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IMPLICATIONS OF HYPOGENIC TRANSVERSE SPELEOGENESIS
5. Some implications of the hypogenic transverse
speleogenesis concept
Despite obvious advances made during the last few
decades, karst and cave science remains of limited
significance and appreciation in such applied fields as
formation of mineral deposits, hydrocarbon prospecting,
groundwater management in artesian basins, mining,
geological engineering, etc. One of the main reasons is that
the predominantly epigenic karst paradigm, and respective
concepts and knowledge of epigenic, unconfined karst,
learned by industry geologists from general geology,
groundwater hydrology and karst textbooks, was
inappropriately and largely unsuccessfully applied to
solving practical problems related to the quite distinct
domain of hypogenic, confined, karst. The conceptual
framework suggested in this book places hypogenic karst
in the systematized context and hierarchical structure of
basinal groundwater flow (in the sense of Tóth, 1999), and
highlights the powerful role of speleogenesis in the
organization of regional flow systems, a consequence of its
unique capacity to dramatically alter the primary porosity
and permeability of soluble formations. This framework
suggests that karstified zones and their function in basinal
groundwater systems are predictable. The new refined
concept of hypogenic speleogenesis has broad implications
in applied fields and promises to make karst and cave
expertise more highly-valued by practicing
hydrogeologists, mining engineers, and economic geology
and mineral resource industries. A detailed discussion of
all possible implications is far beyond the scope of this
book, but below are a few particularly instructive examples
and references given to illustrate the above contentions.
5.1 Variability in aquifer characteristics and
behavior resulting from unconfined
and confined speleogenesis
The specific mechanisms of ascending hypogene
speleogenesis, discussed in Chapter 3, are responsible for
the peculiar features of conduit porosity that develop in
soluble formations under confined settings. This gives rise
to characteristic distinctions between karst systems that
develop in unconfined and confined karst aquifers.
Huntoon (2000) provided an illustrative comparison of
features found in unconfined and confined aquifers in
Arizona, USA. The summary that follows is based on the
discussions in previous sections (see also Klimchouk,
2003a) and the cited work of Huntoon.
Caves formed in unconfined settings tend to form
highly localized linear or dendritic systems that account for
high heterogeneity and extreme anisotropy of unconfined
karst permeability. They receive more or less concentrated
recharge from the immediately overlying or adjacent areas,
with which they have genetic relations. Conduit systems
are hierarchically organized to effectively concentrate and
laterally transmit flow (and hence contaminants) in the
downgradient direction. This organization is frequently
cited to be similar to surface water drainage networks.
Storage is commonly low in karst aquifers that evolved in
unconfined settings, but almost all flow takes place
through conduit systems (Worthington et al., 2000).
System responses to major storm events are characterized
by flow-through hydraulics. Spring discharge from
unconfined conduit systems tends to be flashy and highly
variable.
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