EIA

• Evapotranspiration


  Combined loss of water vapor from the surface of plants and evaporation of moisture from the soil, inputs required for estimation are precipitation, temperature and latitude
• Evapotranspiration


  • Increases the runoff Rate
  • Reduces Infiltration
  • Can worsen flooding and erosion risk
• Flooding


  Occurs where water courses do not have the capacity to transfer the surplus water generated
• Base Flow


  • Movement of water between the surface body and groundwater
  • Contributes to the river flow varies significantly with the geology and topography of a catchment and with season
• Return Period or Recurrence Interval

  • Common way of showing the chances of the flow or rainfall even to reoccur
  • Statistical analysis based on measured historic data
  • Tells us the chances of the same flow of rain increasing in a year
  • Return Period = 1/P (P = probability of Exceedance)
  • Example: For a 2-year return period: P = 1/2 or 50%
• Water Budget

  • Calculated for a period of time and are given in depth (m)
  • Presented as a volume by multiplying the depth by the surface area of the watershed
  • Thornthwaite and Mather (1955): P-R-G-ET= S, where: P = precipitation, R= surface runoff, G= groundwater flow, ET= evapotranspiration, and S = change in storage in a specified time period
• Surface and Groundwater Quality Attributes

  • Chemical
  • Physical
  • Biological
• Surface Runoff


  Runoff curves, developed from combination of hydrologic soil grouping, can be estimated using hydrologic models
• Fluvial Geomorphology


  • Processes of water and sediment movement in rivers and their floodplains
  • Study of sediment sources, the fluxes and the storage within river catchments, study of resultant channel and floodplain morphology
• Fluvial Geomorphology Assessment


  1. Desktop Study: Maps and Aerial Photographs, existing survey information, topographical information and digital elevation models to calculate stream power

  2. Field Study: fluvial audit or stream reconnaissance survey, survey of the channel, sediment analysis, use of unmanned aerial vehicle technology
• Geomorphological threshold


  Condition allowing landform stability, a dynamic equilibrium through many factors
• Factors Affecting the Geomorphology - EXTERNAL

  • Catchment form
  • Drainage network
  • Flora and fauna
  • Land Use
  • Modification
  • Management practices
  • Geology
• Factors Affecting the Geomorphology - INTERNAL

  • Stream gradient
  • Mode of adjustment
  • Cross section morphology
  • Bed and bank conditions
  • Floodplain connectivity
  • River continuity
  • Flow regime
• Simple Geomorphological Classification of Channels

  • Cohesive - A1: Bedrock, A2: Sild-day channels
  • Non-Cohesive - B1: Sand, B2: Gravel, B3: Boulder Bed Channels
• Checklist provides different issues

  • Surface water hydrology
  • River hydrology
  • Surface water quality
  • Erosion and sedimentation
  • Geomorphology
  • Aquatic ecosystems
• Sources of Impact


  • Storage reservoir
  • Flow diversion
  • Standing water
  • Accumulation of sediments
  • Changes in hydrology
  • Potential impact: change in habitat and biota, dewatering, altering fish species, and potential changes to erosion pattern
• Source - Pathway - Receptor Model

  • Source: specific development activity
  • Pathway: mechanism by which that source can affect a receptor
  • Receptor: include physical, human or fauna/flora
• Potential Water Quantity Effects

  • Replacement of natural vegetated, impermeable paved areas
  • Abstraction from rivers
  • Artificial discharges to the water environment
  • Artificial cooling water discharges to the environment from a power station
• Water Quantity Assessment


  1. Desktop Study: catchment boundary/area and drainage patterns, digital terrain models, procurement of existing flow records

  2. Field Study:Temporary stream gauging to determine flow regime
• Water Quality Assessment


  1. Desktop Study: use of existing information, environmental protection agencies, routine monitoring, bathing waters and surface waters used for extraction

  2. Field Study: survey of river, biological or fisheries surveys, groups of freshwater organisms as indicators of given pollutants, biological monitoring methods
• Typical sources of Information and Data for Surface Water

  • River engineering/ manipulation
  • Development on river floodplains
  • Reservoirs and Dams
  • Drainage Schemes
  • Water abstraction
  • Sewage treatment
  • River crossing
• Indirect source of impact on water

  • Roads
  • Urban and Commercial Development
  • Industrial development
  • Landfill
  • Forestry and deforestation
  • Industry agriculture
• Impact Assessment


  • Detailed evaluation of the environmental and social impacts of the planned project and identified alternatives
  • Include qualitative descriptions such as measuring high or low impact and quantitative descriptions such as indicating cubic meters of water withdrawn
  • Done to allow comparisons
  • It is indispensable in order to provide systematic and detailed descriptions of the probable impacts
• Mitigation


  • Minimizing or avoiding the described impacts
  • Mitigation measures are a response to the findings of impact assessment
  • Key focus should be on : preventive measures to avoid occurrence of impacts, measures to limit the severity and duration of the impacts, and compensation mechanisms for those impacts that are unavoidable
  • Mitigation measures are a critical part of the EIA process as these actions aim to prevent adverse impacts from the planned project
• Why conduct IA&M?


  To identify and understand and then prevent or minimize the adverse impacts of the planned project
• Key Contributions of Impacts assessment and mitigation to a good EIA

  • Provides a clear and itemized list of relevant impacts on the environment and the people
  • Detailed list of mitigation actions is identified
  • Impacts and related mitigation actions are evaluated and identified according to the key environmental, social, and cultural characteristics of the area where the project will be implemented
• Methodological Approaches to Impact assessment

  • Expert judgement
  • Quantitative physical and mathematical models
  • Cumulative impact assessment
  • Matrices and interaction diagrams
  • Rapid impact assessment matrix (RIAM)
  • Battelle Environmental Evaluation System
• Mitigation actions to address impacts

  • Development of alternatives to a proposed project
  • Specific mitigation actions are described in project alternatives
  • Examples: technological process to eliminate organic effluents, replanting of vegetation on slopes, building additional protection to limit noise, training people for new kinds of jobs
• Guidelines for devising mitigation actions

  • Identify the mitigation actions that most reduce the impacts
  • Identify mitigation actions that reduce the severity of impacts to the lowest possible level
  • Include activities designed to monitor compliance with agreements established in the assessment
  • Identify potential risks of accidents
• Mitigation Hierarchy


  • Widely accepted approach for environmental conservation
  • Set of prioritized steps to limit negative impacts as far as possible through avoidance, mitigation, restoration, and offsetting
• Leopold Matrix


  • Rows cover the key aspects of the environment and society
  • Columns list the project's activities during all stages of the project
  • Upper left-hand corner of the box indicate the magnitude of the specific action's impact, lower right-hand corner indicate the importance of the impact to the project (rated 1-10, negative indicates negative impact or damages)
  • Result of leopold matrix is the project impact value (PIV)
• Key steps for conducting impact assessment and related mitigation

  • Perform a detailed assessment of impacts of all project phases on the environment, socioeconomic systems, and other areas
  • Conduct an assessment of cumulative impacts
  • Compile similar impacts into groups to make the impact analyses easier to understand
  • Identify mitigation actions to eliminate the identified impacts
  • Identify specific mitigation measures to reduce cumulative impacts