25 Jun 2024

US Army Corps of Engineers (USACE) Wave Information Study: 2021 Annual Update

Purpose: This Coastal and Hydraulics Engineering Technical Note (CHETN) describes the 2021 Wave Information Study (WIS) annual update. Within this CHETN, we summarize the WIS input data, explain the model technologies, detail the quality control / quality assurance (QA/QC), and provide statistical evaluation of the 2021 WIS estimates as compared to in situ buoys and remotely sensed satellite altimeter data.

25 Jun 2024

The Effect of Increasing the Antenna Height on Radio Signal Reception at Tom Bevill Lock and Dam: LOMA-AIS Data Case Study

Abstract: This Coastal and Hydraulics Engineering Technical Note (CHETN) presents the effects on the reception of radio signals due to increasing the antenna height at Tom Bevill Lock and Dam (L&D) in Pickensville, Alabama. The signals are received Automatic Identification System (AIS) broadcasts from commercial vessels operating along the Tennessee-Tombigbee Waterway. These AIS broadcasts are received by the Lock Operations Management Application (LOMA) radio equipment at Tom Bevill L&D.

21 Jun 2024

Observations of Beach Change and Runup, and the Performance of Empirical Runup Parameterizations during Large Storm Events

Abstract: Timeseries observations of beach elevation change and wave runup from a tower-mounted stationary lidar assess the skill of 2% runup exceedance (𝑅2%) estimates during four storm events at Duck, NC. The runup parameterization requires the foreshore beach slope, which generally unknown during high energy events. Pre-storm estimates are often used as a proxy. 𝑅2% hindcasts use the observed time-varying beach slope and a static pre-storm beach profile, yielding an 𝑅2% skill of 0.57. The skill drops to −1.0 using seasonal mean beach slopes and reduces after the peak of two storms with the appearance of beach cusps in the swash zone morphology. One storm’s runup is underpredicted by up to 1.0 m at high tides following the storm peak when cusps are present Additional pre- and post-storm mobile lidar surveys for one storm confirm ubiquitous small-scale beach cusps along 8 km of the local shoreline. The results suggest skillful runup estimates are often attainable given the availability of beach information before a storm. The parameterization errors increase when beach cusps develop, highlighting the need to extend standard one-dimensional runup parameterizations to account for two-dimensional effects.

14 Jun 2024

Application of Coastal Resilience Metrics at Panama City Beach, Florida

Abstract: This study, for the first time, combines the Coastal Engineering Resilience Index (CERI) and Buffer Width (BW) metrics to better understand the historic, current, and future resilience of the coastal system at Panama City Beach, Florida. After the construction of the US Army Corps of Engineers Coastal Storm Risk Management (CSRM) project at Panama City Beach, the CERI resilience metric has increased up to 21.3%, while negative storm impacts in the same have been less than 8%. The frequency of nourishment efforts moving forward is justified by a 24.3% increase in the BW metric when comparing cases that are nourished frequently with cases that are not nourished frequently. Moreover, there is a 129.2% increase in the BW metric when comparing the frequently nourished cases with the cases that are nourished only on an emergency basis. While the CERI and BW metrics have both been considered previously, their combined application provides an understanding of a broader temporal view of how storm events, CSRM projects, and nourishments have played a part in the resilience of the system at Panama City Beach over the last two decades and how they may play a role in the next half century.

13 Jun 2024

Quantifying Coastal Evolution and Project Performance at Beaches by Using Satellite Imagery

Abstract: Accurately delineating the shoreline is crucial for tracking coastal evolution, community vulnerability, storm impacts, and for coastal management decision-making. However, existing shoreline measurement methods are often time-consuming and expensive and therefore, USACE Districts are often forced to narrow areas of interest or monitoring frequency, decreasing the likelihood of making data-driven management decisions, especially over regional scales. In the last decade, space-borne earth observations have captured images subweekly, and can potentially be used for shoreline monitoring. This work investigated the Python-based CoastSat toolkit and compared the shorelines derived from publicly available satellite imagery to ground truth surveys at 37 sites across the nation chosen in coordination with Districts. Mean horizontal errors ranged from 4.21 to 20.58 m with an overall mean of 11.32 m. Tidal corrections improved accuracies at 82% of sites. The CoastSat slope function was tested and there were negligible differences in shoreline accuracy when compared with user-defined slopes Twenty-year satellite-derived trends generally align well with ground truth trends. The satellite approach identified quantifying storm impacts/recovery, beach nourishment equilibration, diffusion and decay, shoreline response to nearshore berm placements and decadal shoreline evolution at the evaluated district sites. Work is ongoing to transition to a user-friendly software tool.

10 Jun 2024

Post-wildfire Curve Number Estimates for the Southern Rocky Mountains in Colorado, USA

Abstract: The curve number method first developed by the USDA Soil Conservation Service (now the Natural Resources Conservation Service) is often used for post-wildfire runoff assessments. These assessments are critical for land and emergency managers making decisions on life and property risks following a wildfire event. Three approaches (i.e., historical event observations, linear regression model, and regression tree model) were used to help estimate a post-wildfire curve number from watershed and wildfire parameters. For the first method, we used runoff events from 102 burned watersheds in Colorado, southern Wyoming, northern New Mexico, and eastern Utah to quantify changes in curve number values from pre- to post-wildfire conditions. The curve number changes from the measured runoff events vary substantially between positive and negative values. The measured curve number changes were then associated with watershed characteristics (e.g., slope, elevation, northness, and eastness) and land cover type to develop prediction models that provide estimates of post-wildfire curve number changes. Finally, we used a regression tree method to demonstrate that accurate predications can be developed using the measured curve number changes from our study domain. These models can be used for future post-wildfire assessments within the region.

10 Jun 2024

Lock and Dam 25, Upper Mississippi River Navigation Study: Ship-Simulation Results

Abstract: The US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory (CHL), used the Ship/Tow Simulator to evaluate navigational conditions for the US Army Corps of Engineers, St. Louis District (MVS), proposed 1,200 feet (ft) lock chamber at Lock and Dam 25 in a tow simulation study. The study considers the impacts to navigation throughout construction sequences of the proposed 1,200 ft lock chamber and the final completed project. Testing occurred at CHL in October–November 2022 with five industry tow pilots. A total of 47 unique test conditions for a total of 187 ship-simulation exercises were evaluated. All final project simulations indicated that the design is feasible. When testing the construction scenarios of the design, it was evident that a tug assist boat would be necessary for entering the 600 ft lock for both approaches. Results found that the intermediate wall construction should begin at the existing structure and progress downstream. Entering the 600 ft lock from the pool side was additionally completed successfully; however, modifications are needed for entering from the tailwater side. Ultimately, the results of this study will aid MVS in the design plan and decision-making regarding the proposed lock.

10 Jun 2024

Getting Started with FUNWAVE-TVD: Troubleshooting Guidance and Recommendations

Abstract: This technical note reviews some common initialization errors when first getting started with the numerical wave model, FUNWAVE-TVD (Fully Nonlinear Wave model–Total Variation Diminishing), and provides guidance for correcting these errors. Recommendations for troubleshooting the source or cause of instabilities in an application of the model as well as recognizing the difference between physical and numerical instabilities are also outlined and discussed. In addition, a quick start troubleshooting guide is provided in the Appendix. This guidance is particularly useful for novice to intermediate users of FUNWAVE-TVD who are less familiar with the workflow of setting up the model and interpreting error output statements.

31 May 2024

Hydraulic Load Definitions for Use in Load and Resistance Factor Design (LRFD) Analysis, Including Probabilistic Load Characterization, of 10 Hydraulic Steel Structures: Report Number 1

Abstract: In the past, allowable stress design (ASD) was used to design steel structures. The allowable stresses used were determined from previous practice, with limited understanding of the reliability and risk performance provided by the structure. Engineering methods based on Load and Resistance Factor Design (LRFD) provide more accurate lifetime models of structures by providing risk-based load factors. Besides improved safety, cost savings can be provided through improved performance and, in some cases, by delaying rehabilitation. This research project develops LRFD-based engineering procedures for the evaluation and design of hydraulic steel structures (HSS). Hydraulic loads are a key element to the LRFD analysis. This report identifies the primary hydraulic loads and describes procedures that can be used to determine these hydraulic loads. Existing design guidance for HSS is described and presented in the individual chapters. The appendixes to the report provide examples of the procedures used to compute the hydrostatic, wave, and hydrodynamic loads. A new approach for determining wind-induced wave loads was developed. Design guidance for computing the hydrodynamic load was limited for many of the HSS. Additional research is recommended to improve capabilities for computing hydraulic loads. Details on these recommendations can be found in this report.

28 May 2024

Statistical Analysis of Storm Surge and Seiche Hazards for Lake Erie

Abstract: Storm surge and seiche events are generally forced by severe storms, initially resulting in a wind-driven super elevation of water level on one or more sides of a lake (surge) followed by a rebound and periodic oscillation of water levels between opposing sides of the lake (seiche). These events have caused flooding along Lake Erie and significant damages to coastal communities and infrastructure. This study builds upon statistical analysis methods initially developed for the 2012 federal interagency Great Lakes Coastal Flood Study. Using the Coastal Hazards System's stochastic Storm Simulation (StormSim) suite of tools, including the Probabilistic Simulation Technique (PST), and regional frequency model, historical extreme events were assessed in a local frequency analysis and a regional frequency analysis to quantify the annual exceedance frequency (AEF) of WLD events specific to Lake Erie. The objective of this study was to quantify AEFs of storm surge and seiche hazards to provide a better understanding of these events to aid flood mitigation and risk reduction for lakeside properties.