Modelling

From SEA.unu.edu/wiki

As in project EIA, many of the impacts of strategic actions can be predicted using range of assumptions and extrapolations from previous data. For instance, the noise impacts of a road network can be calculated based on information about expected traffic on the network, noise receptors along the network, etc.

Most models used in SEA have evolved from EIA, and modelling is primarily used at the programme level. Models typically deal with quantifiable impacts: air pollution, noise, traffic. Many models used for EIA are computerised.

Examples:

Click here for a programme-level example of how models were used to calculate traffic, noise and air impacts of a motorway network in Poland.

This is quite a different, more strategic, example, which predicts the likely impacts of different forms of Park-and-Ride using a series of assumptions based on monitoring of existing Park-and-Ride schemes.

Advantages:

• Objective, scientific, rigorous (as rigorous as possible)

Disadvantages:

• Limited to impacts that can be quantified/modelled
• Can require large amounts of expensive data
• Many models are "black boxes": technocratic, complex and not transparent. They generally do not encourage participation or "ownership" by those people affected by the strategic action
• Many models are based on untested assumptions, and have not been verified/ monitored on the ground, particularly over longer timeframes. For instance, traffic models in the UK assumed for many years that new roads merely dispersed existing traffic: monitoring later showed that new roads also generate new traffic..
• Because most models used in SEA were initially used in EIA, they promote project-level rather than strategic thinking
• Many models can only compare like with like (e.g. road with road, not road with rail)
• Although most countries have accepted traffic/noise/air models, these models are not consistently used from country to country. The European Environment Agency is trying to coordinate modelling approaches for European Member States (click here for the EEA's air pollution model), but variations still exist.

Further information

The whole June 1998 issue of Impact Assessment and Project Appraisal (Vol. 16, No. 2) is on modelling (though primarily in the context of EIA).