Application of Tracers in Arid Zone Hydrology (Proceedings of the Vienna Symposium,
August 1994). IAHS Publ. no. 232, 1995.
183
Aquifer definition: specific (by water properties) or
generalized (by stratigraphie or geographic terms),
examples from Israel
EMANUEL MAZOR
Department of Environmental Sciences and Energy Research, Weizmann Institute of
Science, Rehovot 76100, Israel
Abstract The study and management of groundwaters necessitates proper
identification of the involved aquifers. The aquifer definition implies
groundwater through-flow, to maintain recharge and discharge and to
sustain wells. Thus, all parts of an aquifer have to be hydraulically interconnected, a property that causes a substantial degree of homogenization
of the properties of the water hosted in each aquifer, providing the means
to delineate specific aquifers. Aquifers are often defined by stratigraphie
terms, but these are: (a) thick, constituting a multitude of aquifers that
are separated by aquicludes; and (b) extend over large regions, with topographic and geological barriers. Thus, the stratigraphie terms are misleading when applied to define aquifers. Aquifers are also defined by
geographic terms, pertaining to large regions, built of sequences of
permeable and impermeable rocks, divided by geological barriers and
often crossed by karstic fast flowing systems. Thus, the geographical
terms are misleading as well. These principles are discussed in light of
chemical and geological data obtained from 370 wells drilled all over
Israel.
SCOPE OF THE PROBLEM
Aquifer, the basic term of hydrology, has a countless number of definitions and applications, and as a result the term is esoteric. A basic definition, probably accepted by most
hydrologists is: "a body of a permeable rock that contains water in all its pores and can
sustain producing wells". But how can this simple and clear definition be applied in real
field work, how can an aquifer be identified, and how can its boundaries be established?
A common approach to the problem is to allocate an aquifer to every stratigraphie
unit, and a second common approach is to define an aquifer by a geographic term. However, the stratigraphie and geographic terms apply to rock sequences that contain
alternations of permeable and impermeable rocks that constitute an assemblage of
separated aquifers. Furthermore, these terms disregard structural barriers and lateral
facies changes that can divide stratigraphie and geographic units into hydraulically
disconnected aquifers. These points are discussed in more detail later on.
Groundwater flow and travel time equations are applicable only in the domain of a
single aquifer, and if erroneously applied to data from wells that are drilled into
separated aquifers, meaningless velocity and travel time are obtained (Mazor & Nativ,
184
Emanuel Mazor
1992). Therefore, the proper definition and identification of aquifers is crucial in hydrology. The present communication addresses this topic, advocating a specific aquifer
definition, based on the groundwater properties, coupled with the local geology and
water heads.
THROUGH-FLOW AND STAGNANT AQUIFERS
The definition of an aquifer as a permeable rock unit (commonly in the shape of a bed
or a lens) that contains water in all its pores and can sustain productive wells, leaves
room for two basic aquifer types - through-flow and stagnant (Mazor, 1993; 1994;
Mazor & Nativ, 1992; 1994). The term through-flow aquifer is suggested for aquifers
with groundwater through-flow, and hence, with active recharge and active discharge.
The common example of a through-flow aquifer is a phreatic aquifer that has recharge
over all its area: water flows through it, and it is drained to a base of drainage, e.g. a
sea or a lake ("a" in Fig. 1). A less common example is that of a through-flow confined
aquifer, consisting of a tilted permeable rock bed that outcrops at one end and is
hydraulically sealed by overlying impermeable rocks in its buried section. The outcrop
section functions as a recharge intake zone and the lower end is hydraulically connected
to a base of drainage and functions as a discharge zone.
The term stagnant aquifer is suggested for aquifers with no through-flow, i.e. aquitraps (stagnant confined aquifers, "c" in Fig. 1), and stagnant aquifers (groundwater
traps), that originated from through-flow aquifers that were buried in subsiding basins,
rift valleys and other structural combinations ("d" in Fig. 1). Many artesian systems are
suggested to be stagnant aquifers (water traps), their pressure originating from
compaction by the overlying rocks (Mazor, 1993). Stagnant aquifers have originally
been of the through-flow type and constitute fossil aquifers.
THE HYDRAULIC INTERCONNECTION REQUIREMENT AND
HOMOGENEITY OF WATER PROPERTIES FN AN AQUIFER
The through-flow property implies that in a through-flow aquifer all parts are hydraulically interconnected, a property that is also maintained in fossil stagnant aquifers, as
Fig. 1 (a) Phreatic through-flow aquifer; (b) through-flow confined (artesian) aquifer;
(c) aquitrap (stagnant confined aquifer); and (d) stagnant aquifer (groundwater trap).
Dashed lines show local water table. Well I has to be pumped, wells II, III, and IV are
self-flowing.
Aquifer definition: specific or generalized, examples from Israel
185
demonstrated by their ability to sustain high-yielding wells. The hydraulic interconnection of all parts of an aquifer is an intrinsic property, and should be included in
the aquifer definition.
The through-flow process and the aquifer hydraulic interconnection requirement
imply that water properties in an aquifer are homogenized. Hence, adjacent wells with
nearly the same pressure, temperature, isotopic composition, concentration of age indicators and concentration of dissolved ions (further discussed in the following section)
are likely to tap the same aquifer. In contrast, wells significantly differing in their water
properties belong to separate aquifers (Mazor et al., 1992). Hydraulic barriers separating aquifers are commonly incorporated in the familiar term aquiclude, defined as
a rock body (commonly bedded) with low permeability. The aquiclude definition allows
possible leakage between aquifers. The term hydraulic discontinuity is suggested for
cases of a hydraulic barrier that completely separates different aquifers (mostly stagnant)
for long periods, i.e. 104 to 108 years (Mazor & Bosch, 1992).
The properties of the water encountered in adjacent wells thus provides the means
to identify aquifers and to delineate their lateral and vertical extension (the resolution is
defined by the density of accessible wells and by their depth distribution).
THE CHEMICAL UNDERSATURATION ARGUMENT AND WATER
HOMOGENEITY IN AN AQUIFER
Differences between the chemical composition of water in wells that have been suggested to tap the same aquifer are occasionally explained by (a) heterogeneity of the host
aquifer rocks; and (b) longer times of water-rock contact in the suggested down-flow
direction. Let us examine these explanations for CI and S0 4 concentrations in fresh
groundwater. Halite is the only available mineral in aquifer rocks that can contribute CI,
and its saturation concentration is >200 000 mg CI l"1. Saturation is reached in a few
days, and hence, every groundwater has the chance to reach saturation if NaCl is present
in the rocks of the relevant aquifer. Or, vice versa, undersaturation with regards to halite
indicates that halite is absent from the aquifer rocks. Similarly, gypsum (along with
anhydrite) is the only source of S0 4 in common aquifer rocks. Its saturation concentration is > 1800 mg S0 4 1" 1 , and saturation is reached in a few months. Hence, for all
practical purposes every groundwater has a chance to reach equilibrium with gypsum,
provided this mineral exists in the aquifer rock assemblage, and undersaturation with
regards to gypsum indicates this mineral is absent from the aquifer host rocks. Mixing
of halite saturated water or gypsum saturated water with fresh water may produce undersaturated groundwater, but in this case one no longer deals with a single aquifer, but
with a complex setup. Mixing is identifiable by seasonal composition changes or
"contradicting compositions", e.g. high tritium and low carbon-14, or H2S together with
free 0 2 (Mazor, 1985). In any case, every well and spring has to be checked for possible
mixing (natural, or as an artifact caused by short circuiting within a well). Interpretation
of groundwater properties can be meaningful only for single water types and not for
mixtures.
Most groundwaters are distinctly undersaturated with respect to halite and gypsum
and hence: (a) the respective ions originate from outside the aquifer rock system, i.e.
they are brought in with the recharge water; and therefore (b) groundwater in an aquifer
186
Emanuel Mazor
with distinct lateral through-flow is expected to have a uniform concentration of CI and
S0 4 ; and (c) significant differences in the CI and S0 4 concentrations in adjacent wells
indicate these wells tap different distinct aquifers.
ATMOSPHERIC IONS AS AQUIFER MARKERS
The abundance ratios of CI to Br, Na and Mg in groundwaters often reveal the marine
value and occasionally so also do S0 4 and K, as demonstrated in Fig. 2 for a large range
of groundwater salinities in a case study in Western Australia (Mazor & George, 1992).
An atmospheric (sea-derived, airborne) origin is postulated in such cases. Involvement
of seawater left from a former transgression can in many cases be ruled out on grounds
of (a) ion concentrations that are distinctly below seawater concentration; and (b) the
extended continental history of a studied region.
Ions that deviate from the marine relative abundance reveal the importance of water
interaction with aquifer rocks, e.g. enrichments of Ca and HC0 3 , due to C0 2 induced
calcite dissolution, depletion or gains of Ca, Mg, K and Na as a result of ion exchange,
etc.
The concentration of the atmospheric ions in groundwater is determined by the prerecharge history, i.e. the concentration in the precipitation and in dust fallout and, most
important, the extent of water loss by évapotranspiration (Mazor & George, 1992). The
atmospheric ions and the ions added by water-rock interactions provide good markers
for aquifers that are recharged at different localities and are composed of different rock
assemblages (Mazor etal., 1992).
The bottom line of this section is that distinct differences in ionic compositions of
groundwater in adjacent wells most likely do not stem from rock heterogeneity in a
single aquifer, or the down-flow increase in time of water-rock contact. Instead, significant differences in groundwater composition indicate the existence of different aquifers.
SPECIFIC AQUIFER DEFINITION
The term aquifer is a hydrological term that warrants precise specification in each case
study, including: (a) water properties (heads, temperature, dissolved ions and gases,
isotopic composition, age, arrival of pollutants); (b) the location and spatial extent; (c)
the geological set up (lithology, stratigraphie unit, sedimentary structure, inclination,
tectonic structure); (d) aquifer properties computed from pumping tests; and (e) deduced
nature of the aquifer (phreatic or confined, through-flow or stagnant).
STRATIGRAPHIC AQUIFER DEFINITION
Specific aquifer definitions of the type described in the pervious section are rare in the
hydrological literature. Instead, defining aquifers as coinciding with stratigraphie units
is a common practice, examples are: "Judean Group aquifer" (Israel); "Dogger carbo-
Aquifer definition: specific or generalized, examples from Israel
187
1200
800
S
10
20
3 0
400
3 0
600
?
B
400 -
3 0
3 0
ci
g/i
Fig. 2 Composition diagrams of shallow wells in a study area at Merredin, the Wheatbelt, Western Australia (Mazor & George, 1992). The differences in the ion concentrations are attributed to different évapotranspiration efficiencies prior to infiltration of the
local recharge, and the linear correlation lines observed for Br, Na, Mg, K and S0 4 are
thus évapotranspiration lines. The marine value (triangle) falls on the évapotranspiration
lines, indicating CI, Br, Na, Mg, K and S0 4 are of atmospheric origin (sea-derived,
airborne).
nateaquifer" and "Chamony aquifer" (France); "Oligocèneaquifer" (Poland); "Floridan
Limestone aquifer", "Carrizo Sandstone aquifer", "Madison Limestone aquifer", or
"Dakota Sandstone aquifer" (USA); "Murray Group aquifer", "Gambier unconfined
aquifer" and "Dilwin confined aquifer" (Australia).
The self-contradicting nature of the stratigraphie aquifer definition stems from the
following features:
(a) The stratigraphie units have often thicknesses of hundreds of metres, encompassing
alternations of permeable and impermeable rock beds, constituting potential aquifers
and aquicludes. Thus, the stratigraphie unit includes a poorly defined array of many
aquifers.
(b) The basic requirement of hydraulic interconnection of all parts of an aquifer is
violated in the stratigraphically defined aquifer terminology, as in it many aquifers
that are separated by aquicludes are lumped together.
(c) By lumping together many aquifers their characteristics are lost, e.g. phreatic,
confined, through-flow, stagnant and so on.
(d) Most stratigraphie units have a large scale distribution and occur in regions that are
certainly hydrologically disconnected, e.g. in mountains separated by valleys. Thus,
the geographical singularity of an aquifer is lost with the stratigraphie aquifer definition.
(e) The concept of the aquifer as a duct through which groundwater flows, or a vessel
in which groundwater is stored, is lost with the ambiguous stratigraphie aquifer
terminology that puts together different aquifers, often composed of continental
rocks that occur in lens structures.
The consequences of the mis-definition of aquifers via stratigraphie terms are far
reaching, as will be shown later on. But first let us have a closer look at the stratigraphie
aquifer terminology in one country — Israel.
Emanuel
188
Mazor
RANGES OF DISSOLVED ION CONCENTRATIONS IN WATERS
ENCOUNTERED IN STRATIGRAPHIC AQUIFER UNITS, EXAMPLES
FROM ISRAEL
A valuable collection of groundwater analyses, well representing the various stratigraphic aquifer terms in use in Israel, is provided by two extensive surveys dedicated
to trace element concentrations, but providing also the major ion chemistry (Arad et al.,
1984; Halicz et al., 1991). Altogether over 370 different wells were sampled in the two
surveys, providing a good cover of the country with samples of groundwater encountered in a variety of stratigraphie units (Fig. 3). A number of wells were included in both
surveys, and a high correlation is seen between the analyses of samples collected in the
1984 survey and the 1991 survey (Fig. 4), indicating that: (a) the analytical reproducibility was good; and (b) that the water composition in the wells did not change significantly over the span of 7 years of repeated sampling. Thus, the major ions data reflect
intrinsic properties of the involved aquifers.
Range diagrams of major ion concentrations observed for the various stratigraphie
o ou
X
Kurkar group
Quaternary aquifer
0
Hazeva & Graben Fill
Tertiary-Quaternary aquifers
°
Basaltic
Tertiary-Quaternary aquifer
"+ Avedat group
Eocene aquifer
A
°
J u d e a group
Upper Cretaceous aquifer
Kurnub group
Nubian sandstone L. Cretaceous aquifer
n
Arad group
Jurassic aquifer
•1 0 0
-1 50
50
100
150
200
250
Fig. 3 Location of discussed wells and the stratigraphie units deduced to produce them,
Israel (data from Arad et al., 1984, and Halicz et al., 1991). Examples of geographic
aquifer terms: C — coastal plain aquifer; T — Taninim aquifer; Y — Yarkon aquifer;
B — Beer Sheva aquifer.
Aquifer definition: specific or generalized, examples from Israel
1500
4UO-
•*
» 300-
1000-
S
«
189
•
=5
M
a 20O-
«
500"
u
MOO
1500
400
I
'
1
'
1
'
100 200 300 400
•
##
600
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•
30-
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Ca mg/1 91
Na mg/1 91
200
^
'
.
• •
•
90n
=5
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a 60-1
V
100-
o500
•*
00
60
90
120
Mg mg/1 91
0 200 400 600 8001000
CI mg/191
SO4 mg/191
Fig. 4 Comparison of repeated chemical analyses in samples collected in the 1984 and
1991 surveys (datafromAradeJa/., 1984, andHalicze/a/., 1991). The observed high
correlation indicates a good analytical reproducibility and stability of the natural systems
over the studied 7 year interval.
aquifer units are given in Fig. 5, and fingerprint diagrams of the dissolved ions in water
samples from the different lithostratigraphic units are given in Fig. 6. The following
patterns warrant discussion: (a) all the stratigraphie aquifer units reveal wide ranges of
ion concentrations, stretching over orders of magnitude, indicating that the stratigraphie
units lump together an enormous variety of distinct aquifers; (b) the ion concentrations
of the different stratigraphie aquifer units overlap, i.e. they are indistinguishable; and
(c) the relative ion abundances differ remarkably in each lithostratigraphic unit (Fig. 6).
These patterns lead to the inevitable conclusion that the lithostratigraphic units are
meaningless as hydrological terms defining aquifers. The concentration of the dissolved
ions is determined by local conditions, e.g. salinity of local recharge (determined by
extent of the local évapotranspiration) and the nature of the rocks in a specific aquifer,
and have nothing to do with lithostratigraphy.
A glimpse at the geological map of Israel reveals right away that patches of the
stratigraphie units are separated by the erosion relief and can in no way constitute
continuous aquifers. For example, the Judea Group aquifers in Galilee, the Carmel
Mountains, the Jerusalem Mountains and theNegev are hydraulically disconnected. Yet,
in the local hydrological jargon the term "Judea Group aquifer" is used extensively.
GEOGRAPHIC AQUIFER DEFINITIONS AND GROUNDWATER
COMPOSITION RANGES, EXAMPLES FROM ISRAEL
The data of the groundwater surveys reported by Arad et al. (1984) and Halicz et
û/.(1991) are useful to discuss the validity of geographic aquifer terms that are in
common usage in Israel.
Emanuel
190
Mazor
The term coastal aquifer is applied to the Mediterranean coastal plain, 120 km long
and about 15 km wide (Fig. 3). The term gives the impression that there exists one large
aquifer, and it was handled in this way in several mathematical models. Yet this area,
built of the up to 120 m thick Kurkar Group, is geologically heterogeneous. The coastal
plain is composed of continental cemented sandstone (locally called kurkar), alternating
with fossil red soil (locally called hamra), and close to the sea shore the kurkar is
interbedded with layers and lenses of marine clay. The Kurkar Group is underlain by
impermeable and permeable rocks of older formations and in the eastern foothills it is
in contact with other water bearing formations. Rain falls over the entire coastal plain
and local recharge is important and contributes to the diversity of this groundwater
system. Thus, a multitude of distinct aquifers is expected to exist in the Kurkar Group
section of the coastal plain, based on geological, lithological and hydraulic considerations. This is verified by the chemical data, represented in range diagrams in Fig. 7. The
concentration of the major ions is seen to vary in the coastal plain over one to two orders
of magnitude. The relative ionic abundances vary enormously, as seen for the Kurkar
Group samples, all collected within the coastal plain (Fig. 6). So far for current wells
in the Kurkar Group section of the coastal plain; deeper wells, which are to be more
frequent in future water exploitation, will certainly reveal additional aquifers, further
.nut»»»urn o
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Fig. 5 Range diagrams of major ion concentrations observed for the various stratigraphic aquifer units in Israel (data from Arad et al., 1984, and Halicz et al., 1991).
The concentrations vary within the wide range of one to two orders of magnitude, indicating that different, non-related, aquifers have been lumped together under the lithostratigraphic terms.
Aquifer definition: specific or generalized, examples from Israel
Hazeva
Kurkar
Mg
Ca
Na
191
Q
SO4
Mg
Ca
Na
Cl
SO4
Avedat
Basaltic
îoooor
1000ft
Mg
Ca
Na
Cl SO4
Mg
Judea
Ca
Na
Cl SO4
Kurnub
10000;
Mg
Ca
Na
Cl SO4
Mg
Ca
Na
Cl SO4
Fig. 6 Fingerprint diagrams of main stratigraphie aquifer units (data from Arad et al.,
1984, and Halicz et al., 1991). An enormous variety in relative ion abundances and
concentrations is observable, revealing that the lithostratigraphic units are meaningless
as hydrological terms defining aquifers.
emptying the term coastal aquifer from any meaning.
The term Yarkon aquifer is in extensive use, pertaining to groundwater in the
western flank of the Judean Mountains and the foothills, including the spring complex
of Rosh Ha'ayin, that until recent years supplied much of the water of the Yarkon River
(hence the source of this geographical aquifer term). This terrain (Fig. 3) is extremely
heterogeneous, the rocks building it belonging to several major lithostratigraphic units,
including the Kurnub Group, the Judea Group and the Mount Scopus Group. Thus, a
logical inconsistency is revealed: how can the Yarkon aquifer be defined as one
hydraulic unit, if it is composed of different lithostratigraphic aquifers? Furthermore,
the terrain is rich in karstic features, the Rosh Ha'ayin spring complex being a major
example. Thus, the terrain falling under the Yarkon aquifer term incorporates a variety
of permeable and impermeable rock beds, disconnected by structural features, and
crossed by fossil and active karstic systems, hosting different water types, differing over
a wide range of their dissolved ions (Fig. 7), range of isotopic compositions and water
ages (Kroitoru et al., 1985; Mazor & Kroitoru, 1990).
The term Taninim aquifer is much in use, pertaining to the western half of the
Emanuel
192
o
ooacŒoooooD Coastal p l a n e
+
1
0 0
4f
'
ISB m
m B e e r - S h e va
10
Kmg/1
100
mms
'
Yarkon
BB • • m Beer - Sheva
l
10
Mgmg/1
COOO
'
'
'
' ' ' "1
100
Ca mg/1
1000
n
1
100
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00
Taninim
A AM A
a ca B e e r - S h e v a
' ' ' "1
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'
A
M
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0
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Yarkon
txxooMjaoD © C o a s t a l p l a n e
•
œom am COOŒOO 0 C o a s t a l p l a n e
Taninim
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m mm m m
.
i-i
i i i ii!
10
1
B
1
i
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100
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1000
i
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A
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1000
H C O 3 mg/1
1
10
n
100
S04mg/1
mm
g e e r . Sheva
1000
oDooGooQBosxis Coastal plane
+ + Taninim
A A M A Yarkon
HDH _
10
100
• o Beer - Sheva
1000
CI mg/1
10000
Fig. 7 Range of ion concentrations in geographic aquifer units applied in Israel. Concentrations of the major ions are seen to vary in each geographic aquifer unit over a
range of one order ofmagnitude (data from Aradef al., 1984, andHaliczer ah, 1991).
Shomron Mountains and connected to the coastal plain in the terrain of the Taninim
River, that is fed by a spring complex (Fig. 3). This is another geographic region built
of a variety of rocks belonging to different lithostratigraphic units and crossed by karstic
flow paths.
The term Beer Sheva aquifer is used for the groundwater encountered in the Beer
Sheva Valley and the slopes of the surrounding mountains (Fig. 3). Groundwater is
exploited from wells several hundreds of metres deep, and encountered in different lithostratigraphic units. Precipitation is low, and most of the groundwater in ancient (Mazor
& Kroitoru, 1992).
Hydrological modellers suggest that the three geographically defined aquifers of
Aquifer definition: specific or generalized, examples from Israel
193
Beer Sheva, Yarkon and Taninim are hydraulically interconnected, and constitute one
aquifer. Arguments for the lack of such hydraulic interconnections have been raised by
Mazor & Kroitoru (1992).
The application of geographic terms to define aquifers is hydrologically meaningless, as it lumps together a multitude of aquifers, of varying natures and hosted in
different rock units.
MANAGEMENT IMPLICATIONS
Water quality and quantity are the major criteria guiding groundwater management.
Thus the specific aquifer definition, based on groundwater properties, along with geological data, is best geared for management purposes. In contrast, aquifers defined by
stratigraphie or geographic terms are useless as they lump together groundwaters of
different qualities, belonging to different specific aquifers. Optimal groundwater
management necessitates understanding of the exploited systems in terms of the specific
aquifers; exploitation-induced changes in flow directions; formation of short-circuits
between aquifers of different hydraulic or compaction-induced pressures, resulting in
the mixing of high quality groundwaters with low quality groundwaters; and a variety
of other water deteriorating processes.
Remedial measures can be well defined for specific aquifers alone, but are vague
and inefficient if based on stratigraphie or geographic aquifer units.
Stagnant aquifers are buried and isolated and as such they are protected from pollution. Thus, stagnant aquifers hosting high quality water are too valuable to be exploited
for current consumption — they should be equipped for exploitation and put aside for
use in times of need, e.g. following extra heavy droughts or after pollution catastrophes,
including Chernobyl-type accidents.
CONCLUSIONS
(a) Measurements of groundwater properties are essential for the study of groundwater
systems as they provide the means to identify specific aquifers and to delineate the
spatial extent, as well as to define the nature of aquifers as through-flow or stagnant,
and in terms of confinement, entrapment, local recharge and lateral flow and identification of water deterioration processes.
(b) The wide application of stratigraphie aquifer terms is responsible for the absence of
awareness of the plausible existence of stagnant aquifers. Only with the use of
groundwater properties to define specific aquifers did it become clear that the deeper
parts of inland basins host stagnant aquifers, in which water is trapped for the ages
of the subsidence stages that turned each aquifer in its turn into a stagnant system.
(c) Techniques to measure water properties have to be further developed in order to
define specific aquifers better. In this respect further techniques are necessary to
identify pollutants (in through-flow aquifers) and to date very old groundwaters (to
identify stagnant aquifers).
(e) The concepts of through-flow and stagnant aquifers, and the possible distinction
between local recharge and lateral flow, have to be introduced into the domain of
groundwater management.
194
Emanuel
Mazor
REFERENCES
Arad, A., Kafri, U. Halicz, L. & Brenner, I. (1984) Chemical composition of some trace and minor elements in natural
groundwaters in Israel. Geol. Surv. Israel, Report GSI/29/84.
Halicz, L., Kafri, U. & Bein, A. (1991) Trends in chemical composition (major and trace elements) of groundwaters in
Israel, summer 1990. Geol. Surv. Israel, Report GSI/16/91.
Mazor, E. &Kroitoru,L. (1990) Boundary conditions needed for groundwater modeling, derived from isotopicand physical
measurements:Mediterranean-DeadSeatransect.In:.F(/y»/4nrt. Canadian!AmericanConf.
onHydrogeology,443-452.
Alberta Res. Counc. and National Water Well Ass., Dublin, Ohio, USA.
Kroitoru, L., Mazor, E. & Gilad, D. (1985) Hydrological characteristics of the Wadi Kelt and Elisha springs. In: Scientific
Basis for Water ResourcesManagement (Proc. Jerusalem Symp., September, 1985), 207-218. IAHS Publ. no. 153.
Mazor, E. (1985) Mixing in natural and modified groundwater systems: detection and implicationson quality management.
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