Balanço hídrico em zona de afloramento do sistema aqüífero Guarani a partir de monitoramento hidrogeológico em bacia representativa
Data
2017-11-15
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Biblioteca Digital de Teses e Dissertações da USP
Universidade de São Paulo
Escola de Engenharia de São Carlos
Universidade de São Paulo
Escola de Engenharia de São Carlos
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O objetivo principal deste trabalho é estimar a recarga direta e profunda do Sistema Aqüífero Guarani (SAG) na bacia representativa do Ribeirão da Onça. Paralelamente são analisados os comportamentos do aqüífero e da evapotranspiração na bacia. A bacia do Ribeirão da Onça apresenta características representativas típicas da região de afloramento do Sistema Aqüífero Guarani (SAG) no Estado de São Paulo. A bacia do Ribeirão da Onça tem a vantagem de ser uma bacia amplamente estudada em vários aspectos referentes à sua hidrologia e hidrogeologia. Obtiveram-se dados suficientes para fazer um balanço hídrico da bacia monitorada por um ano hidrológico e extrair uma estimativa da recarga direta e profunda nesta zona de afloramento do Sistema Aqüífero Guarani. Utilizaram-se dados da flutuação do nível do aqüífero para estimar a recarga direta e a variação do armazenamento subterrâneo. Os poços de monitoramento foram distribuídos em diversas culturas, possibilitando uma análise do comportamento do aqüífero por cultura. Estimou-se que a recarga direta do sistema, na bacia, está em torno de 400 mm anuais. A estimativa da recarga profunda indica um valor entre zero e 40 mm. A análise do comportamento do aqüífero mostra que a recarga direta é menor em solos cultivados com eucalipto e maior em áreas cultivadas com pastagem. A variação do nível do aqüífero apresenta forte correlação entre as culturas, exceto a de eucaliptos. A posição dos poços é fator fundamental para a estimativa da recarga direta. Terrenos mais planos tendem a produzir uma maior recarga direta do aqüífero. Avaliaram-se métodos de estimativa de evapotranspiração. A avaliação foi realizada entre alguns métodos empíricos e a evapotranspiração obtida através do balanço hídrico. Estimou-se uma evapotranspiração em torno de 900 mm anuais a partir do balanço hídrico. Todos os métodos empíricos e semi- empiríco, com exceção do de Thornthwaite, superestimaram a evapotranspiração quando comparados ao valor estimado pelo balanço hídrico. O método de Hargreaves-Samani foi o que mais se distanciou, com 1894 mm anuais. O método de Thornthwaite foi o que mais se aproximou, com 936 mm anuais, com discrepância de apenas entre 3% e -6% do valor estimado pelo balanço hídrico. A utilização dos métodos empíricos e semi- empíricos de estimativa da evapotranspiração, para estudos da recarga de aqüíferos na região da zona de afloramento do Sistema Aqüífero Guarani no estado de São Paulo, deve ser vista com cautela. Só uma avaliação prolongada poderá indicar quais os métodos mais se aproximam da realidade. Pelos resultados obtidos, recomenda-se a revisão das estimativas de disponibilidade hídrica sustentável do Sistema Aqüífero Guarani e a utilização com cautela dos métodos empíricos e semi-empíricos de estimativa da evapotranspiração, para estudos hidrológicos no estado de São Paulo. A análise do monitoramento da bacia do Ribeirão da Onça só vem a confirmar a representatividade dos estudos feitos nessa região e a grande relevância que esses estudos terão para o gerenciamento desse importante reservatório que é o Sistema Aqüífero Guarani
The main objective of this work is to esteem the recharge direct and deep in the Guarani Aquifer System (GAS) at the representative basin of Ribeirão da Onça. At the same time, the behavior and the evapotranspiration at the water basin have been studied. The Ribeirão da Onça water basin has typical representative characteristics on the outcrop region in the Guarani Aquifer System (GAS) in the São Paulo State. Its hydrology and hydrogeology have been widely studied under several aspects, what consists of an advantage. It had been gotten enough data to make a water balance of the monitored water basin for one hydrological year and get out the direct and deep recharge estimate at this outcrop region of the Guarani Aquifer System. It had been used data of the aquifer level fluctuation in order to estimate the direct recharge and the subterranean storage. The monitoring wells are distributed in several crops, making the behavior in the aquifer per crop analysis possible. The estimated direct recharge of the system, at the water basin, is about 400 mm. The estimated deep recharge is between zero and 40 mm. The aquifer behavior analysis shows that the direct recharge is smaller in soils with eucalyptus cultivated than it is in other crops. The wells position is also an important aspect to the direct recharge. Plainer and higher lands tend to produce a greater direct recharge of the aquifer. Evapotranspiration esteem methods had been also evaluated. The evaluation was made with some empirical methods and the evapotranspiration gotten through to the water balance. The evapotranspiration estimated through the water balance was about 900 mm per year. All the empirical and semi-empirical methods, excepting Thornthwaite, overestimated the evapotranspiration if compared to the water balance estimated value. The Hargreaves-Samani´s method was the most far-away, with 1894 mm per year. The Thornthwaite method was the closest, with 936 mm per year, only between -6% and 3% of the estimated value through the water balance. The use of empirical and semi-empirical methods to esteem the evapotranspiration, in order to study the aquifers recharge in the region of the outcrop zone of the Guarani Aquifer System at São Paulo State, must be used with caution. Only a long-term evaluation could say which methods get closer to the reality. Through the analysis of the gotten results, it is recommended a revision of the estimated sustained water accessibility of the Guarani Aquifer System and the cautious use of the empirical and semi- empirical methods to esteem the evapotranspiration, to hydrological studies at São Paulo State. The analysis of the monitoring of the Ribeirão da Onça water basin comes to prove the active role of the studies in this region and the importance that this studies will have to the management of this great reservoir that is the Guarani Aquifer System
The main objective of this work is to esteem the recharge direct and deep in the Guarani Aquifer System (GAS) at the representative basin of Ribeirão da Onça. At the same time, the behavior and the evapotranspiration at the water basin have been studied. The Ribeirão da Onça water basin has typical representative characteristics on the outcrop region in the Guarani Aquifer System (GAS) in the São Paulo State. Its hydrology and hydrogeology have been widely studied under several aspects, what consists of an advantage. It had been gotten enough data to make a water balance of the monitored water basin for one hydrological year and get out the direct and deep recharge estimate at this outcrop region of the Guarani Aquifer System. It had been used data of the aquifer level fluctuation in order to estimate the direct recharge and the subterranean storage. The monitoring wells are distributed in several crops, making the behavior in the aquifer per crop analysis possible. The estimated direct recharge of the system, at the water basin, is about 400 mm. The estimated deep recharge is between zero and 40 mm. The aquifer behavior analysis shows that the direct recharge is smaller in soils with eucalyptus cultivated than it is in other crops. The wells position is also an important aspect to the direct recharge. Plainer and higher lands tend to produce a greater direct recharge of the aquifer. Evapotranspiration esteem methods had been also evaluated. The evaluation was made with some empirical methods and the evapotranspiration gotten through to the water balance. The evapotranspiration estimated through the water balance was about 900 mm per year. All the empirical and semi-empirical methods, excepting Thornthwaite, overestimated the evapotranspiration if compared to the water balance estimated value. The Hargreaves-Samani´s method was the most far-away, with 1894 mm per year. The Thornthwaite method was the closest, with 936 mm per year, only between -6% and 3% of the estimated value through the water balance. The use of empirical and semi-empirical methods to esteem the evapotranspiration, in order to study the aquifers recharge in the region of the outcrop zone of the Guarani Aquifer System at São Paulo State, must be used with caution. Only a long-term evaluation could say which methods get closer to the reality. Through the analysis of the gotten results, it is recommended a revision of the estimated sustained water accessibility of the Guarani Aquifer System and the cautious use of the empirical and semi- empirical methods to esteem the evapotranspiration, to hydrological studies at São Paulo State. The analysis of the monitoring of the Ribeirão da Onça water basin comes to prove the active role of the studies in this region and the importance that this studies will have to the management of this great reservoir that is the Guarani Aquifer System
Palavras-chave
águas subterrâneas, evapotranspiração, hidrogeologia, recarga, evapotranspiration, groundwater, hydrogeology, recharge