Adding sediment between the swash zone and depth of closure, or nearshore nourishment, can often provide a cost-effective strategy to mitigate erosion. Scoping level tools have been developed to combine wave information and nourishment characteristics to estimate how quickly placed sediment will move, providing useful information early in project planning. Several nearshore nourishment studies have observed localized beach width gain in the lee of the nourishment, similar to the shoreline response leeward of submerged breakwaters, but most previously developed rapid techniques do not incorporate local shoreline response. Others require tuning with information about local sediment transport or past project behavior. This study combines existing empirical equations in a simple scoping level tool to rapidly predict the shoreline response in the lee of a nearshore nourishment by assuming the shoreline response is dominated by reductions in the alongshore sediment transport due to reduced wave transmission over the nourishment. Intermediate wave sheltering and alongshore sediment transport reduction predictions are validated for the 2021 nearshore nourishment at Harvey Cedars, New Jersey, with a nonlinear wave-resolving model and a simplification of common sediment transport equations. Shoreline response predictions are generally correct within a factor of 3 over a wide variety of case studies, yielding a refined index of agreement of 0.66. This rapid approach yields reasonable predictions for the approximate shoreline response in the lee of nearshore nourishments. Inputs are relatively simple and site-specific tuning is not required. This capability has the potential to help inform nearshore nourishment location and dimension decisions during planning.

This report documents a numerical modeling investigation of shore protection alternatives at Crescent Beach, Indiana. The integrated flow, wave, sediment transport, and morphology change Coastal Modeling System (CMS) and the long-term shoreline evolution model, GenCade, were applied to evaluate alternatives. Sediment, elevation, and hydrodynamic data were collected nearby to improve model calibration and validation. Eight alternatives were evaluated, with coastal structures in four, beach nourishments in three, and one with both. Structures other than the continuous rubble ridge (Alternative 4) had minimal or negative influences on sediment transport. Stone sizes and costs were estimated for Alternative 4 using StormSim and extremal forcing from the Coastal Hazards System (CHS) Great Lakes Study, but CMS does not predict impacts that justify rubble ridge construction costs. CMS and GenCade were applied to beach nourishments across a range of volume and sediment grain size distributions. Model evaluations indicate that beach nourishment is the most effective shoreline protection technique, using coarse sand mixed with small stones to achieve a median grain size (d50) of 1.80 millimeters successfully extends the beach nourishment lifecycle, and increasing nourishment volume to 87,455 cubic meters to span in front of Mount Baldy substantially increases downdrift benefits.

Coastal zones are critical regions that support vital economic and ecological systems, yet they are increasingly threatened by erosion, sea-level rise, and extreme weather. Effective management of these environments can be supported by high-resolution, co-registered topographic and sedimentological datasets. Conventional methods to obtain subaerial topographic datasets such as ground-based real-time kinematic GPS surveys, Unmanned Aerial System (UAS) based Structure-from-Motion (SfM) photogrammetry, and fixed position light detection and ranging (lidar) are limited by safety, mobility, and the inability to capture both elevation and sediment properties simultaneously in dynamic coastal settings. We introduce SandHound, a quadruped unmanned ground vehicle (UGV-Q), modified and operated to conduct a complete and multi-faceted survey in the subaerial beach zone. SandHound's integrated payload includes lidar for topographic mapping, and stereoscopic cameras for onboard grain size prediction via SandSnap. Field experiments at the U.S. Army Corps of Engineers Field Research Facility (FRF) in Duck, North Carolina, were conducted to validate the system's core functions. The evaluation focused on three components: (1) accuracy of SandHound's topographic data compared to SfM and fixed position lidar, (2) effectiveness of the SandSnap system validated against physical sediment samples (Camsizer), and (3) assessment of system mobility across a study area characterized by varied near-surface resistance (measured using Dynamic Cone Penetrometer-DCP-tests). SandHound achieved comparable or improved elevation accuracy (RMSE similar to 0.15 m) when compared to the fixed position lidar as a ground truth, outperforming UAS-based SfM (RMSE similar to 0.24 m). SandHound achieved spatial coverage of (similar to 89%) of the study area, and reliable operation across the range of measured sediment conditions. Site-specific tuning of SandSnap yielded a median absolute percent error of similar to 13.4% in median grain size (D-50) when compared with Camsizer analyses, while DCP cone resistance values (q(d)) from 0.09-5.89 MPa confirmed reliable quadruped operation across loose to moderately compact sand. These results demonstrate that UGV-Q platforms can provide a safe, mobile, and efficient means of integrated topographic and sedimentological measurements, offering a robust new tool for coastal monitoring, erosion assessment, and post-storm reconnaissance.

The nearshore placement of sediments dredged via maintenance of navigation channels is a cost-effective management solution which offers myriad benefits that can include shoreline protection and habitat restoration. Benefits can be offset by concerns due to potential effects on the ecosystem from turbidity generated during placement. This study investigates the turbidity and geomorphic response of dredged sediment placed within the dynamic littoral zone of Lake Erie. Turbidity was measured at nine locations before, during, and after nearshore dredged material placement, and bathymetry was measured in four surveys to capture the effects of placing 39,400 m3 of material from Fairport Harbor, Ohio. Nearshore turbidity measurements collected before dredging occurred could be explained using wave data, which provided an estimate for expected background turbidity during and after dredging. These wave models continued to fit measured turbidity data well during and after dredged material placement and indicate sediment placement did not significantly increase turbidity at any of the monitoring locations. Bathymetry surveys indicate sediment was placed within the active littoral zone and may have contributed to accretion along the onshore edge of the pre-existing bar. These observations indicate that nearshore placement of dredged material in this environment is aligned with natural sediment movement in the littoral zone, with minimal to negligible generation of turbidity beyond what occurs naturally.

Beach nourishment has a high cost but offers large economic benefits. Therefore, extending the nourishment lifespan using dredged sediment from navigation channels could have a significant economic impact. This numerical modeling study develops and compares two approaches incorporating nearshore sediment placements into an existing one-dimensional numerical modeling procedure to predict the lifespans of subaerial beach nourishment strategies. Both approaches build directly on the stochastic lifecycle simulation methodology and results used in the Coastal Texas Protection and Restoration Feasibility Study. Simulations for western Galveston Island were modified to include annually recurring nearshore nourishment. Cross-shore beach transects were forced with 50 years of tropical cyclones and nontropical storms in a cross-shore morphological evolution model, and rebuilt when the dune eroded to half of its initial height. One group of simulations applied this previously developed model forcing to cross-shore profiles that were updated with recurring nearshore nourishments. A second group of simulations included a simplified representation of sediment deposition from the alongshore transport gradient created by the nearshore nourishments. In both sets of simulations, a large sediment feature was incrementally constructed at depths between 2.5 and 6 m. Over 30 life cycles, the number of times the beach was rebuilt was tracked for each 50-year simulation. Comparing the number of predicted beach renourishments indicates that this particular nearshore nourishment strategy did not substantially impact the subaerial beach morphology unless alongshore transport gradients were also included. Simulations that did include this alongshore transport gradient predicted 23% longer lifespans. This work was not able to incorporate validation against measured data, but future testing of this approach should be pursued before widespread or high-impact application. Modeling results indicate that alongshore processes are an important part of quantifying the positive impacts of nearshore nourishment.

The Great Lakes includes 140 federally maintained harbors with an annual dredging program of 2–4 million cubic meters (3–5 million cubic yards)1 of sediment. Many small harbors are not dredged regularly, and there is an undredged backlog of over 9 million cubic meters (12 million cubic yards) of sediment (USACE-LRD 2021). Current policy (Spellmon 2023) is to maximize the beneficial use (BU) of sediment, with a goal of beneficially reusing 70% of the federal navigation dredging volume by 2030 (that is, the 70/30 goal). In the Great Lakes, clean sands have often been placed on beaches or in the nearshore littoral zone to beneficially nourish the shoreline, but since many harbors are not dredged regularly, no plans exist to beneficially reuse dredged sediments. This lack of existing BU plans is particularly true for harbors with finer grained or mixed sediment. To achieve the 70/30 BU goal and support navigation maintenance and coastal management requires a strategic and systematic approach to identifying BU sites. The purpose of the technical note is to (1) provide an approach to identify potential nearshore placement sites using existing information and models; (2) describe available tools for placement site identification, coastal condition information, and the long-term fate of the sediment; and (3) provide a pertinent case study to describe this approach in practice.

Sediment grain size is a critical parameter for sediment mobilization and transport, but often has the highest uncertainty of any coastal sediment transport model input parameter. SandSnap is an initiative to engage the public to amass a beach grain size database by taking photos of the beach sand with a coin in the image for scale and uploading the image to a web application. Images are analyzed with two deep learning convolutional neural networks one to detect the coin and the second to measure the grain size, which is trained on sediment samples within the sand regime. The results for nine gradation metrics are returned to the user within 2 min of image upload. Results from 263 test images have a mean percent error of -6.5% and median absolute error of 22.4% for the median grain size (d50) with a small fine bias of -0.042 mm. The use of the database is highlighted by applying SandSnap output as an input to the AeoLiS aeolian sediment transport model to predict coastal dune growth at a nearly national scale using the full eight grain size classes (d10 - d90) from the SandSnap database. These outputs are used to inform the potential value of having spatially comprehensive grain size distribution information as part of coastal engineering design and planning. Education and outreach techniques for the SandSnap initiative are described in the manuscript. Though some challenges remain, the spatially and temporally robust beach grain size database being developed by SandSnap will help to improve numerous coastal engineering analyses including coastal resilience and vulnerability quantification, beach nourishment life cycle and uncertainty analysis, beach compatibility for the beneficial use of dredged sediment, and large-scale coastal morphology modeling.

The US Army Corps of Engineers (USACE) recently established a goal to beneficially use 70% of material dredged from the nation’s navigable waterways by the year 2030. Most of the sediments dredged by the USACE are heterogeneous mixtures of mud and sand, which can limit beneficial use of dredged material (BUDM) applications. Innovative technologies that can sort material during the dredging process are needed to help increase BUDM practices. This investigation sought to evaluate the ability of a sediment distribution pipe (SDP) to sort particles during transport in a pipeline. Field demonstrations were conducted during dredged material placements at Sturgeon Island, New Jersey. Velocity within the pipeline was found to be inadequate for efficient hydraulic sorting of fines (<75 μm) and produced inconclusive results. Small scale laboratory SDP experiments found that effluent from the SDP holes had an altered sediment texture compared to the initial slurry and that hydraulic sorting was occurring within the pipeline. However, outflow from the SDP holes was inconsistent, and typically >90% of the sediment mass was discharged out the end of the pipeline. Sorting efficiency of the SDP could not be accurately assessed in the current experimental configuration.

Standard dredging operations during thin layer placement (TLP) projects are labor intensive as crews are necessary to periodically move the outfall location, which can have lasting adverse effects on the marsh surface. In an effort to increase efficiency during TLP, a novel Sediment Distribution Pipe (SDP) system was investigated. This system offers multiple discharge points along the pipeline to increase the sediment distribution while reducing pipeline movements. An SDP Modeling Application (SDPMA) was developed to assist in the design of SDP field applications by quickly assessing the pressure and velocity inside the discharge pipe and approximating the slurry throw distances. An SDP field proof of concept was performed during a two-phase TLP on Sturgeon Island, New Jersey, in 2020. The SDPMA was shown to be an accurate method of predicting performance of the SDP. The SDP was successful at distributing dredge material across the placement site; however, further research is warranted to better quantify performance metrics.

The Great Lakes Navigation System is an economically critical waterway. To maintain safe and navigable waterways, approximately 3–5 million yd³ (2.3–3.8 million m³) of sediments are dredged annually. The US Army Corps of Engineers (USACE) and others now recognize that beneficial use of these sediments can achieve positive economic, environmental, and social outcomes. However, historically less than 25% of dredged sediments have been beneficially used in the nearshore environment. Improvements are needed in dredged material management practices in the Great Lakes to achieve the goal of using 70% of dredged sediments beneficially by 2030. Therefore, to overcome these challenges this report reviews beneficial use of dredged material projects with the goal of improving and in-creasing beneficial-use-placement practices in the Great Lakes. Identified needs to advance beneficial-use placement in the Great Lakes include the following: (1) improved modeling of sediment-placement methods; (2) better documentation regarding the cost, benefits, and drawbacks of various placement methods; (3) demonstration of some sediment-placement techniques used successfully in other coastal environments; and (4) monitoring before and after conditions, particularly for sediments that contain greater than 10% fines. Several demonstration projects should be implemented to obtain information addressing the data gaps.

The practice of placing sediment dredged from navigation channels in the downdrift nearshore is common in the US. These nearshore placements of dredged sediment, or nearshore nourishments, often correspond to a variety of positive nearshore morphology and shoreline stability benefits. They are often able to beneficially use sediment not directly suitable for dry beach placement, which increases the volume available to nourish the full beach profile and keeps sediment in the system that would otherwise be removed. Concentrating dredged sediment placement in nearshore berms may dissipate wave energy farther offshore and reduce the sediment needs of the co-located shoreline. This strategy may be able to extend subaerial beach nourishment lifespan, which typically cost substantially more. Co-located nearshore and subaerial beach nourishments could lead to large cost savings, but the potential to increase subaerial beach fill lifespan has not previously been quantified.

U.S. beaches are data rich environments with readily accessible topographic and hydrodynamic data, but a national database of beach grain size information does not exist. Unfortunately, grain size is often poorly parameterized, particularly for geographically large studies, because it is unfeasible to collect beach grain size information on a large, multi-state or national scale with traditional methods. As a result, sediment size often has the largest uncertainty of the input parameters for sediment transport modeling (Soulsby, 1997). “SandSnap” is a research initiative to amass the first nationwide beach sand grain size database with the help of citizen scientists using their smart phones.

In 2020 the US Army Corps of Engineers (USACE) reassigned 14 federally maintained harbors in the Wisconsin waters of Lake Michigan to USACE–Chicago District. The administrative change presents opportunities for increased beneficial use of sediment at harbors that have not traditionally placed sediment beneficially. This paper summarizes a screening-level analysis of 12 harbors to determine which harbors are likely to have sediment appropriate for beneficial use in the future, either in water or upland. The harbors were qualitatively ranked according to the potential for future successful beneficial use of navigationally dredged sediment. Using this screening, data needs were defined and next steps to aid the development of a regional dredged-material management plan were identified.

Coastal resilience is the ability of a system to prepare, resist, recover, and adapt to achieve functional performance under adverse events such as storms and sea-level changes. Usually, previously developed metrics are applied to quantify the resistance portion of coastal resilience, which supports the preparation and adaptation portions. Recent research produced a GIS-based tool that provides a quantitative coastal resilience metric to inform decisions related to protection from coastal storm impacts and to evaluate the success of past management actions. Other research developed a forward-looking metric that uses Beach-fx results to calculate future resilience based on nourishment alternatives. 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.

Coastal Sediments 2023, pp. 906-918 (2023) No AccessSANDSNAP: CREATING A NATIONWIDE BEACH GRAIN SIZE DATABASE BY ENGAGING CITIZEN SCIENTISTSBRIAN C. McFALL, DAVID L. YOUNG, SHELLEY J. WHITMEYER, DANIEL BUSCOMBE, SHANNON N. STEVER, and BROOKE M. WALKERBRIAN C. McFALLU.S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, 3909 Halls Ferry Road, Vicksburg, MS 39180, USA, DAVID L. YOUNGU.S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, 3909 Halls Ferry Road, Vicksburg, MS 39180, USA, SHELLEY J. WHITMEYERJames Madison University, 801 Carrier Drive, Harrisonburg, VA 22807, USA, DANIEL BUSCOMBEMarda Science, LLC., Flagstaff, AZ 86001, USA, SHANNON N. STEVERU.S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, 3909 Halls Ferry Road, Vicksburg, MS 39180, USA, and BROOKE M. WALKERU.S. Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, 3909 Halls Ferry Road, Vicksburg, MS 39180, USAhttps://doi.org/10.1142/9789811275135_0086Cited by:0 PreviousNext AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsRecommend to Library ShareShare onFacebookTwitterLinked InRedditEmail Abstract: This study assesses the effectiveness of SandSnap, a research initiative that engages citizen scientists in amassing the first public nationwide database of beach sand grain sizes on U.S. coastlines. Citizen scientists can contribute to the database by taking a picture of sand at a beach with a U.S. coin, uploading the image to the SandSnap website, and recording the location using the phone's built-in GPS. Sediment gradation is returned to the user within 2 minutes of image upload and the results are stored on a public database. Image processing and outreach initiatives are detailed. Results from an experiment where 31 participants with varying phones took a SandSnap of the same sand show the median grain size had a mean percent error of 21.3%. Image processing techniques are continuing to be improved and the supporting neural networks are regularly retrained with more data to improve the accuracy and robustness of the SandSnap results. The spatially and temporally robust beach grain size database being developed by SandSnap will help to improve numerous coastal engineering analyses including coastal resilience and vulnerability quantification, beach nourishment life cycle and uncertainty analysis, beach compatibility for beneficial uses of dredged sediment, and large-scale coastal morphology modeling. Crowdsourcing beach sand grain size data collection provides a cost-effective way to accumulate unique sand grain sizes on a large scale while increasing public engagement and providing a better understanding of sand on U.S. coasts. FiguresReferencesRelatedDetails Recommended Coastal Sediments 2023Metrics History PDF download

This US Army Corps of Engineers (USACE) special report prepared by the US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, provides an overview of the current state of practice for nearshore nourishment with dredged sediment. This special report was completed with responses and input from professionals across the dredging and placement teams from each of the USACE Coastal and Great Lakes districts, providing comprehensive overviews of the decision trees these districts utilize in the placement of their dredged sediment. This report describes the general practice of nearshore nourishment, the impediments and concerns faced by nearshore nourishment projects, and the practical methods utilized by the Coastal and Great Lakes districts for their nearshore nourishment projects. Understanding the current state of practice, along with the general and specific impediments the districts face, enables further research in and development of best practices for use across the USACE and better communication of the practice to other stakeholders.

To address the important research question of whether implicit (bottom friction) or explicit (stem drag) dissipation models are most appropriate for the prediction of wave attenuation due to aquatic vegetation, the Simulating Waves Nearshore (SWAN) spectral wave model has been extended with an explicit frequency-dependent dissipation model for submerged and emergent vegetation. The new explicit model is compared to existing explicit and implicit dissipation models in SWAN, and the distinguishing features of each of the dissipation models are quantified. The present work verifies the implementation of the new and existing dissipation models, outlines their distinguishing features, and compares model predictions against experimental data. The emphasis is on the transformation of the spectral wave periods T-m0,T-1 and T-m-1,T-0 over a canopy. Model evaluation based on academic and laboratory cases allows for recommendations regarding applicability of the three dissipation models, where the new method has the broadest applicability, since it bridges the gap in applicability between the other two dissipation models. The implementation of Jacobsen, McFall, and van der A (2019; A frequency distributed dissipation model for canopies; Coastal Engineering, 150, 135-146) is publicly available in SWAN version 41.31B.