U.S. Army Corps Of Engineers Research Articles

Coastal morphology from space: A showcase of monitoring the topography-bathymetry continuum

With a large part of the world's population residing in coastal areas, and largely depending on the coastal environment, monitoring natural and human-induced coastal changes are paramount to understand the dynamic and vulnerability of these coastal systems/communities. To understand changes in coastal areas, e.g. environmental and social resilience to environmental change, local measurements are inadequate. Such large-scale issues can only be addressed with perhaps less accurate but large scale measurements from space. Considering vulnerability or exposure to coastal flooding, both the bathymetry (underwater) and topography (above water) are vital boundary conditions to understand and accurately estimate impacts on short (storms) and long (inter-seasonal) time-scales. In this work, we estimate the coastal bathymetry and topography with the optical VENμS satellite for every single overpass at the Field Research Facility of the US Army Corps of Engineers at Duck, NC. The experimental VENμS satellite enables estimation of the topography and bathymetry by two repetitive identical images with a small time-lag. This capability proofs to result in topographies with a few meters accuracy and the bathymetry estimation is at best a few decimetres accurate. As a base for future Earth Observation missions such as Landsat or Sentinel 2, VENμS shows that higher resolution imagery (5 m), repetitive bands and a revisit time of only 2 days, enables unprecedented land/sea monitoring.

DrainCAN—A MATLAB Function for Generation of a HEC-RAS-Compatible Drainage Canal Network Model

The dimensioning of canal geometry in a surface drainage network influences the size and functionality of canal structures, reduces flood hazard, and consequently imposes restrictions on land use. Reliable free-surface flow calculation for optimization of the canal network can be challenging because numerous hydraulic structures and canal interactions influence the flow regime. The HEC-RAS software of the US Army Corps of Engineers’ Hydrologic Engineering Center is often used for this purpose as it allows the user to simulate the effect of numerous hydraulic structures on flow regime. This paper presents a MATLAB function, DrainCAN, for generating a HEC-RAS model from standard runoff input data, i.e., topographic data and canal design geometry (profile and slope). The DrainCAN function allows for fast optimization of the network geometry—it generates normal flow depth estimation and observed water levels in critical locations that need to be optimized. Advantages of the DrainCAN function are fast generation of the HEC-RAS hydraulic model files from simple input files, introduction of optimization variables in the model, and automatic adjustment of model geometry for computational junctions. This allows fast iteration of the canal design parameters, namely cross-sectional geometry, invert elevation, and longitudinal slope, and the evaluation of introduced changes on the flow regime.

Do the standards need modifications? A proposal for geotechnical stability safety factor of breakwater

In different countries and continent, different standards are followed for geotechnical stability safety factors of breakwaters which are not exactly in the same line. Parties involved in breakwater design and construction projects might follow different procedures/standards (load cases to be analysed and the acceptable safety factor). It is a fact that a clear table that shows the acceptable safety factors for different load cases is not clearly presented in the standards. So the aim is to provide a proposal that covers all the standards. In this paper, four guidelines/standards of “Rock Manual”, “US Army Corps of Engineers”, “Eurocodes” and “ROM” are reviewed. Based on the mentioned standards and some considerations a table that shows the acceptable safety factors for different load cases is presented. Another concerns is that the actual more powerful and advanced calculation software allows to find the results with less uncertainty compared to the formerly applied methods. It means that lower safety factors in comparison to the old methods can be applied and accepted with the recent software. The aim of the paper is presenting a procedure for the slope stability safety factors in order to reduce the amount of discussions and disagreements that of course come from the interpretations of different standards. Furthermore, reduced slope stability safety factors for different load cases are proposed.

Comparing single‐phase, non‐Newtonian approaches with experimental results: Validating flume‐scale mud and debris flow in HEC‐RAS

AbstractPost‐fire debris flows and tailing impoundment failures destroy lives and property. These geologic hazards – and other similar processes – fall on a continuum between classic Newtonian flood analyses and geotechnical stability analyses. The US Army Corps of Engineers (USACE) is developing a non‐Newtonian library (DebrisLib) that includes a suite of rheological and clastic approaches to hyper‐concentrated, mudflow and debris flow dynamics. The Hydrologic Engineering Center (HEC) has implemented these non‐Newtonian methods into the widely used, public‐domain open‐channel hydraulics and morphodynamic software, HEC‐RAS (river analysis system). This work presents part of the verification and validation of these non‐Newtonian approaches, applying several rheological equations to published laboratory results high‐concentration flume experiments.This study tested the linear Bingham model as well as the turbulent and Bagnold quadratic terms of the O'Brien equation. HEC‐RAS also includes the non‐linear Herschel–Bulkley (HB) approach, which quantifies shear‐thickening or shear‐thinning processes. The study used these non‐Newtonian models in HEC‐RAS to simulate 10 of Parsons et al.’s (2001) flume experiments, which measured the snout and plug velocity of fluids with high solid concentrations (Cv = 68–74%) and a broad range of material gradations (d50 = 0.05–1 mm, d15 = 0.006–0.1 mm). The experiments also measured and back‐calculated Bingham and HB parameters of the materials, finding HB powers between 0.45 and 1.25 (i.e. fluids that are dilatant, pseudo‐plastic and visco‐plastic).The rheological models incorporated into DebrisLib and implemented in HEC‐RAS reproduce experimental data well for most experiments. The Bingham model generated a plug velocity root‐mean‐square error (RMSE) of 0.21 m/s using standard flow parameters and Parsons et al.’s calibrated parameters, a substantial improvement over the unmodified shallow water flow equations (RMSE 0.77 m/s). Experiments with strong snout effects tended to generate higher residuals, especially in the snout velocity. The RMSE associated with the O'Brien equation was larger with the Parsons et al. fit parameters, but similar (0.23 m/s) with measured parameters. The turbulent parameter was the largest (often the dominant) parameter in most O'Brien simulations, with the dispersive stress only proving significant for the coarsest material. DebrisLib had to use a modified version of the dispersive term to simulate these concentrations. Both the 2D depth‐averaged shallow water equation (SWE) and diffusion wave equation were used to simulate the experiments. The best results were obtained with the SWE with horizontal mixing.

The Treaty Imaginary and Tribal Sovereignty in South Dakota

This article examines the history of the South Dakota "Mitigation Act" (as it is commonly know by Lakota people) in the 1990s and early 2000s. The Mitigation Act, enacted in 1998 and implemented over a period of nine years, was meant to create a negotiated agreement between tribal governments and the state for jurisdiction over the regulation of hunting and fishing on the Missouri River that would avoid a long history of bitter litigation over jurisdictional contests. The act was also meant to return lands held by the US Army Corps of Engineers, originally acquired for the purpose of constructing three main-stem dams on the Missouri, to the tribes that had originally held the land, and to the State of South Dakota. Both the goal of negotiating state and tribal jurisdiction, and returning lands to the state and the tribes, led to heightened intensity of the very tribal-state conflicts that the act was meant avoid. Based primarily on the senatorial records of Senator Thomas Daschle (D-SD) and the gubernatorial papers of William Janklow (R), the article examines the logic of the "treaty imaginary" among Lakota tribal governments and their constituencies, and the liberal democratic principle of negotiation by "all interested parties" at the center of development of the Mitigation Act. The article ties the conflict over the act to its fundamental misrecognition of the continuing validity of treaties for Lakota people, and the family resemblance the act had to the illegal taking of the Black Hills for many Lakota and other Great Sioux Nation tribes.

Dye Test within Mosul Dam Area

Mosul Dam is located on the River Tigris about 60 km north of Mosul city in Iraq. The dam is a multipurpose earth fill dam with a storage capacity of 11.11 million cubic meters, which was in operation since 1986. During the first impounding of its reservoir, seepage of water underneath the foundation of dam was noticed due to the desolation of gypsum beds. This raised concern about the stability of the dam and since then grouting operation were carried out. ISIS occupied the dam 8 - 16 August 2014. Grouting operations stopped and number of equipment and buildings were destroyed during that short period. After the defeat of ISIS, the Iraqi Ministry of Water Resources rebuilt and constructed the destroyed parts within the site and a new maintenance operations program was adopted. New training courses for the staff of Mosul Dam were conducted with Trevi Company and US Army Corps of Engineers. In this paper, the dye test is highlighted to monitor the seepage of groundwater within the dam site. It seems that the dam is stable in its present conditions and water level height.

ASSESSMENT OF DIGITAL TERRAIN MODELS IN DAM BREAK SIMULATION STUDIES

Abstract: Dams are structures built for controlling the flow of water for many useful purposes such as water supply, power generation, retention of mining and industrial waste, as well as recreation and flood control. However, they bring together some risk of dam body collapse causing damage for the dam downstream areas. Therefore, hypothetical dam break studies which provide mapping of areas potentially attainable in the event of a rupture are especially important for planning actions aiming minimization of associated losses. The aim of this research is to assess the degree of adherence or similarity between flood maps obtained by simulation studies and those effectively obtained from the collapse itself occurred in Dam I owned by Vale SA on January 25, 2019. The study focuses mainly on comparing the effects over the simulated flood maps caused by use of different representation of dam downstream topography relief, namely Shuttle Radar Topography Mission (SRTM), Advanced Land Observing Satellite from Alaska Satellite Facility (ALOS_ASF) and Airborne Laser Scanning (ALS) models. The simulations were performed using the HEC-RAS software developed by the US Army Corps of Engineers considering hypothesis of strong influence of relief in flood mapping results. In this way, three simulation tests were carried out for evaluation and discussion. In the first simulation, the digital terrain model derived from ALS was used. The second simulation was carried out associating the digital surface model ALOS_ASF with a spatial resolution of 12.5 m. Finally, the SRTM digital elevation model with 30 m spatial resolution provided by the United States Geological Survey (USGS) was used in third simulation. Results showed better adherence to simulations using data from ALS. This was verified by visual analysis over high resolution orthorectified images and by calculating statistics indicators such as the (F) index. Conclusions pointed out that flood patches resulting from simulation are critical tools for taking actions involving areas and populations to be affected, so the best relief model technologies like ALS data should be used in simulation.

MODAL GRAIN SIZE EVOLUTION AS IT RELATES TO THE DREDGING AND PLACEMENT PROCESS - GALVESTON ISLAND, TEXAS

During the fall and winter of 2015, a beneficial-use of dredged material project taking material from the Galveston Entrance Channel and placing it on a severely eroded beach of Galveston Island was conducted. This material was estimated to have 38percent fines. This operation was conducted again in the fall of 2019 and monitored for estimation of the loss of fines, changes in compaction and color from the dredging source to the beach. The local community and state funded the incremental cost at approximately $8 a cubic yard in 2015, and $10.5 a cubic yard in 2019 to have this material pumped to the beach. The projects were closely monitored by the U.S. Army Corps of Engineers (USACE) Engineer Research and Development Center (ERDC) and the USACE Galveston District. The data from this placement project was used to calculate and better understand the loss of fines during the dredging and placement process as well as aid in the generation of an empirical formula to estimate the loss of fine sediments during dredging and beach placement. This formula takes into account: losses due to dredging equipment operations, slope of the effluent return channel at the beach, sediment settling velocity, and sorting parameter.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/VQ36upT2iQo

Army Corps suspends permit on Formosa plant

The US Army Corps of Engineers suspended a permit for the construction of Formosa Plastics’ $9.4 billion complex in St. James Parish, Louisiana, earlier this month, claiming that the Corps had elim...

Rainfall-Runoff Modelling of the West Rapti Basin, Nepal

A hydrological model helps in understanding, predicting, and managing water resources. The HEC-HMS (Centre for Hydrological Engineering - Hydrological Modelling Systems, US Army Corps of Engineers) is one of the hydrological models used to simulate rainfall-runoff and routing processes in diverse geographical areas. In this study, a semi-distributed hydrological model was developed using HEC-HMS for the West-Rapti river basin. The model was calibrated and validated at each outlet of sub-basins and used to simulate the outflow of each sub-basins of the West Rapti river basin. A total of eight rain gauge stations, five meteorological stations, and three hydrological stations, within the basin, were used. The simulated results closely matched the observed flows at the three gauging stations. The Nash-Sutcliffe Efficiency indicated the good model performance of the simulated streamflow with the observed flow at two stations and satisfactory model fit at one station. The performance based on percentage bias and root mean square error was good. This model provides a reference to study water balance, water resource management, and flooding control of the West Rapti basin and can be replicated in other basins.

Experimental study of base stabilization with fibrillated fiber

Potential benefits in applying polypropylene fiber to stabilize expansive soils and cement treated bases is already been reported in previous studies. So a critical need exists to incorporate the use of fiber into the Texas Department of Transportation’s (TxDOT’s) Guidelines for Modification and Stabilization of Soils and Base for Use in Pavement Structures. The present paper discusses the results collected from the first experimental test section on FM897 in the TxDOT Paris District. Three 500-ft (152.4m) test sections were constructed with 2 percent cement on FM897 in February 2020 in the north bound lane loaded truck direction which includes a new sandstone base, full depth reclamation (FDR), and control. However, only the new sandstone base and FDR sections were built with fiber. In this project, two types of fibers were used —(a) fibrillated fiber Fibermesh300, and (b) macro-synthetic fiber Enduro 600. The surface and base layers from the new sandstone base section were removed and used for the edge widening area of the FDR and control sections. Based on the laboratory tests, the optimum fiber contents were found to be 0.6 percent and 0.4 percent for a new sandstone base and FDR, respectively. The laboratory Unconfine Compression Strength (UCS) results showed significant improvements (<112.36 percent) when fibers were added to the sandstone base. To have better control, fiber and cement were manually distributed, following the US Army Corps of Engineers’ recommendations. Becaus e of unexpected construction equipment failure that caused compaction delays of approximately 5 hours, cement was in contact with moisture for approximately 5 hours before compaction. UCS results showed an approximate 55 percent reduction when there was a 5-hour delay from the time water was introduced (resulting in the start of the hydration process) until the time of compaction. It indicated that there are detrimental effects on UCS if there is delay on compaction. There were significant reductions on the normalized W1 deflections at 5 months after construction. In particular, the FDR and new sandstone base sections (with fiber) experienced over 52 percent reduction as compared to 1 week after construction FWD data. Furthermore, the averaged W1 deflections were lower than before construction for both FDR and new sandstone base sections (with fiber). This indicates that there were rapid increases in structural capacity and significant strength developed in the fiber sections between 1 week and 5 months. Further research is needed to explain the mechanism and phenomena.

Pavement Engineering for Forest Roads

Pavement is an essential component of roads as it carries the traffic and provides the required riding comfort. Considering that numerous forest roads are approaching their end of life, the critical issue is identifying the best rational pavement design methods to reengineer existing and build new pavement structures. The purpose of this contribution was (1) to review the big development lines of pavement systems, (2) to have a critical look at the pavement engineering framework, and (3) to bring selected empirical design equations into a comparable scheme. The study resulted in the following significant findings. First, the Trésaguet and McAdam pavement systems represented the state of the art from the beginning of a formal forest road engineering discipline at the beginning of the 19th century and remained for almost 150 years. Second, the emergence of soil mechanics as a scientific discipline in the 1920s resulted in the optimal grading of aggregates and improvement of soils and aggregates with binders, such as lime, cement, and bitumen. Third, the rational pavement design consists of five essential components: (1) bearing resistance of the subsoil, (2) bearing resistance of the pavement structure, (3) lifecycle traffic volume, (4) uncertainties that amplify deterioration, and (5) the limit state criterion, defining thresholds, above which structural safety and serviceability are no longer met. Fourth, rational, formal pavement design approaches used for forest roads were »downsized« from methodologies developed for high-volume roads, among which the approaches of the American Association of State Highway and Transportation Officials (AASHTO) and US Army Corps of Engineers (USACE) are of primary interest. Fifth, the conversion of the AASHTO '93 and USACE '70 methods into the SI system indicated that both equations are sensitive to soil bearing resistance, measured in California Bearing Ratio (CBR). However, there is a lack of validation for the AASHTO and USACE equations for forest road conditions. Consequently, a factorial observational study to gain a basis for validation should be developed and implemented. Additionally, the conversion of simple soil bearing resistance measures, such as CBR, into the resilient modulus will be improved.

Performances of the New HEC-RAS Version 5 for 2-D Hydrodynamic-Based Rainfall-Runoff Simulations at Basin Scale: Comparison with a State-of-the Art Model

The Hydrologic Engineering Centre-River Analysis System (HEC-RAS), developed by the US Army Corps of Engineers, is one of the most known, analyzed and used model for flood mapping both in the scientific literature and in practice. In the recently released version (release 5.0.7), the HEC-RAS model has been enriched with novel modules, performing fully 2-D computations based on the 2-D fully dynamic equations as well as the 2-D diffusion wave equations; moreover the application of rainfall to each cell of the two-dimensional domain is now possible. Contrarily to the common applications for flood propagation in river reach, this specific module has never been analyzed in the literature. Therefore, the main purpose of this work is to assess the potential and the capabilities of the 2-D HEC-RAS model in rainfall-runoff simulations at the basin scale, comparing the results obtained using both the options (fully dynamic equations and diffusion wave equations) to the simulations obtained by using a 2-D fully dynamic model developed by the authors for research purposes. Both models have been tested in a small basin in Northern Italy to analyze the differences in terms of discharge hydrographs and flooded areas. The application of a criterion for hazard class mapping has shown significant variations between the two models. These results provide practical indications for the water engineering community in the innovative research field related to the use of 2-D SWEs at the basin scale.

Vulnerability of Florida residential structures to hurricane induced coastal flood

This paper presents a methodology to develop hurricane induced coastal flood vulnerability functions for residential construction based on empirical tsunami fragility functions. A force equivalency mapping procedure first transforms the tsunami fragility functions into coastal flood fragility functions. Following the quantification of the damage states and the incorporation of repair costs, the coastal flood fragility functions translate into coastal flood vulnerability functions. Insurance claims data from the National Flood Insurance Program and vulnerability functions independently derived by the US Army Corps of Engineers are employed to validate single-story on-grade timber and reinforced masonry structure model outputs. The limitations of the model and future developments are discussed.

Vegetation Sampling Concepts for Compensatory Mitigation Sites

I n 2018, the Norfolk District of the U.S. Army Corps of Engineers (USACE) and the Virginia Department of Environmental Quality (DEQ), in their roles as co-chairs of Virginia’s Interagency Review Team (IRT), proposed modifications to the Virginia Mitigation Banking Instrument (MBI) Template (Template). The Template is a document used to establish compensatory wetland and stream mitigation banks in the state, serving as a planning-level tool with minimum standards and design criteria for that purpose. Prospective mitigation banks are approved via IRT ratification of an acceptable MBI, which provides the necessary documentation for the “…establishment, use, operation, and management…” of mitigation banks in Virginia.

Uncertainty and Legal Foreseeability in Flood Risk Management

AbstractThe legal concept of foreseeability is an important element of proof in flood loss litigation against the US Army Corps of Engineers. Although hydrologic forecasting and engineering uncerta...

Soil fatigue hazard screening analyses framework for spacio-temporally clustered induced seismicity with examples of damage potential due to liquefaction

Current studies that focus solely on the cause of the increase in seismicity neglect to include considerations for effects of small magnitude cluster events on federal infrastructure. These effects can be almost undetectable at first, but if left unchecked can evolve into a larger issue. The need to reassess and potentially modify the established risk assessment practices for evaluations of federal infrastructure needs to be reviewed to ensure the continued ability of the structure to function as intended. The U.S. Army Corps of Engineers (USACE) is responsible for hydroelectric power, flood protection, recreational areas, navigational channels and water supply along the waterways that were either constructed prior to seismic design requirements or designed to a lower seismic level than current seismic activity. The need to establish revised evaluation methods of critical infrastructure has become very apparent to ensure that risk assessments include the stability of these systems and the safety of those that depend on them.

Design guidelines and optimization of ultra-high-performance fibre-reinforced concrete blast protection wall panels

Ultra-high-performance fibre-reinforced concrete is the latest generation of structural concrete, having outstanding fresh and hardened properties; this includes the ease of placement and consolidation with ultra-high mechanical properties, as well as toughness, volume stability, durability, higher flexural and tensile strength, and ductility. As more research is being focused on it, the material behaviour and characteristics are getting more understood, and the research demand for the special applications of the ultra-high-performance fibre-reinforced concrete is growing higher. One special application that ultra-high-performance fibre-reinforced concrete is thought to have an outstanding performance at is in the field of protective structures, specifically against blast loads. This article presents part of a study that is concerned with the behaviour and response of ultra-high-performance fibre-reinforced concrete wall panels under blast load. Size and shape optimization techniques were combined in this study to optimize the design of a 200-MPa ultra-high-performance fibre-reinforced concrete under blast loads using finite element modelling. This design optimization aims to maximize stiffness and minimize the cost while satisfying both design stresses and construction requirements. The design variable to be optimized for are the thickness ranging from 100 to 300 mm at 25 mm increments, in addition to the reinforcement ratio of 0%, 0.2%, 1% and 3%, and aspect ratio of 1, 1.5 and 2; the boundary condition is four edges fixed and restrained. The numerical simulation has been performed using an explicate finite element software package. The complete behaviour of an ultra-high-performance fibre-reinforced concrete is defined using the concrete damaged plasticity model. The concrete constitutive model has been developed considering the contribution of tensile hardening response, fracture energy and crack-band width approaches to accurately represent the tensile behaviour and guarantee mesh independence of results. The blast load is applied using the Conventional Weapons method of the US Army Corps of Engineers that is readily available in the finite element software. The validity of the numerical model used is verified by comparing numerical results to experimental data.

Stakeholder Involvement in Natural Resource Decisions: The Missouri River

The Water Resources Development Act of 2007 authorized creation of the Missouri River Recovery Implementation Committee (MRRIC) to provide recommendations to the U.S. Army Corps of Engineers (USACE) on a recovery and mitigation plan to avoid jeopardy of three endangered species (Pallid Sturgeon Scaphirhynchus albus, interior least tern Sterna antillarum athalassos, and piping plover Charadrius melodus). Formation of the MRRIC in 2007 ushered in a new era of federal, state, tribal, and nongovernmental stakeholder collaboration in the river basin following nearly 20 years of litigation and legislative actions in Congress related to management of and operations on the river. Over a decade, through its deliberations, MRRIC has been instrumental in influencing the USACE endangered species recovery and mitigation efforts. The diversity of MRRIC membership proved beneficial when examining the socioeconomic impacts of river operations. However, this diversity also presented challenges to the communication of technical issues facing recovery of imperiled species, especially the Pallid Sturgeon. By instituting an independent science panel trusted by MRRIC members, the committee advanced key recommendations to the USACE in the development of an adaptive management plan. Unfortunately, at two key points in the past decade, members of MRRIC opted to work outside of the committee construct, engaging in legislative strategies to limit potential recovery actions. This paper describes actions by MRRIC that have benefited the USACE recovery effort and limitations within the committee that in turn have constrained the recovery effort.

Intensive Cultural Resources Survey of the Proposed City of Conroe Stewarts Creek Wastewater System Improvements Project, Conroe, Montgomery County, Texas

Intensive Cultural Resources Survey of the Proposed City of Conroe Stewarts Creek Wastewater System Improvements Project, Conroe, Montgomery County, Texas