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  • Distinct Sandbar Behavior on a Gently Sloping Shoreface Sea-Breeze Dominated Beach

    Abstract: Sandbars are common features in sandy nearshore environments that readily migrate in response to changing hydrodynamic conditions and can provide coastal protection by inducing wave breaking and through sediment feeding to the beach. A comprehensive 9-year data set of weekly to bi-weekly surveys of the beach and shallow nearshore, undertaken on an accretive micro-tidal sea-breeze dominated beach along the southeastern coast of Mexico, are presented here that shed new insights into hydrodynamic drivers of inner surf zone sandbar and shoreline dynamics. During spring-summer, short period waves drive offshore sandbar migration. Winter storms generate more energetic swell waves that induce onshore sandbar migration. Seasonal changes of shoreline and inner sandbar position are coupled, with on-shore sandbar migration being synchronous to seasonal shoreline advance, suggesting a gradual feeding of sediment from the bar system onto the beach. Analysis of the data are used to explore the physical drivers of sub-seasonal sandbar evolution at the site. The sandbar dynamics in the study area, showing an opposite behavior to conventional expectation of storm-induced offshore transport, are well correlated to seasonal changes of waves properties. This distinct sandbar behavior might be present at other gently sloping shoreface sea-breeze dominated sandy beaches.

  • Active Layer and Permafrost Microbial Community Coalescence Increases Soil Activity and Diversity in Mixed Communities Compared to Permafrost Alone

    Abstract: Permafrost is experiencing rapid degradation due to climate warming. Dispersal of microbial communities from the seasonally-thawed active layer soil into newly thawed permafrost may influence community assembly and increase carbon release from soils. We conducted a laboratory soil mixing study to understand how carbon utilization, heterotrophic respiration, and microbial community structure were affected when active layer and permafrost soils were mixed in varying proportions. Active layer soil and permafrost collected from two sites in Alaska were mixed in five different ratios and incubated for 100 days at 10°C. Respiration rates were highest in the 100% active layer soils, averaging 19.8 µg C-CO2 g−1 dry soil d−1 across both sites, and decreased linearly as the ratio of permafrost increased. Mixing of the two soil layers resulted in utilization of a more diverse group of carbon substrates compared to permafrost alone. Additionally, combining active layer and permafrost soils increased microbial diversity and resulted in communities resembling those from the active layer when soils were mixed in equal ratios. Understanding the effects of active layer-permafrost mixing on functional potential and soil organic matter decomposition will improve predictions of carbon-climate feedbacks as permafrost thaws in these regions.

  • Bayesian Updating of Fatigue Crack Growth Parameters for Failure Prognosis of Miter Gates

    Abstract: Navigable waterways play a vital role in efficient transportation of millions of tons of cargo annually. Inland traffic must pass through a lock, which consists of miter gates. Failures and closures of these gates can significantly disrupt waterborne commerce. Miter gates often experience fatigue cracking due to their loading and welded connections. Repairing every crack can lead to excessive miter gate downtime and serious economic impacts. If the rate of crack growth is shown to be sufficiently slow, immediate repairs may be deemed unnecessary, and this downtime can be avoided. Paris’ law is often obtained from laboratory testing with detailed crack measurements of specimens with relatively simple geometry. However, its parameters for an in situ structure will likely deviate from those predicted from physical testing due to variations in loading and materials and a more complicated geometry. To improve Paris’ law parameter prediction, we propose a framework that utilizes convenient vision-based tracking of crack evolution in the laboratory and the field and numerical model estimation of stress intensity factors. This study’s methodology provides an efficient tool for Paris’ law parameter prediction that can be updated as more data become available through vision-based monitoring and provide actionable information.

  • Clustering to Inform Infrastructure Inspections

    Abstract: Good inspections are crucial for managing risk and making decisions about facility maintenance. This paper proposes a method using the partitioning around medoids (PAM) algorithm to ensure that the inspector inspects a diverse set of components which maximize the information about the facility. We compares a number of different metrics by which to cluster the components using PAM, and evaluated the effectiveness of the clustering using Bayesian ANOVA testing.

  • Using Transfer Learning to Enhance Void Detection and Shear Wave Velocity Model Inversion from Near-Surface Seismic Shot Gathers

    Abstract: A Convolutional Neural Network (CNN) has been designed to delineate the shear-wave velocity (Vs) models and detect subsurface void locations. Addressing the processing and interpretation challenges posed on real seismic data, our strategy emphasizes that leveraging the ground truth, which is the void location in this study, enables the CNN to catch the identical features in real waveforms. Initially, a synthetic dataset is employed, imparting foundational knowledge to the CNN regarding the Vs model and void locations. Drawing inspiration from transfer learning, this pre-trained CNN serves as an initial model and is refined using a real dataset focused on void locations. After refining, the CNN shows enhanced reliability to detect the void and extract the Vs model, as evidenced by the improved alignment between forward modeling and real waveforms. Our findings underscore how leveraging the ground truth can actualize the potential of CNN on velocity model extraction.

  • Damage Parameters and Crack Morphology in High Strength Concrete BBR9 Under Dynamic Uniaxial Compressive Loading: An Experimental Study

    Abstract: There has been significant growth in the use of high-strength concrete in structures designed to withstand extreme events. Continuum damage mechanics has been utilized to develop constitutive models that can capture the damage evolution in concrete materials under such conditions. This study is aimed at investigating the damage initiation, progression, and morphology of HSC-Baseline Basic Research Mixture 9 when subjected to dynamic uniaxial compressive loading. A Kolsky compression bar system was implemented to introduce distinct damage states in the HSC-BBR9 specimens. The partially damaged specimens were tested to quantify their residual mechanical properties. Accordingly, stiffness-based and strength-based constitutive damage parameters were adopted to propose an indirect quantification of the damage state based on the deterioration of mechanical properties. The X-ray micro-computed tomography technique was utilized to extract measurements of 3D crack networks that provide a direct quantification of the damage state based on microstructural evidence. The results demonstrated the HSC-BBR9 material can maintain its residual mechanical properties into the post-peak regime. In the initial stages of damage, stiffness and strength deteriorate at a proportional rate; however, as damage accumulates, the rate of stiffness degradation increases. Correlations between constitutive damage parameters and 3D crack measurements were established.

  • Albuquerque District joins SSCAFCA, others for ribbon-cutting ceremony on Tortugas Arroyo Improvements Project

    Several USACE-Albuquerque District staff joined representatives from the Southern Sandoval County Arroyo Flood Control Authority, and local and state officials to cut the ribbon on the Tortugas Arroyo Improvements Project, Aug. 25, 2025.

  • USACE returning to complete maintenance dredging at Channel Islands Harbor

    The U.S. Army Corps of Engineers Los Angeles District, in coordination with the County of Ventura, is returning to complete the maintenance dredging at Channel Islands Harbor. USACE has conducted routine maintenance dredging of Channel Islands Harbor since the 1960s.

  • Nashville District invests in tomorrow’s leaders through leadership program

    Eighteen employees from the U.S. Army Corps of Engineers Nashville District graduated from the Level I Leadership Development Program, which focused on self-awareness, communication, and adaptable leadership. The six-month course fostered cross-departmental collaboration and emphasized flexible leadership, with participants expressing gratitude for the networking and personal growth opportunities. The program underscores the district’s commitment to developing effective leaders to meet complex, evolving challenges.

  • USACE Value Engineering Team Recognized on Global Stage

    For the first time in its 250-year history, the U.S. Army Corps of Engineers earned a Top 20 finish for its innovative approach to project delivery against corporate powerhouses in the prestigious Project Management Institute (PMI), Program Management Office (PMO) Global Awards.