Método da Eletrorresistividade aplicado à variação temporal do nível freático do aquífero alter do chão, em Santarém, Pará.

Electrical Resistivity method applied to the temporal variation of the groundwater level of the Alter do Chão aquifer, in Santarém, Pará.

Abstract

Based on the observation of permanent floods near the Federal University of Western Pará, this study aimed to verify the fluctuation of the water table level in the free aquifer of the Alter do Chão Formation and the possible relationship with permanent flooding in the research area. In the study area, the techniques of Vertical Electrical Sounding and Electrical Profiling Technique were applied. The measurements of the vertical electrical soundings made it possible to identify as a 1st layer associated with the soil, with an average thickness of 1.42 m and apparent resistivity of ≅1000Ωm, a 2nd layer with an average thickness of 10.91 m and a highly resistive anomaly of ≅4600Ωm and a 3rd layer with an abrupt drop in resistivity (≅300Ωm) at an average depth of 12.34 m. Vertical Electrical Sounding was carried out 5 times in the same location from December 2017 to June 2018, allowing the correction of the variation in the water table level with rainfall in the same period. The results indicate oscillation of the water level of the unconfined aquifer of the Alter do Chão Formation in the period studied in 7 m. Electrical Profiling Technique made it possible to associate the highly resistive anomaly of the 2nd layer with the Matura Lateritic Cover, which is the main cause of flooding in the investigated area.