resources Research (under review.
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Progress 01/01/06 to 12/31/06
Outputs
Releasing contaminants has been a trademark of modern human society. Within a porous media, adsorption and degradation are the main mechanism in nature that can filter out contaminants. On the other hand, preferential flow pathways in a porous media behave like interstate highways that can quickly spread contaminants to cause water pollution and environmental hazards. From 1996 to 2002, field experiments were conducted to quantify contaminant transport through macropore-type preferential flow pathways in unsaturated soil profiles. From 2001 to 2005, a hybrid approach by blending the strength of deterministic and stochastic models was developed and tested to characterize and predict contaminant through macropore-type preferential flow pathways in unsaturated soil profiles. It was found in 2006 that the concept of deriving equivalent pore size spectrum of macropore-type preferential pathways in unsaturated soils could successfully characterize and predict contaminant
transport through preferential pathways in saturated aquifers made of fractured rocks. The tracer mass flux breakthrough patterns measured by di-pole sampling method in fractured rocks revealed that the tails of these patterns had a slope of -2 on a log-log plot. Analytical solutions of contaminant mass flux through one-dimensional cylindrical pores or two-dimensional fractures were derived. These solutions explained the reason of this unique tail slope. When these analytical solutions were plugged into the hybrid approach, the behavior and fate of tracer transport under different potential gradients were revealed.
Impacts
The research finding mentioned avove was based on breakthrough patterns published in seven different papers. The hybrid approach must be first tested against more measured breakthrough patterns. If the hybrid approach is valid, it will become a useful tool to predict the fate of radioactive wastes in groundwater under the worst-case scenario.
Publications
- Kung, K.-J. S., E. J. Kladivko, C. S. Helling, T. J. Gish, T. S. Steenhuis, and D. B. Jaynes. 2006. Quantifying pore size spectrum of macropore-type preferential pathways under transient flow. Vadose Zone J. 2006 5: 978-989.
- Gish, T.J. and K.-J. S. Kung. 2007. Procedure for quantifying a solute flux to a shallow perched water table. Geoderma. 138(1-2):57-64.
- Kung, K.-J. S., C. S. Helling, T. J. Gish, T. S. Steenhuis, E. J. Kladivko, and D.B. Jaynes. 2007. A hybrid approach to characterize and predict contaminant transport through preferential pathways in fractured rocks. Water Resources Research. (in review)
- Gish, T.J., K-J.S Kung, Y.A. Pachepsky, L. McKee, and W.P. Dulaney. 2007. Multiple year observation and analysis of nutrient and pesticide in a shallow water table. JEQ. (in review)
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Progress 01/01/05 to 12/31/05
Outputs
Field experiments were conducted in Elkhorn, Wisconsin. The site, on Pella silt loam soil, is located within the Southern Wisconsin and Northern Illinois Drift Plain. By applying chemicals to a narrow (2.7 H 19.2 m) strip and, then, monitoring chemical mass flux from an underlying tile drain, our results were the first to demonstrate that mass flux breakthrough patterns of chemical transport through macropore-type preferential pathways was a repeatable deterministic process. By varying precipitation intensities (0.89, 1.2, 2.4, and 4.4 mm h-1), we demonstrated the existence of a threshold for the process of activating macropore-type preferential pathways. At 0.89 mm h-1, macropore-type preferential pathways were not hydraulically-active. Chemical was transported though soil matrix pores and arrived in the tile (ca. 1 m depth) drainage more than 90 h after application. At 1.2 mm h-1, some macropore-type preferential pathways with small equivalent pore radii became
hydraulically-active and the chemical arrival time was about 30 h. At 2.4 mm h-1, arrival time was ca. 10 h. At 4.4 mm h-1, the chemical arrival time was dropped to 16 min. When plotted on a log-log scale, the tail of mass flux breakthrough patterns of chemical transport through macropore-type preferential pathways had a slope of -3. This suggested that chemical transport through macropore-type preferential pathways can be conceptualized as that through the capillary tubes. This greatly simplified the task of quantifying the equivalent pore spectrum of the macropore-type preferential pathways. The pore spectrum of the macropore-type preferential pathways could be derived by using the best curve-fitting method to match the predicted with measured mass flux breakthrough patterns. The derived pore spectrum had distinct cut-off points on both sides, beyond which the frequency dropped to zero. Traditionally, it has been commonly accepted that all small pores must first be saturated before
any larger pores can become hydraulically-active. Our results demonstrated that pores with a wide range of equivalent pore radii became hydraulically-active simultaneously when precipitation intensity increased. From field-scale experiments with four sequentially-applied tracers, conducted near Butlerville, Indiana, we found that soil pore spectrum of macropore-type preferential pathways was closely related to the water content near the soil surface. The trends of the large end of the pore spectrum (i.e., the largest effective macropores) from the Wisconsin site match well with those parameters from the Indiana site. The only similarities between the two sites were crop management practices. This strongly suggested that pore spectrum of macropore-type preferential pathways is comparatively universal. One could use the pore spectrum developed from one site to predict macropore-type preferential flow pathways of another site with similar soil texture and perhaps crop management.
Impacts
We determined the mechanism of macropore-type transport of chemicals in soils and quantified how those pores become hydraulically active. This is useful for development of a management model for predicting leaching potential of pesticides.
Publications
- No publications reported this period
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