Improved Post-storm Model Predictions of Barrier Island Response to Extreme Events by Including Land Cover Effects on Sediment Transport Capacity

The objective of this thesis is to present geospatial and numerical tools and methods to study short term barrier island evolution. The first stage in this is achieved by raster based techniques used to asses the barrier island evolution in a decadal time frame by analyzing time series of coastal elevation data in order to extract spatial patterns of barrier island evolution dynamics. Multiple storm events may happen in a decadal time frame which are dominant factors in shaping barrier island morphology. Therefore in the second stage, the eXtreme Beach behavior (XBeach) model is used to simulate the process of barrier island response (e.g., beach and dune erosion, overwash and breaching). It is shown that under inundation overwash conditions XBeach reproduces common overwash features however the amount of erosions were calculated to be higher than the measured erosion and the model exhibited high sensitivity to total surge levels and surge level gradients across the barrier island. The main cause of the problem was identified as the traditional representation of a study location as consisting only sand in the numerical model domain. To address the problem, a methodology was implemented to mimic the effects of land cover features on the sediment transport capacity. The effects of the land cover effect implementation were validated by simulating two breaching cases occurred on the Outer Banks of North Carolina barrier islands during Hurricane Irene. After validation, hypothetical but realistic scenarios were tested in order to demonstrate the usefulness of the modeling framework to stakeholders interested in developing barrier island management and protection strategies. The improvements on the prediction capacity by including land cover effects were also shown to be valid in widely used 1D applications.