Prediction of time-lapse microgravity value based on groundwater change map in 2003 - 2010 at Dayeuhkolot industrial area, Bandung

Abstract

Changes in groundwater levels in the indutrial area were seen on ground air maps from the Directorate of Environmental Geology in 2003 and 2010. Digitization of groundwater level maps was carried out and then the changes were analyzed for getting the volume of water used. Time-lapse microgravity is sensitive to density changes. To get the value of density changes of groundwater, we need information such as rock porosity and water density. In this case we assumed that the porosity value is 30% and the water density value is 1 gr / cc, so the value of water density changes is 0.3 gr/cc. The value of density changes is distributed across the entire volume of groundwater changes during 2003 to 2010. The volume of groundwater changes in interval 2003 to 2010 was around 33,971,200 m3. From calculation of time-lapse microgravity for geometry the reduction of groundwater in the Dayeuhkolot industrial area shows the highest value about -125 microGal. The time-lapse microgravity of the Dayeuhkolot industrial area during 2003 to 2010 shows a value -125 microGal which is very detectable with a gravimeter like Scintrex CG-5 which has accuracy up to 1 microGal.