Aquifers selection to aid geoelectrical methods on drilled well building near the beach

The aquifer was a rock form wherein the water was collected and as well as able to release water economically. The aquifers near the beach were susceptible to intruded sea water, especially areas that have a lot of groundwater taking, therefore, if building a well, should be chosen aquifer that had not been intruded sea water. It was needed a way thus, the water taken is not salt water or brackish water. This study has a long-term goal of finding a way to choose aquifer by geoelectric method aid. In order to build a drilled well, for getting the right aquifer. The research had been conducted in Candidasa Karangasem Bali with the geoelectric method. The results showed that there were two aquifers types, i.e. free aquifer with resistivity was 33.9 ohm.m and distressed aquifer with a resistivity was 70 ohm.m. Taking into account the two resistivity magnitudes, then, the free aquifer was thought to have been intruded by the sea water, while the distressed aquifer was thought to have not been intruded by sea water. Based on water samples on three dug wells that take water in a free aquifer, obtained electric conductivity 850.00, 1288,81, and 1341,55 μmho/cm, means the water has been intruded by sea water. Drilled well water samples, taking water in the distressed aquifer, obtained electric conductivity 200.00 μmho/cm, means the water has not been intruded by sea water. Thus the geoelectric method could be used to select the aquifer in order to build a well near the beach.