Evaluation of Groundwater and Springs Potency in East Java Province

Until now, groundwater and springs are still sources of water for domestic demands in Indonesia, so an inventory and evaluation of the potency of these two water resources is needed as basic data in planning their use. This study aims to evaluate the potency of groundwater and calculate and analyze the potency of springs in each district and city in East Java Province. To determine the groundwater conditions, a qualitative descriptive analysis was carried out based on geological and hydrogeological data, while to determine the potency of the springs a quantitative descriptive analysis was carried out with the help of tables and diagrams. The results showed that groundwater conditions in East Java Province can be divided into three categories, i.e. the tertiary depositional basin path in the north, the tertiary depositional path in the south and the quaternary volcanic pathway. The tertiary basin path in the north includes the Rembang Hills, Kendeng Mountains and the Randublatung Zone in the form of a synclineal zone located between them. The quaternary volcanic path in the middle is a volcanic rock path with very high groundwater potency. In East Java Province also found 1,238 springs, of which 18 springs have a very large discharge or more than 500 liters/second, 147 springs have a large discharge or between 100-500 liters/second, 656 springs have a moderate discharge or between 10-100 liters/second and 462 springs have a small discharge. or less than 10 liters/second.