Geoenvironment Management and Sustainability - Sustainable Practices in Geoenvironmental Engineering - page 15

stressor sources delivering stressors can be elements from the atmosphere, anthrosphere,
biosphere and hydrosphere, and stressors generated in the individual ecospheres by
actions originating in the anthroposphere.
1.3.3.1 Natural Stressor Sources and Stressors
The two categories of stressor sources are natural and anthropogenic , as illustrated in Table
1.1. It is not often easy to distinguish between natural geoenvironment stressor sources
and those associated with or related to human activities and products. Well-deined nat-
ural events that readily classify as natural geoenvironment stressor sources generally
fall under the category of natural disasters or geo-disasters . (The subject of geo-disasters is
covered in Chapter 12.) These include such events as hurricanes, earthquakes, tsunamis,
tornadoes, volcanic eruptions, rainstorms, and blizzards—generating various types of
stressors and stresses in a land or soil mass. For example, earthquakes generate dynamic
forces, e.g., seismic force, to a soil mass through two types of body waves—primary or P
waves and secondary or S waves.
Volcanic eruption and forest ires are also classiied as typical natural disasters that will
generate various types of stressors. They cover land surface with ejecta and ashes, apply
extreme high temperature or heat, and chemical components constituting ejecta and ashes
to land surfaces that will migrate into soil and underground water through percolating
rainwater. Since such heat and chemical compounds are deined as stressors, volcanic
eruption, and forest ires can be classed as stressor sources.
Landslides and loods, which are often classiied as natural disasters, can be classi-
ied as geoenvironment stressor sources. They are disasters that result from situational
vulnerability to provocative events such as earthquakes and rainstorms. Landslides and
loods can also occur in instances where human activities have created vulnerable cir-
cumstances. Deforestation of slopes could make them more susceptible to landslides,
and harvesting of groundwater in low-lying coastal regions can lower ground surfaces
to levels that invite looding. Since landslides and loods transport various matter, such
as soil components and relevant chemicals to downstream areas, these can be classi-
ied as sources responsible for generating such stressors as chemical elements, in the
geoenvironment.
Cyclical events such as regular temperature (cold-hot) cycles and nonregular wetting-
drying cycles that fall under the category as natural events do not normally classify as
natural disasters. Regular cyclical events are events such as winter-summer cycles, and
nonregular events are wetting-drying events where repeat cycles do not adhere to any
time-calendar schedule. In the case of subzero temperatures that accompany winter sea-
sons, for example, under the right conditions, ground uplift due to frost heaving can occur,
thus resulting in considerable damage to overlying structures. The stressor source is sub-
zero freezing temperatures (winter), and the geoenvironment stressors associated with
this stressor source are thermal in nature. In the case of wetting-drying events involving
extreme cases of deluge and drought, the deluge could result in severe looding whereas
the drought event could lead to parched-earth conditions. The types of stressors generated
in the affected include thermal, hydraulic, chemical, and mechanical.
1.3.3.2 Anthropogenic Stressor Sources and Stressors
Anthropogenic geoenvironment stressor sources include (a) various industries such as
mining, agro, manufacturing and processing, and industries associated with all facets