Engineering Commons^™

A Conceptual Framework For Evaluating Agricultural Economic And Environmental Tradeoffs In The Central Nebraska Basins Using Field-Level Area Study Data, P. G. Lakshminarayan, Bruce A. Babcock, Paul Mitchell

United States Environmental Protection Agency: Staff Publications

The high plains aquifer system, which underlies nearly 85 percent of the state of Nebraska, supplies about 95 percent of all groundwater used in Nebraska. Agricultural activities in the state use most of the groundwater (94 percent), while domestic and commercial users also depend heavily on this groundwater source. About 84 percent of the state's public drinking water supplies are from groundwater (Comfort, Shea, and Roeth 1994; Exner and Spalding 1990). With such high dependence on groundwater preserving groundwater quality is of crucial importance.

Intensive agriculture characterizes this region, especially in the Central Nebraska Basin (CNB), in part because of …

Missouri River Gavins Point Dam Degradation Trends Study

US Army Corps of Engineers

This report evaluates degradation trends of a study reach downstream of Gavins Point Dam. Basic pertinent data collected on various hydraulic and geomorphic elements and channel characteristics collected after the construction of the Gavins Point Dam are presented and evaluated. This volume will serve as a permanent record of most of the basic observations.

Results Of A Biological Survey For Leptodea Leptodoll (Rafinesque, 1820) In The Missouri River In Southeastern South Dakota, Arthur H. Clarke

US Army Corps of Engineers

In late September and early October, 1995, a brail survey was carried out to determine the distribution of Leptodea leptodon (Rafinesque) in the Missouri River near Yankton and Vermillion, South Dakota. We did not find L. leptodon but useful information in three areas was nevertheless brought to light, viz. :

(1) Leptodea leptodon is unusual in that adults are deeply buried and are not available by brail. Subsequent investigations which seek to determine its abundance at its only known location in the research area, close below Gavin's Point Dam, can only be carried out with the help of a diver …

Spatial Patterns Analysis Of Field Measured Soil Nitrate, Farida Shaukat Goderya, Mohamed F. Dahab, Wayne E. Woldt, Istvan Bogardi

Department of Biological Systems Engineering: Papers and Publications

The purpose of this study was to assess the spatial variability of residual soil nitrate, measured in three contiguous 16 ha fields. Available data for residual soil nitrate were examined using conventional statistics. Data tended to be skewed with the mean greater than the median. Geostatistical methods were used to characterize and model the spatial structure. Three dimensional spatial variability was examined using two semivariograms: horizontal-spatial and vertical. Two dimensional horizontal-spatial semivariograms were also computed for each 0.3m (1ft) layer. Semivariogram analysis showed that there were similarities in the patterns of spatial variability for all fields. The results suggest that …

Development Of A Tl-3 F-Shape Temporary Concrete Median Barrier, Ronald K. Faller, John R. Rohde, Barry T. Rosson, Richard P. Smith, Kenneth H. Addink

Mid-America Transportation Center: Final Reports and Technical Briefs

A temporary concrete median barrier (CMB) was designed and tested for compliance under the Test Level 3 (TL-3) guidelines specified in the Recommended Procedures for the Safety Performance Evaluation of Highway Features, National Cooperative Highway Research Program (NCHRP) Report No. 350. The barrier is built to the new metric standards and has a traditional pin and loop configuration for interconnection. The objective of this research project was to develop and evaluate a standardized, temporary concrete barrier design while addressing the concerns for safety, economy, structural integrity, constructability, ease of installation, and maintenance. The resulting F-shape barrier segment is 3,800-mm …

Metering Characteristics Accompanying Rate Changes Necessary For Precision Farming, A. Bahri, K. Von Bargen, Michael F. Kocher, L. L. Bashford

Department of Biological Systems Engineering: Papers and Publications

Agricultural machines used in precision fanning must adjust application rates according to the needs of each cell within a field. Changing from an initial application rate to a new rate while the machine travels from one cell to another in the field is accompanied with some misapplication. The severity of this misapplication depends on the down-the-row delivery characteristics of the metering system and the magnitude of the rate change from cell to cell.

On-the-go rate change tests evaluated the down-the-row performance of an operator controlled metering system when increasing and decreasing wheat seeding rates by 10 and 20 kg/ha steps. …

Approximation Of Biodegradation Rate Constants For Monoaromatic Hydrocarbons (Btex) In Ground Water, Todd Weidemeier, Matthew Swanson, John Wilson, Donald Kampbell, Ross Miller, Jerry Hansen

United States Environmental Protection Agency: Staff Publications

Two methods were used to approximate site-specific biodegradation rates of monoaromatic hydrocarbons (benzene, toluene, ethylbenzene, and xylenes [BTEX]) dissolved in ground water. Both use data from monitoring wells and hydrologic properties of the aquifer to estimate a biodegradation rate constant that can be sued in ground water solute fate and transport models. The first method uses a biologically recalcitrant tracer in the ground water, associated with the hydrocarbon plume to normalize changes in concentration of BTEX under anaerobic conditions; attenuation of the tracer is attributed to dilution, sorption, and/or volatilization. Attenuation of BTEX in excess of the attenuation of the …

Variability In Volume Metering Devices, Leonard L. Bashford, Abdeljabar Bahri, K. Von Bargen, Michael F. Kocher

Department of Biological Systems Engineering: Papers and Publications

The inherent variability of seed and fertilizer application from volumetric metering devices is not readily recognized. The Canadian Prairie Agricultural Machinery Institute (P AMI) suggests a maximum coefficient of variation (CV) of 15% among outlets for seeding grain or applying fertilizer. P AMI does not report down-the-row variability of individual outlets. Parameters that influence variability of volumetric measuring external fluted wheels such as rotational speed of the metering wheel, product delivery rate, seed size, and cell collection lengths were examined.

In the first study, external fluted wheel meters on four grain drills were tested for seed delivery variability for wheat …