Environmental Engineering Reference
In-Depth Information
9.2 Indicators
The general understanding of sustainability of a natural capital of the land environment
can be stated as follows: “To ensure that each natural capital maintains its full and uncom-
promised functioning capability without loss of growth or replenishment potential.” Clear
baseline values for the various components that constitute the land environment natural
capital are needed to deine or establish sustainability requirements of the natural capital
in quantitative terms. Since absolute sustainability is not always attainable, the use of indi-
cators is a means to establish benchmarks or targets that point the way toward sustainabil-
ity of speciic components of the natural capital and of the natural capital itself.
9.2.1 Nature of Indicators
Section 1.4 in Chapter 1 has discussed, very briely, the nature of indicators. They are essen-
tially “signs” or “markers” used daily by ordinary people and also by professionals. The
example cited earlier of vehicular trafic lights at an intersection is a very good example of
one's everyday encounter with indicators. In terms of day-to-day living, personal events such
as prolonged headaches, stomach aches, muscle pain, toothaches, etc., are used as indicators of
some form of health distress and that one should visit one's health-care specialist. Numbers,
statistical information, events, etc., can all be used as indicators. Unemployment rates, gross
domestic product (GDP), and inancial indices such as those used for tracking the ups and
downs of various equities are all indicators of the health of the economy. In a sense, indicators
have been used by humans for as long as there has been human life on the planet.
From the geoenvironmental perspective, the indicators discussed in this chapter are
considered to be markers or benchmarks speciied or prescribed by individuals and/or
organizations interested in tracking: (a) the progress of events, (b) operations and perfor-
mance of systems, (c) the outcome of actions on something speciic, and (d) the status of
a particular set of events, actions, process, activity, and situation—all of which are with
speciic reference to the land environment. Indicators can also be used: (1) for performance
assessment of various systems, processes, actions, etc., and (2) to set goals and/or targets
for operation and performance of systems, processes, activities, etc. The example of the
use of soil functionality indices (
SFIs
) shown in Section 1.4 and Figure 1.7 of Chapter 1 is
a good demonstration of the usefulness of indicators for tracking operations of systems.
There are many varieties and types of indicators that can be used to determine or track the
sustainability of the geoenvironment. For convenience, we can group all of these into two
major groups: (1) system status indicators and (2) material performance indicators. System
status indicators refer to the status of a system—an ecosystem, for example, at any time period.
They are essentially performance indicators. This is because the system status at any one time
period is the result of the performance of the system over the time period under consideration.
In that same sense, material performance indicators are designed to provide information on
the performance of materials at any speciied or required time period—quantitatively or qual-
itatively. Since material properties and characteristics may be functions of system processes,
it follows that material performance indicators are also material properties' indicators. When
the term
indicators
is used, it is understood that this refers to both system status and material
performance indicators. The greatest beneit of status indicators comes when they are used in
relation to some predetermined or deined criterion, target, or objective.
Not all indicators are sustainability indicators. A good example is the measurement of
acid precipitation onto the ground where the sources of SO
x
and NO
x
are known. The acidity
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