Modelo conceitual hidroestratigráfico do sistema aquífero costeiro no litoral norte do Estado do Rio Grande do Sul

The expansion of the knowledge of the groundwater resources is of great importance to the decision making processes with regard to management policies. The present work offers substantial contributions to the hydro-stratigraphic characterization of the Coastal Aquifer System on the north coast of the State of Rio Grande do Sul - Brazil. Aquifer geometry was determined by 38 survey profiles done by the Geological Survey of Brazil. The characterization of the different hydro-stratigraphic units was carried out through the analysis and review of geological and constructive profiles of 107 water wells and another 15 geophysical logs containing gamma, resistivity and sonic profiles. Four different hydro-stratigraphic units related to Cenozoic deposits were identified. Each of these units was defined in terms of its granulometric composition, effective porosity and total dissolved solids content of the respective groundwater. Hydro-stratigraphic units 01 and 03 showedhigh values of effective porosity and low salinity as opposed to units 02 and 04 with visibly lower values of effective porosity and higher salinities. The presence of hydro-stratigraphic heterogeneities identified here represents the fundamental scientific contribution of this work.