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Water and Environment Journal. Print ISSN 1747-6585
Hydrogeological characteristics of a groundwater-dependent
ecosystem (La Lantejuela, Spain)
Miguel Rodrı́guez-Rodrı́guez1, Francisco Moral1 & Jose Benavente2
1
Physical, Chemical and Natural Systems, University Pablo de Olavide, Seville, Spain and 2University of Granada, Granada, Spain
Keywords
hydrogeochemistry; playa lakes; Southern
Spain.
Correspondence
Miguel Rodrı́guez-Rodrı́guez, Physical,
Chemical and Natural Systems, University
Pablo de Olavide, C/ Utrera, km 1, Seville
41013, Spain. Email: [email protected]
doi:10.1111/j.1747-6593.2007.00092.x
Abstract
By means of a simple water balance model, together with hydrogeochemical
and morphological interpretation, the hydrogeological characteristics of a series
of playa lakes forming an endorheic complex within the Guadalquivir river
basin in Southern Spain (La Lantejuela) have been evaluated. The lakes are
demonstrated to be groundwater-dependent ecosystems. The main source of
groundwater input to the lakes is from an unconfined detritic aquifer, the playa
lakes being the natural discharge points from the aquifer within the endorheic
complex. High rates of evaporation from the lakes induce a centripetal groundwater flow pattern. This water body has been disturbed by a combination of
extensive drainage works and intensive groundwater abstraction. There is a
need for a sustainable water management strategy for the whole catchment
area. It is hoped this will be an issue addressed within the Guadalquivir river
basin management plan in accordance with the requirements of the European
Water Framework Directive (WFD).
Introduction
Throughout southern Spain, there exist numerous closed
basins hosting playa lakes, where small mountain ranges or
hills separate semi-arid basins (Garcı́a et al. 1997; Montes
et al. 2004). Ephemeral playa lakes occur in arid to semiarid environments whenever internally drained basins are
formed by tectonic activity or dissolution processes, and the
floor of such basins intersects the water table (Duffy &
Al-Hassan 1988). Rainfall onto the related aquifers or the
catchment area of the playas enters the groundwater
through permeable materials overlying the impervious
substratum. Normally, the substratum is related to the
presence of Triassic sediments, which outcrop abundantly
in the Betic Cordillera (Vera 2004) and present very
low hydraulic conductivity. The groundwater returns to
the surface in the form of springs, rivers or discharge to the
playa lake system. However, a second type of circulation,
which is unique to a closed basin, may also occur. Evaporation concentrates the playa lake water, which turns into a
brine. This brine, which is much denser, may flow into the
fresher groundwater. As long as brine is supplied, cellular
flow circulation may take place below the playa lake
bottom until it reaches the impermeable substratum. This
scenario is known as ‘free convective flow’ (Fan et al. 1997).
The surface–groundwater relation between the playa
lakes and the unconfined aquifers in the area is of evident
interest in the correct management of such ecosystems,
which are very sensitive to hydrological alterations such as
groundwater pumping or surface drainage. The Water Framework Directive (WFD), which is applicable in all the
member states, encourages the investigation of groundwater-dependent ecosystems (WFD-CISNo.2 2002, 2003).
Finally, this type of methodology could help close the present
gap that exists between water managers and researchers
(Borowski & Hare 2007), thanks to its simplicity. The main
objectives to be addressed in this work are (i) to describe the
detritic aquifer Osuna-La Lantejuela (O-LL), about which
only a few hydrogeological studies have previously been
published; (ii) to investigate the hydrological relations between this aquifer and the playa lakes of La Lantejuela by
means of a simple water budget and (iii) to carry out a
preliminary hypothesis on the genesis of these systems.
Main exposition
Methods
Study site
The study zone is located near the town of Osuna in the
southeast of the province of Seville (Andalusia, Spain)
(Fig. 1).
c 2007 The Authors. Journal compilation c 2007 CIWEM.
Water and Environment Journal (2007) 1
Hydrogeological characteristics of a groundwater-dependent ecosystem
M. Rodrı́guez-Rodrı́guez et al.
Guadalquivir river basin
Seville province
Spain
Andalusia
Palomarejo hill (309 m a.s.l.)
Playa lakes
La Lantejuela
Salado River
Blanco River
10 km
er
Osuna
Corbones River
Seville
Osuna weather station
Blanco River
Osuna
Gu
ada
lqu
ivir
Riv
Study zone
orre del Aguila reservoir
Puebla de Cazalla
Fig. 1. Geographical sketch.
The topography is characterized by a plain that smoothly
descends towards the north, from an altitude of about
300 m above sea level (a.s.l.) in the proximity of Osuna to
150 m near La Lantejuela. Hills bordering the flood plain
include Palomarejo (309 m a.s.l.), which is in the northern
part of the study zone (Fig. 1). Surface drainage is towards
the west-located Corbones River and towards the eastlocated Blanco River (Fig. 2). The study area belongs to the
Subbetic Units of the Betic Cordillera (External Zones) and
to the sedimentary filling of the Guadalquivir river basin.
Nine water bodies formed the endorheic complex of La
Lantejuela, but the majority of these lakes are nowadays
threatened by drainage and filling and so only two of them
are preserved and hydrologically functional (Calderón and
Ballestera playa lakes, see Fig. 2). Other anthropogenic
stresses such as pollution, eutrophication, catchment cultivation, road construction and groundwater pumping affect
these ecosystems.
Field surveys, analytical procedures and water
balance calculation
DV ¼ P E þ ðSi þ Gi Þ So Go ;
Sampling campaigns were carried out in 2004. Subsequently, occasional morphological surveys were made in
2005. Surface water samples were taken at a distance of
2
4 m from the shore of the playa lakes. Groundwater
samples were collected from the uppermost part of the
47 wells that were included in the inventory. Field parameters measured in surface and groundwater were electric conductivity (EC25), water temperature and pH.
Major ions and nitrates were measured using ion chromatography and spectrophotometry techniques, at the
hydrochemistry laboratory of Pablo de Olavide University
(Seville). Geographic information system (GIS) was used
to determine flooded surface and catchment area characteristics; several hydro-morphological surveys were
undertaken to check the results obtained. The Osuna
weather station, located at an altitude of 255 m a.s.l., was
selected to obtain meteorological data. A 29-year series of
mean temperatures and precipitation was used. Data on
daily evaporation were obtained using a ‘Class A’ evaporation tank located at ‘Torre del Aguila’ reservoir
weather station (55 m a.s.l.).
The equation of the water budget (Mansell & Rollet
2006) for average climatic conditions can be expressed as
ð1Þ
DV refers to the change in playa lake storage and is the
result obtained from the water budget model (unknown
c 2007 The Authors. Journal compilation c 2007 CIWEM.
Water and Environment Journal (2007) M. Rodrı́guez-Rodrı́guez et al.
Hydrogeological characteristics of a groundwater-dependent ecosystem
Ruiz Sanchez
nc
Bla
oR
Consuegra
La Lantejuela
r
ive
r
ve
Ri
es
on
rb
Co
Turquilla
Gobierno
Ballestera
Verde de la Sal
Calderon
Marinaleda
Herrera
El Rubio
Calderon Grande
Pedro Lopez
Marchena
Estepa
Aguadulce
Osuna
La Puebla de
Cazalla
River
N
Roads
Town
Playa lake
Gilena
Pedrera
Permeability and lithology
High. Sandy marls and conglomerates
Medium. Sandy marls
Low. Marls and clays
10 km
5
0
Fig. 2. Permeability of the materials (Osuna-La Lantejuela aquifer).
variable). This component may not change on an interannual scale but important variations may be expected on
a monthly scale. The model can be validated by comparing its results (theoretical water level) with the time series
data for the water level of the playa lake.
P is direct precipitation onto the playa lake, estimated
by multiplying monthly P (mm) by the average flooded
area at each time interval to obtain P (m3).
E is evaporation from the flooded surface. This component of the water budget is estimated from Class A tank
evaporation data (mm), compared by correlation analyses
with other evaporation data from reservoirs of the Guadalquivir river basin and scaled to obtain E (m3).
Si is surface water inflow (i.e. surface runoff) and Gi is
subsurface runoff. These two components of the playa
lake water balance are equal to 50% of the surplus of the
soil–water budget. The remaining 50% infiltrates to recharge the aquifer. Previous studies (CHG-IGME 2001)
have shown a relatively high transmissivity for the materials of the aquifer (10–100 m2/day). Additionally, water
balances in other playa lakes of Andalusia have been
calculated using similar infiltration rates (Carrasco et al.
2004). A soil–water budget in the catchment area was
calculated to determine the water surplus. The soil–water
budget is a simple accounting scheme used to predict
soil–water storage, actual evapotranspiration (ET) and
water surplus by means of precipitation and potential ET
at a given water-holding capacity (Thornthwaite & Mather 1955; Jensen et al. 1990). Water surplus is the fraction
of precipitation that exceeds potential ET and is not stored
in the soil. The simple model used here does not distinguish between surface and subsurface run-off, and so
water surplus includes both.
So is surface water outflow. As the playa lakes are
located at the centre of a closed basin without any waterdischarging river or outlet, So is zero.
Go is groundwater output (i.e. recharge or infiltration)
from the lake to the aquifer. This term is not computed
in the equation because it is already included in the
soil–water budget (50% recharge).
If the evolution of the water level in the playa lake is
similar to that observed in the field, then it is assumed
that the water budget is correct. In that situation, the only
water inputs to the lake are P and Si+Gi. If regional
groundwater discharge or hydrological alterations of the
catchment area such as drainage or over pumping take
place, then the result will not fit the average evolution
of the water level observed in the playa lake. The
c 2007 The Authors. Journal compilation c 2007 CIWEM.
Water and Environment Journal (2007) 3
Hydrogeological characteristics of a groundwater-dependent ecosystem
M. Rodrı́guez-Rodrı́guez et al.
methodology of the water budget model presented in this
work has been validated by successful previous applications in other Andalusian wetlands (Benavente et al.
2006a, b).
to the north of the playa lake complex of La Lantejuela.
These materials display a medium level of hydraulic
conductivity (Fig. 2).
Autochthonous Formation (Upper Miocene and
Plio-Quaternary): these appear discordant to the other
Units described and are postorogenic. The main lithologies are conglomerates, gravels, sands, clays and evaporites that sometimes appear cemented. These materials
are permeable, and have a high level of hydraulic
conductivity (Fig. 2).
Discussion
Geological features
Sedimentation in the Betic Cordillera took place during
the Neogene in two tectonically different phases. From
the Early to Middle Miocene, the Betic basin evolved with
the main movements of orogenic structuring of the
Cordillera, which were the collision between the Alborán
Microplate (Internal Zones) and the South-Iberian Paleomargin (in which deformed rocks of Mesozoic age made
up the External Zones). In this synorogenic phase, a
number of basins formed within the orogene as well as in
the foreland basin outside it, such as the Proto-Guadalquivir basin. The sediments filling these basins were
deformed by the Betic orogeny. The second tectonic phase
took place during the Late Miocene to Quaternary. The
main features of the orogene were already determined
and this was the context in which the postorogenic basins
formed, located in both the Internal and External Zones
and at the contact (Viseras et al. 2005).
Simultaneously, diapiric movements associated with
Mesozoic evaporitic materials occurred, leading to the
formation of elevations and karstification throughout the
External Zones of the Cordillera. From the different
regional geologic studies carried out in the study zone
(Cruz-Sanjulián 1974, 1986; Crespo 1977; Pignatelli &
Crespo 1977), the geologic materials outcropping in the
area can be grouped into three units:
Alochthonous Formations (Subbetic and Olistostromic
Unit): multicoloured marls and clays of Triassic age that
include, in a chaotic mixture, blocks (olistolits) of varied
nature and ages between the Triassic and Miocene (dolomites, volcanic rocks, limestones, marls, sandstones, etc.).
These outcrop to the east and the south of the study zone
and constitute the impervious substratum above which
the youngest materials were deposited. The tectonics of
the Alochthonous Units is determined by the gravitational displacement of these materials, of plastic behaviour, that took place in a SE–NW direction towards the
Miocene marine basin. These materials exhibit a low level
of hydraulic conductivity (Fig. 2).
Para-autochthonous Formation: white marls and
marly limestones, locally with sandy bars, from Upper
Burdigalian to Messinian age. They show abundant
remnants of marine microfauna (sponge spicules,
diatoms, etc.) and display a thickness of almost 100 m.
The most extensive outcrop is that of the Palomarejo hill,
4
O-LL aquifer
The O-LL aquifer (Fig. 2) consists of a detritic unconfined
hydrogeological system made up by Plio-Quaternary alluvial materials. The aquifer has an average thickness of
4–8 m in the northern part (near the playa lakes) and
about 40 m near Puebla de Cazalla and the Corbones River.
Permeable outcrops occupy a surface area of 350 km2 and
the aquifer materials display a heterogeneous hydrogeological behaviour. The impermeable substrate of the aquifer
contains clayey-evaporitic materials of Triassic age, which
are responsible for the relatively high salinity of the
groundwater (CHG-IGME 2001). Recharge takes place by
the infiltration of rainwater and occasional flooding of the
rivers. Discharge takes place by evaporation from the playa
lakes and also by groundwater discharge to the main
streams and rivers of the area. Present-day discharge is also
produced by the pumping activities carried out in numerous irrigation wells throughout the area.
According to our measurements, the piezometric level
is close to the surface (3–4 m). Absolute altitudes a.s.l.
range from 142 to 155 m a.s.l. The piezometric levels
measured in the 47 wells of the inventory (Table 1) lead
us to conclude that the directions of the groundwater flow
have an approximate component N3301E, from the proximity of Osuna towards the playa lakes (Fig. 3).
Piezometric measurements indicate the existence of
a single groundwater system and that the base level of
the playa lakes represents the phreatic level of the
aquifer. However, each lacustrine basin displays its own
separate characteristic hydrogeological behaviour as is
discussed below.
The groundwater in the O-LL aquifer has nonhomogeneous electrical conductivities, ranging from 1.2 mS/cm
in wells located in sandy conglomerates of Pliocene age to
16 mS/cm in wells located on the Quaternary clays and
limes near the playa lakes. The salinity of the groundwater increases towards the lacustrine basins. This hydrochemical pattern seems to indicate that in a natural
regime, transport processes take place towards the playa
lakes (the discharge zones of the O-LL aquifer) where
evaporative brines are generated (Fig. 4).
c 2007 The Authors. Journal compilation c 2007 CIWEM.
Water and Environment Journal (2007) M. Rodrı́guez-Rodrı́guez et al.
Hydrogeological characteristics of a groundwater-dependent ecosystem
Table 1 Location, salinity and water temperature of the wells inventoried
Code
UTMX
UTMY
Z
DWL
(m)
WL
(m a.s.l.)
EC25
(mS/cm)
Twater
( 1C)
O-LL-1
O-LL-2
O-LL-3
O-LL-4
O-LL-5
O-LL-6
O-LL-7
O-LL-8
O-LL-9
O-LL-10
O-LL-11
O-LL-12
O-LL-13
O-LL-14
O-LL-15
O-LL-16
O-LL-17
O-LL-18
O-LL-19
O-LL-20
O-LL-21
O-LL-22
O-LL-23
O-LL-24
O-LL-25
O-LL-26
O-LL-27
O-LL-28
O-LL-29
O-LL-30
O-LL-31
O-LL-32
O-LL-33
O-LL-34
O-LL-35
O-LL-36
O-LL-37
O-LL-38
O-LL-39
O-LL-40
O-LL-41
O-LL-42
O-LL-43
O-LL-44
O-LL-45
O-LL-46
O-LL-47
0312251
0312336
0312608
0312435
0312513
0312899
0312702
0312517
0312762
0313037
0312956
0311313
0309246
0307461
0307501
0307306
0307581
0307616
0308062
0307967
0308075
0308298
0308792
0308855
0311243
0311580
0310888
0310780
0310605
0310167
0309469
0310509
0310131
0310245
0309856
0309824
0309222
0308944
0308744
0307461
0307282
0307809
0307569
0307876
0308027
0308022
0308150
4132435
4132849
4133024
4133252
4133500
4133844
4135107
4135360
4135760
4138336
4138689
4139277
4138769
4136901
4136499
4136451
4136362
4136056
4135074
4134991
4134919
4134935
4135911
4138383
4134537
4134552
4134208
4134396
4134229
4133858
4134001
4134671
4134869
4135161
4136217
4136346
4136271
4136809
4137651
4139046
4139349
4139618
4139841
4139428
4139327
4139249
4139273
159
158
157
157
157
161
155
4.43
3.95
3.27
3.00
2.98
9.03
3.50
155
154
154
154
154
152
152
4.12
5.16
13.69
7.20
10.88
7.09
4.18
19.3
19.3
18.8
19.3
19.3
20.3
20.2
158
3.40
3.10
155
21.5
21.7
150
148
151
151
151
152
156
155
155
155
155
151
148
154
154
156
154
155
157
157
2.50
2.60
3.00
3.40
3.95
3.30
4.10
4.90
4.85
5.30
5.85
3.50
4.30
2.72
3.00
3.93
3.00
3.29
4.26
4.66
4.21
3.50
3.13
3.23
3.30
2.76
2.96
2.01
1.66
4.12
1.53
2.50
2.15
1.75
2.18
1.01
148
145
148
148
147
149
152
150
150
150
149
148
144
151
151
152
153
152
153
152
2.15
11.90
2.50
2.85
4.51
13.8
8.54
7.02
5.61
4.81
6.08
4.74
5.46
6.41
8.90
5.71
3.80
10.22
5.76
6.25
5.72
6.93
5.23
6.70
6.19
8.35
7.34
8.34
6.13
4.86
3.83
1.65
1.20
2.42
5.39
3.10
10.98
9.97
16.1
154
153
151
151
151
150
149
147
146
145
146
145
145
144
145
151
150
148
148
148
147
147
145
142
143
144
143
143
142
144
22.3
20.1
22.8
21.1
21.2
20.6
20.2
20.7
20.4
20.2
20.3
20.8
21.4
18.8
19.6
19.9
20.0
20.2
20.1
19.7
20.5
20.8
20.8
20.4
20.2
21.0
21.0
21.1
22.5
21.9
21.9
21.0
21.1
20.1
20.0
20.6
Date recorded
Observations
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
30 Sept. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
10 Oct. 2004
Aspirating pump
Aspirating pump
Not installed
Not installed
New well
Abandoned
Not installed
Aspirating pump
New well
Submersed pump
Submersed pump
Submersed pump
New well
Aspirating pump
Aspirating pump
Not installed
Not installed
Submersed pump
Submersed pump
Aspirating pump
Aspirating pump
Aspirating pump
Aspirating pump
Not installed
Aspirating pump
Submersed pump
Submersed pump
Submersed pump
Not installed
Aspirating pump
Not installed
Aspirating pump
Not installed
Not installed
Not installed
Not installed
Not installed
Aspirating pump
Aspirating pump
Not installed
Aspirating pump
Aspirating pump
Not installed
Not installed
Not installed
Z, position (m a.s.l.) of the wells with an accuracy of 1 m (AME 2005); DWL, depth of the water level with an accuracy of 0.01 m; WL, water level with an
accuracy of 1 m; O-LL, Osuna-La Lantejuela; a.s.l., above sea level.
This brine infiltrates through the sediments of the playa
lakes by diffusion and probably by advection processes,
creating a zone of high-salinity groundwater below the
system (Figs 3 and 5).
La Lantejuela playa lake endorheic complex
This playa lake system consists of eight ephemeral lakes
that have been considerably altered by human activities.
c 2007 The Authors. Journal compilation c 2007 CIWEM.
Water and Environment Journal (2007) 5
Hydrogeological characteristics of a groundwater-dependent ecosystem
(a)
43
(b)
Consuegra
42
44
145
M. Rodrı́guez-Rodrı́guez et al.
45
8
10
5
47
46
8
5
150
10
Verde de la Sal
8
N
Ballestera
W
N
Calderon
W
E
S
E
S
Cald Grande
5
150
Pedro Lopez
5
Osuna
Osuna
18
4.5
16
4
R = 0.660
EC (mS/cm)
14
3.5
12
3
10
2.5
8
2
6
1.5
1
4
R = 0.638
2
0
1000
1100
1200
1300
1400
1500
1600
1700
Depth of water table (m)
Fig. 3. Flow direction (a) and groundwater salinity (b) in the study area (September 2004).
Legend
47
45 and 46
44
42
80
43
Playa lake
Scale of radii
60
Proportional to Cl
(0 – 5200 mg/L) in the
40
upper diagram
80
60
40
20
20
0.5
0
1800
Mg
Distance from playa lake (m)
SO
80
80
Fig. 4. EC and depth of the water table in six wells (O-LL42 to O-LL47)
located in the studied area plotted against distance from Consuegra playa
lake (see Fig. 3). EC, electric conductivity; O-LL, Osuna-La Lantejuela.
60
60
40
40
20
20
EC (mS/cm) in well ‘O-LL46’
7.38
2
7.4
7.42 7.44 7.46 7.48
7.5
7.52 7.54 7.56 7.58
Depth (m)
60
40
20
20
Na
HCO
40
60
80
Cl
Fig. 6. Piper diagram showing the hydrochemical facies in six wells
located in the studied area. The arrows indicate the geochemical
evolution path of the groundwater: increasing concentrations of Cl and Na+ from well 43 to the playa lake.
3
4
5
6
7
8
Fig. 5. EC log in well No. 46 (O-LL 46, see Fig. 3). EC, electric conductivity; O-LL, Osuna-La Lantejuela.
Formerly, it was a large endorheic area of more than
300 km2 that extended around the town of Osuna. The
Salado River ended at this area, creating a continental fan
delta. Nowadays, most of the playa lakes are drained and
6
80
Ca
the Salado River has been canalized to a tributary of the
Corbones River, in accordance with the Agricultural Plan
for Osuna, established in 1967.
The only playa lakes that have remained well preserved
are Ballestera and Calderón, declared Natural Reserves,
while the others are flooded only sporadically or have
been transformed into agricultural lands (Fig. 7).
The playa lakes of the endorheic complex of La Lantejuela exhibit high water salinity, although there is a large
degree of variation during each hydrological cycle. In the
Ballestera playa lake, the concentration of solids correlates
strongly with water volume and varies between 10 and
c 2007 The Authors. Journal compilation c 2007 CIWEM.
Water and Environment Journal (2007) M. Rodrı́guez-Rodrı́guez et al.
Hydrogeological characteristics of a groundwater-dependent ecosystem
A
B
200
m a.s.l.
175
Calderón
(drained) Ballestera
Gobierno
150
125
100
0
2
4
6
8
10 km
A
Fig. 7. Cross section and hydrological functioning in four of the studied playa lakes (Gobierno
playa lake has been modified to host the water
purifier of La Lantejuela). The downward halokinetic movement refers to the depression formed
up around the diapirs.
90 g/L. Similar salinity values have been measured in the
Calderón playa lake.
With respect to hydrochemistry (Fig. 6), brine dominated by Na and Cl develops in both systems, although
concentrations of sulphate and magnesium are also important. Playa lake brines are interpreted as the endmembers of local groundwater flow lines moving slowly
towards the centre of each endorheic basin.
Table 2 shows the results for the water budgets in the
playa lakes and the soil, together with meteorological
data. The surplus from the soil–water budget totals
107.8 mm for a water-holding capacity of 100 mm (Table
2A), representing 20.5% of annual precipitation.
The monthly water balance of the Calderón and Ballestera playa lakes was determined in accordance with the
methodology described above. We have assumed that, a
priori, there is no water interchange between the playa
lakes and the O-LL aquifer. If the results obtained from
this theoretical balance for the average hydrological year
(basically, the duration of the average flooding period of
the playa lake) are similar to the data known about the
hydroperiod of the lagoon, then the resulting net volume
of the water interchange between the O-LL aquifer and
the playa lakes would be considered negligible. Otherwise, a remarkable contribution of groundwater to the
playa lakes (discharge) or groundwater recharge from the
playa lakes to the aquifer must occur.
The runoff (surplus) was estimated by applying the
precipitation and temperature records from the Osuna
weather station (Table 2A) to the monthly water balance.
Because the catchment area of the playa lakes is located
over relatively permeable materials, it is assumed that half
of the runoff infiltrates, constituting a part of the recharge
of the O-LL aquifer. The other 50% produces direct
surface runoff to the playa lakes.
Table 2B shows the results of the monthly water
balance for the Calderón playa lake. The direct precipitation (P) onto the surface area of 5.9 ha is 31.1 103 m3/
year. Excluding the flooded area, the catchment area has
a surface of 75.1 ha. The surface runoff and subsurface
groundwater recharge to the playa lake (Si+Gi) total
40.5 103 m3/year. The ET estimated in the model is
71.6 103 m3/year. The model predicts a flooding period
with an average duration of almost 8 months, from
January to the end of August, and a maximum water
level of 65 cm.
According to the literature (Moreira & Montes 2005)
and field observations, the playa lake remains flooded for
o6 months each year. Thus, the hydroperiod observed is
shorter than that predicted by the model. These differences
c 2007 The Authors. Journal compilation c 2007 CIWEM.
Water and Environment Journal (2007) 7
Hydrogeological characteristics of a groundwater-dependent ecosystem
M. Rodrı́guez-Rodrı́guez et al.
Table 2 (A) Main characteristics of the hydro-meteorological station and soil water budget results (mm) (B) water balance results in Calderon playa lake
(C) water balance results in Ballestera playa lake
Weather station
Code
Province
Altitude
Years rainf.
Year init.
Year end
Year temp.
Year init.
Year end
Osuna
5998A
Seville
255
29
1967
1996
29
1967
1996
Month
O
N
D
J
F
M
A
M
J
J
A
S
Total
(A)
Precipitation
Temperature
PET
Soil humidity
AET
Surplus
48
18.4
65.9
0.0
48.0
0.0
69
13.8
33.9
35.1
33.9
0.0
78
10.6
20.1
93.0
20.1
0.0
76
9.8
17.9
100.0
17.9
51.1
62
11.1
22.2
100.0
22.2
39.8
52
13.1
37.2
100.0
37.2
14.8
53
15.0
50.9
100.0
50.9
2.1
36
18.4
82.4
53.6
82.4
0.0
16
22.9
125.1
0.0
69.6
0.0
4
27.2
175.3
0.0
4.0
0.0
16
27.3
166.2
0.0
16.0
0.0
17
23.9
115.0
0.0
17.0
0.0
527
17.6
912.1
SW 81 ha
419.2
107.8
SPL 5.9 ha
P (mm) Si+Gi (mm) E (mm) AET (mm) P ( 103 m3) Si+Gi ( 103 m3) ET ( 103 m3) SH ( 103 m3) D level (mm) Water level (mm)
(B) Calderon
October
November
December
January
February
March
April
May
June
July
August
September
Total
48
69
78
76
62
52
53
36
16
4
16
17
527
0
0
0
26
20
7
1
0
0
0
0
0
54
90.8 48.0
58.6 34.0
38.1 20.0
40.5 17.9
54.9 22.2
83.6 37.2
89.9 50.9
115.4 82.4
178.4 69.6
218.6
4.0
201.6 16.0
151.0 17.0
1321.4 419.2
SW 145 ha
2.8
4.1
4.6
4.5
3.7
3.1
3.1
2.1
0.9
0.2
0.9
1.0
31.1
0.0
0.0
0.0
19.2
14.9
5.6
0.8
0.0
0.0
0.0
0.0
0.0
40.5
2.8
2.0
1.2
2.4
3.2
4.9
5.3
6.8
10.5
12.9
11.9
7.6
71.6
0.0
2.1
5.5
5.9
5.9
5.9
5.9
5.9
5.9
5.9
5.9
0.0
0.0
0.0
0.0
354.2
260.4
62.6
23.5
79.4
162.4
214.6
185.6
0.0
0.0
0.0
0.0
354.2
614.6
677.2
653.7
574.3
411.9
197.3
11.7
0.0
SPL 25.4 ha
P (mm) Si+Gi (mm) E (mm) AET (mm) P ( 103 m3) Si+Gi ( 103 m3) ET ( 103 m3) SH ( 103 m3) D level (mm) Water level (mm)
(C) Ballestera
October
48
November
69
December
78
January
76
February
62
March
52
April
53
May
36
June
16
July
4
August
16
September 17
Total
527
0
0
0
26
20
7
1
0
0
0
0
0
54
90.8 48.0
58.6 34.0
38.1 20.0
40.5 17.9
54.9 22.2
83.6 37.2
89.9 50.9
115.4 82.4
178.4 69.6
218.6
4.0
201.6 16.0
151.0 17.0
1321.4 419.2
12.2
17.5
19.8
19.3
15.7
13.2
13.5
9.1
4.1
1.0
4.1
4.3
133.9
0.0
0.0
0.0
30.6
23.8
8.9
1.3
0.0
0.0
0.0
0.0
0.0
64.5
12.2
8.6
5.1
10.3
13.9
21.2
22.8
29.3
45.3
21.1
4.1
4.3
198.3
0.0
8.9
23.6
25.4
25.4
25.4
25.4
25.4
20.1
0.0
0.0
0.0
0.0
0.0
0.0
148.8
100.8
3.2
32.0
79.4
141.5
0.0
0.0
0.0
0.0
0.0
0.0
148.8
249.6
252.9
220.9
141.5
0.0
0.0
0.0
0.0
All symbols are explained within the text.
ET, evapotranspiration; E, evaporation from the flooded surface; P, direct precipitation onto the playa lake; Si, surface water inflow; Gi, subsurface runoff;
SW, surface of watershed; SPL, flooded surface of the lake; AET, actual evapotranspiration; SH, soil humidity; PET, potential evapotranspiration.
could be explained by regional groundwater recharge from
the playa lake to the O-LL aquifer. Piezometric data (Figs 3,
7 and 8) support this idea, because the Calderón playa lake
is situated at 157 m a.s.l. Piezometric measurements (September 2004) indicate that the water level in this sector is
8
close to 150 m a.s.l. Therefore, this playa lake is perched
with respect to the saturated zone of the O-LL aquifer and
can contribute to the recharge of the groundwater body.
The Ballestera playa lake has an average flooded surface
area of 25.4 ha and a catchment area of 145 ha. The
c 2007 The Authors. Journal compilation c 2007 CIWEM.
Water and Environment Journal (2007) M. Rodrı́guez-Rodrı́guez et al.
Hydrogeological characteristics of a groundwater-dependent ecosystem
D
C
400
Palomarejo hill
Osuna
300
Calderón
200
Diapiric movements
100
0
5
0
10
20
15
25 km
C
Local groundwater flow
A
B
La Lantejuela
Regional groundwater flow
Functional playa lake
Drained playa lake
Highway, roads
Rivers
Altitude (m a.s.l.)
Playa lake
Towns
average precipitation onto the surface is 134 103 m3/
year. Surface runoff from the catchment area is estimated
to be 64.5 103 m3/year. The model predicts
198.3 103 m3/year of ET (Table 2C). Under these conditions, the hydroperiod would last from January to the end
of June, and the water level would reach a maximum of
25 cm in the months of February and March. A remarkable similarity exists between the forecasts of the model
and the existing information about the actual hydroperiod of the playa lake. The position of the playa lake
(145.5 m a.s.l.) with respect to the piezometric level of
the O-LL aquifer in this sector (145 m a.s.l.) indicates that
a hydraulic connection between the two systems may
exist. The hydraulic potential may be greater in the playa
D
Fig. 8. Cross section of the Osuna-La Lantejuela
aquifer showing the direction of local and regional groundwater flow.
lake or in the aquifer depending on the hydrological
season. In such a situation, the water of the playa lake
could recharge the aquifer in winter and vice versa. A
simple scheme of the hydrological regime in both playa
lakes and their relation with the O-LL aquifer is presented
in Fig. 7. Systematic piezometric information and detailed
geochemical investigation of this system are needed in
order to confirm this hypothesis.
Geomorphologic features: the fluvial network
The main rivers of the study zone flow in a N–NW
direction, from the southern highlands to the Guadalquivir river basin. From west to east, these rivers are the
c 2007 The Authors. Journal compilation c 2007 CIWEM.
Water and Environment Journal (2007) 9
Hydrogeological characteristics of a groundwater-dependent ecosystem
M. Rodrı́guez-Rodrı́guez et al.
Diapiric processes can be justified by the presence of
Triassic evaporitic materials, as reported by several
authors for nearby areas (Garcı́a et al. 1991; Pérez & Sanz
1994; Calaforra & Pulido-Bosch 1999).
Radial annular drainage network
Conclusions
Palomarejo hill
Blanco River
Salado River
Endorheic complex of La Lantejuela
Peinado River
Cor
bon
es R
iver
Fluvial–lacustrine sediments
Fig. 9. The radial-annular drainage network around the Palomarejo hill
can show the existence of a diapiric structure. The lakes of the endorheic
complex of La Lantejuela are located around the peripheral depression.
Corbones, the Peinado, the Salado (of Osuna) and the
Blanco. Around the Palomarejo hill, with a subcircular
shape and a diameter of more than 10 km, a remarkable
distortion in the general disposition of the drainage network can be observed (Fig. 9). A fluvial network of radialannular shape has developed in the hill, although this
network is very disorganized and presents numerous
endorheic areas, where the playa lake complex of La
Lantejuela is located. The playa lakes occupy a semicircular area to the south of the Palomarejo hill (Fig. 9).
The morphology of the relief and the distribution of the
fluvial network seem to indicate the existence of a diapiric
structure. Accordingly, the Palomarejo hill would correspond to a diapiric dome and the lacustrine complex,
the filling of the peripheral basin formed in the southern
part of the diapir. The existence of active diapiric processes
would explain the modification of the fluvial network
pattern and the formation of the lacustrine basins as well
as the detritic O-LL aquifer (Moral et al. 2006) due to
fluvial–lacustrine sedimentation in the great endorheic
river basins formed (such as that of the Salado River
continental fan delta) formed in the river trajectory before
the diapiric structure (Fig. 9).
10
(1) To the north of Osuna (southern Spain), Triassic
evaporitic materials (Keuper) are abundant. In many
places, Neogene and Quaternary materials are located
above the Triassic clays, and in this area they constitute
the O-LL aquifer.
(2) In the northern sector of the aquifer is the endorheic
complex of La Lantejuela, comprising nine playa lakes.
The analysis of hydrogeological measurements serves to
detect the existence of local groundwater feeding to the
playa lakes. These are related to the O-LL aquifer, constituting local discharge zones and inducing a centripetal
groundwater flow into the playa lakes.
(3) However, drainage works in these wetlands and
intensive groundwater pumping have considerably modified the hydrological relations between the aquifer and
the playa lakes. Advances in understanding these interactions and pressures are needed for a correct hydrological
management of this type of groundwater-dependent ecosystem in the framework of the European WFD.
(4) The geologic and geomorphologic characteristics – the
radial-annular fluvial network – of the area seem to
indicate that a diapiric structure is responsible for the
formation of the relief of the Palomarejo hill, of the basins
where the playa lakes are located and of the O-LL
Plio-Quaternary detritic aquifer.
Acknowledgements
This work is a contribution to the projects ‘Definition of the
Hydrogeological Context of Andalusian Wetlands’ (Guadalquivir River Basin Authority) and IGCP-448 of UNESCO and has been carried out by the Research Group RNM126 of the Andalusian Autonomous Government. The
critical comments of the anonymous reviewers and the
Editor have helped us to improve the quality of this paper.
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