Monitoramento e análise da variação do nível d água para estimativa da recarga do aqüífero livre da bacia do Rio Gramame - PB

Abstract

This study aimed at assessing the direct recharge of the river Gramame basin aquifer, located in the south region of Paraiba state, through the application of the method WTF (water table fluctuation). Moreover, the study aimed at understanding the behavior of static level variation of the unconfined aquifer, in terms of space and time. For that, a monitoring program was carried out in the unconfined aquifer. Static levels of 27 wells were measured as well as rainfall data. During the period of static level monitoring, three different types of behavior were detected. Investigations have sought to correlate these variations with different behaviors, including: rainfall, thickness of the unsaturated soil, digital terrain model, land use, geology and hydraulic conductivity. This last property was obtained using Beerkan methodology. Most of the factors have influence on the fluctuation of static level, except the geology, most likely due to the low level of detail of this information. The direct calculated recharge for the monitored hydrological year (2009/2010) ranged between 53 and 105 mm, which represents between 5 and 10% of average rainfall in the basin during the study. These values were lower than expected for a humid region, probably due to the low values of rainfall during the survey, which was about 42% lower than average annual basin. According to the results, a systematic monitoring of the aquifer for a longer period is recommended, in order to provide better input data to decision making regarding the use of the groundwater basin.