Groundwater identification using VES With Regressive-Regressive PSO Inversion in Pacitan Region, Indonesia

Summary Pacitan Region are located in Alluvium formation that has a good potential in groundwater but has a side effect of high liquefaction when shacked by an earthquake. The experiment’s purpose is to map the distribution of aquifer zone in the designated area and in shallow surface below 30 meter underground. One of geophysics method that can be used in this experiment is Vertical Electrical Sounding (VES) with Schlumberger configuration. This measurement has been done in several points in Pacitan region. Once the data has been gathered, an algorithm method called Regressive-Regressive Particle Swarm Optimization is used to obtain the apparent resistivity that can be used for interpretation purpose, according to the integration of inversion result and local geology, the area is dominated by the sand, gravel and the clay and the free aquifer zone is located in 1 through 4 meter deep and pressurized aquifer zone is located between 4 to 9 meter below the surface and the aquifer layer thickness is ranged between 2 to 25 meter.