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LAND SUBSIDENCE CHARACTERISTICS OF BANDUNG BASIN (INDONESIA) BETWEEN 2000 AND 2005

AS ESTIMATED FROM GPS SURVEYS

HASANUDDIN Z. ABIDIN,HERI ANDREAS, M. GAMAL, D. DARMAWAN

Geodesy Research Division,Faculty of Civil and Environmental EngineeringBandung Institute of Technology, INDONESIA,

hzabidin@gd.itb.ac.id

• subsidence due to groundwater extraction, • subsidence induced by the load of constructions

(i.e. settlement of high compressibility soil), • subsidence caused by natural consolidation of alluvium soil, and • geotectonic subsidence.

Types of Subsidence :Land Subsidence

In Indonesia, land subsidence of urban coastal areasare usually caused by excessive groundwater extraction.

The already observed subsidence areas :Jakarta, Semarang and Bandung

The expected subsidence areasDenpasar, Surabaya and Medan

Hasanuddin Z. Abidin et al., 2006Bandung Institute of Technology, Indonesia

Land Subsidence in Indonesian Cities

Denpasar

Cilegon

Denpasar

Cilegon

• Jakarta• Bandung• Semarang

• Surabaya• Denpasar• Cilegon• Medan

Observed land subsidence : Expected land subsidence :

observed decrease in groundwater level

BandungBandungWest JavaWest JavaIndonesiaIndonesia

Bandung

Hasanuddin Z. Abidin et al., 2006Bandung Institute of Technology, Indonesia

Bandung is the capital of West Java Province and has a population about of 2.5 million (1995).It is surrounded by several medium sized towns which formed the Greater Bandung, and hasa total population of about 3.5 million.

The Greater Bandung lies in the catchment area of the upper Citarum river and is surrounded by range of hills and volcanoes: some of which are still active, formed the inter-montane basin, and has an area of about 2250 km2.

The central part of the basin, where most of which occupied by urban and industrial areas, is a plain measuring about 40 km East-West and about 30 km North-South

Bandung Basin Java Island

Ref. : Soetrisno, 1996

Http://www.bandungcity.homepage.com/

Bandung

Hasanuddin Z. Abidin et al., 2006Bandung Institute of Technology, Indonesia

Bandung Basin

Ref: [Dam et al., 1996]

Structural Setting of Bandung Basin

Bandung

Hasanuddin Z. Abidin et al., 2006Bandung Institute of Technology, Indonesia

INITIAL AIMS OF STUDYINITIAL AIMS OF STUDY

• IS LAND SUBSIDENCE A REAL PHENOMENON IN BANDUNG ?• IF YES, WHY LAND SUBSIDENCE IS HAPPENING ? • HOW IS THE MECHANISM OF LAND SUBSIDENCE ?

Hasanuddin Z. Abidin et al., 2006Bandung Institute of Technology, Indonesia

Spatialplanning

Infrastructuredesign and

constructionFlood

control

Groundwaterextractionregulation

Environmentalconservation

IMPORTANCE OFLAND SUBSIDENCE INFORMATION IN BANDUNG

Hasanuddin Z. Abidin et al., 2006Bandung Institute of Technology, Indonesia

PRINCIPLE OF LAND SUBSIDENCE MONITORINGUSING REPEATED GPS SURVEY METHOD

Coordinates from Survey # 1Coordinates from Survey # 2

GPS networkCovering the study area

GPS satellites

LANDSUBSIDENCE

HEIGHTDIFFERENCES

LAND SUBSIDENCECHARACTERISTICS

Modeling

Statistical andGeometrical

Testings

Hasanuddin Z. Abidin et al., 2006Bandung Institute of Technology, Indonesia

GPS NETWORK FOR MONITORINGLAND SUBSIDENCE in BANDUNG BASIN

GPS PointsGPS Reference Point

SagulingDam

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

RCK1

BNJR

CMHI

MJL2KPO2

KPO1BRGA

CPRY

BM9L

BM13L

BM18L

BM19L BM30LBM30X

BANDUNG BASIN

10 km

SagulingDam

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

RCK1

BNJR

CMHI

MJL2KPO2

KPO1BRGA

CPRY

BM9L

BM13L

BM18L

BM19L BM30LBM30X

BANDUNG BASIN

NORTHSurvey-1 : 21-24 Feb. 2000Survey-2 : 21-30 Nov. 2001Survey-3 : 11-14 July 2002Survey-4 : 1-3 June 2003Survey-5 : 24-27 June 2005

Hasanuddin Z. Abidin et al., 2006Bandung Institute of Technology, Indonesia

GPS NETWORK FOR MONITORINGLAND SUBSIDENCE in BANDUNG BASIN

SOME GPS POINTS IN BANDUNG

PSCA

KOPO1

CMHI

MJLY2

B30X

BNJR

UJBR

RCK1

Hasanuddin Z. Abidin et al., 2006Bandung Institute of Technology, Indonesia

0

0.5

1

1.5

2

2.5

3

3.5

Observed GPS stations (5 surveys)

Survey-2 up to Survey-5

Survey-1 Standar deviation (cm) ofrelative ellipsoidal height

Stan

dard

dev

iati

on (

cm)

0

0.5

1

1.5

2

2.5

3

3.5

Observed GPS stations (5 surveys)

Survey-2 up to Survey-5

Survey-1 Standar deviation (cm) ofrelative ellipsoidal height

0

0.5

1

1.5

2

2.5

3

3.5

Observed GPS stations (5 surveys)

Survey-2 up to Survey-5

Survey-1 Standar deviation (cm) ofrelative ellipsoidal height

Stan

dard

dev

iati

on (

cm)

Hasanuddin Z. Abidin et al., 2006Bandung Institute of Technology, Indonesia

GPS receiver : dual-frequency geodetic-typeSession length : in general 10 to 12 hoursData rate : 30 seconds, Mask angle : 15o

Processing : SKIPro, precise ephemeris, Saastamoinen tropospheric model, ionospheric free linear combination after fixing the integer ambiguities of L1 and L2 signals

GPS SURVEYS IN BANDUNG

SagulingDam

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

RCK1

BNJR

CMHI

BRGA

BM9L

BM13L

BM18L

BM19L

BANDUNG BASIN

NORTH

SagulingDam

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

RCK1

BNJR

CMHI

BRGA

BM9L

BM13L

BM18L

BM19L

BANDUNG BASIN

SagulingDam

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

RCK1

BNJR

CMHI

BRGA

BM9L

BM13L

BM18L

BM19L

BANDUNG BASIN

NORTH

SagulingDam

-6.7

-15.7

-7.7

Fixed

-15.0

-2.6

-10.0

-7.7

-19.0

BANDUNG BASIN

10 km

Feb.2000 – Nov.2001

SagulingDam

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

RCK1

BNJR

CMHI

BRGA

BM9L

BM13L

BM18L

BM19L

BANDUNG BASIN

NORTH

SagulingDam

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

RCK1

BNJR

CMHI

BRGA

BM9L

BM13L

BM18L

BM19L

BANDUNG BASIN

SagulingDam

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

RCK1

BNJR

CMHI

BRGA

BM9L

BM13L

BM18L

BM19L

BANDUNG BASIN

NORTH

SagulingDam

-6.7

-15.7

-7.7

Fixed

-15.0

-2.6

-10.0

-7.7

-19.0

BANDUNG BASIN

10 km

Feb.2000 – Nov.2001

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

RCK1

BNJR

CMHI

KPO2

KPO1BRGA

CPRY

BM9L

BM13L

BM30L

BANDUNG BASIN

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

RCK1

BNJR

CMHI

KPO2

KPO1BRGA

CPRY

BM9L

BM13L

BM30L

BANDUNG BASIN

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

RCK1

BNJR

CMHI

KPO2

KPO1BRGA

CPRY

BM9L

BM13L

BM30L

BANDUNG BASIN

-2.4

-17.2

-4.0-1.1

Fixed

-14.0

-1.6

-5.1

-3.6

-16.7

-0.1

-11.2

-2.8

BANDUNG BASIN

SagulingDam

NORTH NORTH

10 km

Nov.2001 – July 2002

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

RCK1

BNJR

CMHI

KPO2

KPO1BRGA

CPRY

BM9L

BM13L

BM30L

BANDUNG BASIN

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

RCK1

BNJR

CMHI

KPO2

KPO1BRGA

CPRY

BM9L

BM13L

BM30L

BANDUNG BASIN

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

RCK1

BNJR

CMHI

KPO2

KPO1BRGA

CPRY

BM9L

BM13L

BM30L

BANDUNG BASIN

-2.4

-17.2

-4.0-1.1

Fixed

-14.0

-1.6

-5.1

-3.6

-16.7

-0.1

-11.2

-2.8

BANDUNG BASIN

SagulingDam

NORTH NORTH

10 km

NORTH NORTH

10 km

Nov.2001 – July 2002

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

BNJR

CMHI

MJL2KPO2

KPO1BRGA

CPRY

BM9L

BM13L

BM18L

BM19L BM30LBM30X

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

BNJR

CMHI

MJL2KPO2

KPO1BRGA

CPRY

BM9L

BM13L

BM18L

BM19L BM30LBM30X

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

BNJR

CMHI

MJL2KPO2

KPO1BRGA

CPRY

BM9L

BM13L

BM18L

BM19L BM30LBM30X

-6.9

-3.4-2.5 -14.0

Fixed

-0.7

-5.0

-2.8

-13.0

-2.9-5.0

-5.8

-15.9

-4.8-13.2

-4.7 -8.5

BANDUNG BASIN

SagulingDam

NORTH NORTH

10 km

July 2002 – June 2003

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

BNJR

CMHI

MJL2KPO2

KPO1BRGA

CPRY

BM9L

BM13L

BM18L

BM19L BM30LBM30X

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

BNJR

CMHI

MJL2KPO2

KPO1BRGA

CPRY

BM9L

BM13L

BM18L

BM19L BM30LBM30X

MJL1

DHYK

BJNS GDBG

PSCA

RCK2

UJBR

BNJR

CMHI

MJL2KPO2

KPO1BRGA

CPRY

BM9L

BM13L

BM18L

BM19L BM30LBM30X

-6.9

-3.4-2.5 -14.0

Fixed

-0.7

-5.0

-2.8

-13.0

-2.9-5.0

-5.8

-15.9

-4.8-13.2

-4.7 -8.5

BANDUNG BASIN

SagulingDam

NORTH NORTH

10 km

NORTH NORTH

10 km

July 2002 – June 2003

DHYK

GDBG

PSCA

RCK2RCK1

BNJR

CMHI

MJL2KPO2

KPO1BRGA

BM9L

BM13L

BM18L

DHYK

GDBG

PSCA

RCK2RCK1

BNJR

CMHI

MJL2KPO2

KPO1BRGA

BM9L

BM13L

BM18L

DHYK

GDBG

PSCA

RCK2RCK1

BNJR

CMHI

MJL2KPO2

KPO1BRGA

BM9L

BM13L

BM18L

-6.7 -3.3

Fixed

-5.7-2.6

-5.7

-3.6

-3.0-4.2

-1.1

-8.5

-8.3

BANDUNG BASIN

SagulingDam

NORTH NORTH

10 km

June 2003 – June 2005

DHYK

GDBG

PSCA

RCK2RCK1

BNJR

CMHI

MJL2KPO2

KPO1BRGA

BM9L

BM13L

BM18L

DHYK

GDBG

PSCA

RCK2RCK1

BNJR

CMHI

MJL2KPO2

KPO1BRGA

BM9L

BM13L

BM18L

DHYK

GDBG

PSCA

RCK2RCK1

BNJR

CMHI

MJL2KPO2

KPO1BRGA

BM9L

BM13L

BM18L

-6.7 -3.3

Fixed

-5.7-2.6

-5.7

-3.6

-3.0-4.2

-1.1

-8.5

-8.3

BANDUNG BASIN

SagulingDam

NORTH NORTH

10 km

NORTH NORTH

10 km

June 2003 – June 2005

GPS Derived Subsidence Rates (mm/month)

Hasanuddin Z. Abidin et al., 2006Bandung Institute of Technology, Indonesia

0

5

10

15

20

25

30

35

40

45

BNJR CMHI DYHK MJL1 RCK1 RCK20

100

200

300

400

500

600Penurunan tanahVolume airtanahyang diambil

0

5

10

15

20

25

30

35

40

45

0

100

200

300

400

500

600SubsidenceExtracted groundwater

Subsi

den

ce (

cm)

Average volum

e of groundwater

extraction per month (in 1000 cubic-m

eter)0

5

10

15

20

25

30

35

40

45

BNJR CMHI DYHK MJL1 RCK1 RCK20

100

200

300

400

500

600Penurunan tanahVolume airtanahyang diambil

0

5

10

15

20

25

30

35

40

45

0

100

200

300

400

500

600SubsidenceExtracted groundwater

Subsi

den

ce (

cm)

Average volum

e of groundwater

extraction per month (in 1000 cubic-m

eter)

0

2

4

6

8

10

12

14

BNJR CMHI DYHK MJL1 RCK1 RCK2 CPRY KPO20

100

200

300

400

500

600Penurunan tanah

Volume airtanah yang diambil

0

2

4

6

8

10

12

14

BNJR CMHI DYHK MJL1 RCK1 RCK2 CPRY KPO20

100

200

300

400

500

600Penurunan tanah

Volume airtanah yang

Subsidence

Extracted groundwater

Average volum

e of groundwater

extraction per month (in 1000 cubic-m

eter)

Subsi

den

ce (

cm)

0

2

4

6

8

10

12

14

BNJR CMHI DYHK MJL1 RCK1 RCK2 CPRY KPO20

100

200

300

400

500

600Penurunan tanah

Volume airtanah yang diambil

Penurunan tanah

Volume airtanah yang diambil

0

2

4

6

8

10

12

14

BNJR CMHI DYHK MJL1 RCK1 RCK2 CPRY KPO20

100

200

300

400

500

600Penurunan tanah

Volume airtanah yang

Subsidence

Extracted groundwater

Average volum

e of groundwater

extraction per month (in 1000 cubic-m

eter)

Subsi

den

ce (

cm) WHY ?

• the registered groundwater abstraction volume does not reflect the real groundwater abstraction, and/or

• the land subsidence is also governed by other factors.

GPS survey results show that this hypothesis is not always true for all observed stations.

Land Subsidence and Groundwater AbstractionINITIAL HYPOTHESIS :

Land subsidence observed in several locations in Bandung

basin is caused by an excessive groundwater abstraction.

R = 0.643

R = 0.827

Hasanuddin Z. Abidin et al., 2006Bandung Institute of Technology, Indonesia

-19.10

-24.55

-33.00

-69.38

-33.34

-41.60

-80

-75

-70

-65

-60

-55

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Dep

t (m

bel

ow g

roun

d)

Kahatex PT IKahatex PT IIKahatex PT III

Groundwater level variationsin Rancaekek area (3 wells)

-19.10

-24.55

-33.00

-69.38

-33.34

-41.60

-80

-75

-70

-65

-60

-55

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Dep

t (m

bel

ow g

roun

d)

Kahatex PT IKahatex PT IIKahatex PT III

Groundwater level variationsin Rancaekek area (3 wells)

697.8

697.9

698.0

698.1

698.2

698.3

698.4

698.5

698.6

Feb. 2000 Nov.2001 July 2002 June 2003 June 2005

Ellipsoidal height variationof GPS station : RCK2

= 56.9 cm

about 5 years

697.8

697.9

698.0

698.1

698.2

698.3

698.4

698.5

698.6

Feb. 2000 Nov.2001 July 2002 June 2003 June 2005

Ellipsoidal height variationof GPS station : RCK2

= 56.9 cm

about 5 years

SUBSIDENCE ANDGROUNDWATER

ABSTRACTION

in Rancaekek area

There iscorrelation !!

1 km

700 m

Water inundation in the road

Cracking and tilting of road

Groundwaterwells

IMPACT OFSUBSIDENCE AND

in Rancaekek area

Hasanuddin Z. Abidin et al., 2006Bandung Institute of Technology, Indonesia

-80-70-60-50-40-30-20-10

0

1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004

Dept

h be

low

grou

nd (m

) Groundwater level variationMonitoring well : PT. Kahatex no. II RCK2 GPS point

Water Inundation

IMPACT OF SUBSIDENCE AROUND CMHI GPS STATIONHanging wall

Tilting of Infrastructures

Hasanuddin Z. Abidin et al., 2006Bandung Institute of Technology, Indonesia

GPS survey method is a reliable method for studying and monitoring land subsidence should also be integrated with results obtained by Leveling, INSAR and Automatic Water Level Recorder.

Land subisdence in Bandung = f { excessive groundwater abstraction,

building load (?), tectonics (?), natural compaction (?), x1(?), … , xn (?) }

Further research is needed to clarify the real mechanism and pattern of land subsidence phenomena in Bandung.

CLOSING REMARKS

Hasanuddin Z. Abidin et al., 2006Bandung Institute of Technology, Indonesia