Prediction and mitigation of impacts through EIA

After we have screened a project to see if it requires an EIA or not, and after we have conducted the scoping process (which includes baseline study, impact assessment in the form of checklists/matrices/networks and creating a ToR), we come to the third step of Environmental Impact Assessment: Prediction and Mitigation.

This step is the heart of the EIA process. From our impact assessment, we were able to identify the impact our developmental activities will have on our project area and it’s environmental aspects. We also gave it numerical values of magnitude and significance (in the case of matrices). Using this information, we can focus our attention on their supposed effect on the environment.


Predictions help us delve further into the impacts by studying its spatial and temporal extent, along with understanding how severe the activity could prove on an environmental aspect. For example, if the water quality in the area is to be affected by the waste disposal of our developmental activity, we would, in this step, try to figure out

  1. how much will be the pollution.
  2. what will be the pollutants.
  3. how far will these pollutants travel in the water.
  4. what areas will these pollutants affect.
  5. what life forms will the pollutants affect.
  6. for how long will their effects linger.

Such predictions are made for all developmental activities and their effects. Some of the general considerations during prediction are-

  • probability of occurrence.
  • spatial and temporal extent.
  • Impact at different scales.
  • intensity, reversibility and equity (who is affected) of the impact.
  • incremental and/or sudden possible effects.

What are we predicting these values against? We make these predictions based on the data we collected in our baseline study. Better the baseline data, more accurate our predictions can be.

It is important to assign these impacts numerical values of magnitude and intensity, for the better understand of non-experts. This is called weighting.

How are predictions done?

There are many methods to conduct prediction studies, some of which are-

  1. Mathematical models.
  2. Statistical models-that consider impacts by extrapolating figures based on the supposed impact on an environmental aspect.
  3. GIS and Remote Sensing.
  4. Field and lab experiments.
  5. Risk Assessment Matrices.

All of these methods require the work of experts in each field of impact.

Evaluation of predictions

Here, the EAC compares notes on the predictions they made and figure out the high and low impact activities and the aspects that are being severely affected. If required, certain experiments are re-run to test the correctness of the predictions. This helps them identify priorities for mitigation (although, all adverse impacts need to be mitigated to some extent).


Mitigation is the step where experts sit down with the project proponents to come up with alternatives to certain project activities so that they can reduce the adverse impacts on the environmental aspects of the project area. Priority is given to those activities that are having an extremely severe impact and/or cumulatively affect many aspects and/or impact particularly fragile parts of the environment. The mitigation measures can be in the form of alternative technology, design, machinery, process, location, raw materials, etc.

Alternatives are also looked at from the monetary perspective. Depending on the budget of the project, certain extremely beneficial alternatives are discarded (unfortunately) and less costly alternatives are arrived at. “No-project” scenario is also considered by the EAC.

Ideally, the project should only start once all the impacts are assessed, predicted and mitigation measures are suggested. However, EIA tends to take a long time and the project proponents will have already started preparation of the project. Sometimes, the project may even be underway. In such cases, some of the predicted values may be wrong (for better or worse) and some of the mitigation steps cannot be implemented. Again, alternatives are suggested unless the predicted values show that the impact will be very severe.

The Environmental Impact Statement

After compiling the assessment, prediction and mitigation measures, the EAC submits this information along with the baseline study and Terms of Reference to the concerned governmental authority. This report is called the Environmental Impact Statement. Based on the recommendations of this statement and it’s own considerations, the governmental authority will decide whether to give or not give an Environmental Clearance to the developmental project.

Ideally, it is only after receiving an environmental clearance can a project be executed. In many countries, this is the process that is followed.



Author: Saurab Babu

Usually found sitting with a good book, nibbling on a piece of dark chocolate. Always ready for a good story.

2 thoughts

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.