Date of Award
2024
Degree Type
Thesis
Degree Name
Master of Science in Ocean Engineering
Department
Ocean Engineering
First Advisor
M. Reza Hashemi
Abstract
This study investigates sediment transport trends in southern Rhode Island by analyzing seasonal and spatial variations in different wave climates using numerical models, specifically XBeach and Simulating Waves Nearshore (SWAN). SWAN simulates offshore wave propagation, while XBeach simulates beach morphology and sediment transport. In terms of temporal variability, this study focuses on Green Hill Beach, Rhode Island, and simulates four seasonal storm conditions, including Hurricane Sandy, Hurricane Irene, nor’easter in the Spring of 2013, and nor’easter in the Fall of 2012. The data from the US Army Corp of Engineers, Northeast Coast Comprehensive Study (NACCS) were also incorporated to examine spatial variations of storms along the southern shore of Rhode Island at each barrier system from Green Hill Beach to Misquamicut State Beach. Nested SWAN models covering a large area of the northeastern US (parent domain) and Rhode Island local waters (child model) were first validated using observed data. The wave modeling study demonstrated that a parametric hurricane model achieves the best results for the large domain. It was also shown that the spatial variability of waves in Rhode Island's local waters (child model) is small enough that a local model can be forced by a uniform wave height. The XBeach model was then nested inside the SWAN child model. XBeach simulations, based on storms like Hurricane Irene, Hurricane Sandy, and the nor’easter of spring 2013, reveal consistent sediment deposition east of Green Hill Beach and variations in sediment erosion on the west. Hurricane Irene (summer) and the 2013 nor'easter (spring) simulations exhibit similar trends, indicating similar sediment transport patterns for winter and summer storms, although with different intensities. This can be justified as sediment transport is dominated by wave and storm surge impacts, and extreme events can happen during both summer and winter periods. The NACCS dataset highlights spatial variability in wave heights during the 100-year return period event, with a mean of 4.04 m and an 18.32% relative standard deviation across all save points from each beach on the southern Rhode Island coast. East Beach has the largest exposure to wave height (4.99 m), while Point Judith has the lowest exposure (3.0 m). The maximum water level generated by the NACCS 100-year return period water level exhibits slight variation along the south coast with a mean of 2.67 m and a 5.06% relative standard deviation. Only one sediment grain size was considered in the model, and all simulations were run using one consistent bathymetry. A more accurate approach would involve collecting the bathymetry data immediately before and after the hurricane's event and measuring different grain sizes along the southern shore of Rhode Island.
Recommended Citation
Rojchanaborworn, Pumee, "SEASONAL AND SPATIAL VARIATIONS OF THE SEDIMENT TRANSPORT ALONG THE SOUTHERN SHORE OF RHODE ISLAND" (2024). Open Access Master's Theses. Paper 2516.
https://digitalcommons.uri.edu/theses/2516