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How much rainwater contributes to a spring discharge in the Guarani Aquifer System: insights from stable isotopes and a mass balance model.
Donadelli Sacchi, Marcelo; Lilla Manzione, Rodrigo; Gastmans, Didier.
Afiliação
  • Donadelli Sacchi M; Environmental Studies Center, São Paulo State University (UNESP), Rio Claro, Brazil.
  • Lilla Manzione R; Environmental Studies Center, São Paulo State University (UNESP), Rio Claro, Brazil.
  • Gastmans D; School of Sciences, Technology and Education, São Paulo State University (UNESP), Ourinhos, Brazil.
Isotopes Environ Health Stud ; 60(4): 400-416, 2024 Aug.
Article em En | MEDLINE | ID: mdl-39225440
ABSTRACT
Outcrops play an important role in groundwater recharge. Understanding groundwater origins, dynamics and its correlation with different water sources is essential for effective water resources management and planning in terms of quantity and quality. In the case of the Guarani Aquifer System (GAS) outcrop areas are particularly vulnerable to groundwater pollution due to direct recharge processes. This study focuses on the Alto Jacaré-Pepira sub-basin, a watershed near Brotas, a city in the central region of the state of São Paulo, Brazil, where groundwater is vital for supporting tourism, agriculture, urban water supply, creeks, river and wetlands. The area has a humid tropical climate with periods of both intense rainfall and drought, and the rivers remain perennial throughout the year. Therefore, the aim of this study is to investigate the interconnections between a spring and its potential sources of contribution, namely rain and groundwater, in order to elucidate the relationships between the different water sources. To achieve this, on-site monitoring of groundwater depth, rainfall amount, and stable isotope ratios (deuterium (2H) and oxygen-18 (18O)) from rain, spring discharge, and a monitoring well was carried out from 2013 to 2021. The results indicate that the mean and standard deviations for δ18O in rainwater exhibit higher variability, resulting in -4.49 ± 3.18 ‰ VSMOW, while δ18O values from the well show minor variations, similar to those of the spring, recording -7.25 ± 0.32 ‰ and -6.94 ± 0.28 ‰ VSMOW, respectively. The mixing model's outcomes reveal seasonal variations in water sources contribution and indicate that groundwater accounts for approximately 80 % of spring discharge throughout the year. Incorporating stable isotopes into hydrological monitoring provides valuable data for complementing watershed analysis. The values obtained support the significance of the aquifer as a primary source, thereby offering critical insights into stream dynamics of the region.
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Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Isótopos de Oxigênio / Chuva / Água Subterrânea / Monitoramento Ambiental / Deutério País/Região como assunto: America do sul / Brasil Idioma: En Revista: Isotopes Environ Health Stud Assunto da revista: SAUDE AMBIENTAL Ano de publicação: 2024 Tipo de documento: Article País de afiliação: Brasil País de publicação: Reino Unido

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Isótopos de Oxigênio / Chuva / Água Subterrânea / Monitoramento Ambiental / Deutério País/Região como assunto: America do sul / Brasil Idioma: En Revista: Isotopes Environ Health Stud Assunto da revista: SAUDE AMBIENTAL Ano de publicação: 2024 Tipo de documento: Article País de afiliação: Brasil País de publicação: Reino Unido