Regional Sediment Management Research Articles

Regional Sediment Management in US Coastal States: Historical Trends and Future Predictions

Sea level rise and natural disasters, such as hurricanes and tropical storms, are resulting in coastal erosion-related problems across the US. Beach nourishment is one of the most commonly adopted solutions for erosion mitigation. Borrow sources for nourishment are often from offshore or upland mines. However, in some areas, sediment availability from known borrow sources is becoming scarce. This suggests that sediment should be considered a non-renewable resource within the framework of long-term planning and coastal management decisions. Regional Sediment Management (RSM), or the beneficial use of dredge material (BUDM), targets inlets for borrowing material and can also be a more cost-efficient strategy that has widely been supported by the US Army Corps of Engineers as a system-based approach. However, not all states have embraced this approach, and a national-scale evaluation of these projects in coastal management and adaptation is needed. This study examines past RSM/BUDM projects in the top ten most highly nourished states in the US and compares those trends to a selection of minimally nourished states from different coasts. Based on the historical trends identified, the volume of sediment required for future RSM/BUDM projects in these areas over the next 50 years is predicted using Auto Regressive Integrated Moving Average (ARIMA) models. Although growth in the total number of RSM/BUDM projects was measured over time, there was a decline in the volume of sediment placed for these projects. Results of the forecasting model suggest that CA, NC, and the FL Gulf Coast could require the highest volume of sediments for RSM/BUDM activities over the next 50 years. Based solely on proximity to inlets for sediment resources, DE, FL Atlantic, and NJ coasts are potential beaches that can increase BUDM activities. This study aims to provide a framework to evaluate the suitability of future RSM/BUDM projects in efforts to mitigate coastal erosion.

ADVANCING SEDIMENT SOLUTIONS IN THE SEVEN MILE ISLAND INNOVATION LABORATORY

In 2019, the U.S. Army Corps of Engineers (USACE) Philadelphia District partnered with the State of New Jersey, The Wetlands Institute, and the USACE Engineer Research and Development Center to launch the Seven Mile Island Innovation Laboratory (SMIIL). The initiative is designed to advance and improve dredging and marsh restoration techniques in coastal New Jersey through innovative research, collaboration, knowledge sharing and practical application. SMIIL efforts are enhancing the science and engineering that supports dredging and beneficial use placement practices by clearing shoals from the federal New Jersey Intracoastal Waterway for navigation and innovatively placing that sediment on multiple sites described herein. Regional Sediment Management and Engineering with Nature principles and practices serve as a strong foundation for SMIIL actions. Efforts are successfully evolving the practice and advancing techniques for beneficial use of dredged channel sediments with innovative placements that support coastal resilience for habitats and communities.

2020 hurricane impact assessment for the northern Gulf of Mexico: Hurricane Sally and Hurricane Zeta

Regional-scale shoreline and beach volume changes are quantified using the Joint Airborne Lidar Bathymetry Technical Center of Expertise’s digital elevation model products in a change detection framework following the passage of the two landfalling hurricanes, Hurricanes Sally and Zeta, along the northern Gulf Coast in late fall 2020. Results derived from this work include elevation change raster products and a standard set of beach volume and shoreline change metrics. The rapid turn-around and delivery of data products to include volume and shoreline change assessments provide valuable information about the status of the coastline and identification of areas of significant erosion or other impacts, such as breaching near Perdido Key, FL, from Hurricane Sally’s impact. These advanced change detection products help inform sediment budget development and support decisions related to regional sediment management and coastal storm risk management.

Amplified Impact of Climate Change on Fine-Sediment Delivery to a Subsiding Coast, Humboldt Bay, California

In Humboldt Bay, tectonic subsidence exacerbates sea-level rise (SLR). To build surface elevations and to keep pace with SLR, the sediment demand created by subsidence and SLR must be balanced by an adequate sediment supply. This study used an ensemble of plausible future scenarios to predict potential climate change impacts on suspended-sediment discharge (Qss) from fluvial sources. Streamflow was simulated using a deterministic water-balance model, and Qss was computed using statistical sediment-transport models. Changes relative to a baseline period (1981–2010) were used to assess climate impacts. For local basins that discharge directly to the bay, the ensemble means projected increases in Qss of 27% for the mid-century (2040–2069) and 58% for the end-of-century (2070–2099). For the Eel River, a regional sediment source that discharges sediment-laden plumes to the coastal margin, the ensemble means projected increases in Qss of 53% for the mid-century and 99% for the end-of-century. Climate projections of increased precipitation and streamflow produced amplified increases in the regional sediment supply that may partially or wholly mitigate sediment demand caused by the combined effects of subsidence and SLR. This finding has important implications for coastal resiliency. Coastal regions with an increasing sediment supply may be more resilient to SLR. In a broader context, an increasing sediment supply from fluvial sources has global relevance for communities threatened by SLR that are increasingly building resiliency to SLR using sediment-based solutions that include regional sediment management, beneficial reuse strategies, and marsh restoration.

Toward improved coastal sediment management through coordination in California

Sediment is an essential component of contemporary coastal and marine management in California. For decades, multiple coastal sediment management organizations have facilitated and coordinated regional sediment management (RSM) as an approach, and more recently, are increasingly focused on the state’s sea level rise adaptation efforts. From the perspective of representatives and members of some of these organizations, this paper describes challenges of RSM in the areas of organizational capacity and coordination. It also characterizes ways in which organizations are taking leadership and action in overcoming these constraints to fulfill their commitment to improved coastal sediment management.

Best management practices for coastal inlets

Coastal inlets separate individual barrier islands or barrier spits and adjacent headlands (Hayes and Fitzgerald 2013). Inlets modify longshore transport and store sediment in flood and ebb shoals leading to dynamic adjacent shorelines. For example, 80% to 85% of the beach erosion in Florida can be attributed to inlets (Dean 1991). In some cases, structured inlets are designed to trap sand in a preferred location to minimize interference with navigation and facilitate its removal through dredging. Sound coastal engineering practice requires that this sand be placed on adjacent eroding beaches (NRC 1995) to protect coastal resources. This paper provides a brief overview of coastal inlet management and identifies Best Management Practices (BMPs) intended to balance human needs for inlet navigation with the natural systems adjacent to tidal inlets. Today’s conservation measures, which are a result of considerable monitoring, numerical modeling, and other science-based methods, demonstrate that BMPs improve management of sand resources and reduce impacts associated with tidal inlet dredging. For some inlet conditions, BMPs include use of inlet sediment sinks as cost-effective and eco-friendly sand sources for beach nourishment projects located close to the inlet. For optimal coastal inlet management, the ASBPA Science and Technology Committee recommends the following BMPs and conservation measures: • Limit frequency and duration of impacts, • Follow environmental windows, • Implement regional sediment management, • Use beach-compatible sand, • Conduct pre-, during-, and post-dredging monitoring, • Modify dredging equipment/practices, and • Design rechargeable, low-impact inlet borrow sites.

Morphodynamics of barrier-inlet systems in the context of regional sediment management, with case studies from west-central Florida, USA

The temporal and spatial scales controlling the morphodynamics of barrier-inlet systems are critical components of regional sediment management practice. This paper discusses regional sediment management methods employed at multiple barrier-inlet systems, with case studies from West-Central Florida. A decision-support tool is proposed for regional sediment management with discussion of its application to barrier-inlet systems. Connecting multiple barrier islands and inlets at appropriate spatio-temporal scales is critical in developing an appropriately scoped sediment management plan for a barrier-inlet system. Evaluating sediment bypassing capacity and overall inlet morphodynamics can better inform regional sand sharing along barrier-inlet coastlines; particularly where sediment resources are scarce and a close coupling between inlet dredging and beach placement is vital to long-term sustainable management. Continued sea-level rise and anthropogenic activities may intensify the need for investigating longer-term processes and expanding regional planning at a centennial timescale, and are acknowledged as challenging tasks for RSM studies. Specifically, we suggested that a regionally focused, multi-inlet study were necessary for management plan of individual inlet for the west-central Florida case studies. Key recommendations based on the case studies include: 1) allow the natural sediment bypassing to be re-established at Blind Pass inlet through reduced ebb-tidal delta mining, 2) reduce the interruption to sediment bypassing at John's Pass and Pass-a-Grille inlets through an improved design of the dredged mining areas located along sediment bypassing pathways, 3) allow for continued natural sediment bypassing at Bunces Pass, and, 4) incorporate the cyclic swash-bar attachment sediment bypassing into the management plan at Bunces Pass and adjacent barrier-islands.

PROBABILISTIC SHORELINE CHANGE MODELING AND RISK ESTIMATION OF EROSION

Prediction of long-term shoreline changes is a key task in planning and management of coastal zones and regional sediment management. Due to complex natural features of offshore waves, sediments, and longshore sediment transport, quantifying uncertainties of shoreline evolution and risks of extreme shoreline changes (erosion and accretion) is of vital importance for practicing uncertainty- or risk-based design of shorelines. This paper presents probabilistic shoreline change modeling to quantify uncertainties of shoreline variations by using numerical-model-based Monte-Carlo simulations. A shoreline evolution model, GenCade, is used to simulate longshore sediment transport and shoreline changes induced by random waves from offshore. A probability density function with a modified tail distribution is developed to capture stochastic features of wave heights under fair weather and storm conditions. It produces a time series of wave heights including small and extreme waves based on their probabilities (or frequencies of appearance). Probabilistic modeling of shoreline change is demonstrated by computing spatiotemporal variations of statistical parameters such as mean and variance of shoreline changes along an idealized coast bounded by two groins. Maximum shoreline changes in return years with a confidence range are also estimated by using maximum likelihood method. Reasonable results of obtained probabilistic shoreline changes reveal that this model-based Monte-Carlo simulation and uncertainty estimation approach are applicable to facilitate risk/uncertainty-based design and planning of shorelines.

A Quantitative Assessment of the Annual Contribution of Platform Downwearing to Beach Sediment Budget: Happisburgh, England, UK

Field and numerical investigations at Happisburgh, East coast of England, UK, sought to characterize beach thickness and determine geologic framework controls on coastal change. After a major failure of coastal protection infrastructure, removal of about 1 km of coastal defence along the otherwise protected cliffed coastline of Happisburgh triggered a period of rapid erosion over 20 years of ca. 140 m. Previous sensitivity studies suggest that beach thickness plays a major role in coastal recession. These studies were limited, however, by a lack of beach volume data. In this study, we have integrated the insights gained from our understanding of the Quaternary geology of the area, a novel non-intrusive passive seismic survey method, and a 3D novel representation of the subsurface source and transportable material into a coastal modelling environment to explore the role of beach thickness on the back wearing and downwearing of the cliffs and consolidated platform, respectively. Results show that beach thickness is non-homogeneous along the study site: we estimate that the contribution to near-shore sediment budget via platform downwearing is of a similar order of magnitude as sediment lost from the beach and therefore non-negligible. We have provided a range of evidence to support the idea that the Happisburgh beach is a relatively thin layer perched on a sediment rich platform of sand and gravel. This conceptualization differs from previous publications, which assume that the platform was mostly till and fine material. This has direct implication on regional sediment management along this coastline. The present study contributes to our understanding of a poorly known aspect of coastal sediment budgeting and outlines a quantitative approach that allows for simple integration of geological understanding for coastline evolution assessments worldwide.

Estimation of Depth of Closure Near Gangneung Port in Korea

Kang, H., Chun, I., and Oh, B., 2018. Estimation of the Depth of Closure Near Gangneung Port in Korea. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1361–1365. Coconut Creek (Florida), ISSN 0749-0208.Various methods to cope with coastal erosion have been tried in the East Coast of Korea, among which the regional sediment management (RSM) is now being perceived as a very efficient way for managing limited sand resources in a macroscopic scale in both time and space. To apply RSM, it is necessary to set up the littoral cell, a control volume concept whose offshore boundary is given by the depth of closure (DOC). In this study, an independent littoral cell near Gangneung Port was set up, and a method to determine its DOC was proposed and applied utilizing the existing data of deep-water wave climate. Within the method, several formulas were tested, and the results showed that that the average DOC of the study area varied from 10 m to 52 m depending on sediment size, wave condition, and the formula used. Finally, the Hallermeier's formula of outer DOC was postulated to give a reasonable DOC of the Gangneung littoral cell.

A quantitative assessment of human interventions and climate change on the West African sediment budget

The West African coastal barrier is maintained by significant wave-driven longshore sand transport. This sand originates from rivers and large coastal sand deposits. Today, however, much of the fluvial sand is trapped behind river dams and/or interrupted at several locations by port jetties. As a result, the sandy coastal barrier is eroding almost everywhere along its length.The aim of this study is to derive a large-scale sediment budget analysis, following a consistent approach, for the following countries: Republic of Côte d'Ivoire, Ghana, Togo and Benin, and pointing out the effects of major human interventions and climate change in this large common sediment system. The results are used as a basis to raise awareness among local governments and organizations on the effects and interdependency that major anthropogenic interventions (i.e. port jetties and river dams) and climate change (i.e. sea level rise, changes in wave climate, precipitation and temperature) may have on this shared sediment system. These detrimental effects can even occur in neighboring countries, as shown by some of the results. This estimation was carried out using a quantitative approach, based on one consistent numerical modelling system and validated with regional and local data.Based on the outcomes of the study, and with the support of a number of validation workshops in the different countries, suggestions are also provided for the setting up of a regional sediment management plan for the entire region.

The California Seafloor and Coastal Mapping Program – Providing science and geospatial data for California's State Waters

The California Seafloor and Coastal Mapping Program (CSCMP) is a collaborative effort to develop comprehensive bathymetric, geologic, and habitat maps and data for California's State Waters. CSCMP began in 2007 when the California Ocean Protection Council (OPC) and the National Oceanic and Atmospheric Administration (NOAA) allocated funding for high-resolution bathymetric mapping, largely to support the California Marine Life Protection Act and to update nautical charts. Collaboration and support from the U.S. Geological Survey and other partners has led to development and dissemination of one of the world's largest seafloor-mapping datasets. CSCMP provides essential science and data for ocean and coastal management, stimulates and enables research, and raises public education and awareness of coastal and ocean issues. Specific applications include:•Delineation and designation of marine protected areas•Characterization and modeling of benthic habitats and ecosystems•Updating nautical charts•Earthquake hazard assessments•Tsunami hazard assessments•Planning offshore infrastructure•Providing baselines for monitoring change•Input to models of sediment transport, coastal erosion, and coastal flooding•Regional sediment management•Understanding coastal aquifers•Providing geospatial data for emergency response

Alignment of U. S. ACE Civil Works Missions to Restore Habitat and Increase Environmental Resiliency

ABSTRACTThe Civil Works mission area of the U.S. Army Corps of Engineers (USACE) spans multiple programs including navigation, flood risk management, infrastructure construction and operation, and environmental stewardship–including restoration and regulation of protected waterways. The national scope of USACE activities means that habitat preservation and restoration projects vary in size and type, while often intersecting spatially with projects under other USACE missions. This intersection can create management challenges that must be resolved. Two USACE initiatives, Engineering With Nature and Regional Sediment Management, explore and implement best practices that combine natural processes and restoration needs with management requirements. This article presents four case studies describing initiatives to 1) design, rehabilitate, and manage infrastructure in alignment with natural processes; 2) manage sediments on a regional scale to support the re-use of material removed from navigation channels for coastal and riverine resiliency, and 3) develop landscape-level plans for waterways management to support conservation efforts. The cumulative effect of multiple efforts to restore functionality lost through anthropogenic alterations and long-term geological change is expected to be a more resilient system at the landscape scale. However, challenges remain in quantifying resilience and the benefits provided by ecosystem services that are affected by management actions.

Classification of rocky headlands in California with relevance to littoral cell boundary delineation

Despite extensive studies of hydrodynamics and sediment flux along beaches, there is little information on the processes, pathways and timing of water and sediment transport around rocky headlands. In this study, headlands along the California coast are classified to advance understanding of headland dynamics and littoral cell boundaries in support of improved coastal management decisions. Geomorphological parameters for 78 headlands were quantified from geological maps, remote-sensing imagery, navigational charts, and shoreline geospatial databases. K-means cluster analysis grouped the headlands into eight distinct classes based on headland perimeter, bathymetric slope ratio, and the headland apex angle. Wave data were used to investigate the potential for sediment transport around the headland types and determine the efficacy of the headland as a littoral cell boundary. Four classes of headland appear to function well as littoral cell boundaries, with headland size (e.g., perimeter or area) and a marked change in nearshore bathymetry across the headland being relevant attributes. About half of the traditional California littoral cell boundaries align with headland classes that are expected to perform poorly in blocking alongshore sediment transport, calling into question these boundaries. Better definition of these littoral cell boundaries is important for regional sediment management decisions.

Sandy sediment budget of the midcoast of Rio Grande do Sul, Brazil

Calculation of the coastal sediment budget involves estimation of the timing and intensity of processes of erosion, transport, and deposition, as well as an understanding of local and regional sediment dynamics. The modern sedimentary deposits present in the coastal zone constitute the physical basis of coastal ecosystems. Knowledge of the dynamics of these sediments from the source to sink area, through regional sediment management, is critical to understanding the long-term stability of the coastal zone and the fate of these important natural resources. In this article, the littoral cell concept has been applied to the midcoast of Rio Grande do Sul, a wave-dominated and dissipative-intermediate sandy coast in southern Brazil. To analyze littoral drift variations along the 275 km long study area, the shoreline was divided into 12 cells. Littoral drift rates were estimated and compared using the energy flux method. Wave parameters were obtained from WAVEWATCH III. The sand volume of the coastal dune field (4.20 billion m3) was quantified using satellite imagery and the aeolian transport rates estimated utilizing the sediment budget residual. The net annual longshore transport rates obtained with the Coastal Engineering Research Center equation range from 0.60 to 2.63 million m3 per year. The littoral drift rates obtained with the Van Rijn (2001) and Kamphuis (1991) equations range between 0.15 and 1.00 million m3 per year. Based on the sediment budget and dune field age, the CERC formula seems more appropriate to estimate longshore transport.

Morphological evolution of a submerged artificial nearshore berm along a low-wave microtidal coast, Fort Myers Beach, west-central Florida, USA

Nourishment in the nearshore is becoming an increasingly utilized method for regional sediment management, particularly for dredged material that contains more fine sediment than the native beach. A nearshore berm was constructed at Fort Myers Beach, Florida, USA using mixed-sized sediment dredged from a nearby channel. The nearshore berm, which is the shallowest of its kind, was placed in water depths between 1.2 and 2.4m with the berm crest just below the mean lower low water level. Based on time-series profiles surveyed from 2009 to 2013, the nearshore berm migrated onshore while the system was approaching a dynamic equilibrium. The distant passage of two tropical storms in the third year generated exceptionally high waves for the study area. Substantial profile change induced by the energetic conditions contributed to rapid evolution of the berm profiles toward equilibrium. Near the end of the fourth year, the berm profiles had returned to the equilibrium shape characteristic of the study area. Gaps in the berm allowed water circulation when the berm became emergent and watercraft access to the beach for recreational purposes. Gaps should be considered as a design parameter for future berm nourishments. Sediment samples collected and analyzed showed that the fine sediment content in the original placed material was selectively transported and deposited offshore, while the coarser component moved onshore. The dry beach maintained the same sediment properties throughout the study period and was not influenced by the fine sediment in the initial construction of the berm.

Sediment transport patterns in the San Francisco Bay Coastal System from cross-validation of bedform asymmetry and modeled residual flux

Abstract The morphology of ~ 45,000 bedforms from 13 multibeam bathymetry surveys was used as a proxy for identifying net bedload sediment transport directions and pathways throughout the San Francisco Bay estuary and adjacent outer coast. The spatially-averaged shape asymmetry of the bedforms reveals distinct pathways of ebb and flood transport. Additionally, the region-wide, ebb-oriented asymmetry of 5% suggests net seaward-directed transport within the estuarine-coastal system, with significant seaward asymmetry at the mouth of San Francisco Bay (11%), through the northern reaches of the Bay (7–8%), and among the largest bedforms (21% for λ > 50 m). This general indication for the net transport of sand to the open coast strongly suggests that anthropogenic removal of sediment from the estuary, particularly along clearly defined seaward transport pathways, will limit the supply of sand to chronically eroding, open-coast beaches. The bedform asymmetry measurements significantly agree (up to ~ 76%) with modeled annual residual transport directions derived from a hydrodynamically-calibrated numerical model, and the orientation of adjacent, flow-sculpted seafloor features such as mega-flute structures, providing a comprehensive validation of the technique. The methods described in this paper to determine well-defined, cross-validated sediment transport pathways can be applied to estuarine-coastal systems globally where bedforms are present. The results can inform and improve regional sediment management practices to more efficiently utilize often limited sediment resources and mitigate current and future sediment supply-related impacts.

Information Management Related to Regional Sediment Management in the Gulf of Mexico

Currently, a number of organizations across the Gulf Coast are simultaneously collecting and distributing proprietary data. However, if Gulf Regional Sediment Management Master Plan (GRSMMP) users are to perform analysis efficiently and make effective, educated decisions to support various coastal projects, collaboration and data sharing at all levels of government and among the numerous shareholders must be established. One method of doing this is the implementation of an enterprise geographic information system (EGIS)—a geospatial technology infrastructure that delivers spatial information products, services, and standard data sets to all business elements and processes within and among organizations. The U.S. Army Corps of Engineers has developed and/or participated in a number of such enterprise GIS efforts, including the eCoastal, CE-Dredge, and Spatial Presentation Viewer programs. It is therefore proposed that the GRSMMP establish a firm data management plan and implement an organized, enterprise approach to data management through the use of Web Map Services (WMS). By including the publication of planned data acquisition, inventory of available offline data products, and direct access to organization flagship data sets, such a proposal would allow GRSMMP members to locate, connect to, view, and retrieve desirable data sets across many agencies, saving time and money previously dedicated to new data acquisition.

An Introduction to the Technical Framework for the Gulf Regional Sediment Management Master Plan

A partnership has been instituted through the Gulf of Mexico Alliance (GOMA) among the Gulf States to enhance the ecological and economic health of the Gulf of Mexico. Established under the GOMA, the Habitat Conservation and Restoration Team (HCRT) recognized that sediments are integral to and a critical resource in accomplishing the GOMA conservation and restoration objectives. As a result, the Gulf Regional Sediment Management Master Plan (GRSMMP) was initiated for managing sediment resources and corroborates the need for an understanding of regional sediment processes. The plan provides guidelines using the understanding of sediment dynamics to manage resources toward accomplishing environmental restoration, conservation, and preservation while enhancing abilities to make informed, management decisions. A key step in this process is the recognition of a technical framework that provides a foundation associated with regional sediment management processes essential for establishing management guidelines that balance sediment dynamics and available sediment resources with needs and that enhance abilities to make informed management decisions and develop regional strategies. Issues surrounding sediment management, both natural and dredged sediments, have a considerable impact on the ability to sustain coastal habitats. Sediment management must occur on a regional scale unencumbered by agency, state, or political boundaries. Guidelines and recommendations from this effort will aid the Gulf States in more effective management of sediment resources, recognizing they are a part of a regional system involving natural and man-made processes. The effort involves a range of state and federal agencies, as well as nongovernmental representatives. Thus, a technical framework for the GRSMMP was compiled/completed and submitted to the HCRT/GOMA. The decision was made to publish this document as peer-reviewed papers in a special issue of the Journal of Coastal Research for benefit of the global scientific community. In return, feedback in terms of review and comments will be beneficial for the team.

Gulf of Mexico Regional Sediment Budget

Abstract Development of dynamic regional sediment management (RSM) plans is needed for future planning, construction, and monitoring of wetland and barrier island restoration. Broadly speaking, RSM refers to the optimum use of various sediment resources (littoral, estuarine, and riverine) in an environmentally effective and economically feasible manner. Coordination of the supply and demand sides of sand resources in a comprehensive manner will be required as project planning develops and evolves. The sediment budget is a planning tool that provides an accounting of sediment sources, sinks, and pathways as well as engineering activities and sediment budgets have generally been characterized as conceptual, interim, and operational depending upon the quality of the data, the level of analysis, and the uncertainty associated with the volume fluxes in the sediment budget. This paper summarizes existing sediment budget data for the entire Northern Gulf of Mexico. The purpose of this work has been to compile av...