The EIA process is concerned with determining and evaluating environmental change. It is important therefore to first establish the environmental and social characteristics that will be subject to change as a consequence of the project. These characteristics are referred to as the ‘baseline environment’ and consideration is given to how this may evolve in the absence of the project.
One focus of the EIA process to date has been on characterising the environmental baseline. This has relied on different techniques for different assessment topics. Much of it involves collecting information and data from various existing sources through desk research. Where this information is missing or incomplete, site visits and surveys are used to obtain it and survey work to date is summarised below.
Some EIA topics use computer models to forecast how environmental change would occur, both as a prevailing change and as a result of the project. This includes models to predict how road traffic would change and how drivers would behave in response to different factors. These transport models are particularly important where they help inform other assessments, notably air quality and noise. Modelling of flooding is also important, as it would help determine, amongst other things, the vertical profile and footprint of the proposed railway and works, with implications for several EIA topics.
