The scientists used a geoelectric method to study the aquifer properties and groundwater vulnerability in Yenagoa City, Nigeria. They found four distinct layers underground, with fresh water lenses containing low iron concentrations in specific areas. The depth to the aquifer ranged from 4.5 to 27.0 meters, with varying resistivity levels. High resistance values indicated zones of high water flow, matching the geological composition of the area. The vulnerability map showed areas with good protection against contamination and others at risk.