ORIGINAL ARTICLE Land subsidence characteristics of Jakarta between 1997 and 2005, as estimated using GPS surveys Hasanuddin Z. Abidin Æ H. Andreas Æ Rochman Djaja Æ Dudy Darmawan Æ M. Gamal Received: 13 August 2006 / Accepted: 26 February 2007 / Published online: 17 March 2007 Ó Springer-Verlag 2007 Abstract 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 Ja- karta 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 po- sitive 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. Keywords Jakarta  Land subsidence  GPS  Groundwater Introduction Jakarta’s population is about 10 million people, covering an area of about 650 km 2 . Jakarta is centered at about 6°15¢S and +106°50¢E and located on the lowland of the northern coast of the West Java province, as shown in Fig. 1. The area is relatively flat, with topographical slopes ranging between 0° and 2° in the northern and central parts, and between 0° and 5° in the southern part. The south- ernmost area of Jakarta has an altitude of about 50 m above mean sea level. Jakarta is a lowland area with five main landforms (Rimbama and Suparan 1999): (1) alluvial landforms (southern part). (2) Landforms of marine-origin (northern part adjacent to the coastline). (3) Beach ridge landforms (northwest and northeast parts). (4) Swamp and mangrove swamp landforms (coastal fringe). (5) Former channels (perpendicular to the coastline). There are about 13 natural and artificial rivers flowing through Jakarta, of which the main rivers, such as Ciliwung, Sunter, Pesanggrahan, Grogol and their tributaries, form the main drainage system of Jakarta. Land subsidence is not a new phenomenon for Jakarta. The occurrence of land subsidence was recognized in 1926. Evidence for subsidence was based on repeated leveling measurements conducted in the northern part of Jakarta (Schepers 1926; Suharto 1971). Unfortunately, the inves- tigation of land subsidence using leveling was not repeated for 50 years until 1978. Starting in 1978, the impact of land subsidence in Jakarta could be seen in several ways, such as the cracking of permanent constructions located around the center of the Jakarta area (along Thamrin Street), the wider expansion of flooding areas, the lowering of the groundwater level and increased inland seawater intrusion. According to the Local Mines Agency, over the period of H. Z. Abidin (&)  H. Andreas  D. Darmawan  M. Gamal Geodesy Research Division, Faculty of Civil and Environmental Engineering, Institute of Technology Bandung (ITB), Jl. Ganesha 10, Bandung 40132, Indonesia e-mail: hzabidin@gd.itb.ac.id R. Djaja National Coordinating Agency for Survey and Mapping (BAKOSURTANAL), Cibinong, Bogor, Indonesia 123 GPS Solut (2008) 12:23–32 DOI 10.1007/s10291-007-0061-0