Measuring beach topography accurately and with high spatial resolution is an important aspect of coastal management and is crucial for understanding changes in beach morphology, especially along complex, three-dimensional shorelines. Traditional methods of beach surveying even at high resolution are insufficient to measure the complex, dynamic behavior along these coasts. This study investigates the optimization of Unmanned Aerial Systems Structure from Motion (UAS-SfM) data acquisition methodology with regard to flight altitude and the configuration and amount of ground control points (GCPs). A sensitivity analysis was performed to determine the UAS and GCP characteristics that produce the most accurate digital elevation model (DEM). First, an evaluation of the UAS-SfM technique was performed and proved advantageous over traditional surveying techniques with regard to efficiency, automation, ease of use, and repeatability. The results of the sensitivity analysis showed the highest (116 m) flight altitude evaluated was the most accurate and required the least amount of survey and processing time. The optimal configuration of GCPs was determined to be (1) in the corners of the study site, (2) at high and low elevations within the study site, and (3) with sufficient cross-shore and alongshore coverage. Finally, it was found that 15 GCPs produced the best results, but that as few as 11 GCPs could be used without any significant loss in accuracy. It was also observed that fewer (≈7–9) well-placed GCPs in the optimal configuration produced the same magnitude of error as using more (15) poorly placed GCPs. Based on these results, a set of recommendations for conducting UAS-SfM surveys along complex, three-dimensional, developed coastlines is presented.

Coastal erosion is controlled by two sets of factors, one related to storm intensity and the other related to a location’s vulnerability. This study investigated the role of each set in controlling dune erosion based on data compiled for eighteen historical events in New Jersey. Here, storm intensity was characterized by the Storm Erosion Index (SEI) and Peak Erosion Intensity (PEI), factors used to describe a storm’s cumulative erosion potential and maximum erosive power, respectively. In this study, a direct relationship between these parameters, beach morphology characteristics, and expected dune response was established through a classification tree ensemble. Of the seven input parameters, PEI was the most important, indicating that peak storm conditions with time scales on the order of hours were the most critical in predicting dune impacts. Results suggested that PEI, alone, was successful in distinguishing between storms most likely to result in no impacts (PEI < 69) and those likely to result in some (PEI > 102), regardless of beach condition. For intensities in between, where no consistent behavior was observed, beach conditions must be considered. Because of the propensity for beach conditions to change over short spatial scales, it is important to predict impacts on a local scale. This study established a model with the computational effectiveness to provide such predictions.

Coastal erosion is an adverse impact of extreme water levels during major hurricanes. A warmer climate is expected to increase storm surge and wave hazards due to hurricane climatology change (HCC) and sea level rise (SLR). We conduct physics-based morphodynamic modeling to quantify the regional impacts of HCC and SLR on erosion hazards to sandy beaches and dunes along the barrier islands of New Jersey in the United States. Under the RCP8.5 scenario, we find a substantial increase in erosion hazards from the late-20th-century to late-21st-century. The regionally averaged 100-year eroded volume of beach-dune systems would increase by 58 and 84%, respectively, under the HCC and HCC + SLR scenarios. Our projections show a large spatial variability in future changes to erosion hazards, suggesting that, in addition to HCC and SLR, the morphological characteristics of beach-dune systems play an important role in the impacts of climate change on coastal erosion.

Breaching or overtopping of coastal dunes is associated with greater upland damages. Reliable tools are needed to efficiently assess the likelihood of dune erosion during storm events. Existing methods rely on numerical modeling (extensive investment) or insufficiently parameterize the system. To fill this gap, a fragility curve model using a newly developed dune Engineering Demand Parameter (EDP) is introduced. Conceptually, the EDP is similar to the Shield’s parameter in that it represents the ratio of mobilizing terms to stabilizing terms. Physically, the EDP is a measure of storm intensity over the dune’s resilience. To highlight potential applications, the proposed EDP fragility curve models are fit to a spatially and temporally robust dataset and used to predict dune response subjected to varying storm intensities including both extratropical and tropical storm. This approach allows for the probabilistic prediction of dune impacts through an innovative, computationally efficient model. Several different forms of the EDP are tested to determine the best schematization of the dune resilience. The final recommended EDP is the Peak Erosion Intensity (PEI) raised to the fourth power over the product of the dune volume and berm-width squared. Including both storm intensity and resilience terms in the EDP enables comparison of different beach configurations in different storm events fulfilling a need existing vulnerability assessors cannot currently account for directly.

A comprehensive case study of Keansburg Inlet (New Jersey, USA) is presented with the objective of evaluating inlet management alternatives and assessing the influence of an operational flood gate on channel shoaling. The goal of the research is determining the most effective strategy for minimizing the frequency of maintenance dredging. This study compares the effectiveness of (1) traditional structural solutions; (2) modified dredging templates; and (3) assesses the influence of the flood gate operations during conditions representative of a typical year. Alternative analysis is completed using a coupled hydrodynamic–wave model (Delft3D-Flexible Mesh (FM)) with Real Time Control to simulate morphological changes. The model was calibrated and evaluated using collected field data. Water levels are reproduced within 6% of the spring tide range with lag times less than 20 min. The model results and observations suggest sediment transport is dominated by wave action with pronounced variations in dominant wave direction. The results indicate that changes to the operational dredging, or what the authors have termed broadly as “adaptive dredging techniques”, appear to deliver the most promising improvement. Model results suggest that the current operational procedures of the flood gate do not significantly alter the channel infilling rates and patterns during typical (i.e., non-extreme event) conditions.