18 Aug 2021

Houston Ship Channel Expansion Channel Improvement Project (ECIP) Numerical Modeling Report: BABUS Cell and Bird Island Analysis

Abstract: The Houston Ship Channel (HSC) is one of the busiest deep-draft navigation channels in the United States and must be able to accommodate increasing vessel sizes. The US Army Engineer District, Galveston (SWG), requested the Engineer Research and Development Center, Coastal and Hydraulics Laboratory, perform hydrodynamic and sediment modeling of proposed modifications in Galveston and Trinity Bays and along the HSC. The modeling results are necessary to provide data for hydrodynamic, salinity, and sediment transport analysis. SWG provided three project alternatives that include closing Rollover Pass, Bay Aquatic Beneficial Use System cells, Bird Islands, and HSC modifications. These alternatives and a Base (existing condition) will be simulated for present (2029) and future (2079) conditions. The results of these alternatives/conditions as compared to the Base are presented in this report. The model shows that the mean salinity varies by 2–3 ppt due to the HSC channel modifications and by approximately 5 ppt in the area of East Bay due to the closure of Rollover Pass. The tidal prism increases by 2.5% to 5% in the alternatives. The tidal amplitudes change by less than 0.01 m. The residual velocity vectors vary in and around areas where project modifications are made.

18 Aug 2021

The Response of Vegetated Dunes to Wave Attack

Abstract: Vegetation is believed to increase the stability of dunes during wave attack, but limited data is available. A physical model study was performed to evaluate changes in the dune stability with and without biomass, both above and belowground. The above and belowground biomass was modeled using wooden dowels and coir fibers, respectively. For both the collision and overwash storm impact regimes, the results of this study clearly demonstrate that the inclusion of biomass in the model dune reduces the erosion and overwash. The combination of both above and belowground biomass was the most effective at reducing erosion followed by belowground biomass, with aboveground biomass providing the smallest benefit regardless of the wave condition and water level. Additionally, the overwash of sediment and water was decreased with the inclusion of biomass, following the same trends as the erosion. As the dune eroded, the storm impact regime transitioned from collision to overwash. The inclusion of biomass delays this transition in storm impact regime, providing greater protection to coastal communities. This study highlights the need to consider dune vegetation for dune construction and coastal planning.

19 Jul 2021

Metrics of Success for Nearshore Nourishment Projects Constructed with Dredged Sediment

Purpose: This Regional Sediment Management Technical Note (RSM TN) provides practical metrics of success for nearshore nourishment projects constructed with dredged sediment. Clearly defined goals and performance metrics for projects will set clear expectations and will lead to long-term project support from local stakeholders and the public.

25 May 2021

Applying Resilience Concepts to Inland River Systems

Abstract: As environmental uncertainty increases, incorporating resilience into project assessments, research recommendations, and future plans is becoming even more critical. This US Army Engineer Research and Development Center special report (SR) demonstrates how the concepts of resilience can be applied in a uniform framework and illustrates this framework through existing case studies on large inland river systems. This SR presents the concepts of resilience in inland river systems, the application of these concepts across disciplines, basic parameters of a resilience assessment, and the challenges and opportunities available for incorporating a more holistic approach to understanding resilience of the US Army Corps of Engineers mission areas on inland rivers. Finally, these concepts are demonstrated in several case studies in the United States to exemplify how these parameters have been applied to improve the overall performance of the system.

10 May 2021

Modeling the Effect of Increased Sediment Loading on Bed Elevations of the Lower Missouri River

Purpose: This US Army Corps of Engineers (USACE) National Regional Sediment Management Technical Note (RSM-TN) documents the effects of increased sediment loading to the Missouri River on bed elevations in the lower 498 miles. This was accomplished using a one-dimensional (1D) HEC-RAS 5.0.7 sediment model.

10 May 2021

Investigation for Shoaling Reduction along the Gulf Intracoastal Waterway (GIWW) at Caney Creek, Sargent, Texas

Purpose: This US Army Corps of Engineers (USACE) Regional Sediment Management (RSM) initiative considered alternatives for shoaling reduction in the Gulf Intracoastal Waterway (GIWW) in the vicinity of Caney Creek near Sargent, TX (Figure 1). Additionally, new beneficial use (BU) sites were considered along degraded islands adjacent to the GIWW with a threefold objective: increase the quality and quantity of habitat, reduce dredging cost via shorter pump distance, and reduce shoaling in the GIWW through East Matagorda Bay.

29 Jan 2021

Simulations of Shoreline Changes along the Delaware Coast

Abstract: This technical report presents two applications of the GenCade model to simulate long-term shoreline evolution along the Delaware Coast driven by waves, inlet sediment transport, and longshore sediment transport. The simulations also include coastal protection practices such as periodic beach fills, post-storm nourishment, and sand bypassing. Two site-specific GenCade models were developed: one is for the coasts adjacent to the Indian River Inlet (IRI) and another is for Fenwick Island. In the first model, the sediment exchanges among the shoals and bars of the inlet were simulated by the Inlet Reservoir Model (IRM) in the GenCade. An inlet sediment transfer factor (γ) was derived from the IRM to quantify the capability of inlet sediment bypassing, measured by a rate of longshore sediments transferred across an inlet from the updrift side to the downdrift side. The second model for the Fenwick Island coast was validated by simulating an 11-year-long shoreline evolution driven by longshore sediment transport and periodic beach fills. Validation of the two models was achieved through evaluating statistical errors of simulations. The effects of the sand bypassing operation across the IRI and the beach fills in Fenwick Island were examined by comparing simulation results with and without those protection practices. Results of the study will benefit planning and management of coastal sediments at the sites.

1 Oct 2020

Development of a HEC-RAS Sediment Model for the Chippewa River, Wisconsin for Use in Predicting Future Dredging Activities

Purpose: This U.S. Army Corps of Engineers (USACE) Regional Sediment Management Technical Note (RSM-TN) describes the process of constructing and calibrating a sediment model that utilizes recent sediment data collection efforts performed by the U.S. Army Engineer Research and Development Center – Coastal and Hydraulics Laboratory (ERDC-CHL) and the U.S. Geological Survey (USGS) along the Chippewa River in Wisconsin. A USACE Institute for Water Resources (IWR), Hydrologic Engineering Center, River Analysis System (HEC-RAS, version 5.0.7) unsteady flow sediment model was developed to perform a continuous simulation of bed-load and suspended load transport and dredging operations through the Chippewa River and Lower Pool 4 of the Upper Mississippi River navigation channel. The resulting model developed through this effort can be useful in forecasting future channel maintenance needs through this reach of river.

1 Oct 2020

Hydrodynamic and Sediment Transport Modeling for James River Dredged Material Management

Abstract: The fate of material placed during dredging operations within the James River (Dancing Point-Swann Point reach) at a channel adjacent placement mound was modeled within this work. The study focuses on the potential migration of the placement mound into the channel as well as the transport of sediment resuspended during placement. A select combination of US Army Engineer Research and Development-developed models was utilized in this work to appropriately simulate hydrodynamic conditions, pipeline discharge near field suspended sediment estimates, far field transport of the pipeline discharge source term, and mound migration. Results show that the material released into the water column during placement remains in the placement area or is transported out of the area of interest downstream. A small fraction of sediment from the placement mound migrates into the channel after placement. The fine-grained nature of these sediments precludes these small volumes of sediment from depositing in the channel where the currents are strong.

1 Oct 2020

Framework Geology of Cape Shoalwater and Northwest Willapa Bay, Washington: Assessing Potential Geologic Impacts on Recent Shoreline Change

Abstract: The shoreline along Cape Shoalwater and northwest Willapa Bay has experienced the highest rates of erosion along the entire Pacific Coast of the United States, due in part to rapid northward migration of the navigation channel. Recently, channel migration and shoreline erosion in this region have slowed, but the cause of this relative stabilization, and thus the longevity of these new patterns, is unknown. Given the complex neotectonics and geologic framework of the southern coast of Washington, it is possible that underlying, erosion-resistant geologic units have become exposed along the channel and/or in the nearshore, and are acting to reduce or halt channel migration and/or shoreline erosion. Conversely, the apparent reduction may be due to subtle, short-term changes in regional hydrodynamics and/or sediment transport, and thus future rates of channel migration and/or shoreline erosion might increase back to historical rates. The purpose of this special report is to detail the geologic and neotectonic framework of the northern Willapa Bay region, and determine how the underlying framework geology might be impacting channel stability and adjacent shoreline erosion rates. Suggested research questions to quantify potential geologic control are also presented, including the potential benefits of the research to the district.