Land Cover and Sediment Layers as Controls of Inlet Breaching

Abstract

Understanding the processes that take place during a storm leading to coastal morphological change has been a challenging topic for coastal engineers. Over the years, many models have been developed to predict the coastal response to storms evolving from the one dimensional empirical models to two or three dimensional process based models. We hypothesized that the predictive capacity of these models can be improved by incorporating the site specific effect of the land cover features that are in place at the time of the storm. In this work, we present a case study of the development of the Pea Island breach, Outer Banks, North Carolina during Hurricane Irene in August 2011. The inclusion of the land cover effects into the model significantly improves the predictive capability of the model results.

Barrier island breach evolution: Alongshore transport and bay-ocean pressure gradient interactions

“…In the absence of direct observations of sediment concentration and flow velocity, equation is used for estimation of bedload fluxes which are expected to dominate sediment transport in the shallow channel depths herein. Breach bathymetry data collected by NCDOT right after Hurricane Irene show the main channel had a triangular cross section with an average width of 75 m, depth of 1.5 m at the channel center, and side slopes of 0.04 [ Kurum et al ., ]. Because the images for later periods show that the channel rapidly became wider and the goal of this study is to investigate the processes controlling breach evolution in long‐term, side slopes of 0.02 are used based on the elevations estimated from the later images.…”

Land Cover Effect on Dune Erosion and Overwash

“…The results of these cases, which were classified as "sand" cases, were than compared to the results of "land cover" cases. In the land cover cases, nodes in the model are classified into land cover types and then attributed their corresponding land cover properties by utilizing the land cover implementation framework defined by Kurum and Overton, 2012. Using this framework the land cover cases nodes in the model were first classified into their respective land cover classes extracted from pre storm orthoimagery. In this study land cover over the study areas were represented as concrete/pavement, vegetation and sand.…”

“…Therefore, insight into the interactions between the land cover and morphological response of coastal landforms during extreme events will improve the predictive capability of these models. Kurum et al, 2012 introduced a methodology for incorporating land cover using a 2D implementation of XBeach (Roelvink et al, 2009) and showed significant improvements in the predictive capability of the model by comparing model results to post storm field data. However, profile based, 1D models are still widely used due to their simplicity and significantly lower computational requirement.…”