A comparison between DC-resistivity and electromagnetic methods for mapping sea water intrusion in the Llobregat delta

DC-resistivity and electromagnetic techniques are widely used to measure the electrical resistivity/conductivity of materials in the subsurface. Variationsin these two parameters are caused by changes in the soil characteristics -structure, clay content, degree of water saturation and conductivity of this water-. Taking advantage of the relationship between electrical conductivity and chloride ion ie concentration, we have attempted to map the saltwater intrusion in the Llobregat delta (Barcelona). For this purpose two different surveys have been conducted: vertical electrical sounding and electromagnetic mapping. This study allows us to compare the results and to contrast the obtained efficiency using each technique.