Developing groundwater conservation zone of unconfined aquifer in Semarang, Indonesia

Abstract

The increasing exploitation of groundwater affects some environmental problems such as declining groundwater levels and its quality, land subsidence, seawater intrusion, and flooding in Semarang. Nowadays, groundwater protection and its management programs are crucial in Semarang due to raising several environmental problems. Semarang has two different morphologies i.e. lowlands, and coastal plains are in the north while hilly areas spread in the south. The main objective of this research is delineating groundwater conservation zone based on its current status of groundwater both in quantity and quality. The hydrogeology mapping was performed by measuring water table as well as physical parameters of groundwater samples from both dug wells and springs. Results conduct that the groundwater depth is approximately 0.03 m to 34 m below ground surface and flowing from the south to the north. The pH varies between 4.63 and 8.95. The Dissolved Oxygen is around 0.06-3.37 mg/L while salinity has yielded up to 3,600 mg/L in the north of Semarang. The EC value is in a range from 39-6,370 µS/cm. Based on lowering the water table, deterioration of groundwater quality, and land subsidence there are four groundwater conservation zones, i.e. secure, vulnerable, critical, and damaged zones.