Determinação da recarga profunda na bacia-piloto do Ribeirão da Onça em zona de afloramento do Sistema Aqüífero Guarani a partir de balanço hídrico em zona saturada / Determination of the deep recharge in the Ribeirão da Onça pilot basin in the outcrop zone of the Guarani Aquifer System through water balance in the saturated zone

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Main objective of this work was the determination of the deep recharge in the Ribeirão da Onça basin through water balance in the soil saturated zone. This basin is located in the outcrop zone of the Guarani Aquifer System (GAS) in the São Paulo State - Brazil and is covered by cenozoic sedimentary soil. The water balance model involved the determination of the direct recharge, groundwater storage variation and base flow. To obtain these values, the daily precipitation in the basin, the stream flow in the outflow section of the creek and the aquifer level fluctuation in wells installed in the basin was monitored. The direct recharge was determined by the water table fluctuation method (WTF). The base flow was calculated by hydrograph separation method generated by rain-flow model supported by biweekly stream flow measurements. Undisturbed soil samples were collected with the objective of determining the effective porosity (specific yield). The effective porosity is 12.2%, compatible with values found in the literature. Water balances were executed for each one of the 3 hydrological years (February/2004 to January/2007). The direct recharge varied between 14% while 38% and the deep recharge varied between 0.4% and 2.4% of the respective precipitations in the period. The low values of deep recharge reveal the need for the continuity of the water resources studies in the Guarani Aquifer System.

ASSUNTO(S)

monitoring rendimento específico Água subterrânea monitoramento specific yield recarga recharge groundwater

ACESSO AO ARTIGO

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