The full EIA (Environmental Impact Assessment) study is a more significant effort than the preliminary assessment.
Preliminary assessment
Only preliminary, not as detailed as the full EIA study
Full EIA study
More detailed, reserved for activities where screening or preliminary assessment shows significant impacts are likely
Purpose of full EIA study
Not to find impacts that will not be significant, but to allow an informed decision to be made about which significant environmental impacts may be acceptable to obtain a particular development objective
Determining if the environment can hold/accumulate environmental impacts
The main purpose of EIA is to predict and quantify the possible impact of a project or activity, and find ways to mitigate those impacts so the environment can still uphold its functions
Example of environment not being able to hold impacts
A lake that cannot recycle pollution beyond a certain amount, becoming polluted
Purpose of EIA
To predict and quantify the possible impact of a project or activity, and find ways to mitigate those impacts so the environment can still uphold its functions