GROUNDWATER FLOW MODELING IN THE WATES COASTAL AQUIFER, KULON PROGO DISTRICT, YOGYAKARTA SPECIAL PROVINCE, INDONESIA

Due to overcapacity, the current airport of Yogyakarta is going to be replaced with a new one, which is located in Wates coastal area, Kulon Progo District, Yogyakarta Special Province, Indonesia. One of the consequences of the development of the new airport is groundwater abstraction due to the airport’s needs and related supporting activities. An excessive withdrawal of groundwater in the new airport will potentially change the system and the pattern of groundwater flow. Therefore, groundwater modeling should be done to predict the impact of groundwater abstraction in this area. MODFLOW code is used to simulate the groundwater flow and the impact of groundwater pumping in the Wates coastal aquifer. The model is calibrated using water level data from 40 wells in the research area. The results show that the calculated values are fit to the measured data, which indicates that the model is reliable. The effects of groundwater pumping on water table and seawater intrusion are investigated using a calibrated model. The results show that the pumping scenario from the airport area causes the groundwater level to drop 0.75 m and seawater intrusion inland to increase around 100 m.