18 Apr 2023

Comparing Methods for Estimating Water Surface Elevation between Gages in the Lower Mississippi River

Abstract: Predicting a water surface elevation (WSElev) at a particular location has a wide range of applications like determining if a levee will overtop or how much a dike notch will increase water flow into a secondary channel. Five existing methods for predicting the water’s surface, (1) daily slope, (2) average slope, (3) River Analysis System (RAS) 1D, (4) RAS 2D, and (5) Adaptive Hydraulics modeling system (AdH), were used to predict the Mississippi River’s daily water surface from 10 October 2014 to 31 May 2016 at Friar’s Point, Greenville, and Natchez gages. The error, calculated as the model-predicted water surface minus the gage-observed water surface, was compared among the methods. The average slope method, using Helena and Fair Landing gages, and the daily slope method, using either Memphis and Helena or Helena and Arkansas City gages, most closely estimated the observed WSElev. The RAS 1D predictions for Friar Point and Greenville produced more accurate estimates than the RAS 2D model and were the only estimates that did not show a pattern of over- or underestimation. When the daily slope method was applied to gages that were farther apart (Memphis and Arkansas City, Arkansas City and Vicksburg, or Vicksburg and Knoxville), the error became greater than most RAS 1D and 2D predictions. The low error and simple calculations of the daily slope and average slope methods using gages <110 river miles apart make these methods useful for calculating current and historic conditions. The lack of over- or underestimation in the RAS 1D predictions (for locations away from the edges of the model area) make this method a better choice for predicting average WSElevs and a good choice for forecasting future WSElevs.

22 Mar 2023

MODIS Optical Global Water Intelligence (MOGWAI) Web Application User Guide

Abstract: Using the sensor from the Moderate Resolution Imaging Spectroradiometer (MODIS), the MODIS Optical Global WAter Intelligence (MOGWAI) platform is a system created and maintained jointly by the National Geospatial-Intelligence Agency and US Army Corps of Engineers (USACE) that monitors the surface area of lakes and reservoirs using remote sensing in near real time. MOGWAI provides estimates of surface area based on an implementation of the Dynamic Surface Water Extent algorithm that was adapted to use 8-day composites of surface reflectance data from the MODIS sensor, which belongs to the National Aeronautics and Space Administration (NASA). Surface area is monitored for all large waterbodies (greater than 10 km²)* south of 60°N contained in the HydroLAKES database. This information provides near real-time insights related to the regional buffering capacity against flood and drought.

20 Mar 2023

Reception of Automatic Identification System (AIS) Message 21 from US Army Corps of Engineer AIS sites along the Upper Mississippi River, Mile 0 to 301

Purpose: The purpose of this study was to map the on-vessel receipt of message 21 broadcasts from shoreside Automatic Identification System (AIS) sites. Message 21 is one of 27 different AIS messages, and it is used to provide information about real and virtual aids to navigation (AtoNs). Virtual AtoNs are broadcast to warn mariners of hazards like temporary construction zones or submerged debris that may not be marked with a physical buoy. In this study, message 21 was broadcast from different shore-based AIS transceiver sites along the river. Equipment onboard the patrol vessel Pathfinder was monitored for receipt of message 21 during patrols on the Mississippi River that ranged from Lock and Dam (L&D) 22 to Cairo, Illinois, with the confluence of the Ohio River. The Pathfinder is owned by the US Army Corps of Engineers (USACE) and is based out of the St. Louis District (MVS). Understanding where vessels receive, or do not receive, message 21 has important implications for maritime safety in this heavily traveled portion of the inland waterway system.

20 Mar 2023

Hands-Free Mooring for Inland USACE Locks, Phase I: Technical Screening

Purpose: The US Army Corps of Engineers (USACE) Engineer Research and Development Center (ERDC) was asked to evaluate hands-free mooring (HFM) as an option for improving the safety and efficiency of lock operations at USACE locks within the United States. The focus of this research is assessing HFM solutions for barge tows on USACE inland waterway locks. This Coastal and Hydraulics engineering technical note (CHETN) describes the approach and findings from Phase I of this HFM research effort, which was funded through the Navigation Systems Research Program. Phase I includes defining the problem this research effort intends to address, understanding current mooring practices at USACE locks, gathering information on similar systems already in use, and developing design concepts and criteria.

20 Mar 2023

Numerical Modeling of Supercritical Flow in the Los Angeles River: Part I: Adaptive Hydraulics Numerical Modeling of the 1943 Physical Model

Abstract: The Los Angeles District of the US Army Corps of Engineers is assisting the City of Los Angeles with restoration efforts on the Los Angeles River. The city wishes to restore portions of the channelized river to a more natural state with riparian/vegetative green spaces for both wildlife and public recreation usage. The Los Angeles River provides an important role for the City of Los Angeles from a flood-control perspective, and functionality needs to be preserved when contemplating system modifications. This report details the development of an Adaptive Hydraulics (AdH) numerical model capable of representing this complex system consisting of both subcritical and supercritical flow regimes. Due to limited hydraulic data in the study area, an extensive model validation to observed data was not possible. To bridge the data gap, a numerical model was developed from a previously completed physical model study with extensive quantitative measurements and qualitative reports of hydraulic conditions. This approach allowed engineers to evaluate the effectiveness of the AdH model in representing this complex hydraulic system along with determining the best methodology to accurately represent the existing conditions. This study determined appropriate model parameters that will be utilized in further numerical modeling efforts to evaluate system modifications associated with restoration efforts.

15 Mar 2023

Underwater Carbon Fiber–Reinforced Polymer (CFRP)–Retrofitted Steel Hydraulic Structures (SHS) Fatigue Cracks

Purpose: Recent advances in the use of fiber-reinforced polymers (FRP) to retrofit steel structures subjected to fatigue cracks have shown to be a viable solution for increasing fatigue life in steel hydraulic structures (SHS). Although several studies have been conducted to evaluate the use of FRP for retrofitting metal alloys and the promising potential of such has been well-demonstrated, the application has never been implemented in underwater steel structures. This Coastal and Hydraulics Engineering Technical Note presents the implementation of FRP patches to repair fatigue cracks at Old Hickory Lock and Dam miter gate.

9 Mar 2023

Automatic Identification System (AIS) Data Case Study: Vessel Traffic through the Yaquina Bay Breakwater at Newport, Oregon

Abstract: The navigation staff at US Army Corps of Engineers (USACE) Portland District (NWP) asked for information on vessel transits through the two existing openings in the breakwater on the north side of Yaquina Bay in Newport, Oregon. Currently, no authorized federal channel passes through the breakwater openings; however, the design for a possible federal channel is under consideration. NWP staff were interested in historical vessel transits, with a special focus on isolating transits for the largest (i.e., longest) vessels, identified as vessels 80 feet or longer, currently utilizing the area inside the breakwater. The Automatic Identification System Analysis Package (AISAP) software created by USACE-ERDC (2018) was used to analyze vessel traffic.

8 Mar 2023

A Large-Scale Community Storm Processes Field Experiment: The During Nearshore Event Experiment (DUNEX) Overview Reference Report

Abstract: The DUring Nearshore Event EXperiment (DUNEX) was a series of large-scale nearshore coastal field experiments focused on during-storm, nearshore coastal processes. The experiments were conducted on the North Carolina coast by a multidisciplinary group of over 30 research scientists from 2019 to 2021. The overarching goal of DUNEX was to collaboratively gather information to improve understanding of the interactions of coastal water levels, waves, and flows, beach and dune evolution, soil behavior, vegetation, and groundwater during major coastal storms that affect infrastructure, habitats, and communities. In the short term, these high-quality field measurements will lead to better understanding of during-storm processes, impacts and post-storm recovery and will enhance US academic coastal research programs. Longer-term, DUNEX data and outcomes will improve understanding and prediction of extreme event physical processes and impacts, validate coastal processes numerical models, and improve coastal resilience strategies and communication methods for coastal communities impacted by storms. This report focuses on the planning and preparation required to conduct a large-scale field experiment, the collaboration amongst researchers, and lessons learned. The value of a large-scale experiment focused on storm processes and impacts begins with the scientific gains from the data collected, which will be available and used for decades to come.

23 Feb 2023

AIS Data: An Overview of Free Sources

Abstract: The purpose of this Coastal and Hydraulics Engineering technical note (CHETN) is to describe the sources of Automatic Identification System (AIS) data available to the public, with a focus on federal employees who may need AIS data to carry out their official duties. AIS data, in this context, refer to both real-time and historic vessel position information.

13 Feb 2023

Sustainable Sediment Management at US Army Corps of Engineers Reservoirs

Abstract: The US Army Corps of Engineers (USACE) maintains and operates 419 reservoirs nationwide for diverse purposes. This infrastructure is essential to the nation’s continued economic progress and provides numerous benefits. Sedimentation in reservoirs causes the loss of storage capacity, leading to interference with operations, reduction of project benefits, and can eventually render project operation technically infeasible or uneconomical. All reservoirs trap sediment, and sustainable long-term operation can be achieved only if sedimentation is managed. With many of the USACE reservoirs now reaching 50 years of age, sedimentation is starting to encroach on the beneficial pools. Under the paradigm of sustainable use, it is important to identify and implement strategies to sustain reservoir operation in the long term, beyond the period contemplated in the original project design life. This report outlines the major types of sediment management strategies available for reservoirs. Because the rate of new reservoir construction by USACE is very low, this report focuses on remedial strategies at existing reservoirs and presents a general methodology for the preliminary analysis of such sites. This report examines four example USACE reservoirs with known sedimentation issues to highlight the types of problems encountered and the development of strategies that can lead to sustainable use.