14 Oct 2020

Estimating the Density of Secretive, At-risk Snake Species on DoD Installations Using an Innovative Approach: IDEASS

Abstract: The Department of Defense (DoD) expends considerable resources managing and conserving threatened, endangered, or at-risk snake species. Management for these species is often hampered by a lack of basic knowledge regarding their population size and trajectory. The low detectability of most snakes makes it difficult to determine their presence, or to employ traditional methods to estimate abundance. This work demonstrated a novel, simulation-based method, Innovative Density Estimation Approach for Secretive Snakes (IDEASS), for estimating snake density based on systematic road surveys, behavioral observations of snake movement, and spatial movement (radio telemetry) data. This method was used to generate meaningful density estimates for two rare and cryptic snakes of conservation concern, the Southern Hognose and Eastern Diamondback Rattlesnake, at Fort Stewart, Georgia. IDEASS was also applied to an existing dataset to retroactively estimate density of a more common species of management concern, the Western Ratsnake, at Fort Hood, Texas. In all three cases, traditional density estimation via visual surveys and capture-mark-recapture (CMR) failed completely due to lack of captures and re-captures, despite extensive field effort. We conclude that IDEASS represents a powerful tool, and in some cases the only viable method, for estimating density of secretive snakes.

14 Oct 2020

Red River Structure Physical Model Study

Abstract: A proposed Red River Structure (RRS), intended to function as one of three gated structures comprising the Fargo-Moorhead Metropolitan Area Flood Risk Management Project, was tested in a general physical model. A 1:40 Froude-scale was applied to model the structure, engineered channels, existing bathymetry/topography in the Red River and overbank areas, and the proposed Southern Embankment. The physical model was used to ensure that the RRS could pass at least 104,300 cfs during the Probable Maximum Flood while maintaining a maximum pool water surface elevation of 923.5 ft. The physical model was also utilized to optimize the approach structure, stilling basin, retaining walls, and erosion protection designs. The physical modeling effort resulted in an optimized stilling basin wall, retaining wall, and end sill geometry/configuration where erosive conditions were not observed outside and adjacent to the stilling basin. Properly designed riprap (St. Paul District’s R470 gradation) proved to be successful in protecting the proposed RRS from potential scour downstream. The modified approach wall design proved to be successful in creating safe approach flow conditions as well as acceptable flow separation patterns. It is recommended that Alternative 3 be the design used going forward.

14 Oct 2020

The Demonstration and Validation of a Linked Watershed-Riverine Modeling System for DoD Installations – Patuxent Watershed, Maryland

Abstract: This work evaluated a linked watershed and riverine modeling system for the Patuxent River Watershed, Maryland against observed field data and model output from a watershed model. The performance objectives were computed for streamflow, sediment, total phosphorus, orthophosphorus, total nitrogen, ammonium, and nitrate using daily and monthly average model predictions and measured data. Hydrological Simulation Program – Fortran (HSPF) was used to compute runoff, sediment, and nutrient loadings, whereas the Hydrologic Engineer Center – River Analysis Sys-tem (HEC-RAS) was used to evaluate in-stream flow, channel sedimentation, and the fate/transport of nutrients. Model results were successful for calibration, validation, and management scenario analysis. Contaminants were not simulated for this watershed due to a lack of observed data to compare against. The study identified two implementation issues. First, while the Patuxent River did not experience dry bed conditions, where a stream may be intermittent, one can incorporate a very narrow slot at the low point in the cross-section to numerically keep the channel wet during very low flows. Second, to set up the linked model, there needs to be more observed water quality data to better constrain the HSPF output being used as boundary conditions to the HEC-RAS model.

1 Oct 2020

Comparison of Antifungal Efficiencies of Photocatalytic and Antimicrobial-Infused Coatings: Evaluation of Five Antimicrobial Coatings Using Standard Test Methods

Abstract: New buildings are being constructed and existing buildings retrofitted to be more energy efficient to meet increasingly stringent Department of Defense (DoD) energy standards. Although these standards save energy and lower operational costs, they also limit fresh air within a structure and can cause a buildup of harmful substances in indoor environments. Of particular concern are molds, which can put building occupants at risk and damage infrastructure. One possible solution to this increasing Army problem is to coat building materials with photocatalytic paints, which have the ability to both destroy microorganisms as well as the toxic byproducts they produce. This work compared two next-generation photocatalytic coatings against three more traditional antimicrobial-infused coatings for their ability to resist fungal contamination using three accelerated test conditions. Under each test condition the photocatalytic coatings were found to perform poorly compared to the antimicrobial-infused coatings. Moreover, the control coating, which contained no active antimicrobial (standard latex paint), performed as well as or better than all the antimicrobial coatings tested. This suggested that there may be little benefit to using antimicrobial coatings to inhibit fungal colonization over a standard latex paint; however, further testing is required to confirm this perception.

1 Oct 2020

Evaluation of Unmanned Aircraft System Coastal Data Collection and Horizontal Accuracy: A Case Study at Garden City Beach, South Carolina

Abstract: The US Army Corps of Engineers (USACE) aims to evaluate unmanned aircraft system (UAS) technology to support flood risk management applications, examining data collection and processing methods and exploring potential for coastal capabilities. Foundational evaluation of the technology is critical for understanding data application and determining best practices for data collection and processing. This study demonstrated UAS Multispectral (MS) and Red Green Blue (RGB) image efficacy for coastal monitoring using Garden City Beach, South Carolina, as a case study. Relative impacts to horizontal accuracy were evaluated under varying field scenarios (flying altitude, viewing angle, and use of onboard Real-Time Kinematic–Global Positioning System), level of commercial off-the-shelf software processing precision (default optimal versus high or low levels) and processing time, and number of ground control points applied during postprocessing (default number versus additional points). Many data sets met the minimum horizontal accuracy requirements designated by USACE Engineering Manual 2015. Data collection and processing methods highlight procedures resulting in high resolution UAS MS and RGB imagery that meets a variety of USACE project monitoring needs for site plans, beach renourishment and hurricane protection projects, project conditions, planning and feasibility studies, floodplain mapping, water quality analysis, flood control studies, emergency management, and ecosystem restoration.

1 Oct 2020

Eutrophication Management via Iron-Phosphorus Binding

Abstract: The presence of phosphorus (P) in excessive quantities can lead to undesired conditions, such as cyanobacterial/algal bloom. The over-enriched hypertrophic conditions or the excess amounts of nutrients (nitrogen and P, P being the primary nutrient of concern) are the major cause of harmful cyanobacterial blooms, which can be toxic and can also lead to oxygen depletion and anoxic respiration (hypoxia) in the hypolimnion. The presence of iron compounds has been shown to bind phosphorus and diminish harmful algal blooms. Therefore, an iron-plates-packed reactor has been designed to reduce P in surface water. This cost-effective and easy-to-install system has shown promising results in phosphorus reduction.

1 Oct 2020

Physical Factors That Influence Muddy Bed Aggregate Production, Size, and Durability

Abstract: Aggregation state significantly influences the transport characteristics of fine sediments. While research has documented the presence of mud aggregates in multiple coastal and estuarine environments, bed aggregates are largely absent from numerical models used to predict cohesive sediment transport. The U.S. Army Corps of Engineers (USACE) is conducting studies to evaluate the impact muddy bed aggregates have on sediment management issues, and how to account for aggregates in numerical models. In this study, physical properties associated with cohesive behavior were evaluated to determine if they could be used as predictors for bed aggregate production, size, and durability. Results showed that aggregates were consistently produced in cohesive sediments, and that median aggregate size was ~10-450x larger than the disaggregated sediment. Clay content had strong correlation with relative aggregate size, though statistically significant correlations were also found with sand content, water content, and density. Durability testing indicated that aggregate break-up followed exponential models, and that in limited instances, rates of break-up correlated with organic content.

1 Oct 2020

Development of a HEC-RAS Sediment Model for the Chippewa River, Wisconsin for Use in Predicting Future Dredging Activities

Purpose: This U.S. Army Corps of Engineers (USACE) Regional Sediment Management Technical Note (RSM-TN) describes the process of constructing and calibrating a sediment model that utilizes recent sediment data collection efforts performed by the U.S. Army Engineer Research and Development Center – Coastal and Hydraulics Laboratory (ERDC-CHL) and the U.S. Geological Survey (USGS) along the Chippewa River in Wisconsin. A USACE Institute for Water Resources (IWR), Hydrologic Engineering Center, River Analysis System (HEC-RAS, version 5.0.7) unsteady flow sediment model was developed to perform a continuous simulation of bed-load and suspended load transport and dredging operations through the Chippewa River and Lower Pool 4 of the Upper Mississippi River navigation channel. The resulting model developed through this effort can be useful in forecasting future channel maintenance needs through this reach of river.

1 Oct 2020

Hydrodynamic and Sediment Transport Modeling for James River Dredged Material Management

Abstract: The fate of material placed during dredging operations within the James River (Dancing Point-Swann Point reach) at a channel adjacent placement mound was modeled within this work. The study focuses on the potential migration of the placement mound into the channel as well as the transport of sediment resuspended during placement. A select combination of US Army Engineer Research and Development-developed models was utilized in this work to appropriately simulate hydrodynamic conditions, pipeline discharge near field suspended sediment estimates, far field transport of the pipeline discharge source term, and mound migration. Results show that the material released into the water column during placement remains in the placement area or is transported out of the area of interest downstream. A small fraction of sediment from the placement mound migrates into the channel after placement. The fine-grained nature of these sediments precludes these small volumes of sediment from depositing in the channel where the currents are strong.

1 Oct 2020

Microbiological Indicators Reflect Patterns of Life

Abstract:  Resolving patterns of human movement, specifically for actors of interest, in an urban environment is an extremely challenging problem because of the dynamic nature of human movement. This research effort explores a highly unconventional approach, addressing residual or lingering signatures of interest to the Army in an urban operation. Research suggests that unconventional signatures commonly associated with human presence or prior occupation of a space, such as microbes attached to skin cells or in the gut, may linger for an extended amount of time. In this scoping study, our objectives were to detect microbial communities in the built environment, to examine microbial community composition, and to investigate the longevity of a microbial signature. To do so, we conducted a controlled study to obtain a mechanistic understanding of the fidelity of the biological signatures in the built environment, with a particular focus on their longevity and stability.