2~5m

Area-4

IV-F7

THE GOVERNMENT OF THE PHILIPPINESTHE DEPARTMENT OF PUBLIC WORKS AND HIGHWAYS

The Study on Sabo and Flood Control forWestern River Basins of Mount Pinatubo

in the Republic of the PhilippinesJAPAN INTERNATIONAL COOPERATION AGENCY

Cuadrado River

Subic

Castillejos

San Marcelino

San Antonio

San Narciso

San Felipe

Cabangan

Botolan

MalumboyPoonbato

Iba

Maloma

San Rafael

Santa Fe

◎

SUBICBAY

SOU

TH

CH

INA

SEA

Bucao River

LakeMapanuepe

Baquilan River

Cab

atuanR

iver

Balintawak River

Upper Bucao River

Tanguay Ri ver

Kileng Rive

rBalin Baquero River

Anonang Cr

Gorongorong-Kakilingan River

Mar

ella

River

Pamatawan River

Mount Pinatubo

Maloma River

Manila

LuzonLegend

Pyroclastic fans

Lahar deposits0 5 10 kilometers

N

Sampling Location(No. 1 to No. 8)

Sto. Tomas River

No. 1No. 2

No. 3

No. 4

No. 5

No. 6

No. 7No. 8

Figure 2.1.1

Location Map for Riverbed Material Sampling

IV-F8

THE GOVERNMENT OF THE PHILIPPINES THE DEPARTMENT OF PUBLIC WORKS AND HIGHWAYS

The Study on Sabo and Flood Control for Western River Basins of Mount Pinatubo in

the Republic of the Philippines JAPAN INTERNATIONAL COOPERATION AGENCY

Figure 2.1.2 Grain Size of Riverbed Materials in the Study Area

L=4 km L=12 km L=19 kmD= D= D= Bucao0.35 mm 0.35 mm 0.67 mm River

L=3 km L=13 kmD= D= Maloma0.60 mm 0.59 mm River

L=3 km L=13 km L=23 kmD= D= D= Sto.Tomas0.35 mm 0.71 mm 0.72 mm River

Note : L= Distance from River-mouthD = Mean Grain Size

Sout

h Ch

ina

Sea

IV-F9

THE GOVERNMENT OF THE PHILIPPINES THE DEPARTMENT OF PUBLIC WORKS AND HIGHWAYS

The Study on Sabo and Flood Control for Western River Basins of Mount Pinatubo in

the Republic of the Philippines JAPAN INTERNATIONAL COOPERATION AGENCY

Figure 2.1.3 Comparison of Grain Size Distribution of Riverbed Materials

0

20

40

60

80

100

0.01 0.10 1.00 10.00 100.00

Grain Size (mm)

Perc

ent P

assi

ng (%

)

Average (this Study) Average(Sacobia,Abacan: JICA Report in 1996)

IV-F10

THE GOVERNMENT OF THE PHILIPPINES THE DEPARTMENT OF PUBLIC WORKS AND HIGHWAYS

The Study on Sabo and Flood Control for Western River Basins of Mount Pinatubo in

the Republic of the Philippines JAPAN INTERNATIONAL COOPERATION AGENCY

Figure 2.2.1 Flow Chart of Calculation of Annual Sediment Transport

Data Input

Grain Size of Riverbed Material : D(cm)

Specific Gravity of Grain : S=2.60g = 9.8 m/sec2

Bed Slope : I s = S -1 = 1.6d (m) = D(cm)/100

Roughness Coefficient : n=0.030

Flow Discharge : Q(m3/sec)

Hydraulic Calculation

Flow Width : B(m)using Regime Formula

B = 7 Q0.5 (B < River Width) Critical Tractive Force : U*c (m2/sec2)

using Iwagaki's FormulaU*C

2 = 8.41D11/32/10,000Flow Depth : H(m) (for D < 0.0565 cm)

using Manning's Formula U*C2 = 55.0D/10,000

H = (nQ/B/I0.5)0.6 (for 0.0565 cm < D)

Tractive Force : U*2 (m

2/sec2)

No

Sediment Transport Discharge : Qb (m3/s)using Brown's Formula

Qb = 10(U*2/gsd)2.5*(gsd)0.5*dB

Daily Flow Duration Curve

Annual Volume Stepwise Approximation

Annual Sediment Transport Volume : Vo (m3/year)

Qb = 0

Vo = Sum( Qb * Days * 86,400 )

U*2 > U*c

2

U*2 = gHI

Yes

IV-F11

THE GOVERNMENT OF THE PHILIPPINES THE DEPARTMENT OF PUBLIC WORKS AND HIGHWAYS

The Study on Sabo and Flood Control for Western River Basins of Mount Pinatubo in

the Republic of the Philippines JAPAN INTERNATIONAL COOPERATION AGENCY

Figure 2.2.2 Stepwise Approximation of Duration Curve

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

0 50 100 150 200 250 300 350 400

Days

Rat

io to

Ann

ual M

ean

Dis

char

geOriginal Data Stepwise Approximation

IV-F12

THE GOVERNMENT OF THE PHILIPPINES

THE DEPARTMENT OF PUBLIC WORKS AND HIGHWAYS

The Study on Sabo and Flood Control forWestern River Basins of Mount Pinatubo

in the Republic of the PhilippinesJAPAN INTERNATIONAL COOPERATION AGENCY

Figure 2.2.3

Sub-Division of River Basins for Annual Sediment Balance Analysis

LEGEND

RiverRoadCatchmentSub-divide

San Antonio

Castillejos

San Marcelino

Route-7

Vega Hill

9 km²

A=262 km²

San Felipe

Cabangan

South China Sea

Route-7

11 km²

A=152 km²

Bucao River

A=655 km²Botolan 130 km²

212 km²

Balintawak River

Bucao River

Kayanga Creek

Bucao River

(216 km²)

65 km²

Balin B

aquero River

Maraunot River

151 km²CraterLake

Maloma River99 km²

54km²

97 km²

Gorongoro River42 km²

74 km²

(253 km²)

Sto.Tomas River

Mt. Bagang

(91

km²)

88 km²Mapanuepe River

(309 km ²)

37 km²

San Narciso

Balin Baquero River

N

Scale

0 1 2 3km

]

]

]

]

]

]

IV-F13

THE G

OV

ERNM

ENT O

F THE PH

ILIPPINES

THE D

EPARTM

ENT O

F PUBLIC

WO

RKS A

ND

HIG

HW

AY

S

The Study on Sabo and Flood C

ontrol for W

estern River B

asins of Mount Pinatubo in

the Re public of the Philippines

JAPAN IN

TERNATIO

NAL C

OO

PERATION

AGEN

CY

Figure 2.3.1 A

nnual Sediment Transport C

apacity in the B

ucao River

IV-F14