Land Subsidence due to Groundwater Extraction and Natural Consolidation in the Bandung Basin, West Java, Indonesia

Based on GPS and InSAR data, it is known that there is land subsidence in the Bandung Basin of 1.1 - 16.9 cm/year (GPS) and 0.9 - 1.7 cm/year (InSAR). Several types of land subsidence can be expected to occur in the Bandung Basin. However, the detailed characteristics and exact mechanism of land subsidence from a geological perspective in the Bandung Basin are still unknown. Two factors that can cause land subsidence are groundwater extraction and natural consolidation. It is known that there has been a significant decrease in groundwater levels in Bandung since the 1970s due to the very high intensity of groundwater extraction. It is also known that the Bandung Basin comprises one of them, the Kosambi Formation, which consists of organic clays with very high compressibility and undergoes a natural consolidation. Based on these facts, we determine the distribution of land subsidence rates due to groundwater extraction and natural consolidation, along with the percentage of their respective contributions in the Bandung Basin. Research materials include groundwater level depth data and organic clay consolidation data from previous studies. The results showed that the average land subsidence rate due to groundwater extraction was 1.85 cm/year, with a contribution percentage of 44.30%. In comparison, the average land subsidence rate due to natural consolidation was 0.92 cm/year, with a contribution percentage of 15.76%.