River Study – Power Station, Baturaja, South Sumatera
Geoindo
CONSORTIUM
MALAKOFF CORPORATION BERHAD,
TOYOTA TSUSHO CORPORATION AND
HANSON ENERGY
LUBUK BATANG, BATURAJA,
OGAN KOMERING ULU,
SOUTH SUMATERA, INDONESIA
RIVER STUDY AT OGAN RIVER – PHASE 1
REPORT 1
HYDROLOGY AND FLOOD STUDY
REVISION HISTORY
Revision
Date
Description
00
20th December 2013
Initial Issue
01
13th January 2014
-
Revise Consortium’s name
Revise Point. 3.8
Review / Approval Signatures
Prepared by
Reviewed by
Approved by
Kurniayati
Adang Herdhyana
Bob Bacciarelli
Geodetic Engineer
Project Manager
Technical Director
ATR/001/14/Rev.01.Rep.2 – Ogan River, Lubuk Batang, Batu Raja, Ogan Komering Ulu, South Sumatera, 13th January 2014
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River Study – Power Station, Baturaja, South Sumatera
CONSORTIUM
MALAKOFF CORPORATION BERHAD,
TOYOTA TSUSHO CORPORATION AND
HANSON ENERGY
LUBUK BATANG, BATURAJA,
OGAN KOMERING ULU,
SOUTH SUMATERA, INDONESIA
RIVER STUDY AT OGAN RIVER – PHASE 1
REPORT 1
HYDROLOGY AND FLOOD STUDY
EXECUTIVE SUMMARY
The aim of this report is to provide the hydrological basis for assessing the feasibility of using
the Ogan River between Tanjung Dalam and Lubuk Batang as a water supply source for a
proposed power station.
The Ogan River at Tanjung Dalam is fed from three main tributaries, which all join at the town
of Batu Raja: Air Laye, Ulu Ogan and Lengkayap River represent 9%, 41% and 49%
respectively of the catchment area at the confluence of 2024 km 2 catchment area. This is very
similar to the published value of 2046 km2 for the historical Batu Raja gauging station. The
residual catchment area downstream of the Batu Raja confluence is 75 km2, bringing the total
area at Tanjung Dalam to 2099 km2. Based on geological map of Indonesia, the Ogan River
Basin has volcanic rocks exposed at higher elevations and sedimentary rocks at lower
elevations. Tertiary sedimentary rocks outcrop in a NW-SE band across the lower hills
upstream of the town of Batu Raja.
The most prominent aquifer in the region is the Batu Raja limestone, which is exploited for
public water supply, while the other Tertiary sediments are reported to be less productive. Most
of the lower-lying ground NE of Batu Raja is covered by Quaternary sediments and Tertiary
deposits, comprising mudstone, sandstone and coal seams. The Ogan River develops the
characteristics of a typical lowland floodplain 8 km downstream of Batu Raja town, and from
this point there is evidence of river channel mobility across a wide belt of alluvium at Tanjung
Dalam.
Climate data at Kenten station was provided by the Indonesian authority for the period 1977 to
2012, showing a progressive rise in temperature during the period of record, confirming the
impact of global warming at this location. Sunshine is recorded as typically 3-80% of daylight
hours and a relative humidity 75-88%. Wind speed is generally between 2 and 4 knots, rising
ATR/001/14/Rev.01.Rep.2 – Ogan River, Lubuk Batang, Batu Raja, Ogan Komering Ulu, South Sumatera, 13th January 2014
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River Study – Power Station, Baturaja, South Sumatera
occasionally to 6 knots. PET (Potential Evapotranspiration) was calculated from the climate
parameters, resulting in a mean annual total of 1395.8 mm for the Ogan River Basin.
Daily rainfall data was provided for four stations, Kenten (1977 to 20120), Belitang (1991 to
2012), Batu Raja (2003 to 2012) and Martapura (1991 to 2001), none really representative of
the Ogan catchment. Modelling would be improved using data from the following six sites in
and around the catchment: Pulau Panggung, Pandan Enim, Raks Jiwa, Batu Marta, Karang
Endah and Pengandonan. The mean annual rainfall at Kenten is 2590 mm for the period 19772012, which is lower than the catchment rainfall of 2920 mm, quoted in the IH 1983 report for
the Batu Raja catchment. Rainfall derived from the Kenten station was adjusted to take into
consideration this difference.
At Batu Raja, it is suggested that climate change modelling be carried out during Phase 2, in
order to determine the impact of global warming in Southern Sumatra on flood and drought
discharge and the duration of times when the power station may become dependent on other
sources. If the trend of rising temperature at Kenten over the period 1977-2012 were to
continue, it could lead to lower river flows in the future.
The fact that all the rainfall monitoring sites are located outside the Ogan River catchment
imposes a significant limitation on the potential accuracy of river flow simulation. Where there
are no flow records or an observed record is of short duration, a rainfall-runoff model is
frequently used to produce a simulated flow record, using rainfall and PET as input data and
produces river flow as an output. Meteorological data collected for a longer period than the
flow record can then be used to simulate flows over a long period. This is a widely used
practice and HYSIM will typically produce flow records of 50-100 years at any site of interest in
the world, subject to the availability of rainfall and PET time series.
Flow data was provided for several gauging stations in the Musi River Basin including two sites
in the Ogan river basin, Lengkayap River at Batu Putih, and Ogan River at Tanjung Raja.
Tanjung Raja is too far downstream to be of real use, and data for Ogan River at Batu Raja
remains hidden in DPMA archives. DPMA in Bandung is still attempting to recover this
valuable record from archived boxes for the Phase 2 studies, so that it can be digitised for
modelling.
HYSIM was calibrated for the period 1980-1992 using the flow record for Lengkayap River at
Batu Putih, producing observed and simulated mean monthly flows of 42.36 m3/s. The
standard deviation was 49.5 m3/s for the simulated flow and 60.2 m3/s for the observed flow.
The main sub-catchments were simulated for the period 1977-2012 using the Batu Putih model
parameters and physical descriptors of the other catchments. At Tanjung Dalam, the lowest
predicted flow is 3.51 m3/s, and frequency analysis shows that the Q95 minimum flow is 10.8
m3/s, flow which has a 95% probability of being exceeded. Indonesian regulations would
impose a ban on abstraction for flows less than Q95.
The Ogan River at Batu Raja is one of the flow gauging stations used in 1983 by DPMA and
the British Institute of Hydrology in a study of floods in Java and Sumatra. This station is
located 11.4 km upstream of Tanjung Dalam. The MAF for Lengkayap River at Batu Putih is
587m3/s, and for Ogan River at Batu Raja is 1409 m3/s, calculated respectively from 13 and 10
years of annual maximum data.
The 1972 flood identified by residents at Tanjung Dalam is the worst flood in the Batu Raja
record, reported as 2472.5 m3/s, and more than double the other annual maxima. As a rule of
thumb record lengths of only 10 and 13 years should only be extrapolated to predict up to 20 to
30 year return period floods, that is, double the available length of record. The estimated flood
magnitude-frequency results for the Ogan River adjacent to the power station site at Tanjung
Dalam may be summarised as follows:
ATR/001/14/Rev.01.Rep.2 – Ogan River, Lubuk Batang, Batu Raja, Ogan Komering Ulu, South Sumatera, 13th January 2014
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River Study – Power Station, Baturaja, South Sumatera
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Return Period
Peak Flood
Discharge
Years
10
25
50
100
200
3
1387
2076
2662
3354
4716
m /s
Rarely, tropical storms track across Northern Sumatra from the Bay of Bengal, and from the
South China Sea across Malaysia and Singapore. No events have been recorded in southern
Sumatra.
The Ogan River was represented using a 1-dimensional HEC-RAS hydraulic model. The LowFlow model was calibrated against surveyed water levels and discharges at specific locations,
with particular reference to cross-section 3-3’. It was found that the riverbanks were
overtopped at relatively modest flows of about 600 m3/s, which is less than the mean annual
flood. The High-Flow model was calibrated against the surveyed 1972 flood levels (1244 m3/).
The smallest water depth modelled at Cross-section 3 was 2.83 m for a discharge of 3.5 m3/s
flowing at less than 0.1 m/s and having an exceedance probability of 99.9%. The predicted low
water levels may be summarised as follows:
Q95
Q99.9
10.78 m3/s
3.5 m3/s
30.95 m aMSL
30.63 m aMSL Minimum Bed Elevation at XS-3 is 27.80 m aMSL
The 1972 flood of 2472.5 m3/s has an approximate level of 38 m aMSL at Cross-section 3. The
predicted water levels at Cross-section 3 for a range of return periods may be summarised as
follows:
Return Period
Peak Flood Discharge
Floodwater Level
Years
m3/s
m aMSL
10
1387
37.89
25
2076
38.62
50
2662
39.20
100
3354
39.80
200
4716
40.76
The floodwater mapping of the 40.8 m aMSL extents shows that the proposed power station
site lies above the area of inundation, and that most of the area has freeboard of 20 m. It
should be noted that observed flood levels from interview local people was 37.15 m and dry
session level 30.103 m. The modelled predicted levels are similar to those observed given the
accuracy of observations could be ± 1 m or more.
ATR/001/14/Rev.01.Rep.2 – Ogan River, Lubuk Batang, Batu Raja, Ogan Komering Ulu, South Sumatera, 13th January 2014
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River Study – Power Station, Baturaja, South Sumatera
Geoindo
CONSORTIUM
MALAKOFF CORPORATION BERHAD,
TOYOTA TSUSHO CORPORATION AND
HANSON ENERGY
LUBUK BATANG, BATURAJA,
OGAN KOMERING ULU,
SOUTH SUMATERA, INDONESIA
RIVER STUDY AT OGAN RIVER – PHASE 1
REPORT 1
HYDROLOGY AND FLOOD STUDY
TABLE OF CONTENTS
Page No.
REVISION HISTORY
i
EXECUTIVE SUMMARY
ii
TABLE OF CONTENTS
v
TEXT
1.
INTRODUCTION
1
1.1.
1.2.
1
3
Project Description
Definitions / Abbreviations
2.
SCOPE OF WORK
4
3.
FIELD WORK
4
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
4
5
5
5
6
6
6
6
Mobilisation
Field Preparation
Kick off Meeting and Site Inspection
Data Collection
Reference Benchmarks and Geodetic Control Survey
Traverse Survey
River Cross Section Survey
Water Sampling and River Water Temperature Measurement
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River Study – Power Station, Baturaja, South Sumatera
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3.9
3.10
3.11
3.12
3.13
4.
Water Level Observation
Current Measurement
Demobilisation
Drawing Processing
Coordination and Communication with Company
7
8
8
8
8
ANALYSIS OF HYDROLOGY AND FLOOD STUDY
9
4.1
Catchments Characteristics
9
4.1.1
4.1.2
4.1.3
4.1.4
9
10
12
13
4.2
Topographic Mapping
Catchment Geology
Groundwater
Floodplain Characteristics and Local Topography
Climatological Data
14
4.2.1
4.2.2
4.2.3
4.2.4
4.2.5
4.2.6
4.2.7
4.2.8
14
15
15
16
17
17
19
20
Data Processing
Temperature
Sunshine
Wind Speed
Relative Humidity
Rainfall
Potential Evapotranspiration
Climate Change
4.3
Hydrometric Data Acquisition and Review (Historical River Water
Level and Discharge) and Continuous Water Level Monitoring
During the Fieldwork
20
4.4
Simulation of Ogan River Discharge
21
4.4.1
4.4.2
4.4.3
4.4.4
4.4.5
Rainfall-Runoff Modelling
Available River Discharge Data
Hysim Calibration
Simulation
Limitations and Improvement
21
22
24
25
27
4.4.5.1 Possible Improvements in Accuracy
4.4.5.2 River Flow Data
4.4.5.3 Rainfall
4.4.5.4 Climatological Data
4.4.5.5 Artificial Influences
4.4.5.6 Climate Change
27
27
27
27
27
28
4.5
4.6
Flood Hydrology
28
4.5.1
4.5.2
4.5.3
4.5.4
28
28
32
33
Data Available for Flood Analysis
Flood Frequency Analysis
Flood Hydrographs
Tropical Storms
River Cross-Sections and Traverse Survey, to Establish Minimum
and Maximum Water Level, at Five Locations along the Ogan
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4.7
4.8
River, defining Water Level for Each Cross-Section and Measuring
Points Referred to Mean Sea Level
34
4.6.1
4.6.2
4.6.3
34
35
36
River Water Flow Rate Measurement at Section 3, Showing
Minimum and Maximum Values, Following Format of TOR
Appendix 3
Hydraulic Modelling using HEC-RAS to Establish Low Flow
and High Flow Water Levels for Different Severity of Events
4.8.1
4.8.2
4.8.3
4.8.4
4.9
4.10
Reference Benchmarks and Geodetic Control Survey
Traverse Survey
River Cross Section Survey
36
37
HEC-RAS Modelling
Model Configuration
Model Calibration
Model Simulation
37
37
39
43
4.8.4.1 High Flow Configuration
4.8.4.2 Low Flow Water Levels
4.8.4.3 Flood Water Levels
43
44
46
Description of the Geo-Hydrological Conditions at the Power
Plant and in the Study Area
47
Deliverables and Reporting
49
4.10.1 Field Daily Report
4.10.2 Interim Draft Report
4.10.3 Final Report
49
49
49
5
QUALITY CONTROL
49
6.
CONCLUSION AND RECOMMENDATIONS
50
6.1
6.2
50
51
Conclusions
Recommendations For Phase 2
Annex
Annex A
TOR Appendix 4
A-1 Flow and Water Level at Tanjung Dalam
A-2 Summary of Kenten Climatological Data
A-2-1 Climatic Means and Extremes
A-2-2 Seasonal Distribution of Daily Temperature
A-2-3 Seasonal Distribution of Relative Humidity
A-2-4 Rainfall in mm
A-2-5 Wind Speed [knots]
A-2-6 Atmospheric Pressure [mbar]
52
52
52
52
52
52
53
53
53
Annex B
Hydrological Data Summaries
B-1 PET Time Series for Ogan River Basin
54
54
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Annex C
B-2 Monthly Rainfall Summary for Kenten
B-3 Monthly Mean Runoff in m3/s at Tanjung Dalam
55
56
Hydraulic Model Summaries
C-1 Predicted Low Flow Water Levels
C-2 Predicted Water Levels for Dry Season Flows
C-3 Flood Extent Maps
57
57
58
61
Table in Main Text
Table 4.1
Table 4.2
Table 4.3
Table 4.4
Table 4.5
Table 4.6
Drainage Network and Sub-Division of the Ogan River Catchment
Monthly and Annual Rainfall in mm for Kenten Rainfall Station
Monthly and Annual PET in mm for the Ogan River Basin at Batu Raja
Lengkayap River Mean Daily Discharge at Batu Putih
Duration of Low Flows at Tanjung Dalam
Computation of Mean Annual Flood (MAF) for the Batu Raja and Batu
Putih Catchments
Table 4.7 Annual Maxima for Ogan River at Batu Raja Lengkayap River at Batu
Putih
Table 4.8 Flood Discharge Estimates for Ogan River at Batu Raja and for
Lengkayap River at Batu Putih
Table 4.9 Flood Discharge Estimates for Ogan River at Tanjung Dalam
Table 4.10 Values of Manning’s n used for the Floodplain
Table 4.11 Observed and Predicted Water Surface Elevations at Cross Section 3
Table 4.12 “Observed” and Predicted Water Levels for the 1972 Event
Table 4.13 Predicted Maximum Water Depth, Flow Velocity and Width at Three
Cross Sections
Table 4.14 Predicted Flood Water Levels
10
18
19
22
26
29
30
30
32
38
41
42
45
46
Figure in Main Text
Figure 1.1
Figure 4.1
Figure 4.2
Figure 4.3
Figure 4.4
Figure 4.5
Figure 4.6
Figure 4.7
Figure 4.8
Figure 4.9
Figure 4.10
Figure 4.11
Figure 4.12
Figure 4.13
Figure 4.14
Figure 4.15
Figure 4.16
Figure 4.17
Figure 4.18
Figure 4.19
Figure 4.20
Figure 4.21
Location of the Project Site and Ogan Catchment
Drainage Network and Sub-Division of the Ogan River Catchment
Simplified Geology of the Ogan River Catchment
Simplified Geological Cross-Section of the Ogan River Catchment
The Ogan River Corridor adjacent to the Proposed Power Plant
Variation in Temperature at Kenten, 1977-2012
Sunlight as a Percentage of Daylight Hours at Kenten, 1977-2012
Monthly Average Wind Speed at Kenten, 1977-2012
Monthly Relative Humidity at Kenten
Monthly Rainfall at Selected Rainfall Stations
Annual Variation in Rainfall at Kenten
Monthly Variation in PET in the Ogan River Basin at Batu Raja
Projections of Annual Average Temperature in West Java
Lengkayap River Mean Daily Discharge at Batu Putih
Comparison of Rainfall and Runoff in the Lengkayap River
Catchment
Lengkayap River Stage-Discharge Rating
Lengkayap River Model Calibration
Lengkayap River Flow Duration Comparisons
Probability % of Different Flow Durations at Tanjung Dalam
Mean Annual Maximum 24-hourly rainfall (mm)] APBAR
Flood Frequency Curves for Ogan River at Batu Raja and
Lengkayap River at Batu Putih
Flood hydrographs for Ogan River at Tanjung Dalam
1
9
11
13
14
15
16
17
17
18
19
19
20
23
24
24
25
25
26
29
32
32
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River Study – Power Station, Baturaja, South Sumatera
Figure 4.22 Indian-Pacific Tropical Cyclone Tracks 1985-2005
Figure 4.23 Hydraulic Model Schematic
Figure 4.24 Cross Section 3 Velocity Measurement Positions for Discharge
Calculation
Figure 4.25 Stage-Discharge Relationship for a Narrow Range of Flows
Measured at Cross Section 3
Figure 4.26 Comparison of Predicted and Observed Water Levels for Different
Dates using two n-Values
Figure 4.27 Schematic of the Model Configuration for Large Flood Event
Simulation
Figure 4.28 Predicted Water Levels for Dry Season Flows across Cross-Sections
2-4
Figure 4.29 Dry-Weather Flow Maximum Water Depths Predicted across CrossSections 2-4
Figure 4.30 Predicted Stage-Discharge Relationship for Ogan River Flood Flows
at The Power Station Site
34
38
40
40
43
44
45
46
47
TABLES
1.
2.
3.
4.
5.
List of Benchmark Coordinates
GPS Accuracy
Traverse Accuracy
List of Collected Data
A. Water Level Recording
B. Water Level Height Referred to Chart Datum
6. A. Current Measurement
B. Current Measurement Data Summary
C. Water Debit Calculation of Cross Section 3
7. Channel Cross-section Survey Data
8. List of Water Level
9. List Coordinates of Lowest Dry Season Level
10. List of Coordinates of Highest Flood Level
11. List of Coordinates of Riverbed Level at Upstream and Downstream
12. Site Information
13. Local Stratigraphy Column
FIGURES
1.
2.
3.
4.
5.
6.
7.
Regional Map
Location Plan
Geological Map (From Directorate Geology)
Geodetic Control Network
Traverse Survey Network
Elevation Datum Relationship Chart
A. Drainage Network and Sub-Division of the Ogan River Catchment
B. Climatological data: Kenten
C. Hydraulic Model Schematic
D. Lengkayap River at Batu Putih, 2006-2009
E. Storage Option
8. Hydrogeological Map
9. Flood Maps
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River Study – Power Station, Baturaja, South Sumatera
APPENDICES
1.
2.
3.
4.
5.
6.
7.
8.
Reference Control Point
Benchmark Details
Report of GPS Survey Data Processing
Report of Traverse Survey Data Processing
GPS Calibration Certification
Total Station Calibration Certification
Total Station Field Calibration
Data Collection – Flow Rate
A. Flow Rate at Srijabo Post
B. Flow Rate at Batu Putih Post
C. Flow Rate at Belarik Post
D. Flow Rate at Tirtonadi Post
E. Flow Rate at Rantau Bingin Muara Post
F. Flow Rate at Lubuk Rumbai Post
G. Flow Rate at Ulak Surung Post
H. Flow Rate at Mangunjaya Post
I. Flow Rate at Menanga Post
J. Flow Rate at Lebak Budi Post
K. Flow Rate at Sungai Rotan Post
L. Flow Rate at Tanjungraya Post
M. Flow Rate at Tanjung Rembang Post
N. Flow Rate at Kota Agung Post
9. Data Collection – Water Level
A. Water Level at Srijabo Post
B. Water Level at Batu Putih Post
C. Water Level at Belarik Post
D. Water Level at Tirtonadi Post
E. Water Level at Rantau Bingin Muara Post
F. Water Level at Lubuk Rumbai Post
G. Water Level at Ulak Surung Post
H. Water Level at Mangunjaya Post
I. Water Level at Menanga Post
J. Water Level at Lebak Budi Post
K. Water Level at Sungai Rotan Post
L. Water Level at Tanjungraya Post
M. Water Level at Tanjung Raja Post
N. Water Level at Kota Agung Post
10. Data Collection – Climatology Data
A. Climatology Post Sumatera Selatan
B. Climatology Data at Kenten Post (Daily)
C. Climatology Data at Kenten Post (Monthly)
D. Climatology Data at Baturaja Post
E. Rainfall Data at Baturaja OKU
F. Rainfall Data at Martapura Post
G. Rainfall Data at Belitang Post
11. Photographs
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DRAWINGS
No.
DWG No.
Rev
No.
1
ATR/001/01/001
A
Site Plan
1 : 10,000
2
ATR/001/01/002
A
Cross Section 1 – 1’ to 3 – 3’
3
ATR/001/01/003
A
Cross Section 4 – 4’ to 6 – 6’
H
V
H
V
4
ATR/001/01/004
A
Cross Section 7 – 7’ to 10 – 10’
H 1 : 2,500
V 1 : 250
A1
5
ATR/001/01/005
A
Lubuk Batang baru Bridge Plan &
Sections
1 : 500
A1
Drawing Title
Scale
1 : 2,500
1 : 250
1 : 2,500
1 : 250
Size
A1
A1
A1
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