Environmental Impact Assessment: Types and Methods

Classification of Environmental Impacts

Impacts Based on Manifestation Time

• Crouching Impact: Occurs after starting the activity.
• Immediate Impact: Manifests very early in the activity.
• Critical Time Impact: The critical time and magnitude of the impact are accentuated.

Impacts Based on Recovery Possibility

• Critical Impact: Irreversible damage occurs.
• Severe Impact: Requires a long period of time to take effect.
• Moderate Impact: Can be reversed simply by the cessation of the activity.

Impacts Based on Spatial Extent

Impacts can be local, regional, or global.

Impacts Based on Temporal Scope

Impacts may be permanent or transient.

Impacts Based on Environmental Resilience

• Irretrievable Impact: Beyond repair.
• Irreversible Impact: Extreme difficulty in recovery.
• Mitigated Impact: Effects can be mitigated.
• Recoverable Impact: Does not lead to total recovery.

Impacts Based on Effect

Impacts can be positive or negative.

Impacts Based on Mode of Action

Impacts may be direct (direct effect) or indirect (alteration occurs in a different environment than where the activity occurs).

Impacts Based on Degree of Destruction

Impacts can range from total impact (complete destruction) to minimal impact.

Impacts Based on Interrelation of Effects

• Simple Impact: Effects on a particular environmental factor.
• Cumulative Impact: Builds and increases in intensity over time.
• Synergistic Impact: Effects on several environmental factors.

The Extent of Environmental Impact

To perform an environmental impact assessment, one must check the magnitude that has been reached or can be reached. There are different methods:

Quantitative Methods

These methods assign a numerical value to environmental indicators to conduct a mathematical study of the level of impact that has occurred or will occur. The most commonly used is the Leopold matrix, a cross-tabulation used to analyze the numerical degree of impact that a series of actions will have on a set of environmental factors. In the boxes that relate the inputs, two numerical values are introduced, separated by a slash; the upper value represents the magnitude of the impact, and the lower value represents its importance.

Qualitative Methods

These methods depend on the variations obtained in previous studies with similar characteristics. If an activity is to be developed in one place and there are results of studies on similar activities in similar places, one may venture to estimate the level of impact qualitatively within an overall scale.

The Ecological Footprint

The ecological footprint is the area of land capable of producing the necessary resources to meet the needs of a living being and to assimilate the waste generated.

Carrying capacity is the size of the population that a given environment can support without experiencing a significant negative impact.

Environmental Impact Assessment Process

An environmental impact assessment is conducted before engaging in any potentially dangerous activity on the environment. This study determines the potential extent of the impact and establishes measures to minimize it.

The following steps must be followed:

1. Identify the Project or Activity: The project or activity being undertaken should be properly identified, and the necessary permits and licenses to start working must be requested.
2. Environmental Impact Assessment: An impact assessment of the project is required before approval. Specialist reports of all kinds are needed, taking into account potential impacts on the natural, cultural, and social environment.
3. Corrective Action: The report should include proposals and compensatory measures to reduce the magnitude of the impact.
4. Assessment of the Project: The feasibility of a project is assessed from an environmental point of view. The competent authority carries out an assessment of the project and issues a declaration of environmental impact, which can be negative or positive. If positive, the project may obtain legal permits to be carried out. If negative, the project is halted until reforms are made to make it viable.