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Jakarta Land Subsidence and Inundation Vulnerability Based on SAR Data

Agustan, Hartanto Sanjaya PTISDA-BPPT Takeo ITO Grad. School of Env. Studies, Nagoya University Kuta, October 22nd 2013

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Introduction

•  Jakarta as capital city with more then 10 millions population

•  Vulnerable to flood hazard with more frequent cycle in last decades

•  The 2013 Jakarta flood event cause 41 casualties with 32 trillion rupiahs loses due to longer time inundation in some regions

•  The inundated and vulnerable area due to the increasing rainfall rate is identified in the same location from previous events, mainly in the north-western part of Jakarta

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Introduction

•  North-western part of Jakarta is inundated longer •  One factor that increases the inundated area is land

subsidence (Murakami et al., 2012) •  Land subsidence is generally related to:

–  geological subsidence i.e. sediment consolidation due to its own weight and tectonic movements; or

–  related to human activities such as withdrawal of ground water and geothermal fluid, oil and gas extraction (Raucoules et al., 2007; Yuill et al., 2009)

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Land Subsidence in Jakarta

•  The ability of satellite based radar data to detect ground deformation, i.e. land subsidence ! interferometry (InSAR) technique

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Data and Method

•  There are 7 interferograms with 184 – 1472 days ~ 4 years data analysis

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Preliminary Results PALSAR: Jakarta

Interferogram (topo phase not removed) 2007 Jan 31 – 2007 Aug 03 184 days

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Preliminary Results PALSAR: Jakarta

Interferogram (topo phase not removed) 2007 Jan 31 – 2007 Sep 18 230 days

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Preliminary Results PALSAR: Jakarta

Interferogram (topo phase not removed) 2007 Jan 31 – 2008 May 05 460 days

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Preliminary Results PALSAR: Jakarta

Interferogram (topo phase not removed) 2007 Jan 31 – 2008 June 20 506 days

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Preliminary Results PALSAR: Jakarta

Interferogram (topo phase not removed) 2007 Jan 31 – 2009 Aug 08 920 days

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Preliminary Results PALSAR: Jakarta

Interferogram (topo phase not removed) 2007 Jan 31 – 2010 Nov 11 1380 days

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Preliminary Results PALSAR: Jakarta

Interferogram (topo phase not removed) 2007 Jan 31 – 2011 Feb 11 1472 days

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Results

January, 31 2007 – August 3rd 2007 ~ 184 days

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Results

January, 31 2007 – September 18th 2007 ~ 230 days

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Results

January, 31 2007 – May 5th 2008 ~ 460 days

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Results

January, 31 2007 – June 20th 2008 ~ 506 days

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Results

January, 31 2007 – August 8th 2009 ~ 920 days

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Results

January, 31 2007 – November 11th 2010 ~ 1380 days

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Results

January, 31 2007 – February 11th 2011 ~ 1472 days ~ 70 cm in 4 years

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Google Map information

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Preliminary Results PALSAR: Jakarta

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Google Map information

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Google Map information

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Results and Discussions

•  ALOS-PALSAR data can monitor land subsidence in Jakarta

•  L-band SAR is proven to have a good coherence in long range time observation ( 1472 days ~ more than 4 years)

•  Land subsidence in Jakarta is suspected related to ground water extraction ! anthropogenic

•  But there is a clear “another deformation signal” ! boundary line of phase difference ! ground deformation (tectogenic ???)

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The January 2013 Flood Event

The area indicated with red circle and green square is still inundated on February 2nd after the heavy rain on 17th and 18th January (after 14 days), After 17 days the area with red circle has dried up, in contrast to area in the green square, which is still inundated. Inundation map also shows the inundated area on January 24th, 6 days after the peak of the rainfall, and it confirms that the subsided area still inundated