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

Report of the project:

• Indonesia - Good local Governance – Mitigation of Georisks
• Indonesien - Gute lokale Regierungsführung - Verminderung von Georisiken

Project aim:

The HGF Alliance “Remote Sensing and Earth System Dynamics” (EDA) aims at the development and evaluation of novel bio/geo-physical information products derived from data acquired by a new generation of remote sensing satellites; and their integration in Earth system models for improving understanding and modelling ability of global environmental processes and ecosystem change (www.hgf-eda.de). Within this project the BGR is involved in the work package G1: PSI-Technology for future L-Band missions. The aim of the BGR is to validate the PSI results from WP G1 based on GPS measurements, optical time series imagery and geoscientific information

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 (Kühn et al. 2009). Source: Kühn et al. 2009

The city of Semarang, Indonesia, faces land subsidence since more than 100 years. The impact for the cities’ approx. 1.3 Mio. inhabitants is severe: not only does land subsidence affect their living environment, buildings and infrastructure, it also badly influences health and sanitation conditions and may thus diminish the individual chances for development. The strong subsidence in Semarang is caused by

• groundwater extraction,
• soil compaction and
• construction load.

Spatial sampling of the PSI data and the GPS measurements used for validation. The strong subsidence of the north eastern parts of the city of Semarang is clearly visible. A true color IKONOS imagery serves as background Source: BGR

The strong subsidence in Semarang is monitored by various ground- and satellite- based techniques (e.g. GPS, InSAR). In order to assess the quality of the information content which can be extracted from PSI analysis based on L-Band SAR data, the remote sensing section of the BGR is validating PSI results (WP G1) with independent GPS measurements. Furthermore, optical time series imagery and geoscientific information is used to interpret the velocity field.
This project is a part of the HGF Alliance “Remote Sensing and Earth System Dynamics (EDA) - WP G1: PSI-Technology for future L-Band missions. The interested reader is referred to the projects homepage for further information (www.hgf-eda.de).