26 Aug 2025

Tampa Harbor, Florida, Navigation Improvement Study

Abstract: The Port of Tampa Bay services approximately 30.5 million tons of cargo each year (based on 2017–2021 data) and is situated on the Tampa Bay/Orlando I-4 Corridor, which serves the largest concentration of distribution centers in the state. To expand operations to include direct Asia, Mexico, and Central America services, numerous port facility improvements were required. This rapid expansion of port capabilities led to increasing difficulty of port efficiency and navigation. A study was conducted investigating proposed channel improvements addressing these issues. In 2022 and 2023, the US Army Engineer Research and Development Center (ERDC) assisted the US Army Corps of Engineers–Jacksonville District in evaluating proposed deepening and widening alternatives in Tampa Harbor by completing a ship simulation study using ERDC’s Ship/Tow Simulator. During this study, focus areas were passing lanes in Cut B and Gadsden Point Cut, the turning basin at Hooker’s Point/Port Sutton, the turn widener between Cut F and Gadsden Point Cut, and turns into Alafia and Big Bend. The proposed design was evaluated over the course of 2 weeks with four pilots. Proposed modifications were assessed through analysis of data resulting from the ship simulations including track plots, run sheets, and final pilot surveys.

26 Aug 2025

Miami Harbor Navigation Improvements Study

Abstract: In 2019, the US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory (CHL), Ship/Tow Simulator (STS), was used to perform a navigation study assisting the US Army Corps of Engineers, Jacksonville District. The study evaluates channel improvements to allow larger containerships to call at the Port of Miami. This study also evaluates improvements associated with the proposed cruise terminals. This study was conducted at the CHL real-time STS. Real-time refers to the fact that model time uses a 1:1 ratio to prototype time. In addition, real world environmental forces were simulated and acted upon the modeled ships during the study. These forces included currents, wind, bathymetry, and bank effects. Simulations for the project improvements were conducted at CHL for 3 weeks in August 2019 and 1 week in November 2019. Seven Biscayne Bay pilots participated in the validation and testing exercises. The design vessels include the MSC Daniela (14,000 twenty-foot equivalent unit [TEU]) container ship, the Majestic Maersk (18,000 TEU) container ship, the Allure of the Seas cruise ship, the Disney Dream cruise ship, and the M/S Paradise cruise ship. Results, in the form of track plots and pilot questionnaires, were reviewed to develop conclusions and recommendations.

26 Aug 2025

Evaluating Beneficial Use in the 1998–2021 Sediment Placement Data with Updated Placement Categories

Purpose: The objective of this study was to provide a comparable Beneficial Use (BU) to Disposal ratio for the data within the “historic” 1998–2021 Sediment Placement Data Viewer to the data within the 2022–Present Sediment Placement Data Viewer. In conjunction with this primary objective, a secondary target was to quantify a historic average volume of sediment placed by US Army Corps of Engineers (USACE) annually on a national scale.

26 Aug 2025

The Quick Response Toolbox User’s Guide

Abstract: Regional-scale beach morphology, volume, and shoreline changes are quantified using the Joint Airborne Lidar Bathymetry Technical Center of Expertise (JALBTCX) ArcGIS Python toolboxes. This user’s guide details the JALBTCX toolbox framework and the operation of the Quick Response Toolbox. A walkthrough for each individual step within the toolbox will be presented along with example data from Homer, Alaska. Best practices and example data and figures are included as additional documentation for new users.

22 Aug 2025

Evaluating High Water Indicators Along Lake Powell’s Shoreline, Utah-Arizona

Purpose: This document is a technical note (TN) that outlines how to evaluate physical, chemical, biological, and statistical indicators of the ordinary high water mark (OHWM) for reservoirs of the Arid West, with identification of high water indicators around Lake Powell serving as a case study (Figure 1). The focus of this TN is to describe observed indicators, the processes that shape them, and how to put the information in context based on past and present water levels. It can be particularly complicated to evaluate evidence of OHWM in arid west lakes, because of the years of drought that has occurred in this region, leaving indicators high and dry over years. Therefore, this TN also provides information on how to apply the same weight-of-evidence (WoE) approach that was introduced for OHWM delineation in rivers and streams by David et al. (2025) to arid west lakes and reservoirs. Lake Powell is used as a case study to show how to interpret the indicators along the lake and evaluate the relevance, strength, and reliability of these indicators in relation to high water stage in the lake.

22 Aug 2025

Cracking the Code: Linking Good Modeling and Coding Practices for New Ecological Modelers

Abstract: Good modeling practices are essential for producing reliable and reproducible ecological models. Inherent to good modeling practices are fundamental coding and documentation skills, which not only implement the desired modeling capabilities but also clearly outline the goals, methods, and components of a model necessary to reproduce desired results. Coding represents a significant barrier for entry into ecological modeling, since most ecologists have not had formal training in computer science or software development. While software packages do exist that facilitate model development, we have observed that newer modelers still struggle with developing good coding practice throughout the modeling process. During a series of agent-based modeling short-courses and full semester graduate courses, both taught in NetLogo, we identified some common challenges encountered by graduate students and environmental professionals as they learn to code an ecological model, many for the first time. We were able to categorize and provide examples of the main challenges and obstacles, which fell into three main groups that follow the steps of good modeling practice: problem scoping and conceptualization, formulation, and evaluation. We then provide guidance on how to overcome these obstacles while developing good coding and modeling practices that will result in more scientifically defensible models.

20 Aug 2025

Parameterized Statistical Distributions of Unique Origin-Destination Pairs for Major Waterborne Commodity Groups

Abstract: Modeling the spatiotemporal aspects of freight movements within a distributed network is crucial to forecasting transportation infrastructure needs, prioritizing investments, and estimating emissions. Commodity flow patterns and trends along the inland waterway transportation system are significant because of their importance for the economy, in line with priorities of the US Committee on the Marine Transportation System. Analyzing these inland waterway flows better informs multimodal freight transportation modeling. This exploratory research uncovers, describes, and summarizes patterns and trends of the US waterway transportation system by mining waterborne freight data. The purpose of this work is to identify parameterized statistical distributions that describe the relative dispersion of unique waterborne Origin-Destination (OD) pairs when sorted high to low by annual freight tonnage. Best-fit statistical distributions and associated parameters are identified for the leading commodities transported on waterways, and an 11-year time-series analysis of commodity-specific distribution parameters provide their evolution across time. Results show that the power law best explains the distribution of ranked ODs by tonnage for seven of the twelve commodities analyzed. The root-mean-square error (RMSE) of any given commodity modeled is less than 1%. These results provide insights into the underlying behavior of inland waterway freight transportation.

20 Aug 2025

Examining the Impact of the 2007 Zaca Fire on the Long-Term Hydrological Recovery of the Santa Cruz Creek Watershed in Southern California

Abstract: This study focuses on the Santa Cruz Creek watershed in Southern California, an area severely impacted by the 2007 Zaca Fire. The region is representative of wildfire-prone Mediterranean-climate catchments. We assess long-term post-fire hydrological recovery using a novel dual approach: (1) simulating 16 storm events over a 23-year period to evaluate pre-fire, post-fire, and recovery conditions, and (2) directly comparing two similar storm events—one pre-fire and one during recovery—to isolate changes in watershed response. Hydrological modeling employed HEC-HMS with the Deficit and Constant Loss Method, the ModClark Transform Model, and the Linear Reservoir Baseflow Model. Remote sensing data, including Enhanced Vegetation Index and SERVES Soil Moisture, enhanced modeling and analysis. Vegetation cover, soil moisture, and several watershed parameters show substantial recovery after five years. EVI reached 84 % of pre-fire values, while initial soil moisture deficit, time of concentration, and storage coefficient each recovered to roughly 70 %. Fast baseflow exceeded pre-fire levels at 143 %, but slow baseflow declined to 20 %. Peak discharge and direct runoff volume declined from post-fire highs of 173 % and 136 % to 125 % and 84 % of pre-fire levels, respectively. Although vegetative conditions stabilize, watershed hydrology remains altered.

20 Aug 2025

Bioturbation Increases Time Averaging Despite Promoting Shell Disintegration: A Test Using Anthropogenic Gradients in Sediment Accumulation and Burrowing on the Southern California Shelf

Abstract: Bioturbation increases time averaging of young and old shells within the entire mixed layer and accelerating the burial of shells into a sequestration zone. Bioirrigation by oxygenated pore-water promotes carbonate dissolution in the TAZ, and biomixing itself can mill shells weakened by dissolution or microbial maceration, and/or expose them to damage at the sediment–water interface. We fit transition rate matrices to bivalve age–frequency distributions from four sediment cores to assess the competing effects of bioturbation on disintegration and time averaging. Disintegration covaries positively with mixing at all four sites. Mixing and disintegration rates decline abruptly at the base of the 20- to 40-cm-thick, age-homogenized surface mixed layer at the three well-bioturbated sites. In contrast, they are very low in the upper 25 cm at an effluent site with legacy sediment toxicity. Assemblages formed during maximum wastewater emissions vary strongly in time averaging. Thus, even though disintegration rates covary positively with mixing rates, reducing postmortem shell survival, bioturbation has the net effect of increasing the time averaging of skeletal remains on this warm-temperate siliciclastic shelf.

20 Aug 2025

Coastal Sand Dunes: A Review of Management Strategies for Dune Stabilization

Abstract: The primary objective of this technical note is to provide a US-centric review on historic and current management approaches for dune stabilization efforts. This includes methods for promoting dune formation via natural aeolian processes, as well as more hands-on management approaches, including hybrid dune construction.