Spills modeling

When oil spills on water, various transformation processes occur that are referred to as the behaviour of the oil. Two types of transformation processes are discussed in Chapter 4. The first is weathering, with emphasis on evaporation, the formation of water-in-oil emulsions, and natural dispersion, and the second is a group of processes related to the movement of oil in the environment. Spill modelling, wherein the behaviour and movement components of an oil spill are simulated using a computerized model, is also discussed. 

Sensitivity maps can also be integrated with computerized oil spill models so that the impact of an oil spill on the environment can be projected. 

To protect sensitive resources and coastline, spill response personnel need to know the direction in which an oil spill is moving. To assist them with this, computerized mathematical models have been developed to predict the trajectory or pathway and fate of oil. Outputs of one such spill model are shown in Figure 10. 

Today s sophisticated spill models combine the latest information on oil fate and behaviour with computer technology to predict where the oil will go and what state... 

In addition to predicting the trajectory, these models can estimate the amount of evaporation, the possibility of emulsification, the amount of dissolution and the trajectory of the dissolved component, the amount and trajectory of the portion that is naturally dispersed, and the amount of oil deposited and remaining on shorelines. Accurate spill modelling is now a very important part of both contingency planning and actual spill response. 

Spill models operate in a variety of modes. The most typical is the trajectory mode that predicts the trajectory and weathering of the oil. The stochastic mode uses available data to predict a variety of scenarios for the oil spill, which includes the direction, fate, and property changes in the oil slick. In another mode, often called the receptor mode, a site on the shore or water is chosen and the trajectory from the source of the oil is calculated. Increasingly, statistically generated estimates are added to oil spill models to compensate for the lack of accurate knowledge of winds and currents. 

Reed M, Johansen 0, Brandvik PJ, Daling P, Lewis A, Fiocco R, Mackay D, and Prentki R (1999) Oil spill modeling toward the close of the 20th century Overview of the state of art. Spill Science Technology Bulletin 5 3-16 Thomson TW, Liu WT, and Weissman DE (1983) Synthetic radar observation of ocean roughness from rolls in unstable marine boundary layer. Geophys Res Lett 10 1172-1175... 

All of the described processes for the evolution of aqueous concentration, however, would apply to both a one-dimensional and a two-dimensiond spill model. 

Oil spill modeling needs to be performed before a spill occurs as part of a planning process for emergency response. This avoids the chicken-with-its-head-cut-off look that is often apparent in spill response teams. There will not be sufficient time following a spill to collect appropriate data and bring a model up to speed. Oil spill models are also valuable in a forensic investigation following an oil spill event. 

Models toxic gas releases. Two models available SHELL SPILLS and TRPUF (based on EPA PUFF). Graphical output. Requires 512K memory and 132 column printer. 

TOXIC, PUFF, SPILLS, INPUFF, AND INPUFF 2.0 Bowman Environmental Engineering P.O. Bo 29072 Dallas, TX 75229 (214) 241-1895 In ascending order of data complexity, these systems address toxic gas releases using models designed for each type of release, based on emission rate, facility characteristics and weather data. 

David A. Jones Modeling of chemical dispersion and spill behavior. 

AFTOX is a Gaussian dispersion model that is used by the Air Force to calculate tu accidental releases. Limited to non-dense gases, it calculates the evaporation rate from liquid spills. It treats instantaneous or continuous releases from any elevatic ... 

This is a subroutine that calculates an evaporation rate from a pool of spilled liquid in presence of wind (ORG-40), or in still air (TP-10). It was developed by the U.S. Array for downwind hazard prediction following release from smoke munitions and chemical agents. The code calculates the evaporation rate of a liquid pool, given the physical stale variables, wind speed, and diameter of pool. ORG-40 and TP-10 models are coded as a Fortran 77 subroutine, EVAP4.FOR, in D2PC. The user s manual is Whiiacre (1987). 

PSpill determines the mass airborne from a spill of solid powder. It models the. shearing effect of the air on the powder as it falls. The shearing effect is enhanced by the lengthening of the... 

Colenbrander, G. W. and J. S. Puttock, 1980, Maplin Sands experiments 1980 interpretation and modelling of liquified gas spills on the sea, in Atmospheric Dispersion of Heavy Hoses and Small Particles, G. Ooms and H. Tennekes, editors, Springer-Verlag, Berlin. 

Kunkei, B. A., 1983, A Comparison of Evaporative Source Strength Models for Toxic Chemical Spills , AFGL-TR83-0307, ADA139431. 

Eisenberg, N. A., C. J. Lynch, and R. J. Breeding. 1975. Vulnerability model. A simulation system for assessing damage resulting bom marine spills. U.S. Department of Commerce Report No. ADIA015/245. Washington National Technical Information Service. 

Source models describe tlie release rate of material from tlie process equipment into tlie external enviromiient, and tlie rate of release of spilled vapors and volatile liquids into the atmosphere. 

When spills and releases of hazardous gases or liquids occur, the concentration of the hazardous material in the vicinity of the release is often the greatest concern, since potential health effects on those nearby will be determined by the concentration of the substance at the time of the acute exposure. There are many models of routine continuous discharges (e.g., discharges arising from leaky valves in chemical plants), but these carmot be applied to single episodic events. Research on the ambient behavior of short-term environmental releases and the development of models for concentration profiles in episodic releases are cmcial if we are to plan appropriate safety and abatement measures. 

A. A. Allen and D. H. Dale. Dispersant mission planner A computerized model for the application of chemical dispersants on oil spills. In Proceedings Volume, volume 1, pages 393-414. 18th Environ Can Arctic Mar Oilspill Program Tech Seminar (Edmonton, Canada, 6/14-6/16), 1995. 

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