EHS445 UNIT III: IMPACT PREDICTION, EVALUATION AND MITIGATION

Date: Monday, 9 February 2026

Time: 0800-1100

Location: Hall 2

PREDICTION

Objectives of Prediction

The objectives involved in the prediction process include identifying and assessing various environmental components which can be broadly classified as follows:

Environmental Components (Glasson et al, 4th ed, pg. 1.3)

• Physical Environment

  1. Air and atmosphere

  2. Water resources and water bodies

  3. Soil and geology

  4. Flora and fauna

  5. Landscape

  6. Cultural heritage

  7. Climate

  8. Energy

• Socio-Economic Environment

  1. Demography

  2. Economic base - direct

  3. Economic base - indirect

  4. Housing: transport; recreation

  5. Other local services

  6. Socio-cultural

• Quality Indicators

  1. Air quality

  2. Water quality and quantity

  3. Classification, risks (e.g., erosion, contamination)

  4. Flora and fauna (birds, mammals, fish, etc.; aquatic and terrestrial vegetation)

  5. Physical and mental health and well-being

  6. Characteristics and quality of landscape

  7. Conservation areas; built heritage; historic and archaeological sites; other material assets

  8. Temperature, rainfall, wind, etc.

  9. Light, noise, vibration, etc.

• Demographic Trends

  1. Population structure and trends

  2. Direct employment; labor market characteristics; local and non-local trends

  3. Non-basic and services employment; labor supply and demand

  4. Supply and demand

  5. Supply and demand of services: health, education, police, etc.

  6. Lifestyles, quality of life; social problems; community stress and conflict

Dimensions of Prediction

• What aspects to predict?:

  1. Magnitude and significance (both objective and subjective approaches)

  2. Direct and indirect impacts

  3. Geographical extent of impacts

  4. Beneficial and/or adverse impacts

  5. Duration of impacts

  6. Rate of change of impacts

  7. Reversibility of impacts

  8. Cumulative, synergistic, and additive impacts

  9. Quantitative and qualitative impacts

• Estimates of probability (Glasson et al, 4th ed, pgs. 116 – 117)

METHODS AND MODELS FOR PREDICTION

How to Predict?

Predictive methods can be classified in many ways, including:

• Partial

• Holistic

• Extrapolative

• Normative
  (Glasson et al, 4th ed, pg. 117)

Types of Models

1. Mathematical and Computer-Based Models:

   • Based on scientific laws, statistical analysis, and computer-based approaches.

   • Can be spatially aggregated.

   • Can be divided into deterministic and stochastic models.

   • Statistical models.

2. Physical/Architectural Models and Experimental Methods:

   • Includes illustrative/scale models and photo-montages.

   • Field and laboratory experimental methods.

3. Expert Judgment and Analogue Models:

   • Predictions based on analogous situations.

   • Developed from site visits, literature searches, or monitoring of similar projects.

(Glasson et al, 4th ed, pgs. 117 – 119)

EVALUATION

Evaluation in the EIA Process

Criteria for Significance includes:

• Magnitude and likelihood of impacts

• Spatial and temporal extent

• Recovery of the affected environment

• Public concern

• Political repercussions

• Value of the affected environment
  (Glasson et al, 4th ed, pgs. 126 – 127)

Conducting an Evaluation in the EIA Process

Most Formal Method Involves:

• Utilization of legal requirements and standards.

• Evaluation of socio-economic impacts, which involve recognition of key problems including:

  • Applicable standards.

  • Political influence.

  • Distributional dimension to evaluation.
    (Glasson et al, 4th ed, pgs. 126 – 128)

Cost-Benefit Analysis (CBA) and Monetary Evaluation Techniques

Objectives of CBA Include:

1. Comprehensive evaluation of impacts.

2. Aligning with welfare economics principles.

3. Involves several stages of assessment.

4. Operates under basic evaluation principles.

Potential Problems with CBA Include:

• Difficulty in identifying, enumerating, and monetizing intangibles.

• Incompatibility of monetary and non-monetary units.

• Challenges in the choice of discount rate.

• Use of a single evaluation criterion of money.

• Ignores distributional effects.
  (Glasson et al, 4th ed, pgs. 130 – 131)

MITIGATION AND ENHANCEMENT

Types of Mitigation Measures Include:

1. Methods to avoid impacts.

2. Methods to reduce adverse effects.

3. Methods to repair, rehabilitate, or restore affected environments.

4. Methods to compensate individuals for adverse effects.

Wider Classification of Mitigation (Glasson et al, 4th ed, pg. 138)

Enhancement of Potential Benefits Can Include:

• Local employment benefits.

• Opportunities for local contractors.

• Housing, transportation, and infrastructural changes.

• Changes brought about by large projects.