The stratification of channel sediments and their vertical hydraulic conductivity (K v ) are impo... more The stratification of channel sediments and their vertical hydraulic conductivity (K v ) are important hydrologic information in the analysis of stream-aquifer interactions. This paper describes the use of direct-push technology to generate electrical conductivity (EC) logs and collect continuous sediment cores beneath river channels. The techniques were applied to nine study sites along a 130 km reach of the Platte River in southeast Nebraska. EC logs for the channel surface down to as much as 24 m below the channel surface indicate that the channel sediments in the western part of the reach consist predominantly of sand and gravel; low-K v silt-clay layers occur in the rest of the reach. These silt-clay layers are either interbedded with sand and gravel or occur as a major unit within the channel sediments. As a result, the values of K v , determined from the sediment cores, can vary by four to five orders of magnitude in the same vertical profile of channel sediments at a number of sites. The river channel is not lined by a low-K v layer at the surface. Instead, the K v values for the top part of channel sediments were consistently greater than K v values for sediments in deeper parts. They show a decreasing tendency with the depth. This paper also analyzes the effect of low-K v layers within channel sediments on streamflow depletion induced by groundwater pumping. Simulation results suggest that the effectiveness of low-K v layers on the calculation of streamflow depletion depends on their depth, thickness, vertical permeability, the length along the channel, and the width within the channel, as well as the extension into the aquifer on both sides of the river. A low-K v layer present at the channel surface seems to be the most effective hydrologic feature in reducing the hydrologic connection of stream-aquifer. ª
Travis P. Searle, Seminary Instructor The Church of Jesus Christ of Latter-day Saints This study ... more Travis P. Searle, Seminary Instructor The Church of Jesus Christ of Latter-day Saints This study examined the effect of agriculture faculty training in and practice of methodologies to explicitly teach critical thinking skills related to course content and subsequent change in student critical thinking disposition. Twelve instructors in 14 agriculture courses underwent a year-long program of instruction in effective critical thinking development. Students completed the University of Florida-Engagement, Maturity, and Innovativeness assessment (UF-EMI) at the beginning and the end of the semester. Pair-wise comparisons showed significant increases in all three critical thinking dispositions (i.e., engagement, cognitive maturity, and innovativeness). In addition, a step-wise regression on the data gathered at the end of the semester showed that grade point average was positively related to all three critical thinking dispositions and being in one's first year of college was negatively related to each dimension. The 300 course level was negatively related to innovativeness and engagement. Being in the second and third year of college were also negatively related to engagement. This study supports the notion that instructors can influence students' critical thinking disposition within the limited time of a college semester. . (2010). Teaching and assessing critical thinking skills for argument analysis in psychology. Teaching of Psychology, 37, 91-96.
Albano, J., Comfort, SD, Zlotnik, V., Halihan, T., Burbach, M., Chokejaroenrat, C., Onanong, S. a... more Albano, J., Comfort, SD, Zlotnik, V., Halihan, T., Burbach, M., Chokejaroenrat, C., Onanong, S. and Clayton, W.(2010), In Situ Chemical Oxidation of RDX-Contaminated Groundwater with Permanganate at the Nebraska Ordnance Plant. Ground Water Monitoring & ...
The direct-push (DP) approach for characterization of the shallow unconsolidated sub-surface is a... more The direct-push (DP) approach for characterization of the shallow unconsolidated sub-surface is a rapidly developing methodology that deploys hydrogeological, geotechnical, and geophysical tools in the sub-surface. It offers significant advantages as compared to techniques using traditional drilling and permanent piezometers, but requires real-time on-site decisions. Selection of the number of tests, sequence, location, and depth makes the planning stage crucial for successful and effective field studies. Whereas the analysis of various DP-based hydrogeological, geotechnical, and geophysical methods is well presented in the literature, recommendations for planning DP field applications are scarce. We illustrate applications of DP-based techniques (electrical conductivity profiling of the aquifer, groundwater sampling, slug testing, and soil core extraction) for evaluation of aquifer-lake interactions in a remote and poorly accessible area of the Nebraska Sand Hills with numerous saline lakes. In addition to the background data on hydrostratigraphy and groundwater salinity, we report an approach to combining and optimizing the DP techniques, including the work sequence, depth limitations, data quantity, and scheduling. The data and insights gained will be useful in designing characterization programs in other sand dune-lake environments.
physical-chemical characteristics that allow for mobility and moderate persistence. Atrazine, the... more physical-chemical characteristics that allow for mobility and moderate persistence. Atrazine, the most wide-Profiles of ground water pesticide concentrations beneath the Nespread pesticide in the nation's ground water, and its braska Management Systems Evaluation Area (MSEA) describe the effect of 20 yr of pesticide usage on ground water in the central Platte transformation products together with cyanazine, sima-Valley of Nebraska. During the 6-yr (1991-1996) study, 14 pesticides zine, and alachlor and metolachlor and their transformaand their transformation products were detected in 7848 ground water tion products are the most commonly detected herbisamples from the unconfined water table aquifer. Triazine and acetcides in row-cropped regions (Barbash et al., 1999) (see amide herbicides applied on the site and their transformation products for chemical names of pesticides detected in had the highest frequencies of detection. Atrazine [6-chloro-N-ethylthis study).
The stratification of channel sediments and their vertical hydraulic conductivity (K v ) are impo... more The stratification of channel sediments and their vertical hydraulic conductivity (K v ) are important hydrologic information in the analysis of stream-aquifer interactions. This paper describes the use of direct-push technology to generate electrical conductivity (EC) logs and collect continuous sediment cores beneath river channels. The techniques were applied to nine study sites along a 130 km reach of the Platte River in southeast Nebraska. EC logs for the channel surface down to as much as 24 m below the channel surface indicate that the channel sediments in the western part of the reach consist predominantly of sand and gravel; low-K v silt-clay layers occur in the rest of the reach. These silt-clay layers are either interbedded with sand and gravel or occur as a major unit within the channel sediments. As a result, the values of K v , determined from the sediment cores, can vary by four to five orders of magnitude in the same vertical profile of channel sediments at a number of sites. The river channel is not lined by a low-K v layer at the surface. Instead, the K v values for the top part of channel sediments were consistently greater than K v values for sediments in deeper parts. They show a decreasing tendency with the depth. This paper also analyzes the effect of low-K v layers within channel sediments on streamflow depletion induced by groundwater pumping. Simulation results suggest that the effectiveness of low-K v layers on the calculation of streamflow depletion depends on their depth, thickness, vertical permeability, the length along the channel, and the width within the channel, as well as the extension into the aquifer on both sides of the river. A low-K v layer present at the channel surface seems to be the most effective hydrologic feature in reducing the hydrologic connection of stream-aquifer. ª
Travis P. Searle, Seminary Instructor The Church of Jesus Christ of Latter-day Saints This study ... more Travis P. Searle, Seminary Instructor The Church of Jesus Christ of Latter-day Saints This study examined the effect of agriculture faculty training in and practice of methodologies to explicitly teach critical thinking skills related to course content and subsequent change in student critical thinking disposition. Twelve instructors in 14 agriculture courses underwent a year-long program of instruction in effective critical thinking development. Students completed the University of Florida-Engagement, Maturity, and Innovativeness assessment (UF-EMI) at the beginning and the end of the semester. Pair-wise comparisons showed significant increases in all three critical thinking dispositions (i.e., engagement, cognitive maturity, and innovativeness). In addition, a step-wise regression on the data gathered at the end of the semester showed that grade point average was positively related to all three critical thinking dispositions and being in one's first year of college was negatively related to each dimension. The 300 course level was negatively related to innovativeness and engagement. Being in the second and third year of college were also negatively related to engagement. This study supports the notion that instructors can influence students' critical thinking disposition within the limited time of a college semester. . (2010). Teaching and assessing critical thinking skills for argument analysis in psychology. Teaching of Psychology, 37, 91-96.
Albano, J., Comfort, SD, Zlotnik, V., Halihan, T., Burbach, M., Chokejaroenrat, C., Onanong, S. a... more Albano, J., Comfort, SD, Zlotnik, V., Halihan, T., Burbach, M., Chokejaroenrat, C., Onanong, S. and Clayton, W.(2010), In Situ Chemical Oxidation of RDX-Contaminated Groundwater with Permanganate at the Nebraska Ordnance Plant. Ground Water Monitoring & ...
The direct-push (DP) approach for characterization of the shallow unconsolidated sub-surface is a... more The direct-push (DP) approach for characterization of the shallow unconsolidated sub-surface is a rapidly developing methodology that deploys hydrogeological, geotechnical, and geophysical tools in the sub-surface. It offers significant advantages as compared to techniques using traditional drilling and permanent piezometers, but requires real-time on-site decisions. Selection of the number of tests, sequence, location, and depth makes the planning stage crucial for successful and effective field studies. Whereas the analysis of various DP-based hydrogeological, geotechnical, and geophysical methods is well presented in the literature, recommendations for planning DP field applications are scarce. We illustrate applications of DP-based techniques (electrical conductivity profiling of the aquifer, groundwater sampling, slug testing, and soil core extraction) for evaluation of aquifer-lake interactions in a remote and poorly accessible area of the Nebraska Sand Hills with numerous saline lakes. In addition to the background data on hydrostratigraphy and groundwater salinity, we report an approach to combining and optimizing the DP techniques, including the work sequence, depth limitations, data quantity, and scheduling. The data and insights gained will be useful in designing characterization programs in other sand dune-lake environments.
physical-chemical characteristics that allow for mobility and moderate persistence. Atrazine, the... more physical-chemical characteristics that allow for mobility and moderate persistence. Atrazine, the most wide-Profiles of ground water pesticide concentrations beneath the Nespread pesticide in the nation's ground water, and its braska Management Systems Evaluation Area (MSEA) describe the effect of 20 yr of pesticide usage on ground water in the central Platte transformation products together with cyanazine, sima-Valley of Nebraska. During the 6-yr (1991-1996) study, 14 pesticides zine, and alachlor and metolachlor and their transformaand their transformation products were detected in 7848 ground water tion products are the most commonly detected herbisamples from the unconfined water table aquifer. Triazine and acetcides in row-cropped regions (Barbash et al., 1999) (see amide herbicides applied on the site and their transformation products for chemical names of pesticides detected in had the highest frequencies of detection. Atrazine [6-chloro-N-ethylthis study).
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Papers by Mark Burbach