Identification the origin of groundwater in Bulukumba Regency, South Sulawesi Province using stable isotopes

Abstract Bulukumba Regency, located in South Sulawesi, particularly in coastal areas such as Ujung Bulu sub-districts, is currently facing issues related to increasing groundwater extraction. The sustainability of groundwater availability is closely linked to the balance between groundwater abstraction and natural recharge. Therefore, identifying the recharge zone of the utilized groundwater is essential to support effective groundwater management in the region. This study aims to determine the groundwater recharge areas in the coastal zone of Bulukumba Regency using stable isotope analysis of 18 O and 2 H. Field observation and samples collection of rainfall water and groundwater isotopes were conducted in February 2025. Groundwater samples were obtained from existing dug wells and drilled wells. The results indicate that groundwater from both well types originates mainly from the slopes of Mount Lompobattang at an elevation of less than 300 meters above sea level. Groundwater recharge zone conservation efforts to ensure sustainable water use in this area should be focused on the identified recharge locations.