This chapter discusses some considerations involved in modelling the accidental release of hazardous chemicals at sea, and the subsequent transport of the chemicals in the water column. It concentrates on identifying the limitations and constraints in chemical spill modelling, and the requirements for a chemical spill model to be used in an emergency response situation.

This chapter is a summary of a report prepared for the Commission of the European Community.


In the past decade, there has been increasing scientific and international concern over the effects of large-scale oil spills on the marine environment. Many countries have developed computer codes to model such spill, which (typically) arise from tanker exploration/production platform accidents. These codes are designed to calculate the probable path of the oil spill, to aid in combating the spill, and in some cases to assess the resulting environmental damage. As a consequence, there has been considerable research into the technique for modelling oil spills, and in identifying the physical processes that are important. In contrast, computer codes for chemical spill modelling are not as well developed, but form a natural extension to oil spill research.

Recently, there have been a number of potentially serious accidents involving chemical tankers, and it is probable that such accidents will become more frequent. This chapter considers the use of chemical spill models in a situation that represents a risk to human or marine life, i.e. a large-scale spill of a hazardous chemical. The transport of chemicals by sea is small compared to the transport of oil by sea, and so the rationale for chemical spill modelling is different. Chemical spill models can offer.

  • a means of estimating, in advance, the possible effects of a spill in a particular geographical area (the contingency planning mode)

  • an on-the-spot tool for decision-making in an actual emergency (the emergency response mode)

The consequences for a major chemical spill can be serious because many chemicals are highly toxic, and dissolve rapidly in water.

This chapter discusses modelling the transport of hazardous chemicals spilt at sea. The emphasis is not on the development of research codes, which usually require considerable data and are mathematically complex, but on the development of useable, reliable codes for use in emergencies. The conclusions presented in this chapter indicate the areas of research that will provide the knowledge needed for writing practical chemical spill response software.

The Background to Chemical Spill Modelling
The EEC report

In 1896, the Commission of the European Communities contracted Scicon Limited (a UK computer consultancy company) to undertake a study of the present status of chemical spill modelling in the EEC, and to report on possible future developments. The study was largely a review of the works selected agencies within the EEC.

The aim of the study was to identify the limitations and constraints associated with the use of chemical spill models in examining the water column transport of dangerous chemicals spilled at sea.

The objective of the study were

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