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EFFECTS OF CLIMATE CHANGE AND LAND SUBSIDENCE

ON WATER MANAGEMENT ZONING IN TIDAL LOWLANDS Case study Telang I, South Sumatra

Rahmadi Land and Water Development

GIS/RS specialist

.

OUTLINE

Background

Lowlands development in Indonesia and Government

policy

Climate change and land subsidence, their possible

effects to tidal lowlands water management

Case study Telang I, South Sumatra

Methodology

Result and Discussion

Conclusions and recommendations

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BACKGROUND

Lowlands in Indonesia about 34 million ha

About 20 million ha tidal lowland

The other 13.4 million ha non-tidal lowlands along rivers and

inland swamp areas

Tidal lowlands Almost 4 million ha have been reclaimed,

spontaneous settlers (2.5 million ha) and Government (1.5 million ha)

Lambur, Jambi Sei Kakap, West Kalimantan Telang I, South Sumatra SOURCE: WACLIMAD, 2010

PROBLEM DEFINITION

Sea level rise and land subsidenceflooding

and restrict drainage of low-lying areashydro-

topography, drainage capability (drainability)

and salinity intrusion

land quality/suitability and

water management zoning

Water management zoning based on

land capabilities and cropping type

(by considering effects of climate change and

land subsidence)

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OBJECTIVES

study water management zoning model for tidal lowlands

set up water management zoning model by using spatial

analyses with GIS techniques based on present situation

evaluate the possible impacts of climate change and land

subsidence in the future

recommend approaches for future development of tidal

lowlands

INDONESIAN GOVERNMENT POLICY ON LOWLANDS

Past policy:

Original objectives →transmigration of farmers from the overcrowded islands; Security border and balancing of development

Present policy:

to contribute to the required increase in food production

Intensifications of existing reclaimed lowlands area to support food self-sufficiency

proper O&M and rehabilitation in the existing schemes

‘no reclamation’ of any new lowlands for food development

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CLIMATE CHANGE AND LAND SUBSIDENCE, THEIR POSSIBLE

EFFECTS TO TIDAL LOWLAND WATER MANAGEMENT

(source: Nicholls et all, 2007)

(source: Bindoff et al, 2007)

SCHEMATIC OF THE OBSERVED CHANGES IN THE OCEAN STATE

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EFFECT ON HYDRO-TOPOGRAPHY

Category A and B Category C and D

Horizontal water level

water level due to

hydraulic losses Ground surface

elevation

Imaginary

ground surface

C and D Extent of category A and B

Original water level

water level due to

hydraulic losses

Original Ground

surface elevation

Imaginary

ground surface

Effect of Sea level rise

Ground surface elevation

due to land subsidence

EFFECT ON DRAINABILITY

∆H present

∆H future Sea level rise

land subsidence

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EFFECT ON SALINITY INTRUSION

River zonation and salinity intrusion in normal condition:

River zonation and salinity intrusion with predicted sea level rise:

Brackish

water Fresh water only in

wet season

Fresh water in wet and

dry season

tides Q

METHODOLOGY

DUFLOW 3.6 : Hydraulic Losses, salinity intrusion (quality

model)

SWAP : Land subsidence

ARCGIS : Model Builder and Spatial analyses

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MODEL DEVELOPMENT

Digital Elevation

Models

Satellite

image Basemap

Tidal Irrigation

Orthophoto/

leveling

Land Quality

Proposed Water Management

Zoning for wet and dry season

Drainability Soils Map Salinity

Water management

zoning

Data Collection

First Analyses

Second Analyses

Final Analyses

Final output

Existing Land use

Sea Level Rise Salinity Land Subsidence

SWAP

Duflow and ArcGIS

Soil properties, Rainfall

and GWL

CASE STUDY TELANG I, SOUTH SUMATRA

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Average water level of Low Water Springtide in Musi River (2001-2008) : (Source: PT. Pelabuhan Cabang Palembang, 2008)

Average waterlevel of LWS in Musi River (2001-2008)(Source: PT. Pelabuhan Indonesia II Cabang Palembang, 2008)

y = 5E-05x - 0,0815

y = 4E-05x + 0,6665

y = 4E-05x + 0,6462

0

0,5

1

1,5

2

2,5

3

3,5

Jun-0

0

Okt-

00

Jan-0

1

Apr-

01

Jul-01

Nop-0

1

Feb-0

2

Mei-02

Sep-0

2

Des-0

2

Mar-

03

Jun-0

3

Okt-

03

Jan-0

4

Apr-

04

Agust-

04

Nop-0

4

Feb-0

5

Mei-05

Sep-0

5

Des-0

5

Mar-

06

Jul-06

Okt-

06

Jan-0

7

Apr-

07

Agust-

07

Nop-0

7

Feb-0

8

Jun-0

8

Sep-0

8

Des-0

8

Month

Avera

ge w

ate

r le

vel

(m)

Tanjung Buyut Upang Selat Jaran Linear (Tanjung Buyut) Linear (Upang) Linear (Selat Jaran)

RESULT AND DISCUSSION

GROUNDWATER FLUCTUATION

Example of Secondary block P8-12S (Category A)

gr

0.000

0.200

0.400

0.600

0.800

1.000

1.200

1.400

1.600

1.800

7/2

7/2

004

9/1

5/2

004

11/4

/2004

12/2

4/2

004

2/1

2/2

005

4/3

/2005

5/2

3/2

005

7/1

2/2

005

8/3

1/2

005

10/2

0/2

005

12/9

/2005

1/2

8/2

006

3/1

9/2

006

5/8

/2006

6/2

7/2

006

8/1

6/2

006

10/5

/2006

11/2

4/2

006

1/1

3/2

007

3/4

/2007

4/2

3/2

007

6/1

2/2

007

8/1

/2007

9/2

0/2

007

11/9

/2007

12/2

9/2

007

2/1

7/2

008

time (day)

wa

ter le

ve

l (m

+M

SL

)

0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

rain

fall

(m

m)

Rainfall SPD side SDU side Middle side Average Surface level

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SWAP MODELLING FOR LAND SUBSIDENCE

Average Land subsidence in Telang 1

-0.01

-0.005

0

0.005

0 50 100 150 200 250 300 350

time (day)

su

bsid

en

ce

in

cm

subsidence at P8-12S subsidence at P6-3N

total subsidence = 0.3 - 0.7 cm/year

HYDRO-TOPOGRAPHY

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DRAINABILITY

LAND QUALITY, WET SEASON

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WATER MANAGEMENT ZONING, WET SEASON

Sa

lt C

on

ce

ntr

atio

n

distance (km)

SALINITY INTRUSION (NORMAL DRY SEASON)

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WATER MANAGEMENT ZONING (DRY SEASON)

CONCLUSIONS AND RECOMMENDATIONS

Effect of climate change and land subsidence on water

management zoning in the future is significant

MODEL BUILDER technique is very useful tool

Proper operation of water management systems to control

groundwater fluctuation

Further study and groundtruth is needed

To cope with the effect of climate change and land subsidence

on water management zoning in tidal lowlands, some

structural and non structural measures are needed.

Establishment of monitoring station

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THANK YOU