COMUNICAÇÃO TÉCNICA ______________________________________________________________________________________________________________________________________________________________________________________________________

176309

The sustainability of non-renewable groundwater from Guarani Aquifer System (GAS): a case study in a city at São Paulo State, Brazil Tatiana Tavares José Luiz Albuquerque Filho Nádia Correa Luiz Gustavo Faccini Elis Miguele de Sá Emilio Prandi Suraya Modaelli Sergio de Oliveira

Abstract 46th.International Association Hydrogeologists Congress, IAH 2019, Malaga, Spain.

A série “Comunicação Técnica” compreende trabalhos elaborados por técnicos do IPT, apresentados em eventos, publicados em revistas especializadas ou quando seu conteúdo apresentar relevância pública. ___________________________________________________________________________________________________

Instituto de Pesquisas Tecnológicas do Estado de São Paulo S/A - IPT

Av. Prof. Almeida Prado, 532 | Cidade Universitária ou Caixa Postal 0141 | CEP 01064-970

São Paulo | SP | Brasil | CEP 05508-901 Tel 11 3767 4374/4000 | Fax 11 3767-4099

www.ipt.br

MOTIVATION – WHAT IS IMPORTANT?

•The west of São Paulo State – Brazil has a huge dependency on groundwater resources;

• Within an area of approximately 800 km2, there are 09 deep pumping wells in the GAS;

•The Marilia municipality, the biggest city, is supplied by GAS with 1,300 m3/h (33.3% of

the total water resources), with 05 pumping wells;

• The pumped groundwater is being ‘mined’ from the aquifer storage with continuously (but

very gradually) falling potentiometric surface. Residual drawdown between 48 to 59.5 m is

observed in 03 of the pumping wells located at Marilia in a pumping period of 23 years

(Prandi et al, 2013).

•This study was made to help to understand the behavior of the groundwater by measuring

the variation of the groundwater level with the pumping schemes.

RESULTS

CONCLUSIONS

� The SAG drawdown at the region is still in course. In approximately twenty years, the potentiometric

surface decline at a medium of 50 m.

� The results of the PG 2 monitoring showed that there is interference between the pumping wells,

varying the dynamic level in a maximum of 1,6 m at the PG 2.

� The monitoring period was relatively short and has to be maintained with improvements in the

monitoring equipment, to perform a consistent and constant monitoring program.

� The aquifer system characterization - quantification of aquifer storage reserves - specific yields,

assessment of contemporary recharge rates and appraisal of depletion trends, is essential to provide

adequate predictions (Lloyd,1999), to define restriction areas and control of abstraction and use of

groundwater.

REFERENCES

BORGHETTI, N. R.; BORGHETTI, J. R.; FILHO, E. F. R. 2004. Aquífero Guarani: a verdadeira integração dos países do

Mercosul. Curitiba, 2004. 214 p.

IPT - Mapa Geológico do Estado de São Paulo, Divisão de Minas e Geologia Aplicada, volumes I e II, São Paulo, 1981.

IRITANI, M. A.; EZAKI, S. 2012. As águas subterrâneas do Estado de São Paulo. São Paulo : Secretaria de Estado do

Meio Ambiente - SMA, 2012.

LLOYD J.W. 1999. An overview of groundwater management in arid climates. – Livro: Water Management,Purification

and Conservation in Arid Climates, cap. 2, pgs 9-52. Technomic, Lancaster, USA.

PRANDI, E. C.; FILHO, J. A. O.; POLEGATO, J. C.; SILVA, L. A. 2013. Aspectos do Aquífero Guarani na região de Marília –

SP. 1st Joint World Congress on Groundwater.

Figure 1. Location of the area (modified from Borghetti et al, 2004).

THE SUSTAINABILITY OF NON-RENEWABLE GROUNDWATER FROM GUARANI AQUIFER SYSTEM (GAS) – A CASE STUDY IN A CITY AT SÃO PAULO

STATE, BRAZIL

Tavares, Tatiana 1, Albuquerque Filho, José Luiz 1; Correa, Nádia1, Faccini, Luiz Gustavo 1, de Sá, Elis Miguele 1,

Prandi, Emílio 2, Modaelli, Suraya 2, de Oliveira, Sergio 3

1 Technological Research Institute - IPT /LABGEO/CTGeo, 2 Department of Water and Electric Energy of the

State of São Paulo – DAEE, 3 Biologist, São Paulo, SP, Brazil

�Marilia Formation

Poorly selected sandstone, fine to coarse, compacted, with carbonatic

cementation, concretions and nodules. With conglomerated levels and claystone

and siltstone lenses.

�Adamantina Formation

Fine to much fine sandstones, with claystone and siltstone lenses, and secondary

medium quartz sandstones, locally arcosian, with moderated carbonate

cementation.

ACTIVITIES� Maps / Cartographic Survey;

� Database preparation of the 09 deep GAS wells with well log, chemical analysis and

groundwater level data;

� Well selection, installation of the monitoring equipments and download the monitoring

data along 02 years;

� Consolidation and interpretation of data;

� Management recommendations.

Figure 2. Activities and Geologic map.

Figure 4. Dynamic water level x time on PG 2.

Figure 3. Geological cross-section A-A’.

�Araçatuba Formation

Gray-green to brownish sandy silt and claystone, with minor carbonatic cementation, and levels of sandstone and

fine clay sandstones.

�Serra Geral Formation

Hard brown to dark grey basalt, mainly with afanitic texture, and sometimes brecciated, fractured, weathered, or

microfactrurated, with amygdaloidal / vesicular textures, filled with calcite and green zeolites. There are intertraps

composed by fine sandstones.

�Botucatu Formation

Fine to medium uniform sandstones, well selected and high sphericity. Medium to large tangencial cross

stratification are predominat. At the base of the formation, lenses of heterogeneous medium to coarse sandstones

are common, with a gradation to conglomeratic sandstones. (IPT, 1981).

�Pirambóia Formation

Fine to medium sandstones, with clay predominantely at the base of the formation, and coarse conglomeratic

sandstones towards to the top. The plane-parallel estratification is predominant, but medium to large cross

estratification tangencial type are common, as well as ripples and current marks (IPT,1981).

Source: Iritani & Ezaki (2012)

Abstract to 46th IAH Congress Malaga 2019

Topic 3 - Groundwater sustainability and governance

The sustainability of non-renewable groundwater from Guarani Aquifer System – A case study in a city at São Paulo State, Brazil Tavares, Tatiana 1, Albuquerque Filho, José Luiz 1; Correa Franqueiro, Nádia 1, Faccini, Luiz

Gustavo 1, de Sá, Elis Miguele 1, Prandi, Emílio 2, Modaelli, Suraya 2, de Oliveira, Sergio 3

KEY WORDS – Guarani Aquifer, non-renewable groundwater, groundwater management,

sustainability

The Guarani Aquifer (SAG) in South America is a huge hydrogeological system that underlies an

area of about 1,100,000 km2, mainly distributed in Brazil (62%), Paraguay, Uruguay and

Argentina, is composed by a sequence of sandstone beds, mainly weakly-cemented, of

Triassic-Jurassic age, formed by the processes of continental deposition (aeolic, fluvial and

lacustrine). The average thickness is about 250 m, varying from < 50m to > 600m, and reaches

depths of over 1,000 m (Foster et al., 2009).

The west of São Paulo State - Brazil, where is localized the study area, has a huge dependency

on groundwater resources, since the surface water resources are distant from the urban

centers. Around the Marilia municipality, within an area of approximately 800 km2, there are

nine pumping wells in the SAG. The Marilia municipality, the biggest city at the study area, is

supplied by SAG with 1,300 m3/h (33,3% of the total water resources), with five pumping wells.

In this region, the average thickness of SAG is about 218 m, with minimum of 180 m and

maximum of 254 m, and the thickness of basalt varies between 564 and 785 m. This portion of

SAG belongs to the IV resource management zone classified by Foster et al. (2009) as “Deep

Confined Zone”, where pumped groundwater is being ‘mined’ from aquifer storage with

continuously (but very gradually) falling potentiometric surface. Prandi et al. (2013) identified

residual drawdown varying between 48 a 59.5 m in three of the SAG pumping wells located at

Marilia since 1990.

Within this scenario, five SAG’s pumping wells were monitored for two years with the

objective to measure the variation of the groundwater level with the pumping schemes. The

activities developed consisted by the preparation of a database, well selection and installation

of the monitoring equipments, download the monitoring data, consolidation and

interpretation of data, and management recommendations were given.

Besides of many problems during the two years monitoring, some results could be described.

The SAG drawdown is happening at the region and still in course. In approximately twenty

years, the potenctiometric surface decline at maximum 60 m. The hydraulic gradient between

the pumping wells is lower in comparison with at the beginning of the pumping, and bigger

between these pumping wells and other closest confined SAG wells.

Considering that the SAG is a transboundary aquifer and the west of São Paulo State is very

dependent of groundwater resources, this region demands a consistent and constant

monitoring program. The aquifer system characterization (quantification of aquifer storage

reserves – specific yields, assessment of contemporary recharge rates and appraisal of

depletion trends) to provide adequate predictions is essential (Lloyd,1999) to define restriction

areas and control of abstraction and use of groundwater.