Environmental Engineering Reference
In-Depth Information
Introduction
Ecological risk assessment is a process that evaluates the likelihood that adverse
ecological effects may occur or are occurring as a result of exposure to one or
more stressors (USEPA
1998
). Typically, the risk assessment process is used to
systematically evaluate and organise data, information, assumptions, and uncertainties
in order to help understand and predict the relationships between stressors and
ecological effects in a way that is useful for environmental decision making.
An assessment may involve chemical, physical, or biological stressors, and one
stressor or many stressors may be considered.
Accounting for uncertainties is also relevant to a risk assessment. Knowledge of
the uncertainties increases the awareness for decision-makers, and can orientate the
strategy and outcomes of a proposed activity (Geneletti et al.
2003
). In an audit of
environmental impact statements, Wood et al. (
2000
) showed that in only slightly
more than 50 % of cases could the impact assessments be considered accurate.
In New Zealand the
Resource Management Act 1991
is the fundamental legislation
dealing with the management and use of natural resources. At the New Zealand
Environment Court, science-based evidence is used when making judgments about
the reliability of risk assessments (Somerville
2013
).
There are numerous methods available for gathering information to use in
estimating the consequences and likelihoods of environmental risk. Quantitative
methods require empirical data while more qualitative approaches can be based
more on knowledge of the topography and sensitivity of the ecosystems. Although
several defi nitions exist, risk assessment typically encompasses an analysis phase
and risk management and implementation phase (Jones
2001
). The Australian and
New Zealand standard for risk management and related guidelines (AS/NZS ISO
31000:2009, Anon
2009
), and the associated guide for environmental risk management
HB203:2012 (Anon
2012
), provide a framework for assessing risk using a combination
of consequence (or impact) and the likelihood of occurrence of the impact.
During the analysis phase, data are evaluated to determine how exposure to
stressors is likely to occur (characterisation of exposure) and, given this exposure,
the potential and type of ecological effects that can be expected (characterisation of
ecological effects, USEPA
1998
). The fi rst step in analysis is to determine the
strengths and limitations of data on exposure, effects, and ecosystem and receptor
characteristics.
Different environmental conditions and development activities bring different
levels of actual and perceived risks to the environment. Risk to signifi cant habitats
might best be assessed through an understanding of the attributes of the habitat,
such as an understanding of the location, extent, rarity, representativeness and
condition of the habitat type. Where levels of concern are high, effectively addressing
risk is often an exercise that is better accomplished through a range of qualitative
and quantitative approaches. Adopting approaches that empirically model avian
collision risk can provide and inform a structured approach to study design, data
needs and analysis that objectively inform a risk assessment, decisions about the
