electrical conductivity and depth of groundwater at the pergamino zone (buenos aires province,...

Electrical conductivity and depth of groundwater at the Pergamino zone

(Buenos Aires Province, Argentina) through vertical electrical soundings

and geostatistical analysis

Claudia Sainatoa,*, Griselda Galindob, Cristina Pomposielloc, Horacio Mallevillea,Diego de Abelleyraa, B. Losinnoa

aCatedra de Fısica, Facultad de Agronomıa, Universidad de Buenos Aires, Av. San Martın, 4453 (1417DSQ), Buenos Aires, ArgentinabFacultad de Ciencias Exactas y Naturales, UBA, Depto. De Geologıa, Ciudad Universitaria, Pab. II, Buenos Aires, Argentina

cINGEIS-CONICET, Ciudad Universitaria, Buenos Aires, Argentina

Received 1 August 2001; accepted 1 January 2003

Abstract

In the humid Pampean region of Argentina, a rich agricultural zone, the periodic occurrence of droughts of different intensity is one

of the most important factors in the variability of crop yield. Because complementary irrigation is a highly efficient resource to

increase such yields, an understanding of groundwater resources is important. This knowledge is limited in topographically smooth

zones by the absence of outcroppings and observation boreholes. Water conductivity is another limitation factor if the goal is to avoid

soil degradation by irrigation and negative effects for animal and human consumption. The aquifers of the northeastern zone of the

Buenos Aires province have been studied regionally, but information at the local scale is limited to sparse boreholes.

In this work, a survey using vertical electrical soundings was carried out to determine the depth, thickness, and continuity of

shallower aquifers. Both a mapping of the water table and the electrical conductivity distribution of free aquifers were achieved from

well data and geophysical results using geostatistical techniques. Recharge areas of the aquifer were recognized as those areas with

low conductivity and topographic highs. The discharge areas, mainly at the bed of the Pergamino River, have higher values of

conductivity; two zones north and south of the city of Pergamino have conductivities greater than 2000 mS cm21. Isolines of depth to

the fresh-salty water interface showed different values over the Pergamino River, with some local maxima at the swamp zone and

near Pergamino.

q 2003 Elsevier Science Ltd. All rights reserved.

Keywords: Electrical conductivity; Geostatistics; Groundwater; Vertical electrical soundings

Resumen

En la region de la Pampa Humeda de Argentina, una zona agrıcola muy rica, la ocurrencia de sequıas de diferente intensidad

periodicamente es una de las causas mas importantes de variabilidad en los rendimientos de los cultivos. El riego complementario es un

recurso altamente eficiente para incrementar esos rendimientos. El conocimiento de los recursos de agua subterranea es entonces un punto

importante para desarrollar esta tecnologıa, estando limitado como en otras zonas de llanura por la ausencia de afloramientos y la escasez de

perforaciones de observacion. La conductividad del agua es un factor limitante para evitar degradacion de suelos por riego y efectos

negativos en el consumo animal y humano. Los acuıferos de la zona noreste de la Provincia de Buenos Aires fueron estudiados regionalmente

pero no hay suficiente informacion a escala local, limitada a escasas perforaciones.

En este trabajo, se realizo una exploracion por medio de Sondeos Electricos Verticales (SEV) determinando profundidad, espesor y

continuidad de los acuıferos mas superficiales. Se llevo a cabo un mapeo del nivel freatico ası como de la distribucion de la conductividad

electrica del acuıfero libre a partir de datos de pozos y de los resultados geofısicos usando tecnicas geoestadısticas. Fueron reconocidas las

areas de recarga del acuıfero freatico que tienen baja conductividad electrica coincidentes con altos topograficos. Se encontro que las areas de

descarga, principalmente en el cauce del arroyo Pergamino, tienen valores mas altos de conductividad. Particularmente, dos zonas en el norte

y el sur de la ciudad de Pergamino tienen conductividades mayores que 2000 mS cm21. Las isolıneas de profundidades de la interfase agua

0895-9811/03/$ - see front matter q 2003 Elsevier Science Ltd. All rights reserved.

doi:10.1016/S0895-9811(03)00027-0

Journal of South American Earth Sciences 16 (2003) 177–186

www.elsevier.com/locate/jsames

* Corresponding author. Fax: þ54-11-45248099.

E-mail address: [email protected] (C. Sainato).

http://www.elsevier.com/locate/jsames

dulce-agua salada mostraron valores diferentes cruzando el arroyo Pergamino y algunos maximos locales en la zona de los banados y cerca

de la ciudad de Pergamino.

q 2003 Elsevier Science Ltd. All rights reserved.

1. Introduction

The Pampean plain (Humid Pampa) situated north of

Buenos Aires, Argentina (Fig. 1), is a very rich

agriculture zone. The demand for complementary irriga-

tion has grown in this area because of the crop yield

increases produced by the application of irrigation

technology in zones where dry and humid periods alter

climatic conditions. However, exploitation of ground-

water without knowledge of its features and potentialities

risks the sustainable development of this resource.

Furthermore, there is an increasing problem of sodifica-

tion of soils due to the use of poor quality water for

irrigation (Andriulo et al., 1998). The aquifers of the

northeastern zone of the Buenos Aires province have

been studied regionally (e.g. Santa Cruz, 1987; Sala

and Rojo, 1994; Usunoff, 1994), but local-scale studies

of groundwater resources are insufficient because

the hydrogeological and geophysical data are limited

and sparse. The hydrogeology of the Buenos Aires

province is difficult to determine because its smooth

topography limits observation of outcroppings and

requires instead analysis of drilling profiles through

interpolated information. Santa Cruz (1994) and Santa

Cruz and Silva Busso (1995) have characterized a

shallow aquifer, called ‘Pampeano’, through a regional

study with vertical electrical soundings (VES). They

establish a layer of 8–25 Vm of electrical resistivity,

with a thickness of 20–140 m, associated with the

Pampeano aquifer and, at some places, with the

underlying Puelche aquifer. In most sites, a conductive

layer with resistivities between 1–6 Vm was found at

greater depth, associated with the parts of the Pampeano

and Puelche aquifers that contain water of high salinity.

However, Irigoyen (1975) shows that, in geological

sections at the Buenos Aires province, great variations

Fig. 1. Geological map of the location of the study zone in the northern part of Buenos Aires province, Argentina. From Secretarıa de Industria, Comercio y

Minerıa, Gobierno de la Pcia. De Buenos Aires, Argentina.

C. Sainato et al. / Journal of South American Earth Sciences 16 (2003) 177–186178

in the depth of the aquifers may be due to a system of

faults. Different depths to the fresh-salty water interface

were found at Pergamino at both margins of the river

(Pergamino Municipality, pers. comm.).

Therefore, it is necessary to perform local surveys to

determine the depth of the fresh-salty water interface before

drilling projects are started. It is also helpful to understand

the features of the groundwater, which is used for various

agricultural purposes and reflects the hydraulic behavior of

deeper aquifers, as noted by Sala (1975).

Eight VES were performed by Sainato et al. (1997) NW

of Pergamino (NE of Buenos Aires province) to study some

features of the aquifers at the hydrogeological basin of the

Pergamino River. Because of the lack of well data, it is

difficult to determine water properties across the whole

zone. The aim of this work is to obtain the depth and

thicknesses of the aquifers, especially the fresh-salty water

interface, by carrying out nine new VES. The areal

distribution of the water table and the electrical conductivity

of free aquifers were obtained through disposable

information, well data, geophysical results, and geostatis-

tics, taking account the spatial variability of these data.

2. Study area: geological and hydrogeological setting

The study zone is NE of Buenos Aires province,

Argentina. The quaternary sediments, mainly loessic silt,

cover the study zone. There are very few wells in the area,

and no geological cross-sections in the study zone are

available. At the Rosario basin, where the Pergamino zone

is located, the sedimentary sequence is placed over basalts

equivalent to those of Serra Geral, which is found in the

Argentine Mesopotamia. The top of the formation is deeper

at our study zone, reaching approximately 800 m depth

(Fernandez Garrasino and Urba, 1999).

Three main hydrogeological units are recognized at the

Pergamino zone: the Hipoparaniana, the Paraniana, and the

Epiparaniana. Sala (1969) and Sala et al. (1983) describe

them as follows: the tertiary sediments of the Hipoparaniana

section are above the impermeable basement. The lower

part of this section is called the ‘Red Miocene’ and is

formed by sandstones and red clays with an intercalation of

ash and gypsum of continental origin. The thickness reaches

up to 250 m, and its top is 400–500 m depth, deepening to

the southwest. The water is generally salty.

The Paraniana section is formed by marine sediments

called ‘Green Miocene’ (upper Miocene). It is formed by

gray–blue and green clays with some intercalation of sand

(Parana formation). Its thickness varies between 75–135 m.

This section contains very saline water.

The Epiparaniana section is located above the Green

Miocene and contains horizontal and vertical flows that

represent the recharge or discharge path of the deeper

aquifers. It is formed by the Puelches Formation (upper

tertiary–quaternary) and the sediments of the Pampeano

(quaternary) and post-Pampeano. The Puelches sands

constitute a semiconfined aquifer and appear as quartzi-

ferous yellowish sands of medium grain, with intercala-

tions of gravel at greater depths and silt contents at lesser

depths. Santa Cruz and Silva Busso (1995) report a

variable thickness from 10 to 25 m and a top between 50

and 100 m depth, approximately. Water quality of the

Puelches aquifer is worse to the west of the northern

Buenos Aires province (Santa Cruz and Silva Busso,

1995), where saline residual values are greater than

2 g l21. To the east, better quality conditions are indicated

by values ,500 mg l21. Salinity varies with the zone

(recharge and discharge areas). In general, it is considered

a bicarbonate sodium water type.

The Pampeano aquifier, whose thickness may vary

between 20 and 120 m (Santa Cruz and Silva Busso,

1995), contains a phreatic aquifer and some deeper,

semiconfined aquifers. It has a sequence of permeable

(with greater contents of sand) and impermeable (more

clayey) horizontally layered levels, which constitute a

multiple or multiunitarian aquifer. There are also nodules

and continuous layers of permeable calcareous, formed by

agglomerates with spherical shapes. In general, the

direction of the regional phreatic runoff at the northern

part of the Buenos Aires province is W–NW to E–SE,

with local variations at the different hydrogeological

basins. There is an autochthonous recharge (by means of

precipitation) and indirect recharge by upward flow added

to the regional horizontal component (Santa Cruz and

Silva Busso, 1995). The Pampeano aquifer shows an

increase in water salinity to the west; the dry residue is

800 mg l21 at Arrecifes (approximately 50 km SE of the

study zone) and 1000 mg l21 at Pergamino. The water

type is bicarbonate sodium. The salinity of this section

increases at the flooding plains and toward the beds

(discharge zones) with values of conductivity s

.1000 mS cm21 N and S of Pergamino.

3. Geophysical prospecting

Nine VES, which together with previous soundings of

Sainato et al. (1997) constitute a set of 17 VES (Fig. 2), were

carried out using the Schlumberger array. For these

soundings, distances (AB) of up to 1000 m at some sites

and 2000 m at others were reached. The use of the whole set

of soundings enabled a better description of the features of

the aquifers.

Models of electrical resistivity of the earth varying with

depth (horizontally layered, medium, one-dimensional

(1D)) were proposed for each site. The responses of

apparent resistivity fit the experimental data in a least

square sense. An inversion 1D modeling code (Cooper,

1992) was used. Curves of experimental apparent resistivity

as a function of the semidistance between current electrodes

C. Sainato et al. / Journal of South American Earth Sciences 16 (2003) 177–186 179

(AB/2), together with the model fit, are shown in Fig. 3 for

the nine new sites.

There are no wells with geologic logs in the study

area, except at the city or towns, where two (M. Ocampo

and M. Alfonzo) are located a few km from sites VES17

and VES3, respectively. Their lithological descriptions

(Fig. 4) were compared with VES models. The

relationship between electrical layers and lithology is

mainly based on clay sediments being less resistive than

sands. Well data from Fig. 4 do not provide great

contrast in the type of sediments. The presence of a

calcareous crust may increase the resistivity of the layer

that includes it, but it is likely that contrasts in

resistivities are mainly due to water resistivity.

Electrical sections were constructed with 1D models at

each site (Fig. 2) in two profiles, AA0 and BB0, across

the river bed. The electrical sections with resistivities and

associated lithology are shown in Fig. 4. Well data at

M. Alfonzo and M. Ocampo were used for the

interpretation of profiles AA0 and BB0, respectively.

4. VES results

The first layer in the profiles, with electrical resistivities

between 7 and 33 Vm, corresponds to the unsaturated zone

with loessic silt, and the first change in resistivity indicates

the top of the Pampeano aquifer, where, at its upper part, the

water table aquifer is located.

In profile AA0, the groundwater level is at depths ,5 m.

Beneath the water table, changes in electrical resistivity are

influenced by lithology and water quality. From the

soundings, two layers may be recognized with resistivities

between 4 and 38 Vm, with the lower more resistive. The

upper layer is considered clayey silt with calcareous (as

indicated by different layers of the M. Alfonzo well), and

the lower has greater values of resistivities (15–38 Vm)

with more sand content. The presence of calcareous

intercalations (Sala and Rojo, 1994) as nodules or

continuous plates may increase the resistivity of the layers.

A lens of higher resistivity appears beneath SEV12, perhaps

with a great content of calcareous crust, but the poor fitting

Fig. 2. Study zone showing sites of VES.


of this site may indicate lateral inhomogeneities not taken

into account in a 1D model. Below, a more conductive layer

appears (r , 5 Vm). The sounding at the left margin of the

Pergamino River (VES6) shows a greater depth of the

conductive layer than at VES12 and VES3 at the right

margin. The very conductive layer is at 28 m depth to the

SW and 60 m depth at VES6. Very low resistivity values

(,5 Vm) may be attributed to the deterioration of water

quality because the lower Puelche aquifier is composed of

sand. However, because there are no well data for this depth,

we cannot confirm that this layer corresponds to the Puelche

aquifer—which at areas in the western part of Buenos Aires

province was known to have high salinity water values—or

if it also includes the underlying Green Miocene Formation.

The top of this layer deepens toward VES6.

In profile BB0, the groundwater level is at ,5 m depth.

Below, there is a lower resistivity layer

(3 Vm , r , 41 Vm; Pampeano aquifer with silty–clayey

or clayey–silty sediments from M. Ocampo well) with

intercalations of layers of higher resistivity beneath the bed

of the river. This irregular sequence may be influenced by the

river’s dragging material. At VES13, the greater data misfit

may indicate the presence of lateral inhomogeneities. Below,

a silty layer with intercalations of sands and calcareous (M.

Ocampo well) is more resistive. Beneath that, the conductive

layer, which corresponds to a deterioration of water quality,

may be observed to correspond to salty strata of the lower

Puelche or Green Miocene Formation. Its top lies between 30

and 60 m depth, deepening across the river in the NE.

Different depths to the top of the conductive layer were

found. Sites VES9 and VES6 are separated by the Botija

River, a tributary of the Pergamino Stream. At 25–30 m

depth, electrical resistivity is higher at VES9 (113 Vm) than

at VES6 (15 Vm). The top of the conductive layer is at 60 m

(VES6) or 40 m (VES9) depth. In profile BB0, the top of the

salty aquifers deepen to the left margin of the Pergamino

Fig. 3. Fit of 1D model response to experimental apparent resistivity curves from VES.


Fig. 4. Profiles AA0 and BB0 with geoelectrical sections and the associated lithology of two wells, M. Alfonzo and M. Ocampo.


River (NE). These features may be evidence of structural

controls. Cross-sections at different places in the province

show fractures that caused stratigraphic throw in the Red

and Green Miocene Formations (Irigoyen, 1975). Reactiva-

tion of some faults affected the shallower and more recent

formations. Wells at Pergamino, located at both margins of

the river, also show different depths of the fresh-salty water

interface (Pergamino Municipality, pers. comm.).

4.1. Geostatistical analysis of depth and electrical

conductivity of aquifers

To study the spatial distribution of the groundwater

properties at the Pergamino basin, a geostatistical analysis

was carried out to map such properties in the study area. The

geostatistical interpolation, called kriging (Trangmar et al.,

1985; Webster, 1985), is a common tool to achieve this

purpose and estimates the unknown values inside a grid by

taking into account the spatial correlation of known values. It

thereby provides information when no well data are available.

The variogram (Trangmar et al., 1985) measures the

average dissimilarity between data values of the studied

property as a function of the distance between them.

Through modeling the variograms, the range, the maximum

distance of influence of any data point, is obtained.

In the process of kriging, the value at each point of the

grid is estimated as a linear combination of neighboring

points, where the weights depend on the values of

variogram, thus providing unbiased estimates of minimum

variance (Webster, 1985).

4.2. Mapping of water table and depth to the fresh-salty

water interface

The depth of the phreatic level obtained from the VES

and some well data (INTA Pergamino, pers. comm.) was

Fig. 5. Water table contours showing direction and sense of groundwater flow and water parting, together with VES and well sites.


used to carry out a geostatistical kriging interpolation of the

water table. The isolines of depth to the water table are

shown in Fig. 5, together with well and VES sites.

Groundwater parting and the direction and sense of

groundwater flow are shown and mainly orient toward the

bed of the Pergamino River, with some SE components

coincident with regional flow.

Fig. 6 shows the isolines of depth to the fresh-salty water

interface as provided by kriging. Depths increase below

60 m at the SE zone near Pergamino, surrounding B0

(extreme profile BB0), and the swamp zone on the right

margin of the rivulet. In general, east of 608500W, the top of

the conductive layer deepens toward the NE and raises again

near the Botija River. To the west, the situation reverses,

and the depth of the interface increases to the SW.

4.3. Mapping of the groundwater electrical conductivity

To map water electrical conductivity of the phreatic

aquifer, a cokriging interpolation was carried out that made

use of all the disposable information (VES and wells) and

thus provided a map of higher precision. Cokriging

interpolation allows mapping of one property (primary)

and uses a secondary property spatially correlated with the

first. The value at each point in the grid is a linear

combination of neighboring primary and secondary data. It

makes use of the cross-correlation between the two

variables (Webster, 1985).

In the case of water conductivity, this correlation is based

on the relationship between the bulk electrical conductivity

of the aquifer, sbulk; and the conductivity of water filling the

pores, sw: Using Archie’s law (McNeill, 1990) in the

presence of clay, as is the case for this lithology, this

relationship is as follows:

sbulk ¼ fmsw þ sclay; ð1Þ

where f is the porosity, and m is a factor that depends on

grain shape.

A geostatistical cross-correlation was evaluated between

these two variables because the bulk conductivity obtained

from VES models and water conductivity from samples are

located at different sites. The cross-plot of sbulk versus sw is

estimated for within a search distance; that is, the range for

the bulk conductivity is used as the maximum distance at

which a water sample is associated (Geostat, 1996).

The lineal fitting of cross-plot data (Fig. 7(a)) is

evaluated through the normalized correlation between the

two variables:

s ¼Covsbsw

½Covsw·Covsb�; ð2Þ

as estimated with Geostat (1996) program.

The resulting fit shows a slope of 0.207 and a sclay value

of 550 mS cm21. The m value, depending on the shape of

particles, was taken as an average of 1.5 between possible

values (McNeill, 1990). This results in a porosity f of 35%,

which is in agreement with general values known for this

type of lithology (silty/clayey) (McNeill, 1990).

Water conductivity obtained from wells ðswÞ (primary

property), together with the bulk conductivity values ðsbÞ

Fig. 6. Isolines of depth, in meters, to the fresh-salty water interface.


of the phreatic layer from VES (secondary property), was

used to interpolate sw by cokriging, taking into account

the spatial correlation estimated between the two

variables (fit of Eq. (1)). The mapping of the conduc-

tivity of the phreatic aquifer is shown in Fig. 7(b) These

results show good quality salinity zones ðs , 1000 mS �

cm21Þ to the north near M. Ocampo and to the south at

M. Alfonzo. They coincide with recharge areas or

transition zones with greater slopes of the hydraulic

gradient (Fig. 5). Good quality zones are characterized to

the south by a soil texture that enables the quick

circulation of infiltrated water (Argiudoll soils) and a

moderate hydraulic gradient. Higher conductivity zones

appear near the bed of the Pergamino River, a discharge

area. There are also two zones of highest conductivity.

At the northwestern topographic depression of the swamp

zone, conductivity is s . 1800 mS cm21, and the

hydraulic gradient is rather gentle. To the southeast,

conductivity is s . 2000 mS cm21 close to the north and

south of Pergamino, which coincides with transition areas

that contain a component of groundwater flow to the SE.

Surrounding VES6 and VES7, there is a slight slope of

the water table.

Less permeable soils (Natracuolls) with deficient drai-

nage found along the river (discharge zone) and the low

hydraulic gradients at different places in the study area

Fig. 7. (a) Cross-correlation of bulk electrical resistivity ðsbÞ and water conductivity ðswÞ for the phreatic aquifer. Regression line (correlation coefficient 0.8).

(b) Mapping of water conductivity ðswÞ for phreatic aquifer using cokriging between ðsbÞ obtained from VES and sw from well data.


cause a greater time of residence, and water moves more

slowly with a larger time of contact with the subsoil

material, thereby dissolving salts.

5. Conclusions

VES carried out at the study zone have improved the

understanding of groundwater resources. The phreatic

aquifer flow has a recharge that coincides with topographic

high zones, and the discharge is mainly toward the

Pergamino River. The analysis of water electrical conduc-

tivity distribution over the area was performed by

geostatistical cokriging, which enabled the use of not only

well data but also geophysical results. This methodology is

suitable when well data are scarce, as is the case in several

areas of Argentina. Groundwater electrical conductivity is

greater than 1800 mS cm21 at discharge zones where the

soils have a fine texture and at places where the hydraulic

gradient is very small, which increases the water time of

residence. Water of better quality may be found at the

recharge areas or transition zones with a moderate hydraulic

gradient.

The fresh-salty water interface represents a limitation of

the available water for irrigation. Different depths of this

interface were found at two profiles across the river. Water

conductivity greatly increases below 28 m on the right

margin of the Pergamino River and at 60 m depth at the left

margin, which means the top of this conductive layer

deepens to the NE. However, the kriging interpolation of

this interface, using all VES data, confirmed this behavior at

the central part of the stream, and two maximum depths

were also found near the swamp zone and at Pergamino.

Acknowledgements

This work was financially supported by the University of

Buenos Aires. The authors thank Amalia Gonzalez for

helping with the drawings and Daniel de Oto and Martın

Nothardt for their collaboration in the field.

References

Andriulo, A., Galetto, M.L., Ferreyra, C., Cordone, G., Sasal, C., Abrego,

F., Galina, J., Rimatori, F., 1998. Efecto de 11 anos de riego

complementario sobre algunas propiedades del suelo I: Propiedades

fisico-quımicas. XVI Congreso Argentino de la Ciencia del Suelo, Villa

Carlos Paz, Argentina, pp. 247–248

Cooper, G.R.J., 1992. Forward modeling and inversion for Schlumberger

resistivity soundings. Department of Geophysics and Geology.

University of Witwatersrand, South Africa, http://www.wits.ac.za/

science/geophysics/gc.htm.

Fernandez Garrasino, C., Urba, A., 1999. Estructura del tope de la

Formacion Serra Geral (Neojurasico–Eocretacico) en la Mesopotamia

argentina y adyacencias. Actas del XIV Congreso Geologico Argentino.

Salta, Argentina, pp. 185–188

Geostat, 1996. Geostatistical Analysis of Well Log and Seismic Data,

Hampson-Russell Software Services Ltd, Calgary, Alberta, Canada.

Irigoyen, M., 1975. Geologıa del subsuelo y plataforma continental.

Relatorio de la Pcia. De Bs. As., VI Congreso Geologico Argentino,

B. Blanca, pp. 139–169

McNeill, J.D., 1990. Use of electromagnetic methods for groundwater

studies. In: Soc. of exploration geophysicists (Eds). Geotechnical and

Environmental Geophysics, Review and Tutorial 1, 191–218.

Sainato, C., Pomposiello, M.C., Galindo, G., Malleville, H., 1997. Estudio

geoelectrico aplicado a la evaluacion de recursos hıdricos subterraneos

en la cuenca del arroyo Pergamino (Pcia. de Buenos Aires). Actas del 58

Congresso Internacional da Sociedade Brasileira de Geofısica, San

Pablo, Brasil 1, 435pp

Sala, J.M., 1969. In: CIC, (Ed.), El agua subterranea en el NE de la Prov. de

Bs. As. Argentina, Proceedings of the Reunion Geologica del Agua

subterranea, La Plata, Prov. de Bs. As., Argentina, pp. 25–49.

Sala, J.M., 1975. Recursos hıdricos. Relatorio de la Pcia. de Bs. As., VI

Congreso Geologico Argentino, B. Blanca, Argentina, pp. 169–193

Sala, J.M., Gonzalez, N., Kruse, E., 1983. Generalizacion hidrologica de la

Prov. de Bs. As. In: UNESCO, (Ed.), Coloquio internacional sobre

hidrologıa de grandes llanuras, pp. 973–1009.

Sala, J., Rojo, A., 1994. Pasado, presente y futuro de la hidrologıa

subterranea en la Pcia de Buenos Aires, Rep. Arg. In: Bocanegra, E.,

Rapaccini, A. (Eds.), Temas actuales de la hidrologıa subterranea, CFI,

UNMP, pp. 209–224.

Santa Cruz, J., 1987. Caracterizacion del recurso hıdrico subterraneo con

miras al riego suplementario en la region NNE-maicera tıpica de la

Pcia. de Bs. As. (Argentina). Instituto Interamericano de Cooperacion

para la Agricultura. Secretarıa de Agricultura, Ganaderıa y Pesca,

Argentina

Santa Cruz, J., 1994. Aspectos hidrogeologicos e interpretacion de una

nueva caracterıstica formacional de subyacencia del acuıfero Puelches,

Pcia. de Bs. As., Argentina. In: Bocanegra, E., Rapaccini, A. (Eds.),

Temas actuales de la hidrologıa subterranea, CFI, UNMP, pp. 261–272.

Santa Cruz, J., Silva Busso, A., 1995. Disponibilidad del agua subterranea

para riego complementario en las Pcias. de Bs. As., E. Rıos, Cordoba y

Santa Fe. Programa de Servicios Agrıcolas provinciales. Secretarıa de

Agricultura, Ganaderıa y Pesca, Argentina

Trangmar, B.B., Yost, R.S., Uehara, G., 1985. Applications of geostatistics

to spatial studies of soil properties. Advances in Agronomy 38, 45–94.

Usunoff, E.J., 1994. Tecnicas de estudios en llanuras. In: Bocanegra, E.,

Rapaccini, A. (Eds.), Temas actuales de la hidrologıa subterranea, CFI,

UNMP, pp. 103–117.

Webster, R., 1985. Quantitative spatial analysis of soil in the field,

Advances in Soil Science 3, Springer, New York.


http://www.wits.ac.za/science/geophysics/gc.htm.

http://www.wits.ac.za/science/geophysics/gc.htm.

electrical conductivity and depth of groundwater at the pergamino zone (buenos aires province,...

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