Barrier islands can protect the mainland from flooding during storms through reduction of storm surge and dissipation of storm generated wave energy. However, the protective capability is reduced when barrier islands breach and a direct hydrodynamic connection between the water bodies on both sides of the barrier island is established. Breaching of barrier islands during large storm events is complicated, involving nonlinear processes that connect water, sediment transport, dune height, and island width among other factors. In order to assess the impacts barrier island breaching has on flooding on the mainland, we modified a storm surge model, GeoClaw, to impose a Gaussian bell-curve on the barrier island that opens during a hurricane simulation and deepened over time. We added a new method of generating storm surge with storm forcing inputs in the form of wind and pressure fields to expand GeoClaw's current utilization of best track information so that storm forcing from planetary boundary layer models can also be utilized in simulations. We created a statistical method to assess the sensitivity of mainland storm-surge to barrier island breaching by randomizing the location, time, and extent of a breach event across the barrier island at Moriches, NY. My results show that total mainland inundation is affected by the changes in location, size, timing and numbers of breaches. Total inundation has a logarithmic relationship with total breach area and breach location is an important predictor of inundation and bay surge. The insights from this study can help prepare shoreline communities for the differing ways that breaching affects the mainland coastline. The model updates created can also allow others to use this framework to study differing regions. Understanding which mainland locations are vulnerable to breaching, planners and coastal engineers can design interventions to reduce the likelihood of a breach occurring in areas adjacent to high flood risk. / Doctor of Philosophy / Storm surge is one of the most deadly and expensive parts of a hurricane. Storm surge can be reduced if a barrier island exists near the mainland coastline. The sand dunes, beach vegetation, and size of the island aid in reducing the waves and storm-surge generated by large storms. When a barrier island breaches it causes a channel of water that connects the ocean and the bay that separates the island from the mainland. This channel of water allows waves and storm surge to be directly pushed into the bay, increasing the storm surge along the mainland coast. Breaching is complex with many factors such as dune size and total island width determining when or where a breach will form. In order to study how breaching affects the mainland during a hurricane, we chose a program that simulates storm surge from a hurricane, made a simple breaching calculation that opens a hole in a sand dune on a barrier island so that the ocean and bay are directly connected and the storm surge can pass through this hole, and enabled the program to use storm data that is pre-computed rather than generated during the simulation. In order to understand how breaching impacts the mainland coast at Moriches, NY, we simulated a hurricane and varied the number, size, and time of different breaches. We learned that total of all breach dimensions has a linear relationship to the amount of coastal flooding up to a threshold, where the breaches cover most of the island. Coastal communities can use the results of this study to determine where to put interventions in place that will reduce the impacts of barrier island breaching, update flood risk maps, and warn community members of changes in their location's risk assessment. Additionally, other regions with barrier islands nearby can use the software updates we created to study their own regions and assess different risk patterns than this study.

Storm surges induced by tropical cyclones have been ravaging coastal communities worldwide, where a growing number of people reside. Tremendous life and economic losses are caused by tropical cyclones, contributing to more than half of the damages induced by natural hazards. To improve the resilience of coastal communities to surge hazards, it is of great importance to provide reliable and efficient real time forecasts of the spatiotemporal evolution of storm surge, as well as reliable predictions of the probabilistic surge hazards under future conditions. Three specific goals are addressed in this work. Studies on characterization and prediction of surge before a hurricane landfall show that a dimensionless relationship between intensity scaled surge magnitude and wind-duration scaled surge timing may effectively be used for rapid and reliable forerunner surge forecasting. Investigation of how probabilistic surge hazard changes with sea level rise (SLR) shows that the probabilistic surge with SLR can be 1.0 m larger, while different individual storm's surge with the same magnitude can be 1.5 m larger or 0.1 m smaller, indicating the importance of not relying on results from a limited number of storm surge events to assess the probabilistic surge hazard change to SLR. Finally, studying the temporal evolution of coastal flooding changes with SLR shows forerunner surge responds differently to SLR than peak surge, and that storm forward speed is a key factor determining the forerunner-SLR response. / Ph. D.

Hurricanes are a threat to power and telecommunication infrastructure. This work summarizes a method for hurricane characterization using the proposed Localized Tropical Cyclone Intensity Index(LTCII) as a model for estimating damages to Electric power infrastructure. The model considers the effect of storm surge, maximum sustained wind speeds, the duration of time for which the system has been under tropical storm conditions and the area swept by hurricane over land. The measurements focus on major load centers in the system. The validation of the outage data is discussed. The model is evaluated for hurricanes from 2004, 2005 and 2008 hurricane seasons. The degree of influence of various hurricane parameters on the damages suffered by electric power systems are discussed using case studies. The maximum outages are observed to follow a logistic regression curve with respect to log(LTCII), with a correlation of 0.85. The observed restoration times fit a 6th degree polynomial with an R2 = 0.6. The effects of time under tropical storm winds were observed to have great significance in the damage profile observed with the model. / text

Coastal marshes and wetlands are vital natural resources that offer habitats for plants and animals, serve as ecological filtration for soil and water pollutants, and act as protection for coastlines. Fishing, both commercial and sport, has a large economic impact in the study area – the Gulf Coast between Galveston Bay, TX and Oak Grove, LA. The objective of this research was to determine the contribution of Hurricane Ike storm surge sedimentation to long-term marsh aggradation in Texas and Louisiana coastal marshes. The research hypothesized that Hurricane Ike’s storm surge deposit would be equal to decades and possibly even a century’s worth of the average annual non-storm sedimentation. A quantitative field study was performed. The storm surge deposit was examined in a series of 15 transects covering approximately 180 km east of Hurricane Ike’s landfall. Nine of the 15 transects were re-surveyed a year after the initial measurement to assess preservation of the deposit. The results demonstrate that Hurricane Ike contributed between 10 to 135 years’ worth of sediment to coastal marshes along the coasts of Texas and Louisiana, and the sediment deposits have been preserved for over two years.

The most critical hazards impacting the world today are the affects of climate change and global warming. Scientists have been studying the Earth's climate for centuries and have come to agreement that our climate is changing, and has changed, many times abruptly over the history of our planet. This research focuses on the impacts of global warming related to increased hurricane intensities and their surge responses along the coast of the State of Louisiana. Surge responses are quantified for storms that could potentially occur under present climate but 50 years into the future on a coast subjected to current erosion and local subsidence effects. Analyses of projected hurricane intensities influenced by an increase in sea surface temperatures (SSTs) are performed. Intensities of these storms are projected to increase by 5% per degree of increase in SSTs. A small suite of these storms influenced by global warming and potentially realized by abrupt climate changes are modeled. Simulations of these storms are executed using a storm surge model. The surges produced by these storms are significantly higher than surges produced by presentday storms. These surges are then compared to existing surge frequency distributions along the Louisiana coast.

The objective of this study was to determine if numerical models commonly used for large scale applications could also be used to model flow through flood control structures in the Rigolets Pass between Lake Borgne and Lake Pontchartrain. For this purpose a small scale physical model was built. It showed that bi-stable flow can develop downstream of a constriction. Small changes in the distribution of the approaching flow significantly impacted flows downstream of the constriction. This behavior could not be properly reproduced by a small scale 2-dimensional RMA2 model of identical dimensions. A large scale RMA2 model of the Rigolets testing possible locations and geometries of flood control structures showed that this pass is very sensitive to variations in the cross sectional flow area. Even minor reductions can significantly increase headlosses and velocities. To reduce negative impacts a flood control structure should be built in a wide and shallow area of the pass.

The Mid-Atlantic coastal forests in Virginia are stressed by episodic disturbance from storms associated with hurricanes and nor'easters. Using annual tree ring data, we adopt a dendroclimatic and statistical modelling approach to understand the response and resilience of a coastal pine forest to slow progressive climate change and extreme storm surge events. Results indicate that radial growth of trees in the study area is influenced by age, vigor, competition, microsite variability, and regional climatic trends, but dominated periodically by disturbance due to storm surges. We evaluated seven local storm surge events to understand the effect of storm surges associated with nor'easters and hurricanes on radial growth. A general decline in radial growth was observed in the year of the storm and three years following it, after which the radial growth starts recovering. Given the projected increase in hurricanes and storm surge severity with changing global climate, this study contributes to understanding declining tree growth response and resilience of coastal forests to past disturbances. This can help predict vegetation response patterns to similar disturbances in the future.

More frequent and harsh storms coupled with sea level rise are affecting Canada’s sensitive coastlines. This research studies Isle Madame in Cape Breton, Nova Scotia which has been designated by Natural Resource Canada as a sea level rise vulnerable coastal community in Canada. The research models the spatial and temporal impacts of sea level rise from storm surge by focusing on identifying vulnerable areas in the community via geographical information systems (GIS) using ArcGIS, as well as modeling dynamic coastal damage via system dynamics using STELLA. The research evaluates the impacts in terms of the environmental, social, cultural, economic pillars that profile the coastal community for a series of modelled Storm Scenarios. This research synthesizes information from a variety of sources including the coastal ecology and natural resources, as well as human society and socioeconomic indicators included in the four mentioned pillars. The objective of the research is to determine vulnerable areas on Isle Madame susceptible to storm damage, and consequently, to improve local community knowledge and preparedness to more frequent harsh storms. This research therefore presents a dynamic model for the evaluation of storm impacts in Isle Madame designed with the goal to help the community ultimately to plan and implement a strategy to adapt to pending environmental change.

More frequent and harsh storms coupled with sea level rise are affecting Canada’s sensitive coastlines. This research studies Isle Madame in Cape Breton, Nova Scotia which has been designated by Natural Resource Canada as a sea level rise vulnerable coastal community in Canada. The research models the spatial and temporal impacts of sea level rise from storm surge by focusing on identifying vulnerable areas in the community via geographical information systems (GIS) using ArcGIS, as well as modeling dynamic coastal damage via system dynamics using STELLA. The research evaluates the impacts in terms of the environmental, social, cultural, economic pillars that profile the coastal community for a series of modelled Storm Scenarios. This research synthesizes information from a variety of sources including the coastal ecology and natural resources, as well as human society and socioeconomic indicators included in the four mentioned pillars. The objective of the research is to determine vulnerable areas on Isle Madame susceptible to storm damage, and consequently, to improve local community knowledge and preparedness to more frequent harsh storms. This research therefore presents a dynamic model for the evaluation of storm impacts in Isle Madame designed with the goal to help the community ultimately to plan and implement a strategy to adapt to pending environmental change.

This study presents an unsteady-state hydraulic model analysis of hurricane storm surge and rainfall-runoff interactions in the Clear Creek Watershed, a basin draining into Galveston Bay and vulnerable to flooding from both intense local rainfalls and storm surge. Storm surge and rainfall-runoff have historically been modeled separately, and thus the linkage and interactions between the two during a hurricane are not completely understood. This study simulates the two processes simultaneously by using storm surge stage hydrographs as boundary conditions in the Hydrologic Engineering Center’s – River Analysis System (HEC-RAS) hydraulic model. Storm surge hydrographs for a severe hurricane were generated in the Advanced Circulation Model for Oceanic, Coastal, and Estuarine Waters (ADCIRC) model to predict the flooding that could be caused by a worst-case scenario. Using this scenario, zones have been identified to represent areas in the Clear Creek Watershed vulnerable to flooding from storm surge, rainfall, or both.