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Agradeço ao Professor Edson Cezar Wendland (orientador e facilitador), pela confiança e apoio indispensáveis ao desenvolvimento do trabalho. Agradeço a todos os colegas do LHC (Laboratório de Hidráulica Computacional), pelo apoio, conselhos e discussões que foram de grande valia para este trabalho. Agradeço aos técnicos que participaram deste trabalho, em especial a Roberto Bérgamo. Agradeço aos funcionários do SHS (Departamento de Hidráulica e Saneamento). Agradeço a CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior) pela concessão da bolsa de estudos. Agradeço ao GEF (Global Environmental Facility) pelo suporte financeiro para a execução das atividades de campo. Agradeço à Organização dos Estados Americanos (OEA). Agradeço à Secretária Geral do "Projeto de Desenvolvimento Sustentável e Proteção Ambiental do Sistema Aqüífero Guarani". Finalmente, agradeço à minha família pela compreensão e apoio irrestrito. ABST RACT GOMES, L. H. 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. M.Sc.

The contribution of recharge to regional groundwater flow systems is essential information required to establish sustainable water resources management. The objective of this work was to determine the groundwater outflow in the Ribeirão da Onça Basin using a water balance model of the saturated soil zone. The basin is located in the outcrop region of the Guarani Aquifer System (GAS). The water balance method involved the determination of direct recharge values, groundwater storage variation and base flow. The direct recharge was determined by the water table fluctuation method (WTF). The base flow was calculated by the hydrograph separation method, which was generated by a rain-flow model supported by biweekly streamflow measurements in the control section. Undisturbed soil samples were collected at depths corresponding to the variation zone of the groundwater level to determine the specific yield of the soil (drainable porosity). Water balances were performed in the saturated zone for the hydrological years from February 2004 to January 2007. The direct recharge ranged from 14.0% to 38.0%, and groundwater outflow from 0.4% to 2.4% of the respective rainfall during the same period.

Discharge tests are conducted in order to determine aquifers transmissivity (T) and storage coefficient (S). However the interpretation of test data is not unique and the results may vary depending on adopted hypothesis. In this work, the convolution technique is applied for the reconstruction of observed drawdown curves aiming for the reduction of uncertainty. The interference between a flowing well and an observation well is evaluated in order to determine the hydrogeological parameters of the confined Guarani Aquifer