Oil-Spill Risk Analysis for Assessing Environmental Impacts

2003 ◽  
Vol 2003 (1) ◽  
pp. 1125-1129 ◽  
Author(s):  
Zhen-Gang Ji ◽  
Walter R. Johnson ◽  
James M. Price ◽  
Charles F. Marshall
Keyword(s):  
Risk Analysis ◽  
Gulf Of Mexico ◽  
Continental Shelf ◽  
Oil Spill ◽  
Ocean Currents ◽  
Management Service ◽  
Numerical Schemes ◽  
Outer Continental Shelf ◽  
Oil And Gas Development ◽  
Runge Kutta

ABSTRACT The Minerals Management Service (MMS), an agency of the U.S. Department of the Interior, maintains a leasing program for commercial oil and gas development on the Outer Continental Shelf in U.S. territorial waters. The MMS performs an oil-spill risk analysis (OSRA) using, in part, a statistical model of hypothetical oil-spill trajectories. The OSRA Model is driven by analyzed sea surface winds and model-generated ocean surface currents. Instead of focusing on individual oil-spill events, the OSRA examines oil-spill risks over long periods of time, ranging from 5 years to decades. The OSRA Model calculates thousands of oil-spill trajectories over extended areas of the U. S. continental shelf and tabulates the frequencies with which the simulated oil-spills contact the geographic boundaries of designated natural resources within a specified number of days after the simulated spill events. A key element of OSRA Model runs is the particle trajectory simulation based on wind velocities and surface ocean currents. It is critical that the trajectory model has a numerical scheme that is stable, accurate, and efficient. Currently, two numerical schemes are incorporated into the model: the Eulerian scheme and the 4th order Runge-Kutta scheme. To test the numerical schemes, a set of analytical solutions to the Navier-Stokes equations is developed. The analytical velocities and particle trajectories are compared with the numerical solutions from the two numerical schemes. The stability and efficiency of the two schemes are discussed. Applying the model to the Gulf of Mexico using 9 years of winds and ocean currents, we find that the OSRA Model with the 4th order Runge-Kutta scheme is much more efficient and able to better represent the circulation patterns and particle movements in the Gulf of Mexico.

Oil Spill Risk Analysis for Assessing Environmental Contact Probabilities in the Gulf of Mexico

2017 ◽  
Vol 2017 (1) ◽  
pp. 1931-1949
Author(s):  
Zhen-Gang Ji ◽  
Walter R. Johnson
Keyword(s):  
Risk Analysis ◽  
Gulf Of Mexico ◽  
Continental Shelf ◽  
Oil Spill ◽  
Oil Spills ◽  
Surface Wind ◽  
Surface Current ◽  
Oil Well ◽  
Outer Continental Shelf ◽  
Oil And Gas Development

ABSTRACT 2017-051: The U.S. Department of the Interior (DOI) Bureau of Ocean Energy Management (BOEM) maintains a leasing program for commercial oil and gas development on the Outer Continental Shelf in U.S. territorial waters. To evaluate the potential impacts of these activities, BOEM performs oil spill risk analysis (OSRA) using, in part, a statistical model for estimating the movement of hypothetical oil spills on the ocean surface based on model-generated surface wind and surface current. OSRA examines oil spill risks over long periods of time ranging from 5 years to decades. The latest OSRA analysis estimated the contact probabilities of oil spills in the Gulf of Mexico (GOM) region by modeling over 40 million hypothetical oil spill trajectories over extended areas of the U. S. continental shelf and tabulating the frequencies with which the simulated oil spills contacted designated natural resources within a specified number of days. The modeled ocean currents and wind fields used in the GOM analysis are from 1993 to 2007 (15 years). The OSRA model was also applied to analyze the contact probabilities of the Ixtoc Oil Spill, which happened on June 3, 1979 in the Bay of Campeche of the GOM and lasted for 10 months. The Ixtoc I Oil Well suffered a blowout, resulting in one of the largest oil spills in history and 3 million barrels of oil spilled. The OSRA model was applied to simulate particle trajectories released at the Ixtoc location using the same GOM current and wind field data from 1993 through 2007. The model results for the Ixtoc simulation were consistent with the descriptions of the oil spill by Hooper (1982), which shows that the OSRA model can provide a reasonable projection of the contact probabilities of hypothetical oil spills.

STATISTICAL ESTIMATES OF SHORELINE OIL CONTACT IN THE GULF OF MEXICO

2005 ◽  
Vol 2005 (1) ◽  
pp. 547-551 ◽  
Author(s):  
Walter R. Johnson ◽  
Zhen-Gang Ji ◽  
Charles F. Marshall
Keyword(s):  
Wind Speed ◽  
Gulf Of Mexico ◽  
Oil Spill ◽  
Wind Field ◽  
Oil And Gas ◽  
Ocean Current ◽  
Management Service ◽  
Outer Continental Shelf ◽  
Statistical Estimates ◽  
Level Of Concern

ABSTRACT As steward of the Federal offshore lands known as the Outer Continental Shelf (OCS), the U.S. Department of the Interior (DOI), Minerals Management Service (MMS), is responsible for balancing the Nation's search for commercial oil and gas with protection of the human and marine environments. The MMS regulates the development of mineral resources in an environmentally safe manner by analyzing environmental consequences of the OCS program prior to lease sales or approval of industry's plans. The Oil-Spill Risk Analysis (OSRA) model was developed by the DOI for the analysis of possible oil-spill impact from offshore oil and gas operations. The OSRA model produces statistical estimates of hypothetical oil-spill occurrence and contact from projected OCS operations. The model generates an ensemble of sea surface oil-spill trajectories by initiating thousands of oil-spill simulations at hypothetical spill locations to statistically characterize oil-spill risk in areas of prospective drilling and production and along projected pipeline routes. The hypothetical spills are initiated every day and move at the velocity of the vector sum of the surface ocean currents plus an empirical wind-induced drift of speed equal to 3.5% of the local wind speed, with a wind-speed-dependent direction (Samuels et al., 1982). The model generates oil-spill trajectories by integrating interpolated values of the wind and ocean current fields at intervals short enough to use the full spatial resolution of the ocean current and wind fields. The OSRA model, as applied to the Gulf of Mexico, uses 3-hourly ocean current fields over 7 years (1993–1999) generated by the Princeton Regional Ocean Forecast System (PROFS) (Oey et al., 2004). The PROFS is driven by synoptic winds, heat flux, and river flows. The wind field is based on the European Center for Medium-Range Weather Forecasts surface winds enhanced by observations from meteorological buoys and Coastal-Marine Automated Network stations. The same wind field used to force the ocean model is used to move the oil in the spill trajectories. As an example of environmental assessment, the OSRA model was used to estimate the spreading of oil spills by simultaneously modeling fractions of each spill, referred to as spillets. The spillets were used to calculate additional statistics, in particular, the length of coastline contacted by a large spill. The coastline was divided into equal length segments. Assumptions were made regarding what fraction of the spill (i.e., the number of spillets) that contacted a land segment would constitute a contact larger than the “level of concern.” Sensitivity of the analysis to key assumed parameters, such as the number of spillets and the level of concern, were tested.

Isotopic characterization of lifetime movement by two demersal fishes from the northeastern Gulf of Mexico

2021 ◽  
Vol 657 ◽  
pp. 161-172
Author(s):  
JL Vecchio ◽  
JL Ostroff ◽  
EB Peebles
Keyword(s):  
Gulf Of Mexico ◽  
Continental Shelf ◽  
Life Histories ◽  
Linear Mixed Model ◽  
Trophic Position ◽  
Eye Lens ◽  
Outer Continental Shelf ◽  
Red Grouper ◽  
Lens Diameter ◽  
Isotopic Characterization

An understanding of lifetime trophic changes and ontogenetic habitat shifts is essential to the preservation of marine fish species. We used carbon and nitrogen stable isotope values (δ13C and δ15N) recorded within the laminar structure of fish eye lenses, reflecting both diet and location over time, to compare the lifetime trends of 2 demersal mesopredators. Tilefish Lopholatilus chamaeleonticeps inhabit burrows on the outer continental shelf, which results in exceptional site fidelity. Red grouper Epinephelus morio are spawned on the middle to outer continental shelf, move to the inner shelf for the juvenile period, and return offshore upon sexual maturity. Both species inhabit the eastern Gulf of Mexico, a region with a distinctive offshore-inshore gradient in background δ13C values. Within individual tilefish (n = 36), sequences of δ13C values and δ15N values had strong, positive correlations with eye-lens diameter, and strong correlations between the 2 isotopes (mean Spearman r = 0.86), reflecting an increase in trophic position with growth and little lifetime movement. In red grouper (n = 30), δ15N values positively correlated with eye-lens diameter, but correlations between δ15N and δ13C were weak (mean Spearman r = 0.29), suggesting cross-shelf ontogenetic movements. Linear mixed model results indicated strong relationships between δ15N and δ13C values in tilefish eye lenses but no convergence in the red grouper model. Collectively, these results are consistent with previously established differences in the life histories of the 2 species, demonstrating the potential utility of eye-lens isotope records, particularly for investigating the life histories of lesser-known species.

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