No abstract

Noise generated by offshore wind turbines and support structures radiates and propagates through the air, water and sediment. Predicting noise levels around wind turbine structures at sea is required to estimate the effects of the noise on marine life. We used Finite Element (FE) and Parabolic Equation (PE) models to predict long range propagation of noise from the construction and operation of offshore wind turbines. FE analysis produced pressure outputs at short ranges were used as a starting field for a modified PE propagation model. Furthermore, we investigated the optimum range for the transition to PE modeling. The effects of various sediment types were also considered determining the pressure starting field. In FE analysis models, we implemented the axisymmetric elements and implicit dynamic analysis with pressure impact loading and vertical acceleration boundary conditions to simulate pile driving and operational noise radiation. We will present the PE long range pressure field outputs from the offshore pile driving and operation for a shallow water environment around Block Island, Rhode Island.

It is not uncommon for modern aquaria to be built with special entertainment areas. There are no known measurements of sound spillover from such entertainment areas into underwater animal exhibits. Entertainment organizations typically prefer to play music for events at 95 and 100 dBA in a ballroom at Georgia Aquarium. Concern over the potential effects of the music and noise on animals in adjacent exhibits inspired an initial project to monitor and compare sound levels in the adjacent underwater exhibits against the typical in-air sound levels of the ballroom. Measured underwater noise levels were compared to modeled levels based on finite element analysis and plane wave transmission loss calculations through the acrylic viewing window. Results were compared with the model to determine how, if at all, the ambient noise level in the Cold Water Quest exhibit changed as a result of music played in the ballroom.

In the United States, offshore wind farms are being planned and construction could begin in the near future along the East Coast of the US. Some of the sites being considered are known to be habitat for crustaceans such as the American lobster, Homarus americanus, which has a range from New Jersey to Labrador along the coast of North America. Groundfish such as summer flounder, Paralichthys dentatus, and winter flounder, Pseudopleuronectes americanus, also are common along the East Coast of the US. Besides sharing the seafloor in locations where wind farms are planned, all three of these species are valuable commercially. We model the effects on crustaceans, groundfish, and other animals near the seafloor due to pile driving. Three different waves are investigated including the compressional wave, shear wave and interface wave. A Finite Element (FE) technique is employed in and around the pile while a Parabolic Equation (PE) code is used to predict propagation at long ranges from the pile. Pressure, particle displacement, and particle velocity are presented as a function of range at the seafloor for a shallow water environment near Rhode Island. We will discuss the potential effects on animals near the seafloor.

Noise generated by offshore impact pile driving radiates into the air, water and sediment. Predicting noise levels around the support structures at sea is required to estimate the effects of the noise on marine life. Based on high demands developing renewable energy source, the United States will begin the first pile driving within one to two years. It is necessary to investigate acoustic impact using our previously verified coupled Finite Element (Commercial FE code Abaqus) and Monterey Miami Parabolic Equation (2D MMPE) models (J. Acoust. Soc. Am. 131(4), p. 3392, 2012). In the present study, we developed a new coupled FE-MMPE model for the identification of zone of injury due to offshore impact pile driving. FE analysis produced acoustic pressure outputs on the surface of the pile which are used as a starting field for a long range 2D MMPE propagation model. It calculates transmission loss for N different azimuthal directions as function of distance from the location of piling with the inputs of corresponding bathymetry and sediment properties. We will present predicted zone of injury by connecting N different distances of equivalent level fishes may get permanent injury due to the first offshore wind farm installation in the U.S..