Identifying and Evaluating Impacts - Mining and the Environment: From Ore to Metal - page 418

Network and l owchart analysis is a holistic approach to impact assessment, clearly illus-
trating the multiple and often complicated nature of project impacts, and their pathways.
Unlike simpler forms of analysis, indirect impacts and impact interactions are identii ed using
network and l owchart analysis. Processes that need further studies can also be identii ed.
Developing a network or l owchart analysis follows a series of individual steps: listing of
all project activities; identifying environmental components and sensitive receptors; identi-
fying primary impacts and 'knock on' effects; identifying impact interactions; and selecting
either a network or l owchart approach depending on the nature of the assessment. A simple
network may be appropriate at the scoping stage or when assessing project alternatives.
Large-scale mining operations affect a number of different ecosystems, and separate
analyses for each ecosystem may become practical. Similarly, separate network and l ow-
chart analyses may be established for various phases in the life of the mine.

Spatial Analysis

Overlay mapping, preferably done by Geographic Information Systems (GIS), assists in
identifying the geographic extent of impacts, and can assist in identifying where cumula-
tive impacts and impact interactions may occur. Overlay mapping is best suited for identi-
fying physical/chemical impacts and their geographical extent. Overlay mapping involves
preparing maps or layers of information which are then superimposed on one another.
Overlay techniques can provide a composite picture of the baseline environment, identify-
ing sensitive areas or resources. They help to illustrate the inl uences of past, present, and
future activities on a project or receiving environment.
Manual overlay mapping uses a series of transparent maps, each depicting a specii c data
set. When superimposed over other maps, the areas of overlapping information are high-
lighted. These are areas where impacts may potentially take place.
A GIS is a computerized spatial information system with a range of applications that
extend well beyond the simple overlaying of information. Map production, however,
remains one of the core strengths of any GIS. Spatial data are transformed in layers of infor-
mation representing different environmental resources (such as watersheds or soil distribu-
tion) or impact distributions (such as simulated ground concentrations caused by project
emissions). A GIS allows information to be easily overlaid, and as with manual overlay
techniques, areas of potential cumulative impacts or impact interactions are identii ed.
Both manual and GIS overlay mapping provide valuable visual aids, and greatly assist
in identifying where impacts may occur ( Figure 9.9 ). Manually prepared maps or over-
lays are generally relatively inexpensive and quick to compile, but there are some restric-
tions on what can be represented manually with ease and accuracy. A GIS can be regarded
as the high-tech equivalent of the manual overlay mapping method, which allows for the
rapid construction of multi-layered electronic maps. A GIS is a spatial analysis system that
allows the systematic compilation of a wide range of environmental data which can then
be selected according a particular need. A GIS is particularly useful in dealing with large
impact areas, as is the case for most mining projects.
A GIS can replace manual mapping in most applications. Because hard copy maps are
static and inl exible, they are difi cult and expensive to keep up-to-date. A GIS has much
greater l exibility, and hard copy maps can be produced from the electronic database to
meet the needs of the user. Once a site-specii c GIS has been prepared, additional informa-
tion can be added as and when necessary. Impacts can therefore be combined in an addi-
tive way. The main advantage of a GIS, however, is its modelling capability, allowing data
to be analyzed using spatial modelling techniques.

Overlay techniques can provide a
composite picture of the baseline
environment, identifying sensitive
areas or resources.