Ilocos Sur Irrigation Projects (Upper Banaoang Irrigation)
EXECUTIVE SUMMARY
Option 1
Option 2
Option 3
VE/VA Options Considered
Intake and HDPE conveyance
Intake and Concrete Cut and Cover conveyance
Malapaao SRIP
Hydrology
Drainage Area
Climate
Annual Water
Requirement
Score Ranking
3rd
46.0
2nd
47.0
1st
74.0
109 sq.km
Type I
2,780 mm
Malapaao Peak Flows
Return Period
Peak Discharge
Baseflow
Total Discharge
years
3
m /s
3
m /s
m3/s
2
294.20
5.45
299.65
5
460.50
5.45
465.95
10
536.80
5.45
542.25
100
869.30
5.45
874.75
200
982.30
5.45
987.75
500
1,120.20
5.45
1,125.65
Malapaao PMF Comparison
Malapaao (Envelope Curve)
Malapaao (SCS Unit Hydrograph)
Malapaao (PMP and SCS Method)
Peak PMF
inflow, m3/s
Specific
Discharge,
m3/s/km2
4,121
1,561
1,456
37.81
14.32
13.36
Ilocos Sur Irrigation Projects (Upper Banaoang Irrigation)
ENGINEERING SALIENT DATA
ITEMS
Unit
Data
GENERAL
Total Service Area
Existing
New
Catchment Area
Inflow Design Flood
• 5-yr Return Period (log normal)
• 5-yr Return Period
• 10-yr Return Period
• 25-yr Return Period
• 50-yr Return Period
• 100-yr Return Period
• 100-yr Return Period w/ Climate Change
• Probable Maximum Flood
• 10, 000-yr Return Period
Has.
Has
Has.
Km2
m3/sec
m3/sec
m3/sec
m3/sec
m3/sec
m3/sec
m3/sec
m3/sec
m3/sec
5000
2130
2870
109.00
469.72
601.94
1, 010.91
1, 572.56
2, 364.68
2, 856.25
3, 516.70
4, 121.00
8, 173.43
DAM
Type
Elevation
• Dam Crest
• Riverbed at Dam Axis
Dam Height
Dam Crest Length
Dam Crest Width
Slope
• Upstream face
• Downstream face
Rockfill Dam
m
m
m
H:V
H:V
128.0
55.0
73.00
610.70
14.00
4.0 : 1.0
2.75 : 1.0
SPILLWAY
Type
Crest Elevation
Width
Length
Type of Stilling Basin
Inflow Design Flood
Surcharge Height
m
m
m3/sec
m
Ungated Ogee
106.0
50.00
272.00
Flip Bucket
8, 173.43
17.21
SPILLWAY BRIDGE
Type of Slab
Length
Width (Clear Span)
No. of Piers
m
m
No. - Size
Type IV Prestressed
Concrete Girder
53,200
5.50
1 – 2.0m. dia.
OUTLET WORKS
Diversion Conduit During Construction
• Type
• Inflow Design Discharge
• No.-Size
• Length
m3/sec
No. – size
RC Circular Steel Pipe
1,572.56
5 – 5.00 m
549.00
Ilocos Sur Irrigation Projects (Upper Banaoang Irrigation)
DIVERSION TUNNEL
Section
Size
Design Discharge for Irrigation
Length
Inlet Elevation
Control Mechanism
Outlet Elevation
Outlet Structure
Max. Design Discharge for outlet structure
m
m3/sec
m
masl
masl
m3/sec
Modified Horsehoe
2.70 dia.
8.85
7,600.00
79.0
2pcs. – Slide Gate
76.0
Impact-Energy Dissipator
21.90
PEDESTRIAN BRIDGE TO GATE HOUSE
Type
Length
Width
No. of Piers
m
m
No.-Size
80.0
2.0
1 – 2.0m dia.
POWERHOUSE
Type
Turbine
No. of Units
Max. Net Head
Rated flow
Total flow
Installed capacity
Gross Energy
Rated Efficiency
Gross Sales at FIT
Type
Units
m
m3/sec
m3/sec
MW
kWh
%
Php
Underground
Powerhouse
Francis (Vertical Shaft)
2.0
25.00
5.00
10.00
1.83
16, 053, 576.00
93.50
93, 271, 276.56
ACCESS ROADS
• Existing
Access
Road (for improvement)
Langiden
to Dam
Site (W=6m)
• Proposed Access Road
• Overflow Bridge
Dam Right Abutment to Powerhouse (W=6m)
Road/Flood Dike
Km
Km
m
Km
Km
2.80
4.20
120.00
0.90
780.00
RESERVOIR
Elevations
• Maximum Water Surface
123.21
• Normal Water Surface
• Minimum Water Surface
Areas
• Maximum Water Surface
• Normal Water Surface
• Minimum Water Surface
Storage
• Maximum Water Surface
• Normal Water Surface
• Minimum Water Surface
106.00
75.00
ha
ha
ha
396.9
292.21
109.84
m3
m3
m3
130.02
71.53
8.83
Ilocos Sur Irrigation Projects (Upper Banaoang Irrigation)
ECONOMIC ANALYSIS
TOTAL PROJECT COST
– Php 6,611,932,011
ECONOMIC INDICATORS
ALL COMPONENTS
Scenario
EIRR (%)
NPV (PhP)
BCR
Base Case
12.34
1.504 B
1.25
10% increase in costs
11.30
897.668 M
1.13
10% decrease in revenue
11.20
747.242 M
1.12
Simultaneous 10% increase in costs
and 10% decrease in revenue
10.21
140.654 M
1.02
20% increase in costs
10.40
291.080 M
1.04
20% decrease in revenue
9.98
(9.771 M)
1.00
Simultaneous 20% increase in costs
and 20% decrease in revenue
8.25
(1.222 B)
0.83
2 years delay in benefits
9.73
(181.463 M)
0.97
IRRIGATION ONLY
Scenario
EIRR (%)
NPV (PhP)
BCR
Base Case
11.94
1.162 B
1.21
10% increase in costs
10.93
597.776 M
1.10
10% decrease in revenue
10.83
481.562 M
1.09
Simultaneous 10% increase in costs
and 10% decrease in revenue
9.87
(82.805 M)
0.99
20% increase in costs
10.05
33.409 M
1.00
20% decrease in revenue
9.65
(199.019 M)
0.96
Simultaneous 20% increase in costs
and 20% decrease in revenue
7.96
(1.327 B)
0.80
2 years delay in benefits
10.18
117.021 M
1.02
Ilocos Sur Irrigation Projects (Upper Banaoang Irrigation)
HYDROPOWER ONLY
Scenario
EIRR
NPV (Mil PhP)
BCR
Base Case
16.13
243.59
1.47
10% increase in costs
14.47
175.95
1.34
10% decrease in revenue
14.30
153.90
1.33
Simultaneous 10% increase in costs
and 10% decrease in revenue
12.81
109.38
1.22
20% increase in costs
13.09
131.43
1.24
20% decrease in revenue
12.48
89.40
1.19
Simultaneous 20% increase in costs
and 20% decrease in revenue
9.96
(1.55)
1.01