Land subsidence characteristics of Jakarta between 1997 and 2005, as estimated using GPS surveys

Jakarta is the capital city of Indonesia with a population of about 12 million people, inhabiting an area of about 625 km(2). It is well known that several areas in Jakarta are subsiding rapidly. There are four different types of land subsidence that can be expected to occur in the Jakarta basin, namely: subsidence due to groundwater extraction, subsidence induced by the load of constructions (i.e., settlement of high compressibility soil), subsidence caused by natural consolidation of alluvial soil and tectonic subsidence. In addition to the leveling method, Global Positioning System (GPS) survey methods have been used to study land subsidence in Jakarta. In this paper, we characterize subsidence in the Jakarta basin using eight episodic/campaign GPS surveys between 1997 and 2005. The estimated subsidence rates are 1-10 cm/year. The observed subsidence rates in several locations show a positive correlation with known abstraction volumes of groundwater extraction. These basin-wide series of GPS measurements show how this type of measurement can play an important role in multiple public policy decision making in this rapidly growing area.