Elizabeth Sciaudone

In August 2012, a new terminal groin permit associated with the new Basnight Bridge was signed. As with the original (1989) Oregon Inlet Terminal Groin permit, the new permit requires NC DOT to monitor the adjacent beach in order to determine whether or not there is adverse impact of the presence of the terminal groin, including a determination of whether sediment loss is greater than that predicted by the historical rates. In addition, NC DOT has proposed coastal and biological monitoring in support of the NC 12 Transportation Management Plan (NC 12 TMP) alternative (as discussed in the B-2500 ROD) and a review of the historical rate used for a basis comparison. The monitoring associated with the NC 12 TMP is needed in order to determine the location and extent of future phases of the B-2500 project. This study will gather and analyze the data that is needed to satisfy the requirements of both 1) the new terminal groin permit and 2) the coastal monitoring program component of the NC 12 TMP. The present proposal includes the following program elements: 1) data collection by NC DOT, 2) monitoring of the existing Oregon Inlet terminal groin, 3) mapping and modeling of coastal habitat changes, 4) TMP coastal monitoring, including development of vulnerability indicators related to the island morphology, and 5) integration of physical and biological monitoring data from NC DOT with the morphological indicators. An annual report will be developed detailing the program tasks and annual results, including a comparison with baseline conditions.

Sound-side processes including locally-generated waves, storm surge, sea level rise, and long-term morphological changes in the southernmost flood channel of Oregon Inlet are likely the cause of 80-100 ft of marsh loss in the north end of Pea Island between January 2011 and February 2018. The long-term erosion that increases the proximity of the NC 12 highway to the Pamlico Sound, and therefore the vulnerability of the road, calls for immediate attention on the estuarine-side processes in the north end of Pea Island that can affect the maintenance and future operation of the NC 12 transportation corridor. Thus, the proposed project seeks to investigate the erosive effects of locally-generated waves and of the southernmost flood channel of Oregon Inlet parallel to the estuarine shoreline of Pea Island. The research questions to be addressed in this project are: (1) What are the ranges of flow velocities, wave, and wind conditions causing estuarine shoreline erosion near Oregon Inlet in the short- (storms) and long-term (months to years)? (2) Are there technically feasible mitigation options that could be implemented at this location that could help slow down or stop estuarine shoreline erosion?

In August 2012, a new terminal groin permit associated with the new (currently under construction) Bonner Bridge was signed. As with the original (1989) Oregon Inlet Terminal Groin permit, the new permit requires NC DOT to monitor the adjacent beach in order to determine whether or not there is adverse impact of the presence of the terminal groin, including a determination of whether sediment loss is greater than that predicted by the historical rates. In addition, NC DOT has proposed coastal and biological monitoring in support of the NC 12 Transportation Management Plan (NC 12 TMP) alternative (as discussed in the B-2500 ROD) and a review of the historical rate used for a basis comparison. The monitoring associated with the NC 12 TMP is needed in order to determine the location and extent of future phases of the B-2500 project. This study will gather and analyze the data that is needed to satisfy the requirements of both 1) the new terminal groin permit and 2) the coastal monitoring program component of the NC 12 TMP. The present proposal includes the following program elements: 1) data collection by NC DOT, 2) monitoring of the existing Oregon Inlet terminal groin, 3) mapping and modeling of coastal habitat changes, 4) TMP coastal monitoring, including development of vulnerability indicators related to the island morphology, and 5) integration of physical and biological monitoring data from NC DOT with the morphological indicators. An annual report will be developed detailing the program tasks and annual results, including a comparison with baseline conditions.

The purpose of this research is to develop dune construction guidelines for overtopping, for projects where a constructed beach berm affects the maximum runup elevation. Many local communities planning a beach and dune nourishment program find that the distance between established infrastructure (e.g., roads, buildings, etc.) and the active shoreline limits the horizontal extent of a project. In these cases, it is critical to design the dune such that it can resist overtopping and mitigate damage to that infrastructure. Most current methods to assess runup elevation (e.g., Holman 1986, Stockdon et al. 2006) are dependent on the beach slope and wave height, but do not incorporate the effects of a constructed berm width. This likely over-predicts the runup elevation which would lead to an overdesigned (and more expensive) dune; such a dune might not even be feasible to construct in an area where the distance of the infrastructure to the shoreline is small. In those situations where space is limited, a ����������������starter dune��������������� which will resist overtopping while it is allowed to grow naturally can be designed. It is hypothesized based on previous work (de Waal and van der Meer 1992) that an equivalent beach slope can be developed incorporating the effects of the berm and used in empirical formulations to assess runup. This project will test this hypothesis using measured wave, high water mark (runup limit), and nearshore profile slope data collected prior to and after beach and dune nourishment in the Town of Kitty Hawk, North Carolina. XBeach modeling will also be performed and calibrated with field data to assess runup and overtopping with different berm width and elevation scenarios. Project partners include the Town of Kitty Hawk, the consulting firm that designed and is managing the beach and dune nourishment project for the town, CB&I, the USACE Field Research Facility, and North Carolina State University Department of Civil, Construction, and Environmental Engineering. Primary deliverables include dune construction guidelines for overtopping, for projects where a constructed beach berm affects the maximum runup elevation. These guidelines will be communicated in three ways: 1) a workshop to be conducted with town representatives, 2) a presentation at the ASBPA National Coastal Conference in Fall 2017 and 3) a peer-reviewed publication communicating results to the larger research community.

The purpose of this ongoing project (1989 to present) is to monitor and evaluate the shoreline response north and south of the Oregon Inlet due to the construction of the terminal groin built to protect Bonner Bridge at the north end of Pea Island. Phase one of the study was to establish the 'historical erosion rates' for the study area since the change in dredging operations in the inlet in 1984 and before the March 1989 storm. Phase two of the study (ongoing since 1989), was to implement the monitoring program as per the permit requirement to determine position of the shoreline from aerial photography at a two month interval and to evaluate the response of the shoreline in the context of the historical erosion rates. The monitoring agreement specified the triggers and actions if the observed erosion exceeded the historic values over spatial and temporal scales of concern. This monitoring effort continues in support of the new permit for the Oregon Inlet Terminal Groin which was issued in August 2012. As part of the construction of the new Bonner Bridge, Phase three of the project has been established and is underway to monitor an expanded project area and set of metrics in order to inform decision making with respect the NC 12 corridor. This scope has been added to the ongoing terminal groin monitoring project in anticipation of future design and planning need for the NC12 transportation corridor.