Dispersion calculations and risk assessments

SMHI has many years of experience of emission calculations which can provide a good basis for decisions regarding the dimensioning or risk analysis of different types of emissions in the air and water, for example.

With the help of advanced numerical models, expertise in water dynamics and dispersion progress and SMHI's collected databases on measurements in the atmosphere, seas, lakes and watercourses, we can answer questions such as:

  • How high will the concentration levels be at a certain level of emissions?
  • Which areas are in the danger zone?
  • How much time do you have take action if an accidental discharge occurs?
  • Will a contaminant sink to the bottom or will it remain on the surface?
  • Where and how should pollutants be released in order to minimise the concentration in specific areas?

A selection of the services and products which we can offer includes

  • risk analyses for water catchment areas
  • calculations of the mixing and dispersion of industrial releases, for example coolants and process water
  • calculations of emission and dispersion into the air from airports, harbours or other traffic centers
  • atmospheric chemical calculations on the formation and deposition of ozone, particles, PAH or other substances with or without chemical reaction schemes
  • calculations regarding how a spillage, in connection with dredging, is transported and settles in order to optimise dredging efforts with regard to its environmental impact
  • assessment of odour dispersion from production facilities that have known emissions of odours
  • Seatrack, a web service used for forecasts and scenarios on how accidental releases disperse in water. This is already operational in several lakes and seas

Emissions into the air and water can be planned, such as cooling water or stack emissions, or a result of accidents, such as oil spills or gas leaks.
In both cases, the object is to minimise the risks of there being an impact on the natural environment, people's health or economic values.

In the event of planned releases, this may mean that the discharge equipment is optimised based on prevailing flow and stratification conditions in order to comply with prevailing environmental requirements.
It is very important to know how the releases are dispersed. Pollutants can bring about considerable costs in the form of ecological rehabilitation, damage to industrial production and a shortage of drinking water.
If a waterworks does not switch off its raw water intake in time when threatened by a toxic discharge, the entire water production facility may have to be closed down.

It is also important to include information about pollutant dispersion in the planning process, because it is required by law in some Environmental Impact Assessment studies. If the information is not included, the process may be delayed, leading to significant financial and PR-related losses.