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Archive: May, 2022
  • Growth Assessments of Starry Stonewort (Nitellopsis obtusa) in Various Substrate Types for Large-scale Cultivation Studies

    Purpose: The purpose of this study was to compare multiple substrate types to optimize cultivation conditions for the invasive macroalga Nitellopsis obtusa (Desv. in Loisel.) J. Groves, commonly known as starry stonewort. Large-scale cultivation will allow for tiered approaches to management evaluation research while minimizing the influence of confounding variables.
  • Spatial and Temporal Variability of the Alligatorweed Pathogen, Alternaria alternantherae, in Louisiana

    Abstract: Alligatorweed leaf spot is a disease of invasive Alternanthera philoxeroides(Alligatorweed) in the southern US, caused by Alternaria alternantherae. However, little is known about when or where this pathogen naturally occurs. To better understand this species’life history, we examined temporal (every 2–3 weeks) and spatial (latitudinal) patterns of A. alternantherae occurrence at sites in Louisiana for 2 y. Pathogen presence reflectedclear within-year temporal and spatial patterns. Overall, the percentage of leaves infectedwith A. alternantherae was low during spring each year (0–20% infected) but increasedthroughout summer (maximum of 50% infected), and plants in northern sites had lowerfrequency of infection relative to southern sites until later in the year (late summer/early fall) but only in 1 of the 2 years of our study. The mean proportion of leaves infected with A. alternantherae declined with latitude both years (P = 0.01) and variability increasedwith latitude (P = 0.04), a pattern suggestive of range limitation in northern areas. We estimate a northern distributional limit of 34°N for A. alternantherae in Louisiana, but Alligatorweed occurs farther north. Although we did not directly examine disease impacts to Alligatorweed during the study, they may be greatest in southern areas, where the pathogenis more common early and throughout the growing season, and thus may be less likely to provide control in northern infestations of the invasive Alligatorweed.
  • Improving Container Shipment Analysis

    Abstract: US Army Corps of Engineers (USACE) deep-draft navigation economic analyses use assumptions about the sensitivity of vessel operations to channel modification to estimate national economic development benefits. The complexity and proprietary nature of carrier deployment decisions and loading practices adds uncertainty to USACE navigation studies. This report attempts to provide an overview of containership deployment and loading practices as it relates to USACE navigation studies to improve the quality of deep-draft economics. The report relies on trade data, vessel order books, and carrier interviews to study the impact of channel modification on vessel loading and deployment. The report makes recommendations for developing deployment and loading inputs for future economic evaluations.
  • Ballistic Protection Using Snow

    Abstract: Small (5.56 mm, 7.62 mm and 9 mm) and medium (12.7 mm) arms rounds were fired at snow-filled 1.5m cubic gabions in a mid-winter condition in Fairbanks, Alaska. The rounds were excavated and penetration by each ammunition type was measured. A distribution and average of penetration depth was determined. All 320 rounds fired were captured within 1.5m after entering the snow barrier. Comparison with published models of ballistics penetration of snow showed mixed results with several matching our data within 10% and all but one within 32%. However, most of these models are simplistic in that they accommodate limited variables and therefore may not be expected to perform well in all settings. We conclude that snow-based ballistics protection structures can be quickly and efficiently erected in suitable environments and with minimal size, can provide reliable protection against small and medium arms fire.
  • Southern Flying Squirrels (Glaucomys volans) as Major Predators of Avian Nest Boxes

    Abstract: Bird population dynamics are strongly affected by the ability to successfully reproduce, and nest predation is the primary cause of reproductive failure for most birds. Efforts to understand nest predation and manage its effects on species of conservation concern require knowledge of the ecology of associated predator assemblages. Recently, studies using cameras to record events at nests have illuminated this previously under-studied avian life stage, but such studies have been largely limited to open-cup nests. Cavity nests may be depredated by a different suite of predators and incubating or brooding females occupying such nests may be more vulnerable to predation relative to open-cup nests. Here, we used motion-activated, infrared trail cameras to record predators of artificial nest boxes in a Pinus palustris Mill. (Longleaf Pine) forest in southern Alabama. Although Glaucomys Volans L. (Southern Flying Squirrel) have only rarely been captured on film preying on nests, we found them to be responsible for the vast majority (84%) of bird-nest depredations at nest boxes, and these depredations contributed to a surprisingly low overall rate of nest success (~20%). These results may have implications for the conservation of birds that nest in artificial cavities in Longleaf Pine forests and highlight the importance of further studies on predator assemblages and their effects on nesting birds.
  • Low-Sill Control Structure Gate Load Study

    Abstract: The effort performed here describes the process to determine the gate lifting loads at the Low-Sill Control Structure. To measure the gate loads, a 1:55 Froude-scaled model of the Low-Sill Control Structure was tested. Load cells were placed on 3 of the 11 gates. Tests evaluated the gate loads for various hydraulic heads across the structure. A total of 109 tests were conducted for 14 flows with each flow having two gate settings provided by the United States Army Corps of Engineers, New Orleans District. The load data illustrated the potential for higher gate lifting loads (GLL) to occur at the mid-range gate opening (Go) for Gates 3 and 6. While for Gate 10, the highest GLL (452 kips, maximum load in testing) was at a Go = 4.2 ft. Conversely, for the low-flow bays, the highest load occurred at Go = 24.86 ft.
  • Three-Dimensional Underseepage Evaluation for Profit Island Vicinity Levee, North of Baton Rouge, Louisiana

    Abstract: This project developed a three-dimensional (3D) seepage model to evaluate efficiency of 84 relief wells and factors of safety (FoS) along the Profit Island vicinity levee (PIVL), north of Baton Rouge, Louisiana. The PIVL model was built based on US Geological Survey MODFLOW-USG. Moreover, a 3D seepage model of RocScience RS3 was also built for a specific study of relief well experiments conducted by the US Army Corps of Engineers in the 1930s and 1940s. The PIVL model was calibrated with measured piezometric head data and relief well flow rates in 1997. Six flood scenarios were conducted: the extreme flood (56 feet), design flood (52.4 feet), 1997 flood (50 feet), 2008 flood (49.22 feet), 2017 flood (45.55 feet), and 2018 flood (49.1 feet). The modeling results show that FoS are all above 1.5 given relief wells at the 1997 design condition. FoS calculated by the blanket theory are more conservative than those by the PIVL model because designed discharge rates were not observed in the field. In comparison with measured flow rates in 2008, the PIVL modeling result indicates potential clogging at many relief wells. New piezometric data and well discharge data are recommended to re-evaluate factors of safety.
  • Soil and Vegetation Responses to Amendment with Pulverized Classified Paper Waste

    Abstract: The United States Army produces a significant amount of classified paper waste that is pulverized to a fine consistency unsuitable for recycling. However, cheap, high quality organic materials such as classified paper waste are useful as soil amendments. The objective of this research was to evaluate the utilization of pulverized classified paper waste as a soil amendment to improve soil health and increase establishment of desirable native grasses on degraded Army training lands. Paper was applied at rates of 9 to 72 Mg ha-1 to two soil types at Fort Polk, LA: an alfisol (very fine sandy loam - Fine, smectitic, thermic Chromic Vertic Hapludalfs) and an ultisol (loamy fine sandy - Loamy, siliceous, semiactive, thermic Arenic Paleudults). These are common soil orders found on military training lands nationwide and represent fertile (alfisol) and unfertile (ulitsol) soils. Vegetation and soils were monitored over 2 growing seasons. No increase in heavy metals were observed in soils. Extensive analysis showed very low levels of regulated contaminants in the paper, but most were below detection limits. The ultisol site showed improved soil physical and chemical properties, while desirable vegetation benefitted from nutrient immobilization at the alfisol site. Based on the results of this study, applying pulverized paper waste to soil at a rate of 35.9 Mg ha-1 is recommended. Application of paper waste to soils had no adverse environmental effects, improved soil physiochemical properties, and facilitated establishment of desirable native vegetation.
  • Waterborne Geophysical Investigation to Assess Condition of Grouted Foundation: Old River Control Complex – Low Sill Structure, Concordia Parish, Louisiana

    Abstract: The Old River Low Sill Structure (ORLSS) at the Old River Control Complex (ORCC) in Concordia Parish, LA, is a steel pile-founded, gated reinforced-concrete structure that regulates the flow of water into the Atchafalaya River to prevent an avulsion between the Mississippi River and the Atchafalaya River. A scour hole that formed on the southeast wall of ORLSS during the Mississippi River flood of 1973 was remediated with riprap placement and varied mixtures of self-leveling, highly pumpable grout. Non-invasive waterborne geophysical surveys were used to evaluate the distribution and condition of the grout within the remediated scour area. Highly conductive areas were identified from the surveys that were interpreted to consist mostly of grout. Resistive responses, likely representing mostly riprap and/or sediment, were encountered near the remediated scour area periphery. A complex mixture of materials in the remediated scour area is interpreted by the more gradual transitions in the geophysical response. Survey measurements immediately beneath ORLSS were impeded by the abundance of steel along with the structure itself. The survey results and interpretation provide a better understanding of the subsurface properties of ORLSS.
  • AIS Data Case Study: Dredge Material Placement Site Evaluation in Frederick Sound near Petersburg, Alaska

    Abstract: The purpose of this Coastal and Hydraulics Laboratory Technical Note (CHETN) is to present an application of historic vessel position information acquired through the Automatic Identification System (AIS), which provides geo-referenced and time-stamped vessel position information. The US Army Corps of Engineers, Alaska District (POA), needed to evaluate potential placement sites for dredged material near Petersburg, AK, and possible impacts to navigation were considered as part of the evaluation process.