21 Sep 2022

Evaluation of Climatic and Hydroclimatic Resources to Support the US Army Corps of Engineers Regulatory Program

Abstract: Short-term climatic and hydrologic interactions, or hydroclimatology, are an important consideration when delineating the geographic extent of aquatic resources and assessing whether an aquatic resource is a jurisdictional water of the United States (WOTUS) and is therefore subject to the Clean Water Act (CWA). The now vacated 2020 Navigable Waters Protection Rule (NWPR) required the evaluation of precipitation and other hydroclimatic conditions to assess the jurisdictional status of an aquatic resource based on normal hydroclimatic conditions. Short-term hydroclimatic conditions, such as antecedent precipitation, evapotranspiration, wetland delineation, and streamflow duration assessments, provide information on an aquatic resource’s geo-graphic extent, hydrologic characteristics, and hydrologic connectivity with other aquatic resources. Here, researchers from the US Army Corps of Engineers, Engineer Research and Development Center (ERDC) evaluate tools and data available to practitioners for assessing short-term hydroclimatic conditions. The work highlights specific meteorological phenomena that are important to consider when assessing short-term hydroclimatic conditions that affect the geographic extent and hydrologic characteristics of an aquatic resource. The findings suggest that practitioners need access to data and tools that more holistically consider the impact of short-term antecedent hydroclimatology on the entire hydrologic cycle, rather than tools based solely on precipitation.

19 Sep 2022

A Revisit and Update on the Verification and Validation of the Coastal Modeling System (CMS): Report 1–Hydrodynamics and Waves

Abstract: This is the first part of a two-part report that revisits and updates the verification and validation (V&V) of the Coastal Modeling System (CMS). The V&V study in this part of the report focuses on hydrodynamic and wave modeling. With the updated CMS code (Version 5) and its latest graphical user interface, the Surface-water Modeling System (Version 13), the goal of this study is to revisit some early CMS V&V cases and assess some new cases on model performance in coastal applications. The V&V process includes the comparison and evaluation of the CMS output against analytical solutions, laboratory experiments in prototype cases, and field cases in and around coastal inlets and navigation projects. The V&V results prove that the basic physics incorporated are represented well, the computational algorithms implemented are accurate, and the coastal processes are reproduced well. This report provides the detailed descriptions of those test simulations, which include the model configuration, the selection of model parameters, the determination of model forcing, and the quantitative assessment of the model and data comparisons. It is to be hoped that, through the V&V process, the CMS users will better understand the model’s capability and limitation as a tool to solve real-world problems.

19 Sep 2022

Systematic Beneficial Use of Dredged Sediments: Matching Sediment Needs with Dredging Requirements

PURPOSE: This technical note (TN) will outline a framework to identify beneficial and cost-effective coastal beneficial use of dredged sediment (BUDS) projects. Creation of a BUDS framework that can be applied at scale will promote sustainable BUDS practices, facilitating the delivery of flood risk management, social, and environmental benefits while still fulfilling the US Army Corps of Engineers (USACE) navigation mission. This proactive forecasting approach uses multi-criteria decision analysis (MCDA) and optimization tools to balance tradeoffs between navigation dredging and BUDS goals over project-scale timespans. The proposed framework utilizes available tools to quantify ecological system evolution and current and future dredging needs to develop a systems-level approach to BUDS. Required data include current and future information on (1) existing and planned natural and created aquatic ecological systems, which may include natural and nature-based features (NNBFs), (2) dredging requirements and costs, and (3) aquatic system physical and environmental data.

19 Sep 2022

Adapting Agile Philosophies and Tools for a Research Environment

Abstract: There exist myriad project management methodologies, but none is focused solely on scientific research. Research projects are unique compared to other types of projects, including software development, manufacturing, and drug trials; research projects inherently have unplanned risks. These risks provide a challenge to managing resources, developing schedules, and providing team ownership while still achieving project goals. To help mitigate the risks and the challenges associated with scientific research, a methodology to manage research projects needs to be developed.

16 Sep 2022

Flowering Rush Control in Hydrodynamic Systems: Part 1: Water Exchange Processes

Abstract: In 2018, field trials evaluated water-exchange processes using rhodamine WT dye to provide guidance on the effective management of flowering rush (Butomus umbellatus L.) at McNary Dam and Reservoir (Wallula Lake, 15,700 ha). Additional evaluations determined the effectiveness of BubbleTubing (hereafter referred to as bubble curtain) at reducing water exchange within potential flowering rush treatment areas. Dye readings were collected from multiple sampling points at specific time intervals until a dye half-life could be determined. Whole-plot dye half-lives at sites without bubble curtain ranged 0.56–6.7 h. In slower water-exchange sites (≥2.6 h dye half-life), the herbicide diquat should have a sufficient contact time to significantly reduce flowering rush aboveground biomass. Other sites demonstrated very rapid water exchange (<1.5 h dye half-life), likely too rapid to effectively control flowering rush using chemical treatments without the use of a barrier or curtain to slow water exchange. At one site, the use of the bubble curtain increased the dye half-life from 3.8 h with no curtain to 7.6 and 7.1 h with a bubble curtain. The bubble curtain’s ability to slow water exchange will provide improved chemical control and increase the potential for other chemical products to be effectively used.

16 Sep 2022

Analysis of Spectropolarimetric Responses in the Visible and Infrared for Differentiation between Similar Materials

Abstract: Spectropolarimetric research has focused on target detections of materials that have a high degree of contrast from background materials, such as identification of a manmade object embedded in a vegetative background. This study presents an approach using spectropolarimetric imagery in visible, shortwave infrared, and longwave infrared bands to differentiate between similar natural and manmade materials. The method employs Michelson contrast and Kruskal-Wallis one-way analysis of variance (ANOVA) H-test to determine if a distinction can be found in pairwise comparisons of similar and different materials using the Stokes parameters in the visible, shortwave infrared, and longwave infrared bands. Results showed that similar natural and manmade materials were differentiable in spectropolarimetric imagery using the Michelson contrast and ANOVA. This approach provides a way to use spectropolarimetric imagery to distinguish between materials that are similar to each other.

15 Sep 2022

Evaluation of a Prototype Integrated Pavement Screed for Screeding Asphalt or Concrete Crater Repairs

Abstract: Finishing, or screeding, the hot mix asphalt or rapid-setting concrete surface of a crater repair is important for rapid airfield damage recovery (RADR) since it determines the aircraft ride surface quality. The objective of RADR repairs is to expediently produce a flush repair, defined as ±0.75 in. of the surrounding pavement surface, with minimal logistical and personnel burden. Multiple screeds were previously evaluated; the most recent project proposed a prototype design of a telehandler-operated integrated screed for both small and large repairs using asphalt or concrete. This project’s objective was to finalize the prototype design and fabricate and test the prototype RADR screed. The prototype RADR screed was successful for small repairs (8.5×8.5 ft). Large repairs (30×30 ft) were generally successful with modest repair quality criteria (RQC) issues being the only notable deficiencies. Large concrete repair RQC issues were attributed to plastic formwork movement, and large asphalt repair RQC issues were attributed to compaction issues or improper roll-down factors. Methods to mitigate these factors were investigated but should be further evaluated. Overall, the RADR screed was successful from technical perspectives but, functionally, is 600-800 lb overweight. Weight reduction should be considered before entering production.

15 Sep 2022

Microbial Dynamics of a Fluidized Bed Bioreactor Treating Perchlorate in Groundwater

Abstract: Optimization of operation and performance of the groundwater treatment system regarding perchlorate removal at Longhorn Army Ammunition Plant (LHAAP) is dependent on specific conditions within the reactor and the larger groundwater treatment process. This study evaluated the microbial community compositions within the plant during periods of adequate perchlorate degradation, sub-adequate perchlorate degradation, and non-operating conditions. Factors affecting the performance of the LHAAP ground water treatment system (GWTS) perchlorate de-grading fluidized bed reactor (FBR) are identified and discussed. Isolation of the FBR from naturally occurring microbial populations in the groundwater was the most significant factor reducing system effectiveness. The microbial population within the FBR is highly susceptible to system upsets, which leads to declining diversity within the reactor. As designed, the system operates for extended periods without the desired perchlorate removal without intervention such as a seed inoculant. A range of modifications and the operation of the system are identified to increase the effectiveness of perchlorate removal at LHAAP.

15 Sep 2022

Informing the Community Engagement Framework for Natural and Nature-based Projects: An Annotated Review of Leading Stakeholder and Community Engagement Practices

Abstract: In its infrastructure development work, the US Army Corps of Engineers (USACE) engages and collaborates with numerous local, state, and national stakeholders. Projects incorporating innovative approaches, such as beneficial use (BU) of dredged materials and other natural and nature-based features (NNBF), are often not well-understood by stakeholders, including those at the community level. This often results in conflicts and project delays. By sponsoring the development of a Community Engagement Framework, the Dredging Operations and Environmental Research (DOER) program hopes to systematically improve how project teams design, conduct, and measure effective community engagement on infrastructure projects. The purpose of this focused Review was to assesses leading stakeholder and community engagement practices that reflect the state of practice of stakeholder engagement within USACE, and by other leading organizations in the US and internationally, to inform development of the Community Engagement Framework. While the resulting Framework will be particularly well-suited for community engagement on projects incorporating BU and other NNBF, it will be applicable to a broad range of USACE Civil Works’ initiatives where effective stakeholder engagement is critical to project success. The assessment showed the practice of stakeholder engagement has evolved significantly over the past 30 years, with much more focus today on ensuring that engagement processes are purposeful, meaningful, collaborative, and inclusive - reflecting stakeholders’ desire to participate in co-creating sustainable solutions that produce environmental, economic, and social benefits. This, and other key findings, are informing development of the Community Engagement Framework which is scalable and adaptable to a broad range of projects across the USACE missions.

14 Sep 2022

Is Mean Discharge Meaningless for Environmental Flow Management?

PURPOSE: River ecosystems are highly dependent on and responsive to hydrologic variability over multiple time scales (e.g., hours, months, years). Fluctuating river flows present a key challenge to river managers, who must weigh competing demands for freshwater. Environmental flow recommendations and regulations seek to provide management targets balancing socio-economic outcomes with maintenance of ecological integrity. Often, flow management targets are based on average river conditions over temporal windows such as days, months, or years. Here, three case studies of hydrologic variability are presented at each time scale, which demonstrate the potential pitfalls of mean-based environmental flow criteria. Each case study shows that the intent of the environmental flow target is not met when hydrologic variability is considered. While mean discharge is inadequate as a single-minded flow management target, the consequences of mean flow prescriptions can be avoided in environmental flow recommendations. Based on these case studies, a temporal hierarchy of environmental flow thresholds is proposed (e.g., an instantaneous flow target coupled with daily and monthly averages), which would improve the efficacy of these regulations.