Detection of land subsidence in Semarang, Indonesia, using stable points network (SPN) technique

Abstract

Land subsidence in Semarang is a severe hazard threatening people and urban infrastructure. The evolution of land subsidence has been monitored between 1996 and 2000 with few leveling stations. Hence, maps show an overall distribution of land subsidence, but are inaccurate in detail. Stable points network (SPN) technique has been applied to improve land-subsidence mapping. SPN measures ground motion using Synthetic Aperture Radar satellite images. For the SPN processing, 35 radar satellite images acquired between 2002 and 2006 have been selected. Derived land-subsidence rates vary from fractions of 1 mm/year to values of 10 cm/year and even beyond. Classification and visualization of the ground motion data illustrate the boundary between mainly stable ground in the south of Semarang and increasingly landsubsidence-affected land toward the coast. Final result is a map featuring the land subsidence with much higher accuracy as had been possible before. This article presents a brief description of the land subsidence in Semarang and introduces briefly the concept of SPN technique. Results of SPN-based ground motion detection in Semarang are presented and discussed from a user's point of view.

Insight look the subsidence impact to infrastructures in Jakarta and Semarang area; Key for adaptation and mitigation

“…In general, subsidence rates in Semarang have an average rate of about 6 to 7 cm/year, with maximum rates that can go up to 14-19 cm/year at certain locations. The estimation based on the PS (Permanent Scattered) InSAR technique also revealed that the areas close to the shoreline have subsidence rates of more than 8 cm/year [5]. The result is based on the PS InSAR based velocity data derived from 28 ERS-2 and ENVISAT-ASAR radar scenes recorded between 27 November 2002 and 23 August 2006.…”

Land subsidence in coastal city of Semarang (Indonesia): characteristics, impacts and causes

“…Some subsidence studies have been conducted in Semarang city using several geodetic methods, such as Levelling (Sutanta et al 2005, Marfai andKing 2007), Global Positioning System (GPS) surveys, Gravity (Sarkowi et al 2005, Fukuda et al 2008 and Interferometric Synthetic Aperture Radar (InSAR) (BGR 2009, Kuehn et al 2009, Lubis et al 2011.…”

“…The estimation based on the Permanent Scatterer (PS) InSAR technique also revealed that the areas close to the shoreline have subsidence rates of more than 8 cm/year (Kuehn et al 2009 Since 2008, the Geodesy Research Group of ITB began to study land subsidence in Semarang by using GPS surveys and InSAR methods. The GPS derived results are presented in the following section.…”

“…Table 3. Land subsidence rates in Semarang as observed from several geodetic methods (Murdohardono et al 2007, Supriyadi 2008, Kuehn et al 2009, Abidin et al 2010. …”

Advanced interpretation of interferometric SAR data to detect, monitor and model ground subsidence: outcomes from the ESA-GMES Terrafirma project

“…Another study (Nicholls et al 2007) attempts to quantify the impact of climate change and subsidence on population and infrastructures, stating that by the 2070s, total population exposed to coastal floods could grow more than threefold to around 150 million people due to the combined effects of climate change (sea level rise and increased storminess), subsidence, population growth and urbanisation. It is clear that subsidence is and will be a major factor for determining risk exposure in coastal mega-cities and that understanding the relative impact of subsidence is critical to properly estimate related risk (Kuehn et al 2010).…”