Geoenvironment Management and Sustainability - Sustainable Practices in Geoenvironmental Engineering - page 19

1.4.1 Impacts on Land Mass and Soil
The impacts resulting from the various activities of humans take several forms depending
on the types of stressors involved. As noted in Section 1.3.3, the stressors could be mechan-
ical in nature or hydraulic, thermal, chemical, physicochemical, electrical, gaseous, and/
or radioactive. Mechanical stressors generate physical stresses resulting in movement of
land masses or pieces of a particular mass—leading to a degradation of its functionality
and perhaps to an ultimate consequence of instability of the land mass, or failure of that
particular unit of mass, i.e., a particular unit of soil mass. We pay particular attention to
a unit of soil mass since this constitutes the basic building block of a land mass. Since the
collective status of individual soil mass units deines the overall status of a particular land
mass, it would be useful to pay attention to the “health” of a soil. In engineering terms, we
can evaluate or categorize soil health in terms of is functionality.
1.4.1.1 Soil Functionality and Indicators
We deine the functionality of a soil (i.e., soil functionality ) as its capability to perform the
various functions demanded of it, in accord with the status of the soil. For example, a
major role of soil is its capability as a plant growth medium . Loss of functionality is evident
when the soil fails to yield the kinds of crops harvested in previous years. In the case of
soils required to support overlying loads, loss of support capability means diminished
functionality. The key to an understanding of how stressors impact on a piece of land mass
is to determine the functional state of a unit of soil mass in the land mass. The use of soil
functionality indices ( SFI ) proposed by Yong et al. (2012) is a means not only to quantify
the functionality of a soil but also is a means to determine if the soil is no longer capable of
meeting its planned/designed function.
The concept of using soil functionality—i.e., soil functional capability—to denote the
ability of a soil or a site to function according to design or service requirements is a novel
concept, in that it addresses the performance aspects of a speciic piece of soil or a soil
mass. In most cases, the soil attributes used in assessment of soil functionality include
(a) properties and characteristics of the particular soil under consideration and (b) perform-
ance requirements of the soil to meet design or service speciications over the short and
long-term (periods). To determine soil functional capability—i.e., soil functionality—one
needs to use soil functionality index ( SFI ) as an assessment tool. To appreciate how the SFI
can be usefully utilized as a tool in assessment of soil functional capability (a) over the
long term or (b) in relation to stresses generated by soil environment stressors, one needs
to specify soil functionality indicators. These indicators constitute the parameters for
computing soil functionality—using, for example, single-parameter analysis, dimensional
analysis, multivariant analytical techniques, risk-based analysis, fuzzy logic, or lumped-
parameter analysis. Figure 1.7 shows a graphic representation of how SFI might change
with time under stressor impacts.
Indicators that are used or encountered in everyday events and situations include such
common sensory ones as aural, visual, scent, and sensation. In vehicular trafic situations,
for example, green lights at cross-roads indicate that one has the right of way, and red
lights indicate that one should stop at the intersection. Indicators can (a) inform one of the
status or nature of the situation at hand and (b) provide guidance or insight into the per-
formance of a system or even a particular piece of equipment. In soil science, agriculture,
and the earth environment, indicators are often used in soil quality and soil functionality
assessments, with particular interest to soil health in relation to agricultural productivity,