M. Gamal

STUDYING LAND SUBSIDENCE OF BANDUNG BASIN (INDONESIA) USING GPS SURVEY TECHNIQUE

Abstract Bandung basin is a large intra-montane basin surrounded by volcanic highlands, inhabited by more than five million people. Based on four GPS (Global Positioning System) surveys conducted on February 2000, November 2002, July 2002 and June 2003, it can be concluded that in the period of 2000 to 2003 several locations in Bandung basin have experienced land subsidence. In this period of about 3 years, land subsidence in a few locations can reach the amount of 40 to 50 cm, with the speed of about 1-2 cm/month. This paper describes the technical and practical aspects of GPS surveys for land subsidence study in Bandung basin along with the obtained results. This study shows that the amount of land subsidence in several locations of Bandung basin do not show significant correlation with the registered abstraction volume of groundwater in that locations. Paper will sum up with some conclusions and recommendations.

Monitoring Land Subsidence of Jakarta (Indonesia) Using Leveling, GPS Survey and InSAR Techniques

Jakarta is the capital city of Indonesia with a population of about 12 million people, inhabiting an area of about 25-km by 25-km. It has been reported for quite sometime that several locations in Jakarta are subsiding at different rates. Leveling surveys performed in 1982, 1991 and 1997 have detected the subsidence up to about 80 cm during the period of 1982–1991, and up to about 160 cm during the 1991–1997 period; while GPS surveys observed the subsidence up to about 50 cm during the period of 1997–2002. InSAR technique using JERS-1/SAR L-band data estimated a subsidence rate of about 5 to 10cm during the period of 1993 to 1995. Maximum subsidence were found in the northwestern and central eastern parts of Jakarta, while minimum subsidence were found in the southern part. InSAR results show good correspondence with the results from Leveling and GPS Surveys

Studying landslide displacements in the Ciloto area (Indonesia) using GPS surveys

The paper presents and discusses results and performance of GPS surveys in Ciloto, a well known landslide prone area in West Java (Indonesia). Five GPS surveys involving 17 GPS points have been conducted during the period 2002–2005. The results of the GPS surveys show that the magnitude of land movements in the study area vary from centimetres to decimetres, depending on the location and observation seasons. The study also suggests that to confirm the displacements of the GPS points and to infer the type of landslide, GPS estimated displacements should be tested and analysed with different methods.

Land Subsidence, Groundwater Extraction, and Flooding in Bandung Basin (Indonesia)

Increase in urban development activities and urbanization rate in the Bandung Basin have increased groundwater extraction from the aquifers, which has then led to land subsidence in several locations in the basin. Based on GPS (Global Positioning System) and InSAR (Interferometry Syntetic Aperture Radar) data, the estimated subsidence rates vary spatially from 2 to 20 cm/year. Maximum subsidence during the period of 1999–2010 is about 3 m and largest in industrial areas. Site visit surveys were also conducted to map and evaluate the impacts of the land subsidence.

GPS-Based Monitoring of Surface Displacements in the Mud Volcano Area, Sidoarjo, East Java

Since 29 May 2006, gas and hot mud has been gushing from the ground in Sidoarjo, East Java, Indonesia. As of late September 2006 scientists assume that the eruption may be a mud volcano forming, and may be impossible to stop. Surface displacements of the area, both in the vertical and horizontal directions, are expected due to this massive mud extrusion.

Volcano Deformation Monitoring in Indonesia: Status, Limitations and Prospects

Indonesia has 129 active volcanoes. With a population of approximately 200 million, and the fact that the most populated island in Indonesia (i.e. Java) has the largest number of active volcanoes, then it is obvious that the Indonesian people live under the very real threat of volcanic eruptions.