Water regimes governed by seasonality are sensitive to climatological disturbances and human interventions. The Brazilian Cerrados region is characterized by a pronounced dry season of around six months. During this period, natural vegetation and agricultural crops are dependable on groundwater. The Cerrado natural vegetation is adapted to the local climate but the cash-crops cultivated there not. Irrigation is responsible for the maintenance of high productivities during the whole year, and the availability of water resources made it possible. Today, with almost all Cerrado vegetation replaced by agriculture, information about the spatio-temporal dynamics of the water table is important to optimize and balance the interest of economical and ecological purposes in Brazil''s agricultural frontier. This work aims to characterize water resources in a watershed located in a representative Cerrado area by analyzing monitoring data of water heads. We model water table dynamics combining time series modeling and spatial analysis, in order to estimate the water volume lost during a specific season, account for systematic changes in the water regime and predict risks of extreme water levels.