Helmholtz Alliance: Remote Sensing and Earth System Dynamics. Semarang/Indonesia

Country / Region: Indonesia / Semarang

Begin of project: January 1, 2013

End of project: December 31, 2017

Status of project: December 31, 2017

Project aim:

The Helmholtz Alliance “Remote Sensing and Earth System Dynamics”, abbreviated to EDA, is a research alliance with more than 140 interdisciplinary scientists from eight Helmholtz Centers, eight universities, three non-university research institutes, a Federal Research Institute and 2 international organizations. The aim of the Helmholtz Alliance is the development of innovative global bio- and geophysical information products that can be delivered only by a new generation of remote sensing satellites, and their integration into environmental science models.

Within EDA, BGR is involved in the work package G1: PSI-Technology for future L-Band missions. The aim of BGR is to validate the PSI results from WP G1.

Figure 1: Sketch of the subsidence affecting the city of Semarang. The boundary between unconsolidated marine sediments and relatively solid volcanic rocks as well as ground water pumping in the soft sediments are shown Figure 1: Sketch of the subsidence affecting the city of Semarang. The boundary between unconsolidated marine sediments and relatively solid volcanic rocks as well as ground water pumping in the soft sediments are shown Source: Kühn et al. 2009

The area of interest covers the city of Semarang in Indonesia. The City of Semarang faces land subsidence since more than 100 years. The impact for the cities’ approx. 1.3 Mio. inhabitants is severe. The subsidence causes e.g. damages at buildings and infrastructure. The subsidence in Semarang is caused by (Figure 1):

groundwater extraction,
soil compaction and
construction load

In order to validate the results of a PSI analysis based on L-Band SAR data (EDA WP G1), the remote sensing section of the BGR is using independent GPS measurements, optical time series imagery and geoscientific information (Figure 2).

Figure 2: Spatial distribution of the Persistent Scatterers and the location of the GPS measurements. The strong subsidence in the Northern part of the city of Semarang is clearly visible. An optical truecolor IKONOS imagery serves as background Source: BGR