GROUNDWATER MODELING IN SANGON HAMLET AND SURROUNDING AREAS USING FINITE DIFFERENCE METHOD

Sangon Hamlet is included in the mountains which are dominated by andesite rocks and volcanic breccias which cross each other and have a distribution of joints and faults forming a fracture. The fracture is a medium for draining water in the area. There is a difference in ground water level as seen from the well. To re-detail the groundwater flow that has been formed, a groundwater flow pattern modeling is carried out. The modeling is done by numerical method assisted by Modflow Flex Software. For building the model, it is necessary to prepare a concept model, calibration and validation. In this area there are 2 aquifer systems, namely unconfined aquifers and aquitards. Furthermore, the model was calibrated using the sensitivity analysis method. The calibration results are obtained, namely the RMS value of 8.74% with a standard error estimate of 1.27 m and a correlation coefficient of 0.98. From this model, it is known that the flow of water moves from the northwest-north area in the form of a plateau by heading to the east-southeast area which is a lower plain and towards the Plampang River.