geochemical identification of fresh water sources...

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Chemical Geology 21

Geochemical identification of fresh water sources in brackish

groundwater mixtures; the example of Lake Kinneret

(Sea of Galilee), Israel

Ofra Klein-BenDavid*, Haim Gvirtzman1, Amitai Katz1

Institute of Earth Sciences, the Hebrew University of Jerusalem, Givat-Ram, Jerusalem 91904, Israel

Received 14 January 2004; accepted 19 August 2004

Abstract

Fresh waters that dilute brines are considered to have a negligible effect on the ion ratios of the resultant mixture. We show

that the major element composition of the fresh end-member can be deduced from the chemical composition of the mixed

waters. That composition, then, can be used to differentiate between different neighboring carbonate aquifers, which supply the

water. This is demonstrated for the Fuliya and Tabgha saline springs, located on the northwestern shore of Lake Kinneret (Sea of

Galilee), Israel. At these springs, shallow fresh groundwater mixes with brines from deep aquifers. Seven saline springs and

wells located at the Fuliya and Tabgha blocks were sampled over a year, and 32 eastern Galilee fresh springs and wells were

sampled as representatives of the fresh water end-member. All samples were analyzed for major and minor ions. The saline

spring data were used to construct mixing lines, followed by their extrapolation to low concentrations in order to derive the ion/

chloride ratio characterizing the fresh component. We constructed ion/Cl vs. Cl curves; projection of the composition of fresh

water on the calculated curve was used to identify a certain fresh water source as a possible end-member. Results indicate that

the composition of the water feeding the Fuliya springs is different from that at Tabgha, reflecting interactions with different

rocks in each basin. The major fresh water end-member diluting the Fuliya brines is characterized by high Mg/Cl and low Sr/Cl

ratios, and is consistent with the composition of fresh groundwater in the dolomitic Cenomanian and Turonian aquifers widely

exposed in the Fuliya drainage basin. The major fresh water end-member diluting the Tabgha brines, on the other hand, is

characterized by low Mg/Cl and high Sr/Cl ratios, and is consistent with the composition of fresh groundwater in the chalky

Eocene Timrat Fm. and Senonian outcrops. Although the chalky formations in the Tabgha drainage basin are exposed over only

20% of the area they contribute most of the solutes to the fresh water end-member. Rain flows over the chalky formations and

then infiltrates into the Bar-Kokhba Eocene outcrops.

D 2004 Elsevier B.V. All rights reserved.

Keywords: Saline springs; Brine freshwater mixing; End-member; Fuliya; Tabgha

0009-2541/$ - s

doi:10.1016/j.ch

* Correspon

E-mail addr1 Fax: +972

4 (2005) 45–59

ee front matter D 2004 Elsevier B.V. All rights reserved.

emgeo.2004.08.025

ding author: Fax: +972 2 5662581.

esses: [email protected] (O. Klein-BenDavid)8 [email protected] (H. Gvirtzman)8 [email protected] (A. Katz).

2 5662581.

O. Klein-BenDavid et al. / Chemical Geology 214 (2005) 45–5946

1. Introduction

Lake Kinneret is a fresh water lake located within

the Dead Sea Rift (DSR) valley at the northern part of

Israel (Fig. 1). The present (July 2003) average salinity

Fig. 1. (A) locations of springs and wells in the eastern Galilee, the num

located in the lower left corner. One hundred-meter contours are applied. Th

in the Fuliya area. (C) Locations of springs and wells at the Tabgha area.

of the lake is 250mgCl/L, an order of magnitude higher

than the concentration of the Jordan River water and

other surface waters entering the lake (Katz, 2003). The

majority of the salts are contributed from saline springs,

which supply less than 10% of the lake-water, but

bers correspond to the names in Table 4; a general location map is

e lake bathymetry contours are 5 m spaced. (B) Locations of springs

O. Klein-BenDavid et al. / Chemical Geology 214 (2005) 45–59 47

almost 90% of its salts (Simon and Mero, 1992;

Kolodny et al., 1999). Three groups of saline springs

are located on the western shore of the lake: the Tiberias

hot springs whose chloride concentration is around

18,000 mg/L (Mazor and Mero, 1969; Moise et al.,

2000) throughout the year and the Fuliya and Tabgha

springs whose chloride concentrations vary seasonally

between 500 and 3500 mg/L (Mazor and Mero, 1969).

The last two groups are the focus of this article.

The Fuliya and Tabgha springs exhibit abrupt

seasonal salinity variations (Goldschmidt et al.,

1967; Rimmer et al., 1999). At Fuliya salinity is

maximal in March, following the last rains, and at

Tabgha, salinity is maximal in November, by the end

of the dry season (Fig. 2). Mazor and Mero (1969)

plotted the concentration of various ions vs. the Cl

concentration in the Fuliya and Tabgha springs. They

showed that the springs construct linear arrays on such

diagrams indicating a two-component mixing system;

one end-member is brine and the other end-member is

a fresh water component. Extrapolating these mixing

lines to high and low concentrations can give an

estimation of the ion ratios in the end-members.

Many authors have tried to infer the composition

of the saline end-member; it is generally accepted

that the brines are residual evaporated, ancient

seawater that invaded the DSR during the Neogene,

precipitated evaporitic minerals and interacted with

the aquifers (Klein-BenDavid et al., 2004; Starinsky,

1974; Stein et al., 1997, 2000; Zak, 1997).

Fig. 2. Seasonal variation in the Cl concentration in the En Sheva spring o

Gvirtzman et al. (1997) showed that circulating

fresh water from the Galilee aquifers flushes the

brine to the surface. However, The chemical charac-

teristics of the diluting fresh water in the different

spring groups were never established in detail.

Because the fresh end-member d18O and yD is

similar in the Fuliya and Tabgha recharge areas, the

chemical composition of the water may be the only

way to distinguish between them.

Recharge water in the eastern Galilee aquifers flows

over and through different rock formations and

interacts with them. The common rock types are

dolomite, limestone, chalk, marl and basalt. The

changes in Ca, Mg, Sr and Cl concentrations are

examined as indicative of the interaction with the

different rocks. Elevated Mg/Ca and low Sr/Cl ratios

are expected in the interaction with dolomite, whereas

high Sr/Cl and low Mg/Ca ratios will be representative

of chalk-related samples. Water that interacted with

limestone would give intermediate values and water

that flows through basalts would give both high Mg/Ca

and Sr/Cl ratios (Kafri et al., 2002).

The objective of this study is to define chemical

constraints to the composition of the fresh water

end-member feeding the Fuliya and Tabgha groups

of springs through the comparison of the ion ratios

in the calculated Fuliya and Tabgha fresh end-

member and the measured eastern Galilee sources

and to relate the observed groundwater compositions

to specific eastern Galilee aquifers.

f the Tabgha group and in the Fuliya 6/2 spring of the Fuliya group.

Fig. 3. The Tabgha, Fuliya and Tiberias hot springs drainage basin drawn on the eastern Galilee geological map.



2. Hydrogeological setting

The DSR is a left-lateral transform, along which

several rhomb-shaped grabens were formed, including

the Dead Sea and Lake Kinneret (Freund et al., 1970;

Garfunkel, 1981; Ben-Avraham et al., 1996; Al-Zoubi

and Ten-Brink, 2001). This basin includes the deepest

terrestial location on Earth as well as Lake Kinneret—

the lowest fresh water lakes on Earth (Fig. 1). Lake

Kinneret drains groundwater from five surrounding

aquifers: (1) the 200-m-thick, Neogene Bashan Group

basalt (Shaliv, 1989); (2) the 350-m-thick, Eocene

Avdat Group limestone and chalk (Saltzman, 1967;

Michelson, 1975; Sneh, 1988); (3) the 600-m-thick,

Cenomanian–Turonian Judea Group of predominantly

carbonates (Bein, 1967; Kafri, 1972); (4) the 400-m-

thick, Lower Cretaceous Kurnub Group of mainly

sandstones (Eliezry, 1959; Michelson, 1975); and (5)

the 2500-m-thick, Jurassic Arad Group of mainly

carbonates (Dubertret, 1966). The recharge areas of the

first three aquifers are exposed over the eastern Galilee

Mountains (Fig. 3; Table 1), the fourth is exposed over

a small area, while the fifth is totally confined.

The subsiding rift valley is filled by a Miocene–

Quaternary sequence that is at least 4 km thick

(Marcus and Slager, 1985). On the western margin

of the graben, some faulted blocks expose the Judea

aquifer along the margins of Lake Kinneret, channel-

ing the main discharge of the system (Goldschmidt et

al., 1967; Gvirtzman et al., 1997). The faults and the

shear zone along the rift allow mixing of water from

Table 1

Recharge areas of the different formation at the Fuliya and Tabgha

drainage basins

Stratigraphy Age Fuliya Tabgha

km2 % km2 %

Fill units Miocene–Holocene 64 31 33 9

Cover Basalt Pliocene–Pleistocene 17 8 76 21

Bar Kokhba Fm. Middle Eocene 2 1 25 7

Timrat Fm. Lower–Middle Eocene 7 3 32 9

Mount Scopus Group Senonian–Paleocene 17 8 36 10

Bina Fm. Turonian 6 3 8 2

Sakhnin Fm. Cenomanian 20 10 56 15

Deir-Hanna Fm. Cenomanian 42 20 84 23

Kammon Fm. Albian–Cenomanian 19 9 17 5

Ein el Assad Fm. Lower Cretaceous 9 5 5 1

Sum 203 100 371 100

Numbers are rounded to zero decimals.

deep aquifers with shallow fresh groundwater, which

emerges as springs (Moise et al., 2000).

Groundwater drains from the eastern Galilee

Mountains toward Lake Kinneret within three subsur-

face drainage basins: Tiberias, Fuliya and Tabgha.

These basins are separated from each other by major

faults. The borders of these recharge basins are shown

in Fig. 3. The total discharge of groundwater at the

onshore springs at Tiberias, Fuliya and Tabgha is

approximately 1.2, 11 and 25 million m3/year (Bein,

1978). The total estimated discharge of the onshore

and offshore springs is 5, 20 and 40 million m3/year,

respectively (Gvirtzman, unpublished data).

3. Methods

3.1. Sampling

Three springs belonging to the Fuliya group and

four springs and one artesian well from the Tabgha

group were sampled for chemical analyses. Sampling

was performed every 2 weeks (or at shorter intervals)

between April 1997 and May 1998. In addition, 47

samples from 32 fresh water springs and wells spread

over the eastern Galilee (Table 2 and Fig. 1) were

sampled once or twice between August 1996 and May

1998. They were selected according to their geo-

graphic and stratigraphic locations to represent the

entire region’s fresh groundwater. In the Fuliya basin,

wells from the Cenomanian, Turonian and Neogene

(Yavne’el) aquifers were sampled. In Tabgha the water

was sampled from the Eocene aquifer and springs

form Neogene (Korazim), Cenomanian–Turonian,

Senonian and Eocene formations.

Samples were collected as close as possible to the

discharge point. The samples were stored in 330 mL

PET (polyethylene teraphtalate) gas-tight plastic bot-

tles. The water was refrigerated (4–5 8C) until analysis.

3.2. Chemical analysis

Water samples were filtered using Whatmank #40

filters in order to remove all insoluble particles and

were diluted with deionized water (18.3 MV/cm) to

achieve optimal analytical ranges. Each sample was

analyzed in triplicate. Na, K, Mg, Ca, Sr, Si, and S were

measured using ICP-OES by an automated Perkin-

Table 2

Calculated linear regression parameters for ion vs. Cl correlation in the Fuliya and Tabgha saline sources (full analysis in Klein-BenDavid et al.,

2004)

Water source Number

of samples

Temperature

range (C8)aMg

(mg/L)

Ca

(mg/L)

Sr

(mg/L)

Cl

(mg/L)

Fuliya Group

Fuliya 5 31 27.0–28.0 Average 65.3 156 1.45 755

S.D.b 2.95 8.07 0.14 69.6

Slopec 0.042 0.114 0.002

Interceptd 33.9 70.7 �0.066

R2e 0.963 0.960 0.965

Fuliya 6 30 18.3–27.0 Average 64.1 151 1.34 720

S.D. 2.21 7.74 0.12 54.8

Slope 0.037 0.119 0.002

Intercept 37.7 65.5 �0.138

R2 0.825 0.709 0.954

Fuliya 6/2 29 26.7–28.1 Average 73.0 178 1.78 939

S.D. 4.17 11.4 0.19 98.4

Slope 0.041 0.113 0.002

Intercept 34.3 72.1 �0.066

R2 0.942 0.954 0.986

Tabgha Group

En Sheva 35 24.8–28.0 Average 62.3 249 4.84 1112

S.D. 9.93 27.0 0.83 222

Slope 0.044 0.118 0.004

Intercept 13.3 117 0.75

R2 0.975 0.946 0.972

Druzi Springf 17 16.8–28.7 Average 69.9 249 5.00 1277

S.D. 6.98 18.2 0.53 159

Slope 0.043 0.110 0.003

Intercept 14.9 108 0.78

R2 0.958 0.926 0.966

Ma’ayan Matok 33 26.0–28.0 Average 84.8 316 7.12 1770

S.D. 7.32 19.7 0.61 166

Slope 0.044 0.115 0.004

Intercept 7.78 113 0.68

R2 0.976 0.935 0.979

Kinneret 7 33 23.9–28.0 Average 41.7 189 3.31 734

S.D. 10.2 28.3 0.87 206

Slope 0.049 0.137 0.004

Intercept 5.50 88.2 0.21

R2 0.995 0.987 0.997

a Temperatures were measured as close as possible to the spring.b Standard deviation.c a-Linear slope ( Y=aX+b).d b-Linear intercept ( Y=aX+b).e Correlation coefficient.f The Druzi spring was not sampled through the whole sampling period.


Elmer Optima-3000 radial ICP system. Chloride, Br

and NO3 were analyzed using an automated Lachat

Instruments model QE flow injection analysis (FIA)

system with colorimetric detection (Eaton et al., 1995).

Instrumental drift was monitored by analyzing calibra-

tion standards every 10 samples and corrected for by an

in-house correction program (Katz, 1997). The ICP, Cl

and Br (FIA) precision is equal to or smaller than 1%.

The NO3 precision is F2%. Bicarbonate was titrated

using 0.02 NHCl with the BDHk #4480 indicator, at a


precision ofF0.5–1%. Further analytical details can be

found in Klein-BenDavid et al. (2004).

4. Results

Ions vs. Cl diagrams were plotted for seven Fuliya

and Tabgha saline sources. The Cl content of the

Fig. 4. Magnesium, Ca and Sr vs. Cl plots for the Fuliya (left column) and T

for the Fuliya charts: Fuliya 5 o; Fuliya 6 x; Fuliya 6/2 5. Legend for t

Kinneret 7 4.

selected saline sources ranges between 500 and 2000

mg/L. Fig. 4 displays the positive linear regression

between Ca,Mg and Sr and Cl. Such a behavior reflects

mixing between a fresh water component and brine.

We calculated the linear regression equation for

these lines. As the mixing occurs between brine and

fresh water, rather than distilled water, the lines do not

extrapolate through the origin and different points

abgha (right column) sources. Linear regressions are plotted. Legend

he Tabgha charts: En Sheva x; Ma’ayan matok 5; Druzi spring ;


along the line display different ion/Cl ratios. Thus, in

order to estimate the ion/Cl ratios of the fresh water

end-member we extrapolated the line to low concen-

trations and calculated the ratios for a pre-determined

Cl concentration.

Through extrapolation, we tested Cl concentrations

between 10 and 100 mg/L. As fresh groundwater in the

recharge basin displays this concentration range we

assumed that it is representative of the fresh end-

member. Table 2 presents the regression equations for

the Ca, Mg, Sr and Cl relationships and the correlation

coefficient R2. Table 3 presents the calculated ion/Cl

ratios in the tested Cl concentration range. We

calculated the error in the equivalent ion/Cl ratio to

the extrapolation to low concentrations. The calcula-

tions were conducted according to the procedure of

Natrella (1963) sections 5-3 and 5-4.1.2.1, using a 1�afactor of 0.95. The error for the ratios calculated from

16 of the lines is smaller than F10% (mostly smaller

than F5%). Two lines yielded up to 17% error. Three

Table 3

The ion/Cl equivalent ratios calculated from the extrapolated linear re

concentrations ranging between 10 and 100 mg/La

Cl (mg/L) 10 20 30 40

Fuliya

Fuliya 5 Mg/Cl 10.01 5.07 3.42 2.5

Ca/Cl 12.70 6.45 4.37 3.3

Sr/Clb �0.0037 �0.0010 �0.0001 0.0

Fuliya 6 Mg/Cl 11.11 5.61 3.78 2.8

Ca/Cl 11.80 6.00 4.07 3.11

Sr/Clb �0.0095 �0.0039 �0.0021 �0.0

Fuliya 6/2 Mg/Cl 10.14 5.13 3.46 2.6

Ca/Cl 12.95 6.57 4.45 3.3

Sr/Clb �0.0038 �0.0011 �0.0002 0.0

Tabgha

En Sheva Mg/Cl 4.00 2.06 1.42 1.1

Ca/Cl 20.97 10.59 7.13 5.4

Sr/Cl 0.063 0.033 0.023 0.0

Druzi Spring Mg/Cl 4.48 2.30 1.58 1.2

Ca/Cl 19.36 9.78 6.58 4.9

Sr/Cl 0.066 0.034 0.024 0.0

Ma’ayan Matok Mg/Clc 2.40 1.26 0.88 0.6

Ca/Cl 20.25 10.23 6.89 5.2

Sr/Clc 0.058 0.030 0.021 0.0

Kinneret 7 Mg/Cl 1.75 0.95 0.68 0.5

Ca/Cl 15.84 8.04 5.44 4.1

Sr/Cl 0.02 0.012 0.009 0.0

a Errors are up to F10% (mostly smaller then 5%).b ~100% error (see text).c F17% error.

lines, calculated for Sr vs. Cl in the Fuliya springs, gave

errors within the range of 100%. The reason for this

large error is the fact that the regression line crosscuts

the axis very close to the origin and the value of the

ratio is in the order of 10�4. Any minor change in the

value will cause a very large relative error.

A comparison of the ion ratios in the eastern

Galilee fresh water sources to the calculated fresh end-

member may distinguish between different eastern

Galilee sources as possible fresh water feeders to the

Fuliya and Tabgha springs. Table 4 lists the chemical

composition of 32 springs and wells sampled in the

Fuliya and Tabgha drainage basins from eight differ-

ent aquifers and lithologies.

5. Discussion

In order to compare the calculated ion/Cl ratios

in the fresh end-member with the actual ion/Cl

gression equations for Fuliya and Tabgha saline sources for Cl

50 60 70 80 90 100

9 2.10 1.77 1.53 1.36 1.22 1.11

3 2.70 2.28 1.99 1.76 1.59 1.45

003 0.0006 0.0007 0.0009 0.0010 0.0010 0.0011

6 2.31 1.94 1.68 1.48 1.33 1.21

2.53 2.14 1.87 1.66 1.50 1.37

011 �0.0006 �0.0002 0.0001 0.0003 0.0004 0.0006

2 2.12 1.79 1.55 1.37 1.23 1.12

9 2.75 2.32 2.02 1.79 1.62 1.47

002 0.0005 0.0007 0.0008 0.0009 0.0010 0.0011

0 0.90 0.77 0.68 0.61 0.56 0.52

0 4.36 3.67 3.18 2.80 2.52 2.29

18 0.015 0.013 0.012 0.011 0.010 0.009

1 1.00 0.85 0.75 0.67 0.61 0.56

9 4.03 3.39 2.93 2.59 2.32 2.11

18 0.015 0.013 0.012 0.011 0.010 0.009

9 0.58 0.51 0.45 0.41 0.38 0.35

2 4.21 3.54 3.07 2.71 2.43 2.21

17 0.014 0.012 0.011 0.010 0.009 0.008

5 0.46 0.41 0.37 0.34 0.32 0.30

4 3.36 2.84 2.47 2.19 1.98 1.80

08 0.007 0.006 0.006 0.006 0.005 0.005

Table 4

Summary of chemical analyses of fresh water samples collected at springs and wells in the eastern Galileea

Source No. Unit Well

depth

(M)

Typeb Sampling

date

Na

(mg/L)

K

(mg/L)

Mg

(mg/L)

Ca

(mg/L)

Sr

(mg/L)

Si

(mg/L)

SO42�

(mg/L)

Cl

(mg/L)

NO3�

(mg/L)

HCO3�

(mg/L)

Arabe-1 1 Lower

Cenomanian

302 W 12/08/96 33.3 15.7 37.7 79.7 0.185 7.84 23.0 69.2 78.2 327

Arabe-1 W 17/03/98 33.9 16.4 38.6 81.8 0.187 8.27 19.8 61.4 69.0 329

Chazon-2 2 367 W 12/08/96 18.7 1.57 36.3 71.4 0.154 6.78 10.7 34.0 14.8 356

Chazon-2 W 17/03/98 19.0 1.61 36.9 73.0 0.157 6.92 11.1 34.9 17.7 352

Golani 1 3 502 W 12/08/96 70.0 3.78 44.1 95.1 0.358 8.83 17.5 163 24.6 352

Golani 1 W 10/03/98 70.7 3.78 44.7 96.4 0.362 8.78 17.9 166 25.4 355

Golani 2 4 647 W 12/08/96 53.5 1.89 37.1 79.3 0.307 9.76 13.6 102 16.4 349

Golani 2 W 10/03/98 50.4 1.83 36.2 78.3 0.304 10.03 13.6 96.6 16.2 339

Kalanit-1 5 540 W 12/08/96 17.2 1.51 31.9 74.2 0.183 7.19 10.6 32.8 14.5 357

Kalanit-1 W 17/03/98 18.0 1.59 34.7 78.8 0.188 7.94 9.76 33.0 14.9 365

Chazon-1 6 Upper

Cenomanian–

Turonian

300 W 12/08/96 16.6 0.98 34.8 72.4 0.117 6.08 10.4 33.2 15.4 372

Chazon-1 W 17/03/98 18.1 1.14 38.3 74.3 0.116 6.33 11.8 34.3 18.6 355

Chazon-3 7 247 W 12/08/96 19.4 1.25 40.4 73.9 0.122 6.18 13.3 37.8 23.3 392

Chazon-4 8 319 W 12/08/96 30.3 1.07 40.1 81.6 0.167 7.92 12.5 64.8 23.0 397

Chazon-4 W 17/03/98 32.2 1.12 43.5 86.2 0.175 8.69 11.5 65.3 26.2 395

Chitin 1 9 279 W 12/08/96 33.3 1.70 31.3 71.0 0.244 8.31 12.2 63.6 16.0 327

Chitin 1 W 10/03/98 34.5 1.59 30.1 73.2 0.320 10.3 17.7 57.9 14.1 334

Chitin 3 10 501 W 12/08/96 34.3 1.59 32.2 71.1 0.272 8.83 13.2 64.0 15.0 342

Chitin 4 11 374 W 12/08/96 27.8 1.66 33.1 73.3 0.216 7.99 10.4 53.0 14.6 357

Chitin 4 W 10/03/98 30.0 1.72 36.0 77.5 0.221 8.76 9.94 56.0 14.4 350

En Po’em 12 Cenomanian–

Turonian

SP 20/07/98 13.1 0.60 35.7 95.0 0.073 19.1 17.4 29.1 22.6 408

En Taron 13 SP 20/07/98 10.7 3.37 35.7 85.5 0.066 8.20 11.8 20.2 13.1 435

En Yakim 14 SP 20/07/98 10.6 2.99 35.9 85.6 0.065 20.2 12.0 19.7 13.3 408

En Hitra 15 Senonian SP 20/07/98 13.8 0.48 5.08 104 0.419 86.2 12.8 29.8 8.37 300

En Koves 16 SP 20/07/98 33.0 7.10 8.67 121 0.556 17.6 34.4 52.8 49.7 307

En Pash’hur 17 SP 20/07/98 13.4 1.10 5.62 116 0.487 22.5 10.8 39.2 17.9 320

En Zetim 18 SP 20/07/98 12.1 1.24 5.89 120 0.623 14.1 26.9 27.3 6.62 349

Ginosar 19 Eocene

Bar-Kokhba

240 W 12/08/96 18.3 1.75 33.4 72.8 0.163 7.04 9.40 34.1 11.1 382

Hakok 20 112 W 10/03/98 45.7 2.69 29.1 101 0.470 12.8 12.2 86.5 32.6 372

Hakuk W 12/08/96 27.6 1.35 32.6 79.1 0.236 8.72 11.0 46.0 16.8 387

Hakuk 2 21 150 W 12/08/96 44.8 2.56 28.0 98.4 0.462 11.9 13.5 94.1 33.8 372

En Kichli 22 Eocene

Timrat

SP 20/07/98 34.8 14.6 15.8 106 0.854 69.8 46.5 57.3 7.99 350

En Sela 23 SP 20/07/98 32.6 12.4 15.1 119 0.891 74.4 45.9 53.0 25.6 350

En Sela 2 24 SP 20/07/98 32.3 12.3 14.7 119 0.881 74.1 46.1 53.3 25.2 350

En Dovshan 25 Neogene

Basalt–

Korazim

SP 20/07/98 95.0 21.8 34.8 81.4 0.376 15.7 18.3 95.5 13.1 671

En Korazim 26 SP 20/07/98 43.4 8.12 36.5 67.7 0.394 37.3 7.39 44.8 0.45 430

En Shum 27 SP 20/07/98 23.5 2.48 24.3 72.1 0.235 20.2 21.8 39.6 11.9 271

En Tofach 28 SP 20/07/98 23.3 2.36 25.0 56.7 0.200 28.5 19.8 35.3 15.3 261

Yavne’el 1 29 Neogene

Basalt–

Yavne’el

111 W 10/03/98 118 3.07 36.8 56.7 0.585 20.5 47.8 203 45.0 200

Yavne’el 2 30 98 W 10/03/98 97.7 3.58 38.7 38.6 0.658 22.3 21.7 111 32.0 308

Yavne’el B 31 142 W 12/08/96 96.4 3.26 35.0 34.8 0.582 22.7 20.8 98.7 30.9 287

Yavne’el B W 10/03/98 97.2 3.23 38.9 31.3 0.611 21.8 18.4 120 41.7 255

Yavne’el C 32 120 W 12/08/96 93.7 3.18 37.3 30.3 0.632 21.1 20.4 119 42.8 262

(continued on next page)


Source No. Unit Well

depth

(M)

Typeb Sampling

date

Na

(mg/L)

K

(mg/L)

Mg

(mg/L)

Ca

(mg/L)

Sr

(mg/L)

Si

(mg/L)

SO42�

(mg/L)

Cl

(mg/L)

NO3�

(mg/L)

HCO3�

(mg/L)

En Bardic Eocene

Timrat

SP 23.4 36.9 13.1 127 0.566 16.4 40.4 48.0 66.7 362

Bardi runoff c RF 12.6 4.82 2.62 58.3 0.239 5.49 43.1 17.0 5.25 127

En Neriac Upper

Cenomanian–

Turonian

SP 9.70 1.48 45.1 84.0 0.064 4.15 8.9 20.9 13.7 451

Neria runoff c RF 3.29 1.55 4.79 20.6 0.019 3.65 4.97 4.41 2.53 80.6

a Br concentrations in fresh-water samples are below detection limit.b Type: Sp=Spring, W=Well.c Average composition from Burg (1998).

Table 4 (continued)


ratios in the Eastern Galilee fresh water sources we

plotted ion/Cl vs. Cl diagrams (Fig. 5). We used this

projection method because, except for dilution with

extremely pure water, a two-end-member mixing

system would result in hyperbolic curves of the

general form of Ax+Bxy+Cy+D=0 (see Appendix

A). The Eastern Galilee fresh water samples were

plotted on the hyperboles; any fresh water falling

along the hyperboles is a possible end-member

candidate.

5.1. The fresh end-member in Fuliya

Fig. 5 presents the calculated Mg/Cl and Ca/Cl

ratios plotted against Cl concentration for the Fuliya

water sources. The eastern Galilee sources plotted on

the same diagram indicate that the Cenomanian–

Turonian sources as well as the Eocene–Bar-Kokhba

waters follow the calculated curve, whereas the other

sources fall off line, indicating that these sources are

similar in their Mg/Cl and Ca/Cl ratios to the fresh

component feeding the Fuliya springs.

Because the resulting Sr/Cl ratios are negative no

plotting was attempted. Still, this indicates that the

ratio in the fresh water end-member is low. Low

values are observed in the Cenomanian–Turonian

sources.

5.2. The fresh end-member in Tabgha

We also projected Mg/Cl, Ca/Cl and Sr/Cl ratios

vs. the corresponding Cl concentration for the Tabgha

saline springs (Fig. 5). The calculated curves show

some variability due to the large variation in the

salinity of the different saline sources, ranging

between 500 mg Cl/L in the Kinneret 7 well and

2000 mg Cl/L in the Ma’ayam Matok spring. The

Eastern Galilee springs discharging from the chalky

Senonian and Eocenian–Timrat formations are the

only sources that fit the Tabgha curves.

Hence it can be calculated that the water from

Cenomanian and Turonian aquifers as well as those

from the Eocene–Bar-Kokhba Fm. are chemically

similar to the calculated fresh end-member feeding the

Fuliya springs, whereas the Senonian and Eocene–

Timrat springs fit the calculated end-member of the

Tabgha sources. The basaltic aquifers differ from

those of Fuliya and Tabgha.

Thus, the ion ratios in fresh water from carbonate

aquifers can be used to differentiate between neigh-

boring carbonate recharge areas.

5.3. Correlation with local geology

5.3.1. Fuliya basin

Cenomanian–Turonian limestones and dolomites

account for 43% of the exposure of the Fuliya

recharge area (Fig. 1 and Table 1). Smaller areas of

Senonian chalk (8%), Eocene limestone-chalk (4%)

and Neogene basalt (8%) are exposed in the Fuliya

recharge basin, and have only a minor effect on the

groundwater chemical composition. Aquiclude fill

units cover the rest of the area.

Thus, the Cenomanian–Turonian aquifers are the

major fresh water suppliers to the Fuliya springs.

Although the Eocene–Bar Kokhba water composition

is in accord with the calculated Fuliya fresh end-

member, it is not likely that this aquifer provides a

significant amount of fresh water to the Fuliya

springs.

Fig. 5. Calculated Mg/Cl, Ca/Cl and Sr/Cl equivalent ratios vs. Cl concentration (meq/L) for the Fuliya (left column) and Tabgha (right column)

sources. The gray area represents a 10% error range for the hyperbolic curves.



5.3.2. Tabgaha basin

The Tabgha recharge area displays a larger variation

in lithology than the Fuliya recharge area (Table 1).

The chemical analyses indicate that the chalky

Eocene–Timrat Formation and Senonian outcrops

Fig. 6. Calculated Mg/Ca, and Sr/Ca equivalent ratios vs. Cl concentratio

springs and wells.

exposed over 19% of the drainage basin have the

most significant contribution to the water chemical

composition. Conversely, The Cenomanian–Turonian

limestone–dolomite formations exposed over 44% of

the area and the Eocene–Bar-Kokhba limestone for-

n (mg/L) for the Fuliya and Tabgha sources and the eastern Galilee


mation exposed over 7% of the area have only a minor

effect on the water chemical composition. Further-

more, because of the low permeability of the chalky

Eocene–Timrat Formation and Senonian outcrops, it is

hard to explain the amount of water discharging from

the Tabgha springs only by the flow from these

formations (Gvirtzman et al., 1997).

This discrepancy requires an explanation. Conse-

quently, we compared the composition of the calcu-

lated fresh end-member for the Tabgha springs with

the composition of springs from the upper part of the

Tabgha basin discharging from the Deir Hanna and

Timrat formations (En Neria and En Bardi, respec-

tively) and with runoff water from the spring vicinity

that flows over dolomite and chalk, respectively (Burg,

1998). Fig. 6 shows Mg/Ca and Sr/Ca ratios plotted

against the Cl concentration in the En Neria and En

Bardi spring and runoff water compared to the eastern

Galilee sources and the calculated Tabgha end-

member. The Figure indicates that the Mg/Ca and Sr/

Ca ratios in the En Bardi spring water are similar to the

ratios measured in the Timrat Fm. springs and to the

calculated end-member. The runoff water displays

slightly lower ratios as well as low Cl concentrations

but they are still within the range of the calculated end-

member. On the other hand, the En Neria spring and

runoff water do not fit the calculated end-member,

displaying high Mg/Ca and low Sr/Ca ratios. This

observation indicates that the water chemical compo-

sition is acquired at a very early stage of its flow and

that runoff water flowing over the different formations

can be easily distinguished. Due to the lower perme-

ability of the chalky formations, much of the runoff

water does not infiltrate into the bedrock until

encountering more permeable rocks. Surface flow on

the chalky outcrops will finally infiltrate into the Bar-

Kokhba limestone recharging it with water with high

Sr/Ca and low Mg/Ca ratios.

Nevertheless, the Cenomanian–Turonian forma-

tions are exposed over a large part of the recharge

basin but their contribution to the solute content of the

fresh end-member seems to be minor. The Cenoma-

nian–Turonian rock column in this area is divided into

four formations (Fig. 3): Sakhnin (C1, a permeable

aquifer), Deir-Hanna (C2, aquitard), Kammon (C3, a

permeable aquifer) and Bina (t, a permeable aquifer). In

the Tabgha recharge area the Cenomanian–Turonian

rock outcrop consists mostly of the Deir-Hanna

formation (23%), whose hydraulic conductivity is

relatively small (Gvirtzman et al., 1997); moreover,

the Deir-Hanna Fm. surface flow drainage to a western

Galilee system (Kziv stream). Nevertheless, the Sakh-

nin Fm. and to a lesser degree the Kammon Fm.

(exposed over 15% and 5% of the drainage area,

respectively) can contribute water to the local aquifers.

From the observed chemical composition it is evident

that the amount of solutes contributed from these

formations is low. The solute concentration in runoff

water and fresh spring water (17 and 48 mg Cl/L,

respectively) from En Bardi (chalky Timrat formation)

carry more solutes than water interacting with lime-

stone and dolomite in the En Neria vicinity (Burg,

1998). This observation may partly explain the smaller

contribution of the Sakhnin and Kammon water to the

fresh end-member.

In summary, the fresh water end-member in

Tabgha acquires its chemical composition mainly

during its flow over the Senonian and Eocene chalky

rocks. This water flows down and infiltrates into the

Bar Kokhba aquifer and discharges at the Tabgha

springs. The solute addition from the Sakhnin and Bar

Kokhba formations is minor.

To conclude, the fresh component in the Tabgha

basin acquires its solute content from shallow depth

while the Fuliya springs are recharged by deeper

aquifers. This conclusion is consistent with an

independent hydrological model indicating that the

major fresh water recharge to the Tabgha and Fuliya

blocks comes from the Eocene aquifers and Cenoma-

nian–Turonian aquifers, respectively (Gvirtzman et

al., 1997).

6. Conclusions

(1) In two component mixing systems, linear equa-

tions constructed from the ion vs. Cl correlation

can be extrapolated to low Cl concentrations and

be used for the assessment of the ion/Cl ratio in a

fresh end-member.

(2) Hyperboles constructed by projecting ion/Cl

ratios vs. Cl can be used to estimate two end-

member mixing in an aquatic system; projecting

the composition of natural water on the calcu-

lated curve can be used to identify the fresh

water source.


(3) The major fresh water end-member diluting the

Fuliya brines is characterized by high Mg/Cl and

low Sr/Cl ratios, and is consistent with the

composition of fresh groundwater in the Cen-

omanian and Turonian aquifers.

(4) The major fresh water end-member diluting the

Tabgha brines is characterized by low Mg/Cl and

high Sr/Cl ratios, and is consistent with the

composition of fresh groundwater in the Eocene

Timrat formation and Senonian outcrops.

(5) Although the chalky formations in the Tab-

gha drainage basin are exposed over only

19% of the area they contribute most of the

solutes to the fresh water end-member. There

is no significant solute contribution from the

Cenomanian–Turonian aquifers.

Acknowledgments

The Israeli Water Commission—the Ministry of

Energy and Infrastructure (account number 65/01)

supported this study. Einat Kasher, Ahuva Agranat

and Moshe Riban are thanked for technical support.

Onn Crouvi and Ittai Haviv are thanked for help in GIS

analysis, and finally we are grateful to Prof. H. Blatt

and Prof. A Starinsky for their helpful comments. [LW]

Appendix A

The equation for the hyperbolic mixing curve

between components a and b for Ca and Cl.

ACa

Cl

�mix

þ B Cl½ �mix

Ca

Cl

�mix

þ C Cl½ �mix þ D ¼ 0

��

A ¼ Cl½ �b Ca½ �a � Cl½ �a Ca½ �b

B ¼ Ca½ �b � Ca½ �a

C ¼ Ca½ �aCa

Cl

�a

� Ca½ �bCa

Cl

�b

��

D ¼ Cl½ �a Ca½ �bCa

Cl

�b

� Cl½ �b Ca½ �aCa

Cl

�a

��

This equation results will not result in a hyperbolic

curve when: B=[Ca]b�[Ca]a=0.

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