9 Sep 2025

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.

9 Sep 2025

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.

9 Sep 2025

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.

9 Sep 2025

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.

9 Sep 2025

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.

9 Sep 2025

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.

8 Sep 2025

US Army Corps of Engineers Aquatic Restoration Monitoring for Ecosystem Recovery (ARMER) Network

Abstract: Long-term, high-quality ecosystem restoration monitoring is essential to achieve recovery and maximize restoration investments. However, there are many challenges associated with restoration monitoring that inhibit effective collection, storage and management, communication, and utilization of ecosystem recovery information. A nationwide monitoring network of restoration and reference sites is needed to generate high-quality, replicated datasets to address large-scale ecosystem restoration challenges. The US Army Corps of Engineers (USACE) makes significant annual investments in ecosystem restoration projects and monitoring for adaptive management under their aquatic ecosystem restoration mission, and thus, is uniquely positioned to lead the development of an ecosystem recovery monitoring network. Investments in large-scale, long-term data collection and management would allow USACE to (1) improve data consistency and data replication to reduce uncertainty in ecological recovery assessments, (2) demonstrate the socioecological benefits of restoration to better inform future restoration investments, and (3) improve the USACE’s ability to publicly communicate returns on investments and the nationwide value of aquatic ecosystem restoration. This report details a roadmap for how USACE could leverage aquatic ecosystem restoration investments to operationalize the USACE Aquatic Restoration Monitoring for Ecosystem Recovery (ARMER) Network and advance the science of aquatic ecosystem restoration.

4 Sep 2025

The Edge of Crisis: Discovery of Young of Year Black Carp Mylopharyngodon piceus (Richardson, 1846) in the Lower Mississippi River

Abstract: Understanding changes in the status of invasive species is important to managers in order to prevent or minimize impacts to native communities. Out of the four invasive carp imported to the U.S. from Eastern Asia, black carp Mylopharyngodon piceus have been generally overlooked due to the difficulty in capturing these fish even using targeted efforts. Because of this, limited resources have been channeled towards managing this species. Concerns over the expansion of black carp have been expressed, but direct evidence of reproduction in U.S. waters was lacking until young of year black carp were caught in tributaries of the Middle Mississippi River in 2015. This remained the known extent of the naturalized invasion until fish community surveys conducted in the fall of 2022 and 2023 documented young of year black carp in three oxbow lakes connected to the mainstem Lower Mississippi River. These collections provide evidence for increased population growth and exhibit expanding threats to the diverse mussel communities native to the Lower Mississippi River basin.

3 Sep 2025

Optimal Transport-Based Full-Waveform Inversion for Shallow Seismic Data

Abstract: Full-waveform inversion is widely used to reconstruct subsurface properties at different geologic scales. For shallow land applications using surface waves, a lack of information on the source wavelet, dispersion, and presence of higher modes increases the nonlinearity of the inverse problem. The inversion can become more challenging with the presence of near-surface complexities associated with scattering, attenuation, and high-contrast variations in the elastic parameters. Compared with the least-squares formulation, GSOT provides a more convex misfit function and reduces dependence on the accuracy of the initial model. Although a few field-data applications have shown the potential and benefits of using GSOT-based FWI with body waves, there are limited real applications of the inversion with a GSOT misfit function for NS characterization. Despite considerable effort with blind benchmark tests in exploration seismology, typically synthetic FWI examples for NS applications are demonstrated through an “inverse crime” approach. Synthetic FWI examples performed compare the performance of LS- and GSOT-based FWI with more realistic scenarios. We demonstrate the GSOT misfit function improves the initial 1D velocity models and guides the updates toward the actual subsurface properties. This enables the recovery of higher-mode Rayleigh waves and reconstruction of the cavity with better precision.

3 Sep 2025

Acute Toxicity of Carbon Nanotubes, Carbon Nanodots, and Cell-Penetrating Peptides to Freshwater Cyanobacteria

Abstract: Synthetic non-metallic nanoparticles have been explored to treat harmful algal blooms, but their strain-specific algicidal activities have been rarely investigated. Three batches of CNDs were prepared in-house using glucose or chloroform and methanol as the substrate and one batch of single-walled CNTs. The axenic laboratory culture of each cyanobacterial strain was exposed to an NMNP at two dosage levels for 48 h, followed by measurement of five endpoints. The endpoints were optical density at 680 nm for chlorophyll-a estimation, OD at 750 nm for cell density, instantaneous pigment fluorescence emission after being excited with 450 nm blue light for chlorophyll-a or 620 nm red light for phycocyanin, and quantum yield for photosynthesis efficiency of photosystem II. The results indicate the acute toxicity was strain-, NMNP type-, dosage-, and endpoint-dependent. The two benthic strains were more resistant to NMNP treatment. SWCNTs and fraction A14 of CND-G were more toxic than CND-G and CND-C/M. The CPP was the least toxic. The high dose generally caused more severe impairment. OD750 and OD680 were more sensitive and QY was the least sensitive. The strain dependence of toxicity suggested the potential application of these NMNPs as a target-specific tool for mitigating harmful cyanobacterial blooms.