Data Collection Survey on Parañaque Spillway in Metro Manila Final Report in the Republic of the Philippines
CHAPTER 3. GENERAL FLOOD MANAGEMENT PLAN IN THE LAGUNA DE BAY COASTAL REGION
3.1 Collection and Organization of Basic Information on Hydrology and Topography
3.1.1 Hydrologic Data
(1) Rainfall Data
Rainfall observation around Laguna de Bay is conducted by the following six institutions. Daily rainfall data is collected from PAGASA, PRBFFWC, NPC and MWSS. Regarding the hourly rainfall, EFCOS has been observing hourly rainfall and recording since 2003. Also, DOST ASTI has started the observation of hourly rainfall since 2015.
1. PAGASA (Philippine Atmospheric, Geophysical and Astronomical Services Administration) 2. EFCOS, MMDA (Effective Flood Control Operating System) 3. PRBFFWC (Pampanga River Basin Flood Forecasting and Waring Center, PAGASA) 4. NPC (National Power Corporation) 5. MWSS (Metropolitan Waterworks and Sewerage System) 6. DOST-ASTI (Advanced Science and Technology Institute)
Table 3.1.1 shows the outline of rainfall observation data in the Laguna de Bay Basin. Table 3.2.1 shows the installation status of the rainfall observation data and Figure 3.2.1 shows the location map of rainfall observation stations. There are thirty-eight rainfall observation stations around the Laguna de Bay basin, and the observation stations where the rainfall observation data exists throughout the year varies from year to year. The station with the longest observation record of daily rainfall is Port Area where the observation has started since 1949.
The hourly rainfall observation has been conducted by EFCOS since 2003; however, the observation is only in the Pasig–Marikina River Basin, and the hourly rainfall observation station is not yet established around Laguna de Bay. Also, the observation of the hourly rainfall and water level has been conducted by DOST ASTI since 2015, but the observation period is short which is not sufficient as the hourly data for the flood control plan.
Table 3.1.1 Outline of Rainfall Observation Data Number of Daily Hourly No. Organization Department observation Remarks Rainfall Rainfall station For the large-scale flood 1 PAGASA DOST 24 ● ▲ events, the 6-hour rainfall data is available. 2 EFCOS MMDA 7 ● Observation started in 2003. 3 PRBFFWC DOST 3 ● 4 NPC - 2 ● 5 MWSS - 2 ● 6 ASTI DOST 15 ● Observation started in 2015 ●：Available, ▲：Partly Available
CTI Engineering International Co., Ltd. 3-1 Nippon Koei Co., Ltd. CTI Engineering Co., Ltd.
Data Collection Survey on Parañaque Spillway in Metro Manila in the Republic of the Philippines Final Report
2016
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2015
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2014
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2013
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2012
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2011
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2010
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2009
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2008
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2007
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2006
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2005
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2004
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2003
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2002
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2001
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A
A A
2000
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p
p
A
A
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A
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A
A A
1999
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p
A
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A
A A
1998
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p
A
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A
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A
A A
1997
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A
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1996
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1995
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1994
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1993
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1992
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1991
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1990
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1989
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1988
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1987
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1986
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1985
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1984
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1983
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1982
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1981
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p
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p
p
A
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A
A
A
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A
A A
: Not available :Not
1980
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A
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1979
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1978
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A
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1977
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p
A
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A
A A
1976
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p
A
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A
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A
A A
1975
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p
p
A
A
A
A
A
A
A A
1974
p
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p
A
A
A
A
A
A A
1973
p
A
A
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A
A
A
A A
1972
p
p
p
p
p
A
A
A
A A
1971
p
p
p
p
A
A
A
A A
1970
p
p
p
p
A
A A
1969
A
A
A
A
A
A A
1968
p
p
A
A
A
A A
1967
A
A
A
A
A A
1966
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p
A
A
A
A A
1965
p
A
A
A
A
A A
1964
: Partly available :Partly
p
A
A
A
A
A A
1963
A
A
A
A
A
A A
1962
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A
A
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A
A A
1961
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p
A
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A
A A
1960
p
A
A A
1959
A
A
A A
1958
A
A
A A
1957
A
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1956
A
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1955
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1954
A
A
A A
1953
A
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1952
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A
A A
1951
A
A
A A
1950
A
1949
A
: Completely available :Completely
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Daily
Status of Development of Rainfall Observation Data (Daily Rainfall Data) Rainfall (Daily Data Observation Rainfall of of Development Status
Data Type Data
NPC
NPC
MWSS
MWSS
Agromet
Agromet
Agromet
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Synoptic
Synoptic
Synoptic
Synoptic
Synoptic
Synoptic
Synoptic
Synoptic
0.000
121.255
121.165
121.365
121.477
121.230
121.368
120.945
121.078
121.083
121.017
121.058
120.967
121.438
121.183
121.238
121.413
121.038
120.933
120.950
121.650
120.967
121.050
121.043
121.004
120.917
121.583
120.966
2
Longitude
.
0.000
14.914
14.911
14.928
14.382
14.172
14.612
14.743
14.544
14.567
14.383
14.486
14.122
14.500
14.767
14.642
14.281
14.367
14.450
14.172
14.750
14.122
14.083
14.646
14.507
14.500
14.033
14.589
3.1
Latitude
Type
Table Table
―
―
―
―
Agromet
Agromet
Agromet
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Synoptic
Synoptic
Synoptic
Synoptic
Synoptic
Synoptic
Synoptic
Synoptic
Operation
NPC
NPC
MWSS
MWSS
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
PAGASA
5
22
999
153
151
424
418
417
415
409
408
407
406
434
433
432
430
429
428
427
425
06-3
06-1
1309
1306
1305
1304
1301
Code
Name
Matulid
Angat Dam Angat
La Mesa La
Umiray
Pakil, Laguna Pakil,
NAS, UPLB, Los Banos Los UPLB, NAS,
Bureau of Soil, Cuyambay, Tanay, Rizal Tanay, Soil, of Cuyambay, Bureau
Polo, Valenzuela, M.M. Polo,Valenzuela,
Tipas Taguig MM TipasTaguig
Pasig Elem. Sch. Pasig MM Pasig Sch. Elem. Pasig
NPP Research Bu.of Prison Muntinlupa Prison Bu.of Research NPP
Bagumbayan Taguig MM Taguig Bagumbayan
Tagaytay
Macasipac, Sta. Maria, Laguna Macasipac,Sta.
Sitio Tabak Montalban Rizal Montalban SitioTabak
Boso-Boso Antipolo Rizal Boso-BosoAntipolo
Sta Cruz Laguna Cruz Sta
San Pedro, Laguna San
Mabolo Elem Sch. Bacoor Cavite Sch. Elem Mabolo
Barrio Maitim Amadeo Cavite Amadeo BarrioMaitim
Infanta
Tanay (Radar) Tanay
Ambulong Batangas Ambulong
Scienec Garden Scienec
NAIA
Sangley Point Cavite Point Sangley
Port Area Port
9
8
7
6
5
4
3
2
1
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10 No.
3-2 CTI Engineering International Co., Ltd. Nippon Koei Co., Ltd. CTI Engineering Co., Ltd.
Data Collection Survey on Parañaque Spillway in Metro Manila Final Report in the Republic of the Philippines
2016
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p
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p
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p
p
p
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p
A
A
A A
2015
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
A
A
A A
2014
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p p
2013
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
p
A
A
A
A
A A
2012
p
p
p
p
p
p
p
p
p
A
A
A
A A
2011
p
p
p
p
p
p
p
p
p
A A
2010
p
p
p
p
p
p
p
p
p
A A
2009
p
p
p
p
p
p
p A
2008
p
p
p
p
p
p
A A
2007
p
p
p
p
p
p
p
p
A A
2006
p
p
p
p
A
A
A
A
A A
2005
p
p
p
p
p
p
p
p
p p
2004
p
p
p
p
p
p
p
A
A A
2003
p
p
p
p
A
A
A
A
A A
2002
p
p
p
A A
2001
p
p
p
p p
2000
p
p
p
p A
1999
p
p
p
p
p
1998
p
p
p
p p
1997
p
p
p
A A
1996
p
p
p
A A
1995
p
p
p
p A
1994
p
p
p
p p
1993
p
p p
1992
p
p p
1991
p
p p
1990
1989
1988
p
p p
1987
p
p p
1986
p
p p
1985
p
p p
1984
1983
1982
p
A A
1981
p
A A
1980 available :Not
p
p p
1979
1978
1977
1976
1975
1974
p
p p
1973
p
p p
1972
1971
1970
1969
1968
1967
1966
1965
1964
: Partly available :Partly
1963
1962
1961
1960
1959
1958
1957
1956
1955
1954
1953
1952
1951
1950
1949
: Completely available :Completely
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Hourly
Data Type Data
Status of Development of Rainfall Observation Data (Hourly Rainfall Data) Rainfall (Hourly Data Observation Rainfall of of Development Status
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
EFCOS
EFCOS
EFCOS
EFCOS
EFCOS
EFCOS
EFCOS
PRBFFWC
PRBFFWC
PRBFFWC
121.061
121.052
121.044
121.030
121.032
120.946
121.034
121.040
121.007
120.993
120.994
120.931
120.960
121.003
121.293
121.092
120.965
121.146
120.759
121.158
121.223
121.108
121.169
121.291
121.067
121.043
3
Longitude
.
14.530
14.372
14.645
14.659
14.700
14.706
14.384
14.581
14.705
14.685
14.611
14.696
14.699
14.724
14.667
14.590
14.959
14.875
14.939
14.763
14.640
14.675
14.663
14.668
14.557
14.646
3.1
Latitude
Type
Table Table
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Climatic
Telemetry
Telemetry
Telemetry
Telemetry
Telemetry
Telemetry
Telemetry
Telemetry
Telemetry
Telemetry
Operation
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
ASTI
PRBFFWC
PRBFFWC
PRBFFWC
EFCOS
EFCOS
EFCOS
EFCOS
EFCOS
EFCOS
EFCOS
9
8
5
4
3
2
1
P3
P2
P1
Code
ASTI9
ASTI8
ASTI7
ASTI6
ASTI5
ASTI4
ASTI3
ASTI2
ASTI1
ASTI16
ASTI15
ASTI14
ASTI13
ASTI12
ASTI11
ASTI10
Name
Ususan
Tunasan
Science Garden Pagasa Garden Science
Quezon City Science High School High Science City Quezon
Qcpu
Pio Valenzuela Elementary School Elementary PioValenzuela
New Bilibid Prison Brgy Poblacion NewBilibid Brgy Prison
National Center For Mental Health For Mental Center National
Mapulang Lupa Mapulang
Gen T De Leon De T Gen
E Quintos Street Quintos E
Dampalit Elementary School Elementary Dampalit
Dalandanan
Bagbaguin
Mt. Campana Mt.
Master Station Master
San Rafael San
Ipo Dam Ipo
Sulipan
Mt.Oro
BosoBoso
Nangka
Aries
Mt.Campana
Napindan
Science Garden Science
9
8
7
6
5
4
3
2
1
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
No.
CTI Engineering International Co., Ltd. 3-3 Nippon Koei Co., Ltd. CTI Engineering Co., Ltd.
Data Collection Survey on Parañaque Spillway in Metro Manila in the Republic of the Philippines Final Report
Figure 3.1.1 Location Map of Rainfall Observation Stations
3-4 CTI Engineering International Co., Ltd. Nippon Koei Co., Ltd. CTI Engineering Co., Ltd.
Data Collection Survey on Parañaque Spillway in Metro Manila Final Report in the Republic of the Philippines
(2) River Water Level Data
In the Pasig-Marikina River Basin, EFCOS has started the observation of river water level since 1994. The maintenance status of the water level observation data is shown in Table 3.1.4, and locations of the observation stations are shown in Figure 3.1.2.
The HQ curve (Figure 3.1.3) is available at the Sto. Nino point (Marikina Bridge) in the Marikina River Basin. The yearly maximum water level and the estimated discharge at the Sto. Nino point are shown in Table 3.1.5. The HQ equation at the Sto. Nino point has been prepared in the Pasig Marikina River Channel Improvement Project (III) Cooperation Preparation Survey (2011, JICA), Master Plan for Flood Management in Metro Manila and Surrounding Area (2011, WB), and Data Collection and Confirmation Survey on Manila Metropolitan Area Flood Control Plan (2014, JICA), respectively.
Table 3.1.4 Status of Water Level Observation Data (Pasig-Marikina River Basin)
Name River Operation 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Rosario JS Marikina EFCOS A A A A A A A A A A A A A A P P P A A A A A A Rosario LS Marikina EFCOS A A A A A A A A A A P P P P P A A A A Napindan JS Pasig EFCOS A A A A A A P A A A A P A A P P A A A Napindan LS Pasig EFCOS A A P P A A A A A A A P P P P P A A A Nangka Marikina EFCOS A A A A A A A P P A A A A A A San Juan San Juan EFCOS A A A P A A P P P A A A A A A Montalban Marikina EFCOS A P P P A A A A P A A P A A P P P A A A A A A Sto. Nino Marikina EFCOS A A A A A A A A A P A P A A A P P A A A A A P Pandacan Pasig EFCOS A A A A A A A A A A A P A A P P P A A A A A A Fort Santiago Pasig EFCOS A A A P A A A P A A A P A A P P P A A A A A A PARANAQUE RIVER PARANAQUE BRS PA FA FA FA FA FA FA A A A A ZAPOTE RIVER ZAPOTE BRS PA FA FA FA FA FA FA A A A A LAGUNA LAKE_Los Banos BRS A A A A A A A A A A A A A P P P P N A A MAYOR RIVER MAYOR BRS A A A A A A A A F A A PILILIA RIVER PILILIA BRS A A P A SAN JUAN RIVER SAN JUAN BRS PA FA FA FA FA FA FA A A A P STA. CRUZ RIVER STA. CRUZ BRS A A P P A A A A A A A A A: Fully available P: Partially available FA: Fully average PA: Partially average “ “: No Data
CTI Engineering International Co., Ltd. 3-5 Nippon Koei Co., Ltd. CTI Engineering Co., Ltd.
Data Collection Survey on Parañaque Spillway in Metro Manila in the Republic of the Philippines Final Report
Figure 3.1.2 Water Level Observation Points
3-6 CTI Engineering International Co., Ltd. Nippon Koei Co., Ltd. CTI Engineering Co., Ltd.
Data Collection Survey on Parañaque Spillway in Metro Manila Final Report in the Republic of the Philippines
Table 3.1.5 Yearly Maximum Water Level and Estimated Discharge at Sto. Nino Point
Source: Data Collection and Confirmation Survey on Metro Manila Flood Control Plan (2014, JICA)
Source: Data Collection and Confirmation Survey on Metro Manila Flood Control Plan (2014, JICA) Figure 3.1.3 H-Q Curve at Sto. Nino Point
(3) Laguna de Bay Water Level Data
Daily water level data of Laguna de Bay has been observed by four institutions: DPWH, LLDA, EFCOS and NPC. The maintenance situation of water level observation data at Laguna de Bay is shown in Table 3.1.6 and the location map of lake water level observation stations is shown in Figure 3.1.4.
Table 3.1.6 Status of Laguna de Bay Water Level Observation Data
Name Code Operation 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 Los Banos 114 BRS P A A A A A A A A A A A A A A A A A A A A A A A P A A A A A A A Looc 201 LLDA Angono 017 EFCOS Caliraya 301 NPC
Name Code Operation 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Los Banos 114 BRS P P P P P P P P P A Looc 201 LLDA P A A A A A A A P A P A A P P P A A A A A A A A A P P P Angono 017 EFCOS P P A A A A A A A P P P A A P P P A A A P P A Caliraya 301 NPC P A P A A A A A A A A A A A A A : Completely available : Partly available : Not available
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Figure 3.1.4 Laguna de Bay Observation Location Map
Figure 3.1.5 and Table 3.1.7 show the change of yearly maximum lake water level of Laguna de Bay. The maximum lake level for 71 years from 1946 to 2016 was 14.03m (before the construction of the Mangahan Floodway), and the lake level at the Typhoon Ondoy in 2009 was 13.85m. In addition, in the influence of monsoon rain in 2012, the higher water level of 13.83m was recorded as same as in 2009. For the top ten years of the yearly maximum lake water level, typhoon or cyclone caused by the lake level rise is shown in Table 3.1.8, and the isohyet map of the Laguna de Bay Basin in the past flooding events is shown in Figure 3.1.6.
Annual Maximam Surface Level
15.0
14.5 14.03 13.83 13.85 14.0
13.5
13.0
12.5
12.0 Lake Surface Level (m) Level Surface Lake 11.5
11.0
10.5
1946
1947
1948
1949
1950
1951
1952
1953
1954
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1956
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1958
1959
1960
1961
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1963
1964
1965
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1991
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1998
1999
2000
2001
2002
2003
2004
2005
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2008
2009
2010
2011
2012
2013
2014
2015 2016
Figure 3.1.5 Long-term Change of Year Maximum Lake Level
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Table 3.1.7 Maximum Lake Level at Laguna de Bay (1946 to 2016) Surface water Surface water Days of above Days of above Year level Year level 12.5m 12.5m m m 1946 12.36 0 1983 11.94 0 1947 12.36 0 1984 12.67 16 1948 12.54 19 1985 12.20 0 1949 11.76 0 1986 13.34 93 1950 11.98 0 1987 12.35 0 1951 12.15 0 1988 13.55 48 1952 13.08 68 1989 12.24 0 1953 12.28 0 1990 12.67 21 1954 12.10 0 1991 12.60 26 1955 11.71 0 1992 12.39 3 1956 12.76 38 1993 12.27 0 1957 12.33 0 1994 12.27 0 1958 11.92 0 1995 12.94 81 1959 11.41 0 1996 12.52 0 1960 13.17 64 1997 11.83 0 1961 12.29 0 1998 12.70 20 1962 12.77 36 1999 12.72 37 1963 12.24 0 2000 13.39 65 1964 12.20 0 2001 12.69 6 1965 12.04 0 2002 12.55 5 1966 12.16 0 2003 11.72 0 1967 12.87 3 2004 11.85 0 1968 11.59 0 2005 12.15 0 1969 11.19 0 2006 12.30 0 1970 11.00 246 2007 12.49 0 1971 No data - 2008 12.14 0 1972 14.03 88 2009 13.85 108 1973 12.08 0 2010 12.12 0 1974 12.40 0 2011 12.65 21 1975 12.22 0 2012 13.83 111 1976 12.77 16 2013 13.01 61 1977 12.03 0 2014 12.26 0 1978 13.58 62 2015 11.83 0 1979 No data - 2016 11.89 0 1980 No data - Min 11.00 0 1981 No data - Ave 12.41 22 1982 12.13 119 Max 14.03 246 *For the lake water level, the yearly maximum lake water level is calculated from the average of the water level observation results at four points.
Table 3.1.8 Top 10-Year Maximum Lake Level Surface Date No. Year Month Day water level Typhoon or Cyclone m Start End 1 1972 8 3 14.03 Tropical Storm Winnie 1972/7/29 1972/8/3 2 2009 10 4 13.85 Typhoon Ondoy 2009/9/25 2009/9/30 3 2012 8 11 13.83 2012 Habagat 4 1978 10 28 13.58 Super Typhoon Rita 1978/10/15 1978/10/29 5 1988 11 9 13.55 Tropical Storm Tess 1988/11/1 1988/11/6 6 2000 11 5 13.39 Tropical Storm Bebinca 2000/10/30 2000/11/7 7 1986 10 20 13.34 Typhoon Ellen 1986/10/11 1986/10/19 8 1960 10 15 13.17 Typhoon Lola 1960/10/8 1960/10/17 9 1952 10 30 13.08 Typhoon Trix 1952/10/15 1952/10/26 10 2013 10 3 13.01 2013 Habagat *Habagat: Monsoon Rainfall Source：Survey Team organized from Pacific typhoon climatology (https://en.wikipedia.org/wiki/Pacific_typhoon_climatology )
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＜1972.Jul.17 – Aug.3 18 days rainfall＞ ＜2009.Sep.25 – 26 2 days rainfall＞
＜2012.Aug.6 – 7 2 days rainfall＞ ＜1978.Oct.26 1 day rainfall＞
Source: Using rainfall observation data collected in this survey, JICA survey team created equal rainfall lines Figure 3.1.6 Isohyet line of the Laguna de Bay Basin in Past Flooding Events
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To understand the relationship between the lake level of Laguna de Bay and rainfall in the surrounding basins of Laguna de Bay, the correlation between the yearly maximum lake level and the basin average rainfall from one to six months was calculated. The correlation diagram between the Laguna de Bay water level and the basin average rainfall of surrounding basins of Laguna de Bay is shown in Figure 3.1.7.
According to the correlation diagram, there was no significant correlation between the water level rise in Laguna de Bay and the basin average rainfall in the surrounding basins. This is presumably because the number of the rainfall observation stations in the Laguna de Bay Basin is not sufficient, and the regional distribution of rainfall around the area of Laguna de Bay with a large catchment area was not be fully grasped.
1 month 2 month 3 month
1,200 1,800 2,500
1,600 1,000 2,000 1,400
800 1,200 1,500 1,000 600 800
1,000
3 month Rainfall monthRainfall 3 2 month Rainfall Rainfall month2 1 month Rainfall Rainfall month1 400 600 y = 259.8x - 2402.7 y = 323.48x - 2886.1 y = 187.2x - 1814.7 400 R² = 0.4584 500 R² = 0.4177 200 R² = 0.4954 200
0 0 0 10 11 12 13 14 15 10 11 12 13 14 15 10 11 12 13 14 15 Laguna Lake Surface Level (m) Laguna Lake Surface Level (m) Laguna Lake Surface Level (m)
4 month 5 month 6 month
3,000 3,000 3,500
3,000 2,500 2,500
2,500 2,000 2,000 2,000 1,500 1,500
1,500
5 month Rainfall Rainfall month5 6 month Rainfall 6 4 month Rainfall monthRainfall 4 1,000 y = 364.41x - 3125 1,000 1,000 R² = 0.3947 y = 373.09x - 2972 y = 382.63x - 2869.4 500 R² = 0.3874 R² = 0.4125 500 500
0 0 0 10 11 12 13 14 15 10 11 12 13 14 15 10 11 12 13 14 15 Laguna Lake Surface Level (m) Laguna Lake Surface Level (m) Laguna Lake Surface Level (m)
Figure 3.1.7 Correlation between Maximum Lake Level of Laguna de Bay and Average Basin Rainfall
3.1.2 Topographic Data
(1) Outline of Using Data
In this survey, the obtained terrain and survey data are shown in Table 3.1.9.
Table 3.1.9 Outline of Using Data Data Organization How to Use Understanding of Laguna Lake flood inundation area LiDAR（5m） NAMRIA Characteristics of river channels of major 21 rivers LiDAR（1m） NAMRIA Analysis of Parañaque and Las Pinas District
(2) Terrain Survey of Laguna de Bay
Regarding the topographical data in Laguna de Bay, the water depth data of Laguna de Bay has been collected and organized as follows. The latest data of Laguna de Bay Map, 2017 (paper based map) was
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electronically prepared by the JICA Survey Team, and the H-A-V of Laguna de Bay was prepared. Table 3.1.10 shows the topographical data in Laguna de Bay and Table 3.1.11 shows the H A V prepared based on the water depth data of Laguna de Bay of NAMRIA in 2016. Also, Figure 3.1.9 and Figure 3.1.10 show the topographic status of Laguna de Bay in 1997 and 2016.
Table 3.1.10 Topographic Data in Laguna de Bay Observed No. Name of Data Issued Publisher Datum Remarks item Laguna de Bay Map, Water Mean Lower Lake 1 1963 NAMRIA Hard copy 1963 Depth Level*1 LLDA Spot 2 1997 LLDA Elevation LLDA Datum Elevation Data Laguna de Bay Map, Water Mean Lower Lake 3 2009 NAMRIA Lack of data in east part 2009 Depth Level*1 Laguna de Bay Map, Water Mean Lower Lake 4 2016 NAMRIA Hard copy 2016 Depth Level*1 *1：0.799 m above MLLW
Mean Lake Level
Mean Lower Lake Level 0.610m
Mean Sea Level 0.329m
Mean Lower Low Water 0.470m Depth
10m Bed
LLDA Datum=DPWH Datum
Figure 3.1.8 Datum in Laguna de Bay
Table 3.1.11 Topographic Data in Laguna de Bay H (m) A (km2) V (MCM) 6.00 0.37 0.90 6.50 4.86 2.21 7.00 66.06 19.94 7.50 167.18 78.25 8.00 240.24 180.11 8.50 331.20 322.97 9.00 493.95 529.26 9.50 609.75 805.18 10.00 670.89 1,125.34 10.50 740.44 1,478.17 11.00 789.43 1,860.64 11.50 842.47 2,268.62 12.00 892.24 2,702.29 12.50 913.00 3,153.60 13.00 936.87 3,616.07 13.50 961.87 4,090.75 14.00 987.87 4,578.19 14.50 1,013.14 5,078.44 15.00 1,035.26 5,590.54
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Source: JICA Survey Team based on LLDA data Figure 3.1.9 Laguna de Bay Map, 1997, LLDA
Source: JICA Survey Team based on NAMRIA data Figure 3.1.10 Laguna de Bay Map, 2016, NAMRIA
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3.2 Setting of Design Scale
3.2.1 Setting of Design Scale and Design Target Rainfall
(1) Organization of the Previously Implemented Flood Control Projects
The results of survey on the existing flood control projects in the master plan are summarized in Table 3.2.1 and the ODA loan projects are summarized in Table 3.2.2.
Table 3.2.1 Summary of the Previously Implemented Flood Control Projects Flood Control and Drainage Project in Metro Master Plan for Flood Management in Metro Project Name Manila Manila and Surrounding Areas Organization JICA The World Bank Year of Implementation 1991 2013 Target Area Metro Manila and Surrounding Areas (981 km2) Metro Manila and Laguna de Bay Coastal Area MP Target Completion 2020 2035 Year River 100-Year 100-Year Improvement Design Structure 100-Year 100-Year Scale Design Lake Water Level ＝ 13.8 m Design Lake Water Level: EL 13.8 m Lake Bank Crest Height of Lake Levee＝15.5 m Crest Height of Lake Levee: EL 15.2 m ⚫ Marikina Dam, MCGS, River Channel ⚫ River channel improvement, the Marikina Dam Improvement (Pasig River, Marikina River, Construction, renovation of the Pasig River and Proposed Flood Control tNapindan River) the Marikina River, improvement of the San Measures (Parañaque Spillway was not included in MP Juan River and the Napindan Channel are since the construction cost was very large.) proposed.
Table 3.2.2 Summary of Previously Implemented Flood Control Projects (Related to ODA Loan Projects) Metro Manila Flood Control Project – West Pasig-Marikina River Channel Improvement Project, Project Name of Mangahan Floodway Phase I, II & III Organization JICA JICA 1999 to present Year of Implementation 1997 to 2007 (Currently, Phase III is being implemented) Target Area Western Mangahan District Pasig-Marikina River Basin Lakeshore Embankment: 10 km River Channel Improvement：42.2km Project Contents Drainage Plant: 4 locations Section：Delpan Bridge – San Mateo Bridge Construction of Bridges, etc.: 2 locations Design Water Level at the Most Downstream of the Lake Water Level Design Water Level: EL 13.8 m Mangahan Floodway = 14.0m Condition Crest Height of Lake Levee: 15.0 m Mangahan Floodway Crest Height of Lake levee at the most downstream =14.0m ⚫ The design scale of the Pasig-Marikina River Basin is a 100-year probability. ⚫ The degree of safety at that time is Remarks ⚫ The flood safety level becomes a 100-year equivalent to a 40-year probability. probability after the construction of the Marikina Dam and the Marikina Retarding Basin.
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(2) Outline of the Previous Hydrology and Hydraulic Analysis Model
In the Pasig-Marikina River Basin around the Laguna de Bay, several flood control projects and plans have been implemented. As for the Pasig-Marikina River Channel Improvement Project, the Feasibility Study (F/S) for the Phase IV section and the Detailed Design (D/D) of the Phase V section have been completed.
In the existing studies, the flow distribution of the Pasig-Marikina River has changed, and the outline of the hydrological-hydraulic model in the existing studies is as summarized below. In consideration of these conditions, the design scale and boundary condition of the runoff inundation analysis in this study are set not to be inconsistent with the hydrological and hydraulic analysis used.
Table 3.2.3 Summary of Previously Implemented Flood Control Project Phase III Preparatory Survey Items JICA Study (1990) JICA Study (2014) Phase IV&V Survey (2011) Wave pattern of design Centralized type two- Centralized type two- Typhoon Ondoy Case: Typhoon Ondoy Case: rainfall day rainfall day rainfall one-day rainfall one-day rainfall Same value in entire Same value in entire Considering the spatial Considering the spatial Basin Average basin basin distribution distribution Probability Rainfall 1/30=540mm 1/30=392mm 1/30=232.4mm 1/30=255.5mm Amount 1/100=660mm 1/100=446mm 1/100=285.5mm 1/100=309.0mm Rainfall and Runoff Storage Function Storage Function WEB-DHM Model NAM Model Model Method Method River channel: one- River channel: one- River channel: one- dimensional unsteady dimensional unsteady dimensional unsteady Inundation Analysis Not implemented river flow＋floodplain river flow＋floodplain river flow＋floodplain area: two-dimensional area: two-dimensional area: two-dimensional unsteady flow unsteady flow unsteady flow 13.90m 13.90m 12.50m 12.20m Maximum water level Maximum water level Water Level at Laguna Average Yearly Average water level since the completion of since the completion of de Bay Maximum during major flood the Mangahan the Mangahan 13.80m Floodway Floodway 11.4m 11.4m 11.4m 11.4m Tide Level at Manila Average synodic high Average synodic high Average synodic high Average synodic high Bay tide level tide level tide level tide level Discharge Allocation 1990MP JICA2014A JICA2014B Phase IV&V Map
1990MP JICA2014A JICA2014B Phase IV&V
Figure 3.2.1 Transition of Flow Distribution
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(3) Design Scale
The design scale is set by comprehensively evaluating the importance of the target basin, the actual condition of the past flood damages, the existing plan in the vicinity area and the design scale specified in the DPWH Design Guidelines, Criteria and Standards (DGCS) 2015.
- For the Pasig–Marikina River Basin which is in the vicinity of this study, the design scale is a 100- year scale. Typhoon Ondoy in 2009 brought massive damages to the Laguna de Bay Basin, and the basin average rainfall in the Marikina River Basin was 290.8mm (one day) which is equivalent to a 100-year scale. - In the “Manual on Flood Control Planning 2003.3” which was prepared in the JICA Technology Cooperation Project - ENCA, the main eighteen (18) basins of the Philippines are specified including Laguna de Bay in the Pasig-Laguna Bay Basin. - According to the DPWH DGCS 2015, the design scales are specified for rivers (Table 3.2.4) and drainages (Table 3.2.5). In addition to the DPWH Standard Guideline, there is the memorandum of understanding in 2011 which specifies the design scales, as shown in Table 3.2.6. - The catchment area of Laguna de Bay is 3,280 km2, and the design scale in the DPWH DGCS (Rivers) is a 100-year scale.
Table 3.2.4 Design Scale for Rivers Specified in DPWH DGCS 2015 River Type Design Flood Principal and Major Rivers (40km2 drainage area and above) 100-year For Small Rivers (below 40km2 drainage area) 50-year Source: DPWH Design Guidelines, Criteria and Standards 2015
Table 3.2.5 Design Scale for Drainages Specified in DPWH DGCS 2015 Minor System Major Drainage System Drainage Land-use Design Capacity Check Capacity Capacity (Note2) Drainage Pipes 15-year flood 25-year flood Culverts 25-year flood 50-year flood 100-year flood Esteros/ creeks/ drainage channels 15-year flood 25-year flood Source: DPWH Design Guidelines, Criteria and Standards 2015
Table 3.2.6 Design Scale Specified in 2011 Memorandum Type Target Level Design Flood Principal and Major Rivers (40 km2 D.F.L.*1 50-year drainage area and above) D.F.L + Freeboard 100-year River For Smaller Rivers (below 40 km2 D.F.L. 25-year drainage area) D.F.L + Freeboard 50-year Drainage Pipes*2, Esteros/Creeks, Pipe D.F.L. 15-year Culverts D.F.L + Freeboard 25-year D.F.L. 25-year Drainage Box Culverts D.F.L + Freeboard 50-year D.F.L. - Drainage Channels D.F.L + Freeboard - *1 Design Flood Level *2 Minimum size of drainage pipes shall be 910 mm in diameter
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Table 3.2.7 Setting of Design Scale Evaluation Classification Design Scale Setting Rationale Index Since Laguna de Bay is considered as one of the important basins in the Philippines, the design scale is set at 100-year which is equivalent to the value for the Pasig - Flood caused by Water Marikina River Basin. water level rise of 100-year Level The water level observed data of Laguna de Laguna de Bay Bay has been accumulated over a long period of time as compared to the rainfall data. Therefore, the water level probability scale is adopted. Since there are several rivers in the 21 river basins located in the Laguna de Bay Coastal [Rivers] Area, the design scale is set based on the basin A=40km2 or more：50-year area of each river. A=less than 40km2 Laguna de Bay The design scale used in DPWH Standard 10km2 or more: 25-year Coastal Area Rainfall Guideline 2015 may be an excessive design A=less than 10km2:15-year (21 River Basins) scale, therefore, the design scale of each basin area is set based on the memorandum of 2011. This will be the design scale when internal [Drainage canal] water (drainage) countermeasures are Drainage canal: 15-year targeted. [Rivers] A=40km2 or more: 50-year This will be the design scale when the external A=less than 40km2 water countermeasures are targeted. Las Piñas・ 10km2 or more: 25-yea-year Rainfall Parañaque District A=less than 10km2, 15-year This will be the design scale when internal [Drainage Canal] water (drainage) countermeasures are Drainage Canal: 15-year targeted.
(4) Examination of Design Rainfall Duration
In some areas located within the scope of this study, EFCOS has been conducting hourly rainfall observations since 1994. However, in order to calculate the design rainfall for the flood control plan, the observation period is not sufficient. In addition, no hourly rainfall observation station exists within the Laguna de Bay Coastal Area. Therefore, the design rainfall duration period is by daily unit.
Generally, the setting of design rainfall duration will set from flood concentration time to 1 day in catchment basin with a catchment area less than 100 km2, but as is also described in the River Sabo Technical Standards, the design rainfall duration will set by examining the situation, condition of catchment basin, measurement time at the time of flooding, etc. However, even in Japan, it is not necessarily that hydrological data is sufficient, the design rainfall duration will set one day to three days adopted for reasons such as statistical analysis.
The design rainfall duration period is set to one day because the river catchment area in the Laguna de Bay Coastal Area (21 river basins) and the Las Piñas-Parañaque area.
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(5) Examination of Design Target Hyetograph (Laguna de Bay Coastal Area and Las Piñas-Parañaque Area)
Setting of the design target rainfall targets the Laguna de Bay coastal area (21 river basins) and the Las Piñas-Parañaque area. For floods caused by lake level rise in Laguna de Bay, the evaluation index of the design scale is “water level.” The design water level waveform is separately set.
The design target rainfall is based on the actual rainfall in Typhoon Ondoy (2009), which caused great damages. In addition, the model hyetograph is also prepared by using the Rainfall Intensity Equation of DPWH (Specific Discharge Curve Rainfall, Intensity Duration Curve, Isohyet of Probable One-day Rainfall). Extending the design rainfall amount will confirm whether or not the rainfall amount of a short- period has been calculated excessively by the rainfall extension.
Regarding the time distribution and regional distribution of hyetograph, two types are set including the extended actual rainfall (Typhoon Ondoy, 2009) and the model rainfall, as shown in Table 3.2.8, and the validity of the design hyetograph is examined. In addition, in this survey, by roughly examining the type and scale of flood countermeasure proposal in the surrounding basin of Laguna de Bay, following past studies in the neighboring watershed Pasig - Marikina River, waveforms with the highest peak discharge in rivers Typhoon Ondoy type of actual flood was adopted.
Table 3.2.8 Setting of Time Distribution and Regional Distribution Classification Actual Hyetograph of Typhoon Ondoy in 2009 Model Hyetograph Prepare the model hyetograph based on Time Distribution Extension of actual rainfall time the rainfall intensity equation* and perform the extension. Regional Provide spatial distribution of actual rainfall None Distribution time by using Thiessen Division * Rainfall Intensity Duration Curve, Isohyet of Probable 1-day Rainfall) < Method for Examining the Validity of the Design Hyetograph > - Calculated two types of design hyetograph (extended actual rainfall and model hyetograph); and, - If a short period rainfall is an excessive amount, it is dismissed from the target rainfall.
Extended actual rainfall Typhoon Ondoy Model Hyetograph
120 250 Extended Part Extended Part 100 100-year 200 100-year
80
Select Design Rainfall 150 Peak rainfall is more 60 Waveform than 200mm, it become
Rainfall (mm/h) Rainfall 40 100 excessive hourly rainfall Rainfall (mm/h) Rainfall
20 50
0 8 9 1011121314151617181920212223 0 1 2 3 4 5 6 7 8 9 1011121314151617181920212223 0 1 2 3 4 5 6 7 8 2009/9/25 2009/9/26 2009/9/27 0 Time (hr) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hr) Source:JICA Survey Team Figure 3.2.2 Design Hyetograph (Extension of Actual Hyetograph and Model Hyetograph)
The design hyetographs prepared in this Study are summarized in Table 3.2.9.
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Table 3.2.9 Design Hyetograph Employed in this Study Classification Design Hyetograph Laguna de Bay Coastal Actual Hyetograph of Typhoon Ondoy in 2009 Area Las Piñas-Parañaque Actual Hyetograph of Typhoon Ondoy in 2009 District However, a study using the model hyetograph is also conducted.
(6) Examination of Design Target Water Level Waveform (Lake Level Rise of Laguna de Bay)
The design target water level waveform is set for floods caused by the lake level rise of Laguna de Bay. During the 28 years from the completion of the Mangahan Floodway construction (completed in 1989) to 2016, the highest levels of Laguna de Bay were WL.13.85m in 2009 and WL.13.83m in 2012.
Figure 3.2.3 shows the daily changes of Laguna de Bay water level in 2009 and 2012. Regarding the water level rise reaching the highest water level, the water level rise in a month was 2.33 m in 2012, which is larger than the water level rise of 1.35 m in 2009. In this study, the design target water level waveform is prepared based on the water level waveform in 2009 and 2012. The safety side is examined by evaluating the effectiveness of lake level reduction by the Parañaque Spillway, the waveform with large damages (the waveform with less effect of lake level reduction by the Parañaque Spillway) is adopted.
Annual Maximam Surface Level Port Area_Annual rainfall Maximum surface level Average annual rainfall 1500
15.5 2500 2946.2 14.5 14.03 3337 3534.9 3500 13.85 13.83
13.5 4500
12.5 5500
Annual Rainfall (mm) Rainfall Annual Lake Surface Level (m) Level Surface Lake 6500 11.5
7500
10.5
1946 1953 1955 1962 1964 1971 1978 1980 1987 1996 2003 2005 2012 1948 1949 1950 1951 1952 1954 1956 1957 1958 1959 1960 1961 1963 1965 1966 1967 1968 1969 1970 1972 1973 1974 1975 1976 1977 1979 1981 1982 1983 1984 1985 1986 1988 1989 1990 1991 1992 1993 1994 1995 1997 1998 1999 2000 2001 2002 2004 2006 2007 2008 2009 2010 2011 2013 2014 2015 2016 1947 After Mangahan Floodway was constructed Figure 3.2.3 Long-Term Changes of the Maximum Water Level of Laguna de Bay (1946 to 2016)
2009 Daily rainfall (Port Area) Surface level 14.5 0
50 14.013.85m 100 13.5 150 13.0 Increased 1.35m in one month 200
12.512.5m 250
300 Lake Surface Level (m) Level Surface Lake 12.0 350
11.5 (mm) Rainfall Daily 400 11.0 450
10.5 500 2009/1 2009/2 2009/3 2009/4 2009/5 2009/6 2009/7 2009/8 2009/9 2009/10 2009/11 2009/12
Figure 3.2.4 (1) Laguna de Bay Lake Level Changes (2009)
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2012 Daily rainfall (Port Area) Surface level 14.5 0
50 14.0 13.83m 100 13.5 150 13.0 Increased 2.33m in one 200 month 12.5 250
300 Lake Surface Level (m) Level Surface Lake 12.0 11.5m 350
11.5 (mm) Rainfall Daily 400 11.0 450
10.5 500 2012/1 2012/2 2012/3 2012/4 2012/5 2012/6 2012/7 2012/8 2012/9 2012/10 2012/11 2012/12
Figure 3.2.4 (2) Laguna de Bay Lake Level Changes (2012)
3.2.2 Design Tide Level of Manila Bay
(1) Setting Method of Design Tide Level
The design tide level of the Manila Bay was studied based on the collected information. In Japan, it is customarily studied in the following three methods:
Method 1: Observed maximum tide level (HHWL)
Method 2: Mean spring tide level (HWL) + Surge deviation based on storm surge analysis
Method 3: Mean spring tide level (HWL) + Observed maximum surge deviation
Source: JICA Survey Team Figure 3.2.5 Design Method for Design Tide Level and Coastal Dyke Level
“Storm surge” is an abnormal rise of water generated by a storm, over and above predicted astronomical tides. Storm surge should not be confused with storm tide, which is defined as the water level rise due to combination of storm surge and the astronomical tide. Storm surge is produced by water being pushed toward the shore by the winds moving cyclonically around the storm. The impact on surge of the low pressure associated with intense storms is minimal in comparison to the water being forced toward the shore by the wind.
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Source: Preparatory survey for Cavite industrial area flood management project Figure 3.2.6 Storm Surge (Left) and Syzygy Diagram (Right)
The design tide level was studied with the three methods above based on the tide level data collected from National Mapping and resource Information Authority (NAMRIA). The collected data are summarized in Table 3.2.10. The analysis on tide level is described below. Table 3.2.10 Summary of Collected Tide Data
No. Data Descriptions 1947 to 2016 (67 years） Observed Tide Monthly highest and lowest (from 1947 to 2016) 1 (monthly) The data from 1947 to 2006 are recorded based on MSL. The data from 2007 to 2016 are recorded as reading of the gauge. 1995 to 2016 (22 years) The data are reading of the gauge. According to the past JICA Study (The Study on Comprehensive Flood Mitigation for Cavite Lowland Area), the reading of Observed Tide 2 the gauge minus about 3 m equals the values based on MSL. In this study, the (hourly) reading is converted to the values based on MSL. The correction values are determined for each year on the assumption that the observed values equal astronomical tide from January to April when storm surge is not likely to occur. 1947 to 2014 (67 years) Astronomical Tide The datum level is lower low water (MLLW). According to NAMRIA, it can be 3 (hourly) converted to the values based on MSL by subtracting 47 cm (2007 to 2010）or 49 cm (after 2011). *All data were provided by NAMRIA Source: JICA Survey Team
(2) Tidal Measuring Stations
The distance between the Manila South Harbor Station and the outfall of the Parañaque and Zapote rivers, the candidates for outlet of the Parañaque Spillway is about 10 km. In the 2009 JICA Study, it was reported that the tide level at Manila South Harbor was almost the same as that at the river mouth of the Imus River (see Figure 3.2.7). Therefore, the tide level at Manila South Harbor was used for the design tide level study.
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Source: JICA Survey Team Figure 3.2.7 Location Map of Manila South Harbor and Outfalls of Imus, Zapote and Parañaque Rivers
Source: The study on comprehensive flood mitigation for Cavite lowland area (JICA 2009) Figure 3.2.8 Comparison between Water Level at Outfall of Imus River and Tidal Level of Manila South Harbor
(3) Recorded Highest Tide Level
Based on the collected observation data, record-high water level was decided. The monthly highest/lowest tide level is shown in Figure 3.2.9. The highest tide level is 1.4 m above MSL recorded in September 2011. However, it is noted that the tidal levels after 2003 is higher than those of before. It might be a sign of an observation error, but there are no concrete reasons to prove it. Therefore, 1.4 m above MSL was used as the highest tide level.
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Tidal Tidal Level (m above M.S.L)
Source: JICA Survey Team Figure 3.2.9 Monthly Highest/Lowest Tide level (Manila South Harbor)
(4) Syzygy Average High Water Level
Syzygy average high water level was calculated using hourly tidal data from 2010 to 2014, which is shown in the figure below. The average is 0.73 m above MSL. This value is near the design tide level of the Imus River (0.8 m above MSL). In Japan, syzygy average water level is calculated for typhoon season in some cases. The typhoon season in Manila Bay is April to December. The syzygy average for this period is 0.77 m above MSL and that was adopted as the syzygy average water level in this study for
safety’s sake.
S.L)
Tidal Tidal Level (m above M.
Source: JICA Survey Team Figure 3.2.10 Syzygy High Water Level (Manila South Harbor, 2012-2016)
(5) Storm Surge
(a) Influence of Typhoon
Before showing the result of storm surge analysis, the relation between typhoon and storm surge is explained in this section. Storm surge is produced by the winds and the low pressure associated with intense storms, although the surge by the low pressure is much smaller than that by the wind. In the
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northern hemisphere, the direction of typhoon’s rotation is counter-clockwise due to the strength of Coriolis. It causes storm surge in the direction of the wind (rotation). Regarding the storm surge with low pressure, it is 1 cm rise above predicted tidal value for each 1 hPa below the standard atmospheric pressure of 1013 hPa.
The table below shows the list of major typhoons which passed near Manila Bay, extracted from Digital Typhoon (http://agora.ex.nii.ac.jp/digital-typhoon/). Looking at central pressure when passing near Manila Bay, Pedring (2011) and Glenda (2014) are relatively stronger (960 hPa) in recent years. They have the potential to raise sea water level by 53 cm by the low pressure only.
The storm surge caused by Pedring and Glenda is discussed below. The path, central pressure and maximum wind velocity of the two typhoons are shown in Figure 3.2.11.
Table 3.2.11 Major Typhoons that Passed near Manila Bay
Lowest International Name in the Occurrence Dissipation No. Life Span Pressure Name Philippines (UTC) (UTC) (hPa)
1 Iris - 1951/4/29 1951/5/11 11Days 18Hours 909 2 Emma Welming 1967/10/31 1967/11/8 8Days 0Hours 908 3 Joan Sening 1970/10/10 1970/10/18 8Days 0Hours 905 4 Patsy Yoling 1970/11/14 1970/11/22 8Days 0Hours 910 5 Ora Konsing 1972/6/23 1972/6/27 4Days 0Hours 980 6 Mac Pepang 1979/9/16 1979/9/23 5Days 0Hours 985 7 Vera Loleng 1983/7/12 1983/7/19 6Days 6Hours 965 8 Sibyl Mameng 1995/9/28 1995/10/3 5Days 6Hours 985 9 Angela Rosing 1995/10/26 1995/11/6 10Days 18Hours 910 10 Xangsane Reming 2000/10/26 2000/11/1 6Days 6Hours 960 11 Bebinca Seniang 2000/11/1 2000/11/7 6Days 0Hours 980 12 Xangsane Milenyo 2006/9/26 2006/10/2 6Days 0Hours 940 13 Conson Basyang 2010/7/12 2010/7/18 6Days 0Hours 970 14 Nesat Pedring 2011/9/24 2011/9/30 6Days 18Hours 950 15 Rammasun Glenda 2014/7/12 2014/7/19 7Days 12Hours 935 16 Fung-Wong Mario 2014/9/17 2014/9/24 6Days 12Hours 985 17 Hagupit Ruby 2014/12/1 2014/12/11 10Days 6Hours 905 18 Koppu Lando 2015/10/13 2015/10/21 7days18hours 925 19 Nock-Ten Nina 2016/12/21 2016/12/27 6days0hours 915 20 Doksuri Maring 2017/9/12 2017/9/16 3days12hours 955 Source: JICA Survey Team
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Source: JICA Survey Team Figure 3.2.11 Paths of Typhoon Pedring (Sep. 2001) and Glenda (Jul. 2014)
Figure 3.2.12 shows the storm surge at Manila South Harbor during typhoons Pedring (September 2011) and Glenda (July 2014). The storm surge of 76 cm occurred on 27 September 2011, when Pedring was crossing Luzon Island. On the other hand, no storm surge was observed, when Glenda was passing. On the contrary, sea water level declined. That can be explained by the direction of wind at Manila South Harbor. Considering that typhoons are in counter-clockwise direction, when typhoons pass the south side of the Manila Bay, wind direction is from Manila South Harbor out to sea. When it passes the north side of the Manila Bay, wind direction is toward Manila South Harbor. Thus, at the Manila South Harbor, in case typhoons pass the south side of Manila Bay, the offshore wind pushes the water offshore and cause decline of the sea water level and offsets the sea level rise by the low pressure. When it passes the north side of Manila Bay, both coastward wind and low pressure contribute to sea water level rise and cause storm surge. Therefore, at the Manila South Harbor, storm surge was observed when Pedring was passing the north side of Manila Bay, and sea water level declined when Glenda was passing the south side.
[September 2011 Typhoon Pedring]
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[July 2014 Typhoon Glenda]
Source: JICA Survey Team Figure 3.2.12 Storm Surge by Typhoon
(b) Record-High Storm Surge
Storm surge was studied based on the astronomical tide level and observed tide level. Astronomical tide data for 10 years (2007-2016) were used. The datum level of those are MLLW, while the observed tide level is recorded as the reading of staff gauge. However, the relationship between the 0 level of the staff gauge and MLLW is not provided. Hence, assuming that astronomical tide equals observed tide from January to April when typhoons hardly hit the Philippines, correction values to convert the staff’s reading to the values based on MLLW and MSL were estimated. Table 3.2.12 shows the estimated correction values and Table 3.2.13 shows annual maximum storm surge converted with correction values.
Table 3.2.12 Correction Values Correction Values to From above MLLW No. Year MLLW (cm) To above MSL (cm)* 1 2007 238.4 48 2 2008 250.9 48 3 2009 241.5 48 4 2010 239.5 48 5 2011 250.6 49 6 2012 255.7 49 7 2013 250.3 49 8 2014 244.9 49 9 2015 241.9 49 10 2016 245.2 49 *Reference: NAMRIA Source: JICA Survey Team
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Table 3.2.13 Annual Maximum Storm Surge Annual Maximum No. Year Date and Time Note Storm Surge (cm) 1 2007 40 11/27 1:00 2 2008 45 10/17 2:00 3 2009 40 8/2 5:00 4 2010 63 12/22 22:00 5 2011 76 9/27 11:00 Typhoon Pedring, flood occurred 6 2012 71 7/30 0:00 7 2013 51 10/12 0:00 8 2014 31 9/19 23:00 Flood occurred 9 2015 57 10/18 4:00 10 2016 42 12/20 2:00 Average (cm) 52 Maximum (cm) 76 Adopted as the maximum value. Minimum (cm) 31 Source: JICA Survey Team
(c) Probable Storm Surge
Fitting to Probability Distribution Functions (PDF) was carried out to estimate probable storm surge, by harnessing the annual maximum values in Table 3.2.13. It is noted that the number of samples is not enough. The hydrological statistic utility version 1.5 (released by Japan Institute of Country-ology and Engineering, JICE) was used as an analytical tool. The table below shows the result. Consequently, Gumbel distribution was selected for the design, because its storm surge of 50-year return period is the highest among PDFs which satisfy SLSC 1 <= 0.04. The storm surge of 50-year return period is customarily used for the design in Japan, and this study also adopts it. The storm surge of 50-year return period of GEV, Gumble and LN2LN are all about 95 cm and the estimated PDFs are almost the same as shown in the figure below. Therefore, Gumbel that has the highest 50-year storm surge value of 95.7 cm was selected.
Table 3.2.14 Probable Storm Surge Unit:cm Return Period Probability Density Function (Year) Gumbel Gev Iwai IshiTaka LN3PM LN2LM LN2PM 2 49.1 49.2 50.3 50 49.9 49.9 49.9 3 56.2 56.3 57.1 56.8 56.6 57.1 56.7 5 64.1 64.1 64.1 63.9 63.7 64.9 64 10 73.9 73.9 72.5 72.3 72.3 74.6 72.9 20 83.4 83.3 80.1 80 80.1 83.6 81.2 30 88.9 88.6 84.3 84.3 84.5 88.7 85.9 50 95.7 95.3 89.4 89.5 89.9 95 91.6 80 101.9 101.4 93.9 94.2 94.8 100.7 96.9 100 104.9 104.2 96.1 96.4 97.1 103.5 99.4 150 110.3 109.4 99.9 100.4 101.2 108.4 103.8 200 114.1 113.1 102.6 103.2 104.1 111.9 107 400 123.2 121.8 109 109.8 111 120.3 114.6 P-COR(99%) 0.987 0.987 0.984 0.985 0.985 0.987 0.986 X-COR(99%) 0.977 0.977 0.979 0.979 0.979 0.978 0.979 SLSC(99%) 0.039 0.039 0.04 0.04 0.04 0.036 0.039 Source: JICA Survey Team
1 Standard Least Square Criterion (SLSC): Criterion for judging goodness of fit of samples and probability distribution
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Source: JICA Survey Team Figure 3.2.13 Gumbel, GEV and LN2LN Distributions and Observed Annual Maximum
(6) Design Tide Level
Based on the analysis results, design tide level was determined with the three methods in Figure 3.2.5. The design tide level with each method are shown in the table below. These results were compared, and it was concluded that the methods 2 and 3 are difficult to apply due to insufficiency number of samples. Therefore, Method 1 was applied, and the record-high of 1.4 m (above MSL) was adopted as the design tide level.
Table 3.2.15 Design Tide Level Design No. Method Description Remarks Tide Level 1 Record-High ⚫ Record-high tidal level is 1.4 m 1.4 m ⚫ It was considered reliable and thus Tidal Level (September 2011) according to above MSL adopted as the design tidal level NAMRIA. because it was based on the long- term observation record (1947 to 2016)
2 Syzygy average ⚫ Syzygy average high water level：0.77 1.73 m ⚫ Number of samples is 10 only, high water level m above MSL above MSL which is not enough for statistical ＋Probable ⚫ Calculated from Syzygy high water analysis so that the result was not storm surge levels from April to December. adopted. ⚫ Probable storm surge：0.96 m (50-year return period) ⚫ In Japan, probable storm surge of 50- year return period is customarily used for design. This study also adopts it. 3 Syzygy average ⚫ Syzygy high water level：0.77 m 1.53 m ⚫ Number of samples is 10 only, high water level above MSL above MSL which is not enough for statistical ＋Record-High ⚫ Calculated from Syzygy high water analysis so that the result was not Storm Surge levels from April to December. adopted. ⚫ Record-high storm surge：0.76 m ⚫ The storm surge occurred in September 2011 when typhoon Pedring hit Manila Bay. Source: JICA Survey Team
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3.3 Hydrological Statistical Analysis
For the design scale of Laguna de Bay, the probability evaluation based on water level was conducted. For the Laguna de Bay Coastal Area and the Las Piñas-Parañaque District, the probability evaluation of basin average rainfall or rainfall at the site rainfall observation was conducted. The data used for the hydrological statistical analysis is organized in Table 3.3.1.
Table 3.3.1 Data Utilized in Hydrological Statistical Analysis Target Index Utilized Data Calculate yearly maximum water level based on the Water Level of Laguna de Bay Water Level observed lake water level data from 1946 to 2016. Calculate the basin average rainfall for each basin. For the calculation of average rainfall for each basin, the Laguna de Bay Coastal Area Rainfall Thiessen Division by year is conducted in view of maintenance status of rainfall observation data. The probability rainfall at NAIA point of PAGASA in Las Piñas-Parañaque District Rainfall Las Piñas-Parañaque District was calculated.
For the statistical analysis, the Hydrological Statistics Utility ver. 1.5 developed by the Japan Institute of Country-ology and Engineering (Japan) is employed. The calculation method of probability water level and the probability rainfall is as described below.
- The probability hydrological amount is calculated by the following thirteen models. - The goodness of fit evaluation is conducted by SLSC for the three distributions including the Gumbel distribution based on the extreme theory, the generalized extreme value distribution (Gev), and the square root index maximum value distribution (Sqrt-Et). The distribution (SLSC2<=0.04) which satisfy the selection criteria is selected. If these three distributions do not satisfy the selection criteria, it is selected from the remaining seven distributions. - For the selected distribution, the stability evaluation by resampling (Jackknife method) is performed. The distribution with the smallest estimation error is used as the probability distribution model in the plan. - The unbiased estimated value by Jackknife method is used as the probability hydrological amount in the plan.
Table3.3.2 Probability Distribution Model Name Abbr Name Abbr Exponential Distribution Exp Ishihara/Takase Method Ishihara Gumbel Distribution Gumbel Log-Normal Distribution (Quantile Method) LN3Q Extreme Value Distribution Gev Log-Normal Distribution 3 (Slade II) LN3PN Square Root Exponential Type Maximum Log-Normal Distribution 2 (Slade I L- Sqrt-Et LN2LM Distribution Moment Method) Log-Normal Distribution 2 (Slade I, Product Peason Type III Distribution (Real Space) LP3Rs LN2PM Moment Method) Peason Type III Distribution (Logarithmic Log-Normal Distribution 4 (Slade I, Product LogP3 LN4PM Space) Moment Method) Iwai Method Iwai Source: Japan Institute of Country-ology and Engineering
2 Standard Least Square Criterion (SLSC): Criterion for judging goodness of fit of samples and probability distribution
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3.3.1 Statistical Analysis of Laguna de Bay Water Level
For the water level statistical analysis of Laguna de Bay, the yearly maximum lake level is calculated from the average value of four lake water level observations and the statistical processing is performed. For the lake water level data, the observation values from 1946 to 2016 (missing data in 1971, 1979 to 1981) were employed. The results of the water level statistical evaluation in Laguna de Bay are shown in Table3.3.3 and Figure 3.3.1
The 100-year probability water level in Laguna de Bay is 14.3 m. The recorded maximum water level (14.03 m, 1972) is the water level equivalent to a 50-year probability. In addition, the maximum water level during Typhoon Ondoy in 2009 was 13.85m which is equivalent to a 40-year probability.
Table3.3.3 Probability Water Level at Laguna de Bay Return Period Water Level (year) (m) 2 12.3 3 12.6 5 12.9 10 13.2 20 13.6 30 13.7 50 14.0 80 14.2 100 14.3 150 14.5 200 14.7
Distribution Model：Gumbel SLSC:0.034
Figure 3.3.1 Calculation Results of Probability Water Level at Laguna de Bay
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3.3.2 Rainfall Analysis
(1) Outline of Laguna de Bay Basin
Basin specifications of each small basin in the Laguna de Bay Basin are shown in Table3.3.4 and Figure 3.3.2. Several rivers are included in the small basin, and representative river names are listed in the following table. The basin specification of each river in the basin is shown in Table3.3.4. The Laguna de Bay Basin (including Laguna de Bay) is about 3,280 km2, and the catchment area of the entire Laguna de Bay Basin which is the scope of this study (SB-03～SB-23) (hereinafter “Laguna de Bay Basin”) is 2,241 km2.
Table3.3.4 Basin Specification of Laguna de Bay Basin SB_ID Name Main River Name*1 Area (km2)*2 SB-00 Laguna de Bay Surface - 904.0 SB-01 Marikina Marikina River 538.1 SB-02 Mangahan Mangahan Flood way 91.8 SB-03 Angono Angono River 86.6 SB-04 Morong Morong River 95.9 SB-05 Baras Baras River 21.7 SB-06 Tanay Tanay River 52.2 SB-07 Pililla Pilila River 40.4 SB-08 Jala-jala Jala-jala River 70.6 SB-09 Sta. Maria Sta Maria River 202.2 SB-10 Siniloan Romeo River 71.7 SB-11 Pangil Pangil River 50.1 SB-12 Caliraya Caliraya River 128.8 SB-13 Pagsanjan Pagsanjan River 301.2 SB-14 Sta. Cruz Sta. Cruz River 146.7 SB-15 Pila Pila River 89.3 SB-16 Calauan Calauan River 154.5 SB-17 Los Baños Los Baños River 102.1 SB-18 San Juan San Juan River 191.7 SB-19 San Cristobal San Cristobal River 140.6 SB-20 Sta. Rosa Sta. Rosa River 119.8 SB-21 Binan Binan River 84.8 SB-22 San Pedro San Pedro River 46.0 SB-23 Muntinlupa Alaban River 44.1 SB-24 Taguig Napindan Channel 44.5 Total (SB00-SB23) 3,774.9 Laguna de Bay Bain in this survey (SB-03~SB-23) 2,241.0 Laguna de Bay (SB-00) and Surrounding Basin (SB-02~SB-24) 3,281.3 *1: Major river is shown for each sub-basin *2: The catchment area is not the catchment area of the river but the area of the basin divided by the small basin.
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Source: JICA Survey Team created based on Open Street Map Figure 3.3.2 Basin Boundary in Laguna de Bay Basin
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(2) Calculation of Basin Average Rainfall in Laguna de Bay Basin
For the calculation of the basin average rainfall in the Laguna de Bay Basin, the daily rainfall data from 1951 to 2016 is used. Also, since the observation situation changes every year, the basin average rainfall of the Laguna de Bay Basin (SB03 to SB23) is calculated by selecting the site where daily rainfall data of one year exists in each year and conducted by the Thiessen Division. The yearly maximum basin average rainfall of each river basin is shown in Table 3.3.6 and Table 3.3.7. The pattern of the Thiessen Division used in this study is shown in Table 3.3.8.
The yearly maximum basin average rainfall is calculated based on the calculated basin average rainfall of the Laguna de Bay Basin, and the rainfall analysis is conducted. The rainfall by probability scale in the Laguna de Bay Basin is shown in Table 3.3.5.
Table 3.3.5 Rainfall Rate by Probability Scale in Laguna de Bay Basin (SB03~SB23) (Unit: mm/day) Sub-Basin ID SB03 SB04 SB05 SB06 SB07 SB08 SB09 SB10 SB11 SB12 SB13 Name Angono Morong Baras Tanay Pililla Jala-jala Sta. Maria Siniloan Pangil Caliraya Pagsanjan Area(km2) 86.6 95.9 21.7 52.2 40.4 70.6 202.2 71.7 50.1 128.8 301.2 Statistical Gev Gumbel Gev Gev Gev Gev Gev Gumbel Gev Gev Gev model SLSC 0.024 0.031 0.035 0.029 0.031 0.022 0.025 0.036 0.018 0.025 0.027 2 117.4 154.2 150.6 141.9 135.3 114.6 128.3 135.7 137.8 135.8 122.9 3 140.4 185.2 181.5 169.2 162.8 136.1 150.5 161.1 170.0 165.2 144.9 5 168.9 219.8 217.6 201.7 194.7 162.8 175.4 189.3 208.6 199.4 171.1 10 209.4 263.3 265.8 246.0 236.6 200.7 207.0 224.9 261.6 244.6 206.6 15 234.9 287.8 294.5 272.8 261.2 224.5 225.0 244.9 293.9 271.3 228.1 20 254.0 305.0 315.2 292.4 278.9 242.2 237.6 259.0 317.6 290.4 243.7 25 269.4 318.2 331.6 308.0 292.8 256.6 247.3 269.8 336.5 305.5 256.2 30 282.5 329.0 345.2 321.0 304.2 268.7 255.3 278.6 352.3 318.0 266.5 50 321.4 359.0 384.2 358.9 336.9 304.7 277.5 303.1 398.4 353.6 296.5 80 360.3 386.4 421.5 395.6 367.8 340.8 298.0 325.5 443.5 387.4 325.6 100 380.1 399.4 439.7 413.8 382.8 359.1 307.7 336.1 465.9 403.9 340.0
Sub-Basin ID SB14 SB15 SB16 SB17 SB18 SB19 SB20 SB21 SB22 SB23
Name Sta. Cruz Pila Calauan Los Banos San Juan San Cristobal Sta. Rosa Binan San Pedro Muntinlupa Area(km2) 146.7 89.3 154.5 102.1 191.7 140.6 119.8 84.8 46 44.1 Statistical Gev Gev Gev Gev SqrtEt Gev Gev Gumbel SqrtEt Gev model SLSC 0.025 0.017 0.029 0.019 0.035 0.024 0.022 0.027 0.027 0.025 2 120.6 115.8 138.3 146.2 138.5 127.2 113.9 109.3 105.5 101.4 3 142.6 139.0 164.5 175.8 167.5 152.4 138.7 133.2 128.9 124.9 5 168.8 167.3 193.8 209.2 202.5 182.4 166.4 159.9 157.3 155.8 10 204.6 207.0 230.9 251.9 250.7 223.1 201.6 193.3 196.5 202.9 15 226.3 231.7 252.0 276.4 279.9 247.7 221.5 212.2 220.3 234.3 20 242.2 250.1 266.8 293.7 301.1 265.6 235.6 225.5 237.7 258.7 25 254.8 264.8 278.3 307.1 318.0 279.8 246.4 235.7 251.5 279.0 30 265.4 277.3 287.6 318.0 332.0 291.7 255.3 244.0 263.0 296.5 50 296.1 313.9 313.8 348.8 372.6 326.1 280.0 267.1 296.2 350.5 80 325.9 350.4 337.8 377.4 411.6 359.4 302.8 288.2 328.2 407.5 100 340.7 368.7 349.3 391.0 430.6 375.9 313.7 298.2 343.8 437.4
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Data Collection Survey on Parañaque Spillway in Metro Manila in the Republic of the Philippines Final Report
Table 3.3.6 1 Year Maximum Basin Average Rainfall in Each Basin (1/2) (Unit：mm) Year SB-02 SB-03 SB-04 SB-05 SB-06 SB-07 SB-08 SB-09 SB-10 SB-11 1951 87.6 82.9 84.3 84.3 92.4 83.5 84.7 155.2 199.1 199.1 1952 177.4 221.5 228.6 228.6 209.0 224.7 194.9 105.2 107.7 107.7 1953 158.4 136.3 140.0 140.0 127.7 137.5 122.4 133.3 199.4 199.4 1954 111.5 114.0 117.9 117.9 112.9 116.9 99.3 86.3 110.5 110.5 1955 109.3 83.1 84.1 84.1 77.2 82.7 79.5 164.8 227.6 227.6 1956 157.2 145.5 146.6 146.6 133.9 144.1 141.6 111.3 159.0 159.0 1957 105.0 115.3 119.1 119.1 108.2 116.9 101.1 107.1 109.7 109.7 1958 293.7 339.7 353.8 353.8 322.5 347.5 286.8 156.4 103.9 103.9 1959 116.7 108.7 111.5 111.5 104.9 110.2 98.0 74.3 95.3 95.3 1960 226.2 225.7 229.1 229.1 213.8 226.0 213.1 132.8 172.5 172.5 1961 126.1 144.2 137.2 128.1 163.6 215.9 215.9 209.8 215.9 215.9 1962 187.9 136.5 174.5 190.5 122.1 113.5 113.5 110.2 113.5 113.5 1963 113.4 145.6 107.4 114.4 122.9 166.1 166.1 161.2 166.1 166.1 1964 195.9 195.6 206.9 194.7 97.4 94.2 94.2 91.5 94.2 94.2 1965 157.0 76.7 144.7 158.9 151.3 126.7 61.3 119.5 164.9 164.9 1966 167.6 121.2 157.8 170.6 156.6 149.8 149.8 154.7 149.8 149.8 1967 325.4 94.2 285.9 331.5 307.2 228.3 119.8 80.5 99.0 99.0 1968 143.4 105.0 134.3 144.8 139.2 121.0 100.4 137.7 223.0 223.0 1969 100.8 61.1 92.0 102.2 60.2 82.8 82.8 80.6 82.8 82.8 1970 274.1 151.8 263.5 275.9 150.3 176.0 176.0 174.8 176.0 176.0 1971 85.3 97.2 88.5 85.0 124.9 157.5 157.5 162.8 157.5 157.5 1972 216.9 339.1 211.9 218.1 168.5 179.6 179.6 174.4 179.6 179.6 1973 127.5 93.9 112.5 130.6 106.0 105.2 105.2 110.6 105.2 105.2 1974 212.2 113.6 203.1 214.4 136.4 151.1 151.1 149.5 151.1 151.1 1975 209.6 138.3 210.7 210.2 123.4 110.5 110.5 110.6 110.5 110.5 1976 240.1 278.5 275.0 242.2 261.9 128.1 118.1 115.7 118.1 118.1 1977 136.6 131.3 150.7 139.5 146.2 79.4 86.4 83.8 86.4 86.4 1978 97.6 120.5 93.5 88.1 142.2 266.0 315.0 312.6 315.0 315.0 1979 122.8 82.3 112.5 110.4 123.8 67.2 84.0 83.0 84.0 84.0 1980 56.3 58.3 56.8 53.1 68.2 55.8 162.1 157.4 234.7 210.4 1981 128.7 82.2 128.2 134.3 117.8 82.0 103.4 101.2 103.4 103.4 1982 108.6 83.9 102.6 106.8 104.3 67.5 69.8 67.8 69.8 69.8 1983 137.8 114.7 132.4 140.3 122.3 67.1 76.7 75.1 76.7 76.7 1984 84.2 77.6 86.5 87.6 79.5 107.2 126.4 127.6 126.4 126.4 1985 134.1 159.8 335.2 342.4 342.4 336.9 131.4 168.5 131.0 132.3 1986 189.5 185.8 89.8 87.6 87.6 88.2 117.3 106.5 116.4 117.6 1987 97.4 87.2 163.3 168.1 168.1 168.1 103.9 168.1 166.4 85.8 1988 92.1 172.5 263.8 266.0 266.0 263.3 133.4 181.6 130.8 132.1 1989 70.4 71.1 102.4 100.2 113.8 113.8 68.6 87.9 81.9 62.2 1990 130.1 150.0 63.6 74.7 108.1 108.1 85.4 87.4 79.2 92.0 1991 158.5 133.7 121.0 110.3 116.8 116.8 52.7 79.3 71.0 58.9 1992 161.1 122.7 134.7 135.5 141.8 141.8 71.6 112.2 99.5 57.2 1993 149.4 73.9 112.7 88.2 151.9 178.5 100.2 172.9 194.4 138.5 1994 140.4 69.2 147.4 145.2 263.6 199.0 97.2 184.6 229.4 384.3 1995 117.8 121.7 164.6 103.6 142.6 137.7 125.8 173.8 170.9 462.0 1996 75.1 98.3 105.0 107.0 74.4 77.0 100.6 84.5 97.2 150.2 1997 92.0 79.7 192.6 194.0 158.4 129.2 113.0 122.3 114.8 108.3 1998 190.7 245.9 271.0 271.0 224.9 246.1 251.0 213.4 229.3 334.1 1999 249.1 131.7 341.8 351.3 215.9 83.0 80.4 75.7 83.0 64.4 2000 250.7 135.8 221.5 221.0 221.0 213.6 59.0 95.9 59.0 59.0 2001 201.0 115.2 190.3 190.0 190.0 147.4 80.6 83.5 84.3 84.3 2002 144.5 100.1 181.2 182.0 182.0 137.9 111.2 200.1 213.3 213.3 2003 151.4 122.5 231.0 231.0 242.9 237.1 80.2 147.9 88.2 80.2 2004 122.8 95.9 190.0 191.0 135.0 69.8 92.6 68.7 114.6 309.7 2005 101.7 64.8 115.0 115.0 95.7 85.9 121.5 100.2 128.4 201.7 2006 95.7 113.9 106.0 106.0 74.0 105.9 84.7 102.3 113.9 244.8 2007 120.3 72.2 120.0 120.0 126.3 117.9 137.5 214.4 243.6 243.6 2008 128.7 105.9 153.6 155.0 155.0 118.5 158.5 238.6 251.2 251.2 2009 303.2 265.7 352.0 352.0 352.0 243.3 152.3 242.4 255.5 255.5 2010 89.3 73.5 108.0 108.0 102.7 132.1 306.5 130.7 140.5 140.5 2011 182.3 152.2 165.0 165.0 165.0 165.0 150.4 165.0 165.0 165.0 2012 257.3 216.2 245.0 245.0 245.0 245.0 221.1 245.0 245.0 245.0 2013 163.4 155.5 130.0 130.0 130.0 130.0 132.8 130.0 130.0 130.0 2014 236.2 216.7 220.0 220.0 220.0 220.0 220.0 220.0 220.0 220.0 2015 127.7 148.9 193.0 193.0 246.2 237.4 127.0 148.5 131.5 127.0 2016 98.0 75.5 158.0 158.0 133.3 83.4 54.9 73.8 83.4 57.1
3-34 CTI Engineering International Co., Ltd. Nippon Koei Co., Ltd. CTI Engineering Co., Ltd.
Data Collection Survey on Parañaque Spillway in Metro Manila Final Report in the Republic of the Philippines
Table 3.3.7 1 Year Maximum Basin Average Rainfall in Each Basin（2/2） (Unit：mm) Year SB-12 SB-13 SB-14 SB-15 SB-16 SB-17 SB-18 SB-19 SB-20 SB-21 SB-22 SB-23 SB-24 1951 199.1 112.1 117.1 117.1 117.1 117.1 117.1 117.1 107.1 91.9 89.0 84.3 84.3 1952 107.7 129.5 134.6 134.6 134.6 134.6 134.6 134.6 118.4 136.4 159.5 228.6 228.6 1953 199.4 78.5 84.3 84.3 84.3 84.3 84.3 84.3 81.9 91.7 103.8 140.0 140.0 1954 110.5 54.3 59.7 59.7 59.7 59.7 59.7 59.7 52.2 67.0 79.8 117.9 117.9 1955 227.6 63.4 59.9 59.9 59.9 59.9 59.9 59.9 63.0 71.5 74.7 84.1 84.1 1956 159.0 111.1 120.1 120.1 120.1 120.1 120.1 120.1 123.5 132.8 136.3 146.6 146.6 1957 109.7 78.2 85.3 85.3 85.3 85.3 85.3 85.3 74.2 79.3 85.1 119.1 119.1 1958 103.9 238.9 261.1 261.1 261.1 261.1 261.1 261.1 237.3 173.2 216.2 353.8 353.8 1959 95.3 84.0 84.3 84.3 84.3 84.3 84.3 84.3 75.7 74.5 83.8 111.5 111.5 1960 172.5 138.6 144.8 144.8 144.8 144.8 144.8 144.8 155.8 185.3 196.2 229.1 229.1 1961 215.9 215.9 215.9 215.9 159.4 231.0 301.5 301.5 291.6 264.9 255.0 225.3 204.3 1962 113.5 113.5 113.5 113.5 160.0 232.8 270.8 270.8 254.9 212.2 196.4 166.1 151.8 1963 166.1 166.1 166.1 166.1 125.4 75.2 84.3 84.3 88.8 121.8 148.6 228.9 196.9 1964 94.2 94.2 94.2 94.2 103.5 188.6 233.0 233.0 238.8 254.6 260.4 277.9 261.0 1965 164.9 82.5 90.7 90.7 90.7 90.7 90.7 90.7 78.9 54.2 57.0 65.3 84.2 1966 149.8 149.8 149.8 149.8 132.8 106.6 127.0 127.0 126.4 124.7 124.1 145.3 131.1 1967 99.0 189.6 202.5 202.5 202.5 202.5 202.5 202.5 189.2 153.5 140.2 100.4 91.7 1968 223.0 71.5 60.3 60.3 60.3 60.3 60.3 60.3 58.3 75.9 85.5 114.5 104.5 1969 82.8 82.8 82.8 82.8 74.6 78.3 80.3 80.3 78.4 73.3 71.4 81.4 74.1 1970 176.0 176.0 176.0 176.0 175.9 175.7 175.6 175.6 166.3 141.2 140.4 198.5 211.3 1971 156.5 122.9 130.6 157.5 147.9 145.3 141.5 141.5 138.6 130.7 127.8 119.0 111.6 1972 178.8 150.1 156.6 179.6 173.2 185.1 188.3 188.3 225.2 324.7 361.6 472.4 409.2 1973 104.8 123.0 113.9 105.2 105.5 110.6 112.3 111.3 29.7 19.2 34.9 33.4 125.1 1974 151.1 150.7 150.8 151.1 131.9 139.3 152.0 150.5 36.5 21.9 43.8 36.3 158.1 1975 110.0 114.6 107.9 110.5 107.9 107.8 105.6 101.6 101.6 101.6 101.6 62.4 216.5 1976 122.5 276.4 241.2 118.1 254.4 407.7 499.2 444.2 197.5 205.3 200.4 164.8 369.3 1977 85.5 79.6 69.6 86.4 91.2 116.7 129.0 125.2 105.4 104.3 108.2 74.8 175.3 1978 313.5 260.4 261.4 300.5 185.9 182.9 169.3 161.0 131.1 130.6 125.6 149.5 113.9 1979 83.3 87.1 83.6 84.0 86.9 149.0 194.9 173.6 112.3 109.7 118.9 103.3 107.4 1980 224.5 219.9 208.1 195.4 196.9 195.4 165.9 146.8 85.9 92.9 87.7 64.8 51.8 1981 102.5 131.9 104.1 92.7 110.8 114.6 111.9 129.1 58.5 55.1 61.8 50.8 105.9 1982 69.1 104.9 98.0 70.9 145.0 145.0 173.9 114.1 49.7 37.0 64.8 61.1 79.1 1983 76.1 100.4 89.5 68.6 187.4 195.7 196.1 128.4 107.2 100.0 83.4 95.5 101.4 1984 125.6 130.7 128.9 121.2 186.9 196.0 168.7 105.2 48.0 31.2 41.6 56.2 85.4 1985 132.3 132.1 138.1 145.6 243.3 253.0 247.9 209.7 155.2 130.5 131.4 101.1 155.6 1986 118.8 161.9 161.8 137.6 291.4 299.8 223.6 136.8 173.7 194.3 173.6 208.8 271.0 1987 155.4 155.4 155.4 143.6 80.9 78.8 78.8 54.1 133.6 138.5 115.4 105.5 127.0 1988 132.9 161.7 157.6 139.1 194.3 195.3 163.0 127.4 129.0 114.9 110.0 98.4 159.0 1989 62.5 119.2 103.8 62.2 86.0 114.7 131.4 94.6 129.8 126.5 121.6 85.6 77.8 1990 92.0 91.2 88.9 90.0 151.4 157.7 219.4 152.3 144.5 145.3 138.1 124.2 196.3 1991 58.5 83.1 78.0 54.3 141.8 143.6 128.9 94.7 104.8 110.4 105.8 95.3 215.5 1992 57.5 94.2 88.3 85.9 309.1 334.0 189.5 117.4 101.4 69.5 67.4 76.8 152.9 1993 69.2 100.1 93.2 73.5 145.1 149.9 116.3 106.4 80.2 70.6 74.0 55.3 89.7 1994 323.1 94.4 88.6 77.7 159.1 166.1 137.0 127.4 77.0 61.1 67.8 62.7 108.5 1995 388.1 129.2 127.2 99.8 208.2 212.1 166.8 146.0 126.9 90.6 88.0 79.7 91.9 1996 127.2 119.0 112.0 117.8 145.2 150.5 173.4 185.7 150.5 138.2 138.8 98.3 81.5 1997 92.5 96.7 99.9 109.8 133.4 137.2 172.5 137.7 83.8 92.9 89.4 87.4 54.0 1998 329.0 266.2 234.8 205.4 189.5 187.2 158.5 128.5 144.1 118.2 119.4 123.5 131.6 1999 102.7 107.2 110.1 111.7 179.4 185.4 168.4 127.9 106.6 124.5 103.3 99.7 234.5 2000 60.2 143.1 136.8 78.2 286.6 293.2 239.3 156.5 143.6 146.3 125.5 86.1 205.0 2001 82.1 153.6 124.7 95.0 96.7 98.2 83.7 82.0 79.1 55.4 47.2 69.5 166.0 2002 186.8 116.9 118.2 119.7 142.5 144.5 124.9 122.3 132.0 124.6 133.9 113.7 123.4 2003 79.6 69.7 70.8 75.6 91.5 93.0 88.6 102.8 107.6 120.2 121.7 110.3 122.1 2004 260.2 115.5 117.0 134.0 138.6 150.6 83.6 55.7 69.4 98.4 78.3 86.8 103.1 2005 180.5 162.8 142.7 126.2 82.6 80.6 83.6 72.3 59.7 64.4 63.6 68.5 91.0 2006 209.4 101.0 97.8 114.5 291.9 308.0 225.0 158.6 136.1 57.4 59.4 101.8 153.6 2007 215.3 118.3 122.6 154.6 138.7 143.5 123.5 134.6 128.0 131.7 118.4 80.8 114.9 2008 228.5 160.9 149.7 126.4 196.9 196.5 171.6 176.6 191.8 128.8 112.3 83.6 154.2 2009 228.3 105.2 111.3 152.4 116.1 181.3 214.5 252.3 249.6 216.9 190.8 123.6 385.8 2010 118.6 297.1 311.3 426.6 124.6 135.4 107.1 169.5 104.6 156.2 129.5 78.1 97.4 2011 140.7 156.0 160.8 160.8 160.8 160.8 160.8 175.6 172.6 140.7 122.6 141.0 158.2 2012 214.4 232.7 242.8 242.8 242.8 242.8 242.8 248.6 219.2 174.8 152.1 114.2 380.9 2013 130.9 165.6 173.0 176.2 176.2 176.2 176.2 176.2 173.2 130.0 126.3 244.0 281.9 2014 220.0 220.0 220.0 220.0 99.8 84.0 84.0 84.0 84.0 84.0 84.0 85.1 218.4 2015 125.9 92.1 90.4 117.2 93.1 92.6 103.2 93.9 86.5 113.2 116.5 125.5 127.5 2016 60.7 73.3 67.6 55.9 64.1 69.7 69.7 81.8 67.0 68.2 74.1 88.6 95.3
CTI Engineering International Co., Ltd. 3-35 Nippon Koei Co., Ltd. CTI Engineering Co., Ltd.
Data Collection Survey on Parañaque Spillway in Metro Manila in the Republic of the Philippines Final Report
8
9
8
7
7
6
6
5
5
6
5
6
6
6
6
4
4
4
4
4
4
4
4
4
4
19
15
10
10
11
14
16
16
20
22
21
20
19
16
15
14
16
14
17
18
21
21
19
20
20
20
20
19
15
17
18
18
17
16
16
13
10
14
13
12
10
number
Station
Using
1
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
0
0
1
1
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Mt.Oro
1
1
1
1
0
0
0
1
1
1
1
1
1
1
1
1
1
0
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
BosoBoso
1
1
1
1
1
1
0
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Nangka
1
1
1
1
1
1
1
1
0
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Aries
1
1
0
0
0
0
0
0
0
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
a
Mt.Campan
1
0
0
0
0
0
0
0
0
1
1
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Napindan
1
0
0
0
0
0
0
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Garden
Science
0
0
0
0
1
1
1
1
1
1
1
0
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Umiray
0
0
0
0
0
0
1
1
1
1
1
1
1
0
1
1
0
0
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Laguna
Pakil
1
1
0
0
0
0
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
1
0
1
1
1
1
1
1
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
LosBanos
NAS UPLB NAS
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Tanay Rizal Tanay
Cuyambay
Soil
Bureau of Bureau
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
M.M.
Valenzuela
Polo
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Taguig MM Taguig
Tipas
0
0
0
0
0
0
0
0
1
1
0
0
1
0
1
1
1
1
0
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
MM
Sch. Pasig Sch.
Pasig Elem. Pasig
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Rainfall Observation Station used Station Observation Rainfall
Muntinlupa
Bu.of Prison Bu.of
Research
NPP
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
0
0
0
1
0
1
1
1
1
1
0
1
0
1
1
1
1
1
1
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
MM
n Taguig n
Bagumbaya
0
0
0
0
1
1
1
1
1
1
1
1
0
1
1
0
0
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Tagaytay
1
0
0
0
0
0
0
0
0
0
1
1
1
0
0
0
0
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Laguna
Sta. Maria Sta.
Macasipac
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
1
1
1
1
1
1
0
0
1
1
0
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Rizal
Montalban
SitioTabak
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Rizal
Antipolo
Boso-Boso
1
1
0
0
0
0
1
1
1
1
1
1
1
1
1
0
1
1
0
1
1
1
1
1
1
1
1
1
1
0
1
1
1
1
1
1
0
1
1
1
1
1
1
1
1
1
1
1
0
0
1
0
1
1
1
1
0
0
0
0
0
0
0
0
0
0
Laguna
Sta Cruz Sta
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
0
0
1
1
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Laguna
San Pedro San
1
0
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Cavite
Bacoor
Elem Sch. Elem
Mabolo
Pattern of Thiessen Polyline and and Polyline Thiessen of Pattern
0
0
0
0
0
0
0
0
0
0
1
1
1
0
0
1
1
1
0
0
1
1
1
1
1
1
1
1
1
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Cavite
Amadeo
Maitim
Barrio
1
1
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
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1
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1
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8
Infanta
.
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3.3
(Radar)
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1
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
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1
Batangas
Ambulong
Table
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
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1
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1
1
1
1
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1
1
1
1
1
1
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1
1
1
1
1
1
1
1
1
1
1
1
1
1
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0
0
0
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0
0
0
0
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0
Garden
Scienec
1
1
0
1
0
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
NAIA
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Cavite
Point
Sangley
1
1
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
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0
Quezon
Tayabas
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
1
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
PortArea
9
8
7
7
6
6
5
5
4
3
2
2
2
2
1
1
1
1
1
1
1
1
1
1
48
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sing Rainfall station Rainfall sing
U
Pattern
Thieesen
：
2016
2015
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2013
2012
2011
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year
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66
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No
3-36 CTI Engineering International Co., Ltd. Nippon Koei Co., Ltd. CTI Engineering Co., Ltd.
Data Collection Survey on Parañaque Spillway in Metro Manila Final Report in the Republic of the Philippines
(3) Estimation of Probable Rainfall in Las Pinas and Parañaque District
(a) Status of Rainfall Observation Station in Las Pinas-Parañaque Area
There are four (4) rainfall observation stations in Las Pinas -Parañaque area (including Zapote River Basin) which are NAIA station, Mabolo Elem Sch. Bacoor Cavite station,Bagumbayan Taguig MM station and NPP Research Bu.of Prison Muntinlupa.
These stations are observing only daily rainfall data. The hourly observation data is not existed for long term period around Las Pinas - Parañaque area, so the daily rainfall data was used in this project.
The inventory for each station is shown in Table 3.3.9. Since the observation situation changes every year, the basin mean rainfall of Las Pinas - Parañaque area is calculated by selecting the site where daily rainfall data of one year exists in each year and conducted by the Thiessen Division.
Figure 3.3.3 Location of Rainfall Gauging Stations
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Data Collection Survey on Parañaque Spillway in Metro Manila in the Republic of the Philippines Final Report
Table 3.3.9 Status of Rainfall Observation Data and Thiessen Division Pattern
No. 4 10 17 18 NPP Target year to Mabolo Elem Type of Bagumbayan Research calculate annual Name NAIA Sch. Bacoor Thiessen Taguig MM Bu.of Prison maximum daily Cavite polygon Muntinlupa rainfall Code 429 407 1301 1304 1951 1 0 0 0 ● 0 1952 1 0 0 0 ● 0 1953 1 0 0 0 ● 0 1954 1 0 0 0 ● 0 1955 1 0 0 0 ● 0 1956 1 0 0 0 ● 0 1957 1 0 0 0 ● 0 1958 1 0 0 0 ● 0 1959 1 0 0 0 ● 0 1960 1 0 0 0 ● 0 1961 1 0 0 0 ● 0 1962 1 0 0 0 ● 0 1963 1 0 0 0 ● 0 1964 1 0 0 0 ● 0 1965 1 0 0 0 ● 0 1966 1 0 0 0 ● 0 1967 1 0 0 0 ● 0 1968 1 0 0 0 ● 0 1969 1 0 0 0 ● 0 1970 1 0 0 0 ● 0 1971 1 0 0 0 ● 0 1972 0 0 0 0 1973 1 0 0 0 ● 0 1974 1 0 0 1 ● 1 1975 1 0 0 1 ● 1 1976 1 1 1 0 ● 2 1977 1 1 1 1 ● 3 1978 1 1 0 1 ● 4 1979 1 1 1 0 ● 2 1980 1 1 1 0 ● 2 1981 1 1 1 0 ● 2 1982 1 1 1 0 ● 2 1983 1 1 1 0 ● 2 1984 1 1 1 1 ● 3 1985 1 1 1 0 ● 2 1986 1 1 1 0 ● 2 1987 1 0 1 0 ● 5 1988 1 1 1 0 ● 2 1989 1 1 1 0 ● 2 1990 1 1 1 1 ● 3 1991 1 1 1 1 ● 3 1992 1 1 1 1 ● 3 1993 0 1 1 1 ● 6 1994 0 1 1 1 ● 6 1995 0 1 1 1 ● 6 1996 0 1 0 1 ● 7 1997 0 1 0 0 1998 0 1 1 0 ● 8 1999 0 1 0 0 2000 0 1 1 0 ● 8 2001 0 1 1 0 ● 8 2002 0 1 1 0 ● 8 2003 0 1 1 0 ● 8 2004 0 1 1 0 ● 8 2005 0 1 1 0 ● 8 2006 0 1 1 0 ● 8 2007 0 1 1 0 ● 8 2008 0 1 0 0 2009 0 1 0 0 2010 0 1 0 0 2011 1 1 0 0 ● 9 2012 0 0 0 0 2013 1 1 0 0 ● 9 2014 0 1 0 0 2015 1 0 0 0 ● 0 2016 1 1 0 0 ● 9 66 45 38 28 12 58 10 ：Station was used 1: Available daily rainfall data through a year. 0: No data for complete one year
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Data Collection Survey on Parañaque Spillway in Metro Manila Final Report in the Republic of the Philippines
(b) Calculation of Basin Mean Rainfall (BMR)
NAIA station is only one station which exist daily observed rainfall data from 1951 to 1973. Therefore, if two (2) or more stations were available, Basin Mean Rainfall (BMR) was estimated. When only NAIA station was available, BMR was calculated using correlation equation which was calculated using by basin mean rainfall based on 2 or more stations available and annual maximum rainfall of NAIA station.
The correlation is shown in Figure 3.3.4. The Basin Mean Rainfall (BMR) was estimated using by Thiessen Polygon when there were two (2) or more available stations.
＜Method to calculate Basin Mean Rainfall (BMR)＞
➢ If there are two (2) or more stations available: using Thiessen Polygon
➢ Only NAIA station is available using correlation equation
The result of Basin Mean Rainfall from 1951 to 2016 is shown in Table 3.3.11. In addition, in the year when the observation data are not sufficient, for years without observation data only for the Mabolo Elem Sch. Bacoor Cavite Observatory situated outside the Laspinas-Parañaque area, it was excluded from the target year for maximum annual rainfall.
Table 3.3.10 Annual Maximum Rainfall and BMR
NAIA BMR Year mm/day mm/day 1974 144.1 88.8 1975 218.3 134.0 400 1976 256.0 220.9 y = 0.7381x + 9.1744 1977 199.0 149.6 350 R² = 0.8428 1978 274.5 196.8 1979 104.0 111.1 300 1980 87.0 87.8 1981 76.4 68.8 250 1982 69.4 70.4 1983 112.2 65.9 200 1984 93.2 82.6 1985 316.8 334.0 150 1986 321.4 240.1 1987 103.0 101.3 100
1988 158.2 124.5 Basin Mean Rainfall :BMR (mm):BMR Rainfall Mean Basin 1989 102.0 84.6 1990 280.2 200.3 50 1991 130.8 91.2 1992 191.0 110.4 0 2011 151.5 138.2 0 50 100 150 200 250 300 350 2013 326.0 222.3 NAIA Rainfall (m) 2016 92.0 88.2 Figure 3.3.4 Correlation Between Annual Maximum Rainfall at NAIA and Basin Mean Rainfall (BMR)
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Data Collection Survey on Parañaque Spillway in Metro Manila in the Republic of the Philippines Final Report
Table 3.3.11 Annual Probable Basin Mean Rainfall Probale Maximum Basin Mean Return 1 Day Rainfall Period Rainfall mm Annual Maximum 2 108.7 Year Daily Rainfall 5 153.8 (mm) 10 187.3 1951 67.4 15 207.5 1952 182.9 1953 112.0 25 233.9 1954 94.3 50 271.5 1955 67.3 1956 117.3 100 311.3 1957 95.3 1958 283.0 1959 89.2 Statistic Model :SprtEt 1960 183.3 SLSC :0.038 1961 180.2 1962 132.9 1963 183.1 1964 222.3 1965 52.2 1966 116.2 1967 80.3 1968 91.6 1969 65.1 1970 158.8 1971 95.2 1973 103.2 1974 88.8 1975 134.0 1976 220.9 1977 149.6 1978 196.8 1979 111.1 1980 87.8 1981 68.8 1982 70.4 1983 65.9 1984 82.6 1985 334.0 1986 240.1 1987 101.3 1988 124.5 1989 84.6 1990 200.3 1991 91.2 1992 110.4 1993 60.9 1994 77.3 1995 95.1 1996 120.9 1998 97.7 2000 140.1 2001 67.4 2002 136.2 2003 117.8 2004 71.3 2005 81.8 2006 102.0 2007 90.0 2011 138.2 2013 222.3 Figure 3.3.5 Result of Probable Rainfall 2015 100.4 2016 88.2
3-40 CTI Engineering International Co., Ltd. Nippon Koei Co., Ltd. CTI Engineering Co., Ltd.
Data Collection Survey on Parañaque Spillway in Metro Manila Final Report in the Republic of the Philippines
3.4 Runoff and Inundation Analysis, and Laguna de Bay Water Level Fluctuation Analysis
In this study, as shown below, the runoff and hydrological analysis is conducted for two types of floods with different rainfall duration, catchment area and shape, and inundation characteristics.
Table 3.4.1 Characteristics and Target of Runoff and Hydrological Analysis No. Characteristics Target Flood caused by rising water level of Laguna de Bay, 1 Laguna de Bay which lasts several days to several months River flooding by the Laguna de Bay inflow rivers and Rivers flowing to Laguna de Bay, 2 inland flooding, which lasts several hours to one day Las Piñas-Parañaque District
3.4.1 Water Level Fluctuation Analysis of Laguna de Bay (Long-term Evaluation)
For flood events that accompany the rise of water level of Laguna de Bay, it is necessary to assess the impact of flood damage over several days to several months, and the inundation time after a long-term monsoon rain such as the 2012 flood (Local Name: Habagat). For the analysis of water level variation of Laguna de Bay, which requires a long-term study, the construction of the analysis model is conducted to analyze the water balance (the balance of inflow and outflow) flowing to Laguna de Bay, which has a large catchment area (2,380 km2).
2009 Marikina River Basin Mean Rainfall Water Level (Marikina River/Rosaio Weir) Water Level (Lake Laguna/Angono) Tide Level (Manila de bay/FortSantiago) 【Typhoon Ondoy 2009】 15 0 Water level rise of about 1 m in one day Max Water Level 13.85m at Typhoon (Ondoy: September 2009) 14 Water level rising of about 1m in 1-day 100 (4.Oct.2009) The water level equal to or over 12.5m Period of about 12.5m or more (130-days) lasted for 130 days or more. 13 200 The inundation damage caused by the rise Period of about 12.0m or more (170-days) of the Laguna de Bay water level continued several months.
12 300
Rainfall (mm) Rainfall Water Water Level(m)
11 400 Daily rainfall about 320mm (26.Sep.2009)
10 500 1 2 3 4 5 6 7 8 9 10 11 12 Month
2012 Marikina River Basin Mean Rainfall Water Level (Marikina River/Rosaio Weir) Water Level (Lake Laguna/Angono) Tidal Level (Manila bay/Fortsantiago) 【Monsoon Rainfall 2012】 15 0 Due to the influence of Monsoon rainfall in 2012, the water level raised slightly by 14 100 Water level rising of about 1m in 4-day Max Water Level 13.89m 2 m in about one month. Period of about 12.5m or more (110-days) (16.Aug.2012) The water level more than 12.5m lasted 13 200 for 110 days or more. Period of about 12.0m or more (140-days)
12 300
Rainfall (mm) Rainfall Water Water Level(m)
11 400
Daily rainfall about 264mm (6.Aug.2012) 10 500 1 2 3 4 5 6 7 8 9 10 11 12 Month
Figure 3.4.1 Laguna de Bay Water Level Fluctuation in 2009 and 2012
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Data Collection Survey on Parañaque Spillway in Metro Manila in the Republic of the Philippines Final Report
(1) Development of Laguna de Bay Water Level Fluctuation Analysis Model
The main inflow and outflow affecting the water level fluctuation of Laguna de Bay are as follows:
- Inflow from the Laguna de Bay Basin (surrounding basins) - Inflow from the Marikina River Basin to the Mangahan Floodway - Outflow from Laguna de Bay to Mangahan Floodway to the Marikina River - Direct rainfall to and evapotranspiration from the Laguna de Bay lake surface - Inflow and outflow from Laguna de Bay to the Napindan Channel to the Pasig River
For the inflow and outflow from the Mangahan Floodway, and the inflow and outflow from the Napindan Channel, the flow direction changes sequentially according to the relationship between the water level at the confluence of the Marikina-Pasig River and the water level of Laguna de Bay.
To express the long-term lake level fluctuation of Laguna de Bay, the Laguna de Bay Water Level Fluctuation Analysis Model was constructed as shown below. The water level variation analysis model consists of three hydrological and hydraulic models, including the runoff model, the river channel network model (flood tracking model) and the Laguna de Bay inundation model. The construction procedure is shown below.
1. Runoff Analysis (NAM Module)
・ Dividing the basin ・ Implementation of runoff calculation by the design rainfall ・ Setting of evaporation amount
2. River Channel Tracking Model (MIKE11) ・ Cross-section data (the Marikina River, the Pasig River the Mangahan Floodway, the Napindan Channel) ・ Setting of River Channel Roughness Coefficient ・ Setting of main river crossing structures
3. Laguna de Bay Water Level Fluctuation Model (MIKE11) Construction of H-A-V data in Laguna de Bay by using the topographic data in Laguna de Bay (NAMRIA) and ifSAR Data (5 m elevation data) Based on the analysis results of Steps 1 and 2, the water level fluctuation of Laguna de Bay by the inflow to the lake is examined. Also, the runoff amount to the Mangahan Floodway and the Napindan Channel by the water level fluctuation of Laguna de Bay is examined.
4. Laguna de Bay Inundation Model Based on the water level fluctuation obtained in Step 3, by the comparison of DEM and water level, the inundation area around Laguna de Bay by the Lake water level fluctuation is examined.
Figure 3.4.2 Procedure of Developing the Hydrological and Hydraulic Analysis Model
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[Inflow to Laguna de Bay]
∆푉 = 퐴(푃 − 퐸) + 푉퐼푁 + 푉푀,퐼푁 + 푉푁,퐼푁 − (푉푁,푂푈푇 + 푉푀,푂푈푇) Where, ∆푉 ＝ Change Capacity of Laguna de Bay 퐴 ＝ Surface Area of Laguna de Bay 푃 = Rainfall Amount of Laguna de Bay 퐸 ＝ Evapotranspiration from Laguna de Bay 푉퐼푁 ＝ Inflow from the Laguna de Bay Basin 푉푀,퐼푁 ＝ Inflow from the Mangahan Floodway 푉푁,퐼푁 ＝ Inflow from the Napindan Channel 푉푁,푂푈푇 ＝ Outflow of the Napindan Channel 푉푀,푂푈푇 ＝ Outflow from Mangahan Floodway The volume change and the surface area of Laguna de Bay are calculated by the H-A-V of Laguna de Bay prepared in this study. In addition, the evaporation amount from the Laguna de Bay is referred to the existing study. Estimation equations of evapotranspiration are shown below.
퐸 =∝1 퐸0 (P<0.5mm/day)
퐸 =∝1∝2 퐸0 (P>0.5mm/day)
Where, 퐸0：Pan Evaporation Amount, ∝1=0.6、∝2=0.5
Table 3.4.2 Monthly Average Pan Evaporation Amount in Los Baños (Unit：mm/day) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 4.28 5.70 6.72 7.90 7.31 5.66 4.66 4.50 4.48 4.38 4.19 3.80 Source：Detailed Engineering Design of the North Laguna Lakeshore urgent Flood Control and Drainage Project, 1992 DPWH
St.Nino ：Runoff Analysis Marikina （NAM Module）
：River Channel Tracking A=103km2 2 A=538km Model (MIKE11) Pasig ：Downstream Boundary
Tide Rosario Weir
Manila Bay
Napindan VM,IN VM,OUT Weir SB02-SB23 2 VN,IN VN,OUT A=2,380km VIN Laguna Lake Catchment P=Precipitation
E=Evaporation Laguna de Bay
Figure 3.4.3 Conceptual Diagram of Hydrological and Hydraulic Analysis Model
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(2) Runoff Analysis Model
For calculating the runoff amount from each basin, NAM (Nedbor-Afstromnings-Model) of DHI1 is employed. NAM is the tank-type centralized runoff model developed by the Technical University of Denmark. Runoff phenomena are expressed by using four tanks including surface runoff, intermediate flow, and groundwater flow. It is possible to analyze a short-term and long-term runoff phenomenon. The outline of NAM and the model parameters are shown in Figure 3.4.4. In addition, the parameters employed in the analysis are shown in Table 3.4.3.
For the runoff model used for the analysis of lake level fluctuation of Laguna de Bay, the basin was divided into three (the Marikina River basin, the Pasig River basin, and the Laguna de Bay basin).
Run-off Analysis Run-off parameters NAM: A lumped, conceptual rainfall-runoff model, Surface and root zone parameters
simulating the overland-, inter-flow, and base-flow Umax Maximum water content in surface storage components as a function of the moisture contents L Maximum water content in root zone storage in four storages. max CQOF Overland flow runoff coefficient CKIF Time constant for interflow Time constant for routing interflow and CK 12 overland flow TOF Root zone threshold value for overland flow TIF Root zone threshold value for interflow Groundwater parameters
CKBF Baseflow time constant Root zone threshold value for groundwater TG recharge
CQLOW Recharge to lower groundwater storage
CKLOW Time constant for routing lower baseflow Ratio of groundwater catchment to C area topographical catchment area Maximum groundwater depth causing GWL BF0 baseflow
Sy Specific yield
GWLFL1 Groundwater depth for unit capillary flux
Structure of NAM model
Figure 3.4.4 Outline of NAM Model and Explanation of Parameters
Table 3.4.3 List of Parameters Area No. Basin Umax Lmax CQOF CKIF CK1,2 TOF TIF km2 1 Laguna de Bay Basin 2,380 2 5 0.95 10 3 0.9 0 2 Marikina River Basin 538 2 5 0.95 10 3 0.9 0 3 Pasig River Basin 103 2 5 0.6 10 3 0.9 0
(3) River Channel Network Model
Since the rivers flowing in low-lying lands are affected by the confluence of tributaries and tide (backwater), for the discharge and water level calculation, one-dimensional unsteady flow model is employed which is capable of calculating the changes of water level and discharge over time for each section. The river channel network model is developed by using the MIKE11 of DHI. In addition, the Dynamic Wave Model is employed for the flood trucking calculation in this study.
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The concept of unsteady flow is shown in Figure 3.4.5, and the outline of the river channel network model is shown in Table 3.4.4.
Cloud
Peak Discharge Strong rainfall occurs Even if the flow rate / water level in the upstream reaches the peak, the downstream is still in the increasing period before the peak. The river flows toward the downstream while increasing the
volume. Discharge/Water Level Discharge/Water
Time
River flow reaches the sea When the flow rate / water level in the downstream reaches the peak, the upstream already passes the peak and
is in the reduction phase. Discharge/Water Level Discharge/Water
Time lagTime Sea 1) Flow rate, water level, and flow velocity of a river vary from moment to moment during a flood event. 2) Since it takes time for the river current to reach the downstream, the downstream hydrograph is different from the upstream. It is
particularly noticeable in rivers where the flow path is long and the gradient is gentle. Figure 3.4.5 Concept of Unsteady Flow
Table 3.4.4 Outline of River Channel Network Model Items Contents Hydraulic Model One-Dimensional Unsteady Flow Analysis (DHT-MIKE11 HD module) River Channel Network Refer to Figure 3.4.3 Marikina River： D/D Cross Section Survey in 2002 Pasig River： D/D Cross Section Survey in 2002 River Cross Section Mangahan Floodway：D/D Cross Section Survey in 2002 Napindan Channel：D/D Cross Section Survey in 2002 Structures Rosario Weir, Napindan Weir Laguna de Bay H-A-V Lake Based on the NAMRIA 2016 data, H-A-V is prepared. Every year (January 1 to December 31) Compilation Period ※ When calculating consecutive years, the calculation is conducted so that the conditions of December 31 of the previous year is set as the initial condition. Upstream end: Hydro calculated in the runoff model Boundary Condition Downstream end: average tide level: EL.10.47 m (M.S.L) Water Discharge Method: Pressure Tube Type/Design Discharge: 200 m3/s Floodway length; since the route is not confirmed, it is considered as 10km. Pipe Diameter: 12.0 m / Pipe Roughness Coefficient: 0.015 Parañaque Spillway Inflow Gate: 10.0 m × 3 sluice gates ※ Develop the pipeline model of pressure pipe type, and model the discharge control mechanism by gates at the inflow point. For detailed specifications, see “3.3.5, Review of Parañaque Spillway”
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Source：Mangahan Floodway Project Figure 3.4.6 Rosario Weir Cross Section
Source：Technical Report on Construction Supervision Napindan Hydraulic Control Structure Project Final Report in 1983 Figure 3.4.7 Napindan Weir Cross Section
Table 3.4.5 Tidal Level at Manila Bay
Source：The value is based on DPWH, The Study on Flood Control and Drainage System Improvement for the Kalookan-Malabon-Navotas- Valenzuela (KAMANAVA) Area, 1998
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(4) Calculation Cases
The calculation cases of the Laguna de Bay water level fluctuation analysis are summarized below. In addition, the calculation cases to examine the effectiveness of the Parañaque Spillway by each probability scale is shown in Table 3.4.7.
Table 3.4.6 List of Calculation Cases for Laguna de Bay Water Level Fluctuation Analysis Starting Target With or Without Case Classification Water Contents Year Parañaque Spillway Level ・ Parameter setting in the developed analysis model. Reproduction Case 1 2009 Without ― ・ Development of the reproduction Calculation model that matches the actual water level waveform of Laguna de Bay. ・ Verification of the parameters set in the Verification abovementioned case. Case 2 2012 Without ― Calculation ・ Comparison with the actual water level waveform of Laguna de Bay in 2012. ・ 12-year long-term reproduction Long-term calculation from 2002 to 2013. 2002- Case 3 Reproduction Without ― ・ Calculation to understand the 2013 Calculation effectiveness of the Parañaque Spillway over a long period. Case 4-1 With 11.5m ・ Understanding the effectiveness of the Case 4-2 With 12.0m Parañaque Spillway. Long-term 2002- ・ Understanding the effect of the water Prediction 2013 level reduction by the operation Case 4-3 Calculation With 12.5m starting water level of the Parañaque Spillway.
Table 3.4.7 Case by Probability Scale Parañaque Probability Year (Return Period) Case Spillway 2 3 5 10 20 30 50 100 Case-5 Without ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ Case-6 With ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔
(5) Model Validation by Past Flood Events
The verification of the water level fluctuation analysis model of Laguna de Bay is conducted based on two cases with different rainfall patterns including Typhoon Ondoy in 2009 and the monsoon rainfall in 201.2 The reproduction target year of the analysis model was set to 2009 which caused a massive flood damage, and the verification target year was set to 2012.
《Reproduction Target Year: 2009》
- The measured maximum lake water level of Laguna de Bay is 13.85 m, and the calculated water level is 13.75 m. The difference is 0.1 m. - In the latter half of September in 2009, the water level rises by about 1 m, and the phenomena is well reproduced.
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- Also, the water level reduction of Laguna de Bay after the flood event is well reproduced. - Throughout the year, it is considered that the developed analytical model can reproduce the water level fluctuations of Laguna de Bay well.
2009 WL(Calculated) WL(Observed) BMR(Lake Surface) BMR(Marikina River Basin) BMR(Lake Shore Area) 20.0 0
19.0 50
18.0 100
17.0 150 Ondoy 16.0 200
15.0 Maximum Water Level 250 14.0 Observed 13.85 m 300
Lake Surface Level (m) Level Surface Lake Calculated 13.75 m
13.0 350 Basin Mean Rainfall (mm) Rainfall Mean Basin 12.0 400
11.0 450
10.0 500 1 2 3 4 5 6 7 8 9 10 11 12 Figure 3.4.8 Case 1: Laguna de Bay Water Level Fluctuation in 2009 (Observation Value and Calculated Value)
《Reproduction Target Year: 2012》
- The measured maximum lake level of Laguna de Bay is 13.83 m, and the calculated water level is 13.77 m (0.06 m difference), which is a good representation of the peak lake level. - In addition, the water level reduction of Laguna de Bay after the flood is also reproduced well.
2012 WL(Calculated) WL(Observed) BMR(Lake Surface) BMR(Marikina River Basin) BMR(Lake Shore Area) 20.0 0
19.0 50
18.0 100
17.0 150
16.0 200
15.0 Maximum Water Level 250 14.0 Observed 13.83 m 300
Lake Surface Level (m) Level Surface Lake Calculated 13.77 m
13.0 350 Basin Mean Rainfall (mm) Rainfall Mean Basin 12.0 400
11.0 450
10.0 500 1 2 3 4 5 6 7 8 9 10 11 12 Figure 3.4.9 Case 2: Laguna de Bay Water Level Fluctuation in 2012 (Observation and Calculated Values)
As mentioned above, for the actual floods in 2009 and 2012, the water level fluctuation analysis model developed in this study was able to reproduce the behavior of the lake level in Laguna de Bay.
(6) Analysis of Factors and Trends of Lake Water Level Rise
Based on the calculation results of 2009, the factors of water level rise in Laguna de Bay are examined. The water level rise at the time of Typhoon Ondoy in 2009 is summarized below.
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◼ At the time of Typhoon Ondoy in 2009 (25 to 28 September 2009)
Since the calculated water level of 25 September 2009 is 12.70m (actual measurement: 12.77m) and the water level of 28 September is 13.84m (actual measurement: 13.81m), it is concluded that the water level rose by 1.14m. Based on the calculation results, the volume of inflow to and outflow from Laguna de Bay is summarized below.
[Breakdown of Inflow and Outflow of Laguna de Bay (Total Amount of 25 to 28 September 2009)] Ratio to Inflow V Inflow from the Laguna de Bay Basin VIN = 736.0 MCM (64.6%) Inflow from the Mangahan Floodway VM,IN = 181.0 MCM (15.9%) Inflow from the Napindan Channel VN,IN = 11.8 MCM (1.0%) Rainfall to the Laguna de Bay Lake Surface VR = 211.0 MCM (18.5%) Evapotranspiration from the Laguna de Bay Lake Surface VEVA = 4.7 MCM Outflow from the Napindan Channel VN,OUT = 53.8 MCM Outflow from the Mangahan Floodway VM,OUT = 8.4 MCM
Inflow Volume of Laguna de Bay = VIN + VM,IN + VN,IN + VR = 736.0+181.0+11.8+211.0 = 1,139.8 MCM
ΔV = VIN + VM,IN + VN,IN + VR －（VEVA + VN,OUT + VM,OUT ） = ,139.8 – 66.9 = 1,072.6 MCM - Inflow into Laguna de Bay is largely from the Laguna de Bay Basin (about 65%), and about 16% of inflow is from the Marikina River Basin. Therefore, it is considered that the rise in the water level of Laguna de Bay is affected by the inflow volume from the Laguna de Bay Basin. - In addition, in terms of the inflow rate to the Laguna de Bay lake surface, the rainfall amount to the lake surface of the Laguna de Bay is 18.5% which is larger than the inflow from the Marikina River Basin.
(7) Long-term Reproduction Calculation Results (2002 to 2013) - Case 3
To understand the effectiveness on the water level reduction by the construction of the Parañaque Spillway, the long-term reproduction calculation is performed. In the past 15 years, lake levels of more than 13.8 m were observed in 2009 and 2012.
To investigate the water level fluctuation of Laguna de Bay during the drought years, and also these two years (2009 and 2012), the long-term calculation targeted the years from 2002 to 2013 (until the year after the flood in 2012). The results map of the long-term reproduction calculation is shown in Figure 3.4.10.
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SML WL without PSW withoutSML WL
SML WL without PSW without SML WL
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2013/1
Observed
Observed
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Term Reproduction Calculation (2002 to 2012) to 2012) (2002 Calculation Reproduction Term
-
2005/1
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Laguna de Bay Lake Water Level Change Level Water Lake Bay de Laguna
3 3 Long of the Diagram Results
Case
10
.
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Figure
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Lake Surface Level (m) Level Surface Lake
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(8) Study on the Laguna de Bay Lake Water Level Lowering Effect due to Parañaque Spillway
The influence of Parañaque Spillway to the Laguna de Bay water level has been studied.
(a) Discharge Capacity
The discharge capacity of the Parañaque Spillway has been set at approximately 350 m3/s at a maximum in the previous studies in an open channel type. In order to propose the equivalent capacity with the pressure pipe type (underground tunnel type) which is proposed and described in Section 4.3 in detail, the inner diameter of the tunnel should be 15.0 m.
On the other hand, if the pressure pipe type (underground tunnel type) is applied, the construction cost is expected to be very high comparing to the open channel type. Taking it into consideration, the influence of Parañaque Spillway to the Laguna de Bay water level for the cases with the inner diameter of 15.0 m and 12.0 m were studied. Conditions of those study cases and the lowered highest water level due to the Parañaque Spillway were shown in Table 3.4.8 and Figure 3.4.11.
Table 3.4.8 Effects of Parañaque Spillway with Its Inner Diameters of 12.0 m and 15.0 m Pipe Maximum Highest Lake Inundated Period with the lake Case Diameter Discharge Water Level water level at 12.5 m or higher 14.3 m Case -0 - - 120 days (100-year return period) 13.9 m (-0.4 m) PSW_D12 12.0 m 200 m3/s (approximately equivalent 79 days (- 45 days) to 50-year return period) 13.7 m (-0.6 m) PSW_D15 15.0 m 370 m3/s (equivalent to 30-year 54 days (- 70 days) return period)
Water Level of Laguna and Out Flow Discharge From Paranaque Spillway Discharge of PSW_D12 Discharge of PSW_D12 Water Level of Laguna Case-0 Water Level of Laguna _PSW15 Operation Start Water Level Water Level of Laguna _PSW12 600 15
550 14 500 13 450 12 400
350 11
300 10
250 9 Surface Level (m) Level Surface Discharge (m3/s) Discharge 200 8 150 7 100
50 6
0 5 1 2 3 4 5 6 7 8 9 10 11 12
Figure 3.4.11 Effects of Parañaque Spillway with Its Inner Diameters of 12.0 m and 15.0 m
The construction costs for the two cases, with the diameter of 12.0 m and 15.0 m were roughly estimated and shown in Table 3.4.9.
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Table 3.4.9 Effects of Parañaque Spillway with Its Inner Diameters of 12.0 m and 15.0 m Estimated Annual Estimated Estimated Construction Average Damage EIRR Pipe Diameter Length of Cost Reduction Cost (Approximate Value) Spillway (million Peso) (million Peso) 12.0 m 10 km 35,000 to 50,000 3,200 7.3 to 9.1% 15.0 m 10 km 55,000 to 75,000 4,300 6.6 to 8.0%
As shown in Table 3.4.9, in case that the pipe inner diameter is 12.0 m, the construction cost is 35,000 to 50,000 million Peso. In case that the pipe inner diameter is 15.0 m, it is necessary to invest about 1.5 times, 55,000 to 75,000 million Peso. On the other hand, the benefit is about 1.3 times, resulting in a smaller EIRR for the pipe inner diameter of 15.0 m.
From the above, when adopting the pressure pipe system, the pipe inner diameter of 12.0 m is adopted.
(b) Operation Starting Water Level
It is effective on reduction of the flood damage at the Laguna de Bay Lakeshore area to start operation of the Parañaque Spillway and to conduct pre-discharge in reference to the target water level.
Frequency of the water level rise at Laguna de Bay is shown in Table 3.4.10.
Table 3.4.10 Frequency of the water level rise at Laguna de Bay (from 1946 to 2014) Laguna Lake Water Level (m) Number of Days above Water Level Year >10.0 >10.5 >11.0 >11.5 >12.0 >12.5 >13.0 >13.5 >14.0 Max. Min. Ave. m m m m m m m m m 1946 12.360 10.620 11.315 365 365 215 126 73 0 0 0 0 1947 12.360 10.600 11.428 366 366 256 193 69 0 0 0 0 1948 12.540 10.660 11.435 365 365 233 159 74 19 0 0 0 1949 11.700 10.500 11.061 365 365 195 55 0 0 0 0 0 1950 11.980 10.630 11.289 365 365 249 123 0 0 0 0 0 1951 12.150 10.660 11.316 366 366 244 151 30 0 0 0 0 1952 13.080 10.570 11.686 365 365 265 201 148 68 8 0 0 1953 12.280 10.740 11.476 365 365 310 179 55 0 0 0 0 1954 11.540 10.640 11.078 365 365 210 6 0 0 0 0 0 1955 11.710 10.500 10.977 366 366 157 21 0 0 0 0 0 1956 12.760 10.760 11.626 365 365 269 197 141 38 0 0 0 1957 11.870 10.560 11.082 365 365 189 75 0 0 0 0 0 1958 11.920 10.430 11.112 365 329 189 89 0 0 0 0 0 1959 11.540 10.350 10.904 366 283 186 9 0 0 0 0 0 1960 13.170 10.620 11.627 365 365 267 197 124 64 10 0 0 1961 12.290 10.500 11.341 365 365 238 143 73 0 0 0 0 1962 12.770 10.560 11.361 365 365 203 154 63 36 0 0 0 1963 12.240 10.480 11.096 366 362 179 81 37 0 0 0 0 1964 12.200 10.370 11.380 365 310 255 219 36 0 0 0 0 1965 11.760 10.630 11.095 365 365 203 40 0 0 0 0 0 1966 12.240 10.560 11.322 365 365 295 123 41 0 0 0 0 1967 12.870 10.470 11.268 366 361 211 133 37 3 0 0 0 1968 11.590 10.240 10.758 365 219 118 20 0 0 0 0 0 1969 11.190 10.170 10.694 365 236 84 0 0 0 0 0 0 1970 ------1971 ------1972 14.030 10.600 11.776 365 365 250 190 121 88 66 40 1 1973 12.080 10.580 11.212 365 365 232 108 25 0 0 0 0 1974 12.400 10.730 11.455 365 365 264 173 83 0 0 0 0 1975 11.670 10.620 11.019 366 366 201 25 0 0 0 0 0 1976 12.770 10.540 11.500 365 365 258 167 117 16 0 0 0 1977 12.030 10.360 11.000 365 289 173 87 7 0 0 0 0 1978 ------1979 ------1980 ------1981 ------
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Laguna Lake Water Level (m) Number of Days above Water Level Year >10.0 >10.5 >11.0 >11.5 >12.0 >12.5 >13.0 >13.5 >14.0 Max. Min. Ave. m m m m m m m m m 1982 12.130 10.450 11.125 335 314 212 77 9 0 0 0 0 1983 11.940 10.320 10.957 366 281 154 66 0 0 0 0 0 1984 12.670 10.320 11.164 365 287 176 127 44 16 0 0 0 1985 12.200 10.320 11.221 365 282 207 175 42 0 0 0 0 1986 13.340 10.190 11.689 365 317 242 210 151 93 50 0 0 1987 11.520 10.220 10.912 366 284 179 8 0 0 0 0 0 1988 13.550 10.520 11.479 365 365 294 104 76 48 24 5 0 1989 12.240 10.480 11.281 365 359 231 131 41 0 0 0 0 1990 12.670 10.410 11.470 364 318 258 173 109 20 0 0 0 1991 12.600 10.500 11.291 363 363 192 139 64 26 0 0 0 1992 12.390 10.460 11.248 365 346 202 137 80 0 0 0 0 1993 12.270 10.410 11.225 365 307 233 134 40 0 0 0 0 1994 12.200 10.636 11.326 365 365 235 134 30 0 0 0 0 1995 12.936 10.460 11.586 366 343 261 173 126 81 0 0 0 1996 12.098 10.686 11.332 365 365 214 160 12 0 0 0 0 1997 11.826 10.451 10.951 365 349 137 53 0 0 0 0 0 1998 12.716 10.437 11.398 365 321 198 164 106 30 0 0 0 1999 12.631 11.043 11.820 366 366 366 221 168 27 0 0 0 2000 13.391 10.953 11.936 365 365 352 254 163 71 35 0 0 2001 12.187 10.595 11.347 365 365 285 155 22 0 0 0 0 2002 12.550 10.482 11.398 365 354 211 173 105 5 0 0 0 2003 11.715 10.364 11.050 366 354 217 52 0 0 0 0 0 2004 11.854 10.409 11.035 365 320 190 54 0 0 0 0 0 2005 12.149 10.504 11.309 365 365 232 146 31 0 0 0 0 2006 12.305 10.701 11.377 365 365 237 172 27 0 0 0 0 2007 12.486 10.587 11.453 366 366 238 192 61 0 0 0 0 2008 12.088 10.932 11.590 365 365 344 225 24 0 0 0 0 2009 13.849 10.594 12.070 365 365 334 246 172 108 65 38 0 2010 11.701 10.518 11.191 365 365 261 72 0 0 0 0 0 2011 12.607 10.779 11.854 366 366 350 271 176 35 0 0 0 2012 13.893 11.080 12.028 365 365 365 211 144 114 75 27 0 2013 13.077 10.824 11.703 365 365 303 165 129 91 19 0 0 2014 12.444 10.670 11.395 331 331 233 170 38 0 0 0 0 Maximum 14.030 11.080 12.070 366 366 366 271 176 114 75 40 1 Minimum 11.190 10.170 10.694 331 219 84 0 0 0 0 0 0 Average 12.370 10.548 11.332 364 345 234 133 56 17 6 2 0 ① Count - - - 63 63 63 63 63 63 63 63 63 (year) ②Count >0 - - - 63 63 63 62 46 22 9 4 1 (year) ②／① - - - 100% 100% 100% 98% 73% 35% 14% 6% 2%
15
14
Operation Starting Water Level 13
12.5 m Lake Surface Level Level (m) Surface Lake 12.0 m 12 11.5 m
11
10
1945
1950
1955
1960
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
2015 2020 Year Source: JICA Survey Team Figure 3.4.12 Comparison of Laguna de Bay Lake Water Level and Operation Starting Water Levels
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As shown in Table 3.4.10 and Figure 3.4.12, the number of years with lake water level going up to EL 11.5 m is 62 (out of 63 years, 98%), the one to EL 12.0 m is 46 (73%) and at last, the one to EL 12.5 m is 22 (35%).
Referring to those results, the simulations of the lake water level with above mentioned three kinds of operation starting water levels. It should be noted that the inner diameter of the Parañaque Spillway was EL 12.0 m (the maximum discharge of 200 m3/s) for each simulation. The results are as follows.
i Operation Starting Water Level = EL 11.5 m (Case 4-1)
- Peak water level lowered by 0.74 m in 2009, and by 0.43 m in 12-year average. - The period that the water level was over EL 12.5 m in was dramatically shortened from 110 days to 39 days in 2009 when a relatively higher water level was recorded, from 108 days to 54 days in 2012, and from 62 days to 11 days in 2013. - In the case that operation starting water level is EL 11.5 m, the discharge to the Parañaque Spillway was conducted every year and the pre-discharge was carried out even in the year of relatively low rainfall (the lake water level is low). It tends to have the effect on large runoff of the following year.
Table3.4.11 Case 4-1: Long-term Prediction Calculation Results (Operation Starting Water Level: EL 11.5 m) Maximum Water level Days of more than 12.5m SML Year [1] [2] [3]=[1]-[2] [4] [5] [6]=[4]-[5] Observed WL without WL without With PSW Difference With PSW Days PSW PSW 2002 12.55 12.57 12.22 0.35 8 0 8 2003 11.72 11.64 11.54 0.10 0 0 0 2004 11.85 11.69 11.59 0.11 0 0 0 2005 12.15 12.12 11.94 0.18 0 0 0 2006 12.30 12.30 11.97 0.33 0 0 0 2007 12.49 12.47 11.92 0.55 0 0 0 2008 12.14 12.19 11.71 0.48 0 0 0 2009 13.85 13.84 13.10 0.74 110 39 71 2010 12.12 12.12 11.52 0.60 0 0 0 2011 12.65 12.65 11.93 0.72 17 0 17 2012 13.83 13.80 13.37 0.43 108 54 54 2013 13.01 13.11 12.59 0.52 62 11 51 Min 11.72 11.64 11.52 0.10 0 0 0 Ave 12.56 12.54 12.12 0.43 25 9 17 Max 13.85 13.84 13.37 0.74 110 54 71
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10
11
12
13
14
15
10.5
11.5
12.5
13.5
14.5
10.5
11.5
12.5
13.5
14.5
Figure
Lake Surface Level (m) Level Surface Lake
Lake Surface Level (m) Level Surface Lake
Paranaque Spill Way control level=11.5m control Way Spill Paranaque
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ii Operation Starting Water Level ＝ EL 12.0 m (Case 4-2)
- Peak water level lowered by 0.55 m in 2009, and by 0.24 m in 12-year average. - The period that the water level was over EL 12.5 m in was shortened from 110 days to 46 days in 2009, from 108 days to 63 days in 2012, and from 62 days to 15 days in 2013. - In the case that operation starting water level is EL 12.0 m, the discharge to the Parañaque Spillway was conducted 9 times for 12 years. Although the effect is lower than the one with EL 11.5 m, a certain effect was obtained especially in shortening the excessive water level period.
Table 3.4.12 Case 4-2: Long-term Prediction Calculation Results (Operation Starting Water Level: EL 12.0 m) Maximum Water level Days of more than 12.5m SML Year [1] [2] [3]=[1]-[2] [4] [5] [6]=[4]-[5] Observed WL without WL without With PSW Difference With PSW Days PSW PSW 2002 12.55 12.57 12.29 0.28 8 0 8 2003 11.72 11.64 11.64 0.00 0 0 0 2004 11.85 11.69 11.69 0.00 0 0 0 2005 12.15 12.12 12.03 0.10 0 0 0 2006 12.30 12.30 12.27 0.03 0 0 0 2007 12.49 12.47 12.33 0.14 0 0 0 2008 12.14 12.19 12.10 0.10 0 0 0 2009 13.85 13.84 13.29 0.55 110 46 64 2010 12.12 12.12 11.64 0.48 0 0 0 2011 12.65 12.65 12.22 0.43 17 0 17 2012 13.83 13.80 13.50 0.30 108 63 45 2013 13.01 13.11 12.66 0.45 62 15 47 Min 11.72 11.64 11.64 0.00 0 0 0 Ave 12.56 12.54 12.31 0.24 25 10 15 Max 13.85 13.84 13.50 0.55 110 63 64
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12.0m
Operation Water Level Water Operation
Operation Water Level Operation Water
2007/1
2013/1
With PSW With
With PSW With
SML WL without PSW without SML WL
SML WL without PSW without SML WL
2006/1
2012/1
Observed
Observed
2005/1
2011/1
2004/1
2010/1
term Prediction Calculation Results from 2002 to 2012 with Operation Starting level of EL EL of level Starting Operation with 2012 to 2002 from Results Calculation Prediction term
-
Long
2003/1
2009/1
2
-
2013/12/31
Case 4 Case
2007/12/31
～
～
14
.
3.4
2008/1/1 2008/1/1
2002/1/1 2002/1/1
2002/1
2008/1
10
11
12
13
14
15
10
11
12
13
14
15
10.5
11.5
12.5
13.5
14.5
10.5
11.5
12.5
13.5
14.5 Figure
Lake Surface Level (m) Level Surface Lake
Lake Surface Level (m) Level Surface Lake
Paranaque Spill Way control level=12.0m control Way Spill Paranaque
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iii Operation Starting Water Level ＝ 12.5m (Case 4-3)
- Peak water level lowered by 0.27 m in 2009, and by 0.11 m in 12-year average. - The period that the water level was over EL 12.5 m in was shortened from 110 days to 64 days in 2009, from 108 days to 67 days in 2012, and from 62 days to 30 days in 2013. - In the case that operation starting water level is EL 12.5 m, the discharge to the Parañaque Spillway was conducted 5 times for 12 years and the effect is lowest among the three cases. One of the reasons is that the operation frequency is low, and the effect of the pre-discharge is not appeared.
Table 3.4.13 Case 4-3: Long-term Prediction Calculation Results (Operation Starting Water Level: EL 12.5 m) Maximum Water level Days of more than 12.5m SML Year [1] [2] [3]=[1]-[2] [4] [5] [6]=[4]-[5] Observed WL without WL without With PSW Difference With PSW Days PSW PSW 2002 12.55 12.57 12.52 0.05 8 4 4 2003 11.72 11.64 11.64 0.00 0 0 0 2004 11.85 11.69 11.69 0.00 0 0 0 2005 12.15 12.12 12.12 0.00 0 0 0 2006 12.30 12.30 12.29 0.01 0 0 0 2007 12.49 12.47 12.47 0.00 0 0 0 2008 12.14 12.19 12.19 0.00 0 0 0 2009 13.85 13.84 13.57 0.27 110 64 46 2010 12.12 12.12 11.65 0.47 0 0 0 2011 12.65 12.65 12.50 0.15 17 2 15 2012 13.83 13.80 13.60 0.20 108 67 41 2013 13.01 13.11 12.91 0.21 62 30 32 Min 11.72 11.64 11.64 0.00 0 0 0 Ave 12.56 12.54 12.43 0.11 25 14 12 Max 13.85 13.84 13.60 0.47 110 67 46
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12.5m
Operation Water Level Water Operation
Operation Water Level Operation Water
2007/1
2013/1
With PSW With
With PSW With
SML WL without PSW without SML WL
SML WL without PSW without SML WL
2006/1
2012/1
Observed
Observed
2005/1
2011/1
2004/1
2010/1
term Prediction Calculation Results from 2002 to 2012 with Operation Starting level of EL EL of level Starting Operation with 2012 to 2002 from Results Calculation Prediction term
-
Long
2003/1
2009/1
3
-
2013/12/31
2007/12/31
Case 4 Case
～
～
15
.
3.4
2008/1/1 2008/1/1
2002/1/1 2002/1/1
2002/1
2008/1
10
11
12
13
14
15
10
11
12
13
14
15
10.5
11.5
12.5
13.5
14.5
10.5
11.5
12.5
13.5
14.5
Figure
Lake Surface Level (m) Level Surface Lake
Lake Surface Level (m) Level Surface Lake
Paranaque Spill Way control level=12.5m control Way Spill Paranaque
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Adoption of Operation Starting Water Level
Long-term recalculation results for 12 years (2002 to 2013) when the operation start water level is 11.5 m, 12.0 m, 12.5 m are summarized in Table 3.4.13 and Figure 3.4.16. Table 3.4.14 Influence on the number of days at which lake level is about 11.5 m or more by the start water level With PSW Operation With PSW Operation With PSW Operation Without PSW Maximum above 11.5m above 12.0m above 12.5m Year Water Level [1] [2] [3]=[2]/[1] [4] [5]=[4]/[1] [6] [7]=[6]/[1] Observed Days higher Days higher Days higher Days higher Reduction Difference Difference than 11.5m than 11.5m than 11.5m than 11.5m 2002 12.55 171 81 47% 156 91% 171 100% 2003 11.72 40 10 25% 39 98% 40 100% 2004 11.85 51 21 41% 51 100% 51 100% 2005 12.15 117 68 58% 117 100% 117 100% 2006 12.30 208 65 31% 183 88% 199 96% 2007 12.49 159 91 57% 159 100% 159 100% 2008 12.14 263 71 27% 232 88% 263 100% 2009 13.85 270 173 64% 259 96% 270 100% 2010 12.12 126 15 12% 76 60% 96 76% 2011 12.65 192 144 75% 192 100% 192 100% 2012 13.83 244 121 50% 155 64% 193 79% 2013 13.01 158 102 65% 122 77% 137 87% Min 11.72 40 10 12% 39 60% 40 76% Ave 12.56 167 80 46% 145 88% 157 95% Max 13.85 270 173 75% 259 100% 270 100%
120% With PSW Operation 100% above 12.5m
With PSW 80% Operation above 12.0m
With PSW 60% Operation above 11.5m
40% Reduction (Days higher than 11.5m) thanhigher (Days Reduction 20%
0% 2000 2002 2004 2006 2008 2010 2012 2014 Year
Figure 3.4.16 The number of days at which lake level is 11.5 m or more
As shown above, in the case without Parañaque Spillway, the number of days at which lake level is 11.5 m or more is 167 days, and when operation lake level of the Parañaque Spillway is 11.5 m, the number of days is 80 days (46%), 12.0 m is 145 days (88%) and 12.5 m is 157 days (95%). In this way, when operation start water level is set to 11.5 m, the period for maintaining the annual average lake level is less than half. Laguna de Bay is also widely used for water intake purposes such as raw water intake for Maynilad water purification plant, fishery, water transport, so when the period of maintaining the annual average lake level or higher is less than half, there is a danger of affecting the use of these water use purposes. According to this study, if operation level is 12.0 m, there is a sufficient effect of reducing the flooding damage of Parañaque Spillway and does not significantly affect the period of maintaining the lake level of 11.5 m or more. As a conclusion, the following study will be conducted with the operation starting water level of EL 12.0 m.
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(9) Analysis of Water Level Fluctuation by Probability Scale
(a) Calculation Cases
To examine the effectiveness of the Parañaque Spillway by probability scale, following calculation cases were performed.
Table 3.4.15 Cases by Probability Scale (Previously Shown) Parañaque Probability Case Spillway 2-year 3-year 5-year 10-year 20-year 30-year 50-year 100-year Case-5 Without ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ Case-6 With ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔
(b) Calculation Conditions
Calculation conditions in the water level fluctuation analysis by probability scale are summarized below.
Table 3.4.16 Calculation Conditions for Water Level Fluctuation by Probability Scale
Items Setting Value Basis
Operation Starting Water 12.0m • Based on the calculation results that set the operation starting water level of three patterns in 3.4.1(8), the case with 12.0 m Level of Parañaque was adopted because it has the effect in water level reduction and less influence even in drought years. Spillway
Design Water Level Actual water • The design water level waveform is set based on the policy specified in 3.1.1(6). Waveform level • Based on the calculation results in 3.4.1(8) with the operation waveform in starting water level of 12.0m, the water level lowering effect in 2009 and 2012 was confirmed. 2012 Parañaque Spillway Water Level Year Without With Reduction 2009 13.84m 13.29m 0.55m 2012 13.80m 13.50m 0.30m • As mentioned above, the waveform of 2012 has less water level reduction effect by the Parañaque Spillway. In considering the effect by the probability scale, the safety review was conducted by adopting the 2012 water level waveform.
Calculation Period One year • As shown in Figure 3.1.7, the correlation between the yearly maximum water level of Laguna de Bay and the basin averaged rainfall per rainfall duration is not good. Therefore, in the Laguna de Bay Flood Control Plant, it is difficult to set the design rainfall duration used in the ordinary river flood control plan. • Therefore, the calculation period is set as one year and the water level fluctuation throughout the year is examined and evaluated.
Water Level Waveform of ― • The water level waveform by probability scale is prepared by trail calculations of the rainfall amount to Laguna de Bay Basin, Probability Scale the Marikina River Basin and the Laguna de Bay lake surface in order to match the probability water level in Laguna de Bay.
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(c) Analysis Results of Water Level Fluctuation by Probability Scale
The results of the water level fluctuation analysis by probability scale are summarized inTable 3.4.17. The calculation results by probability scale are shown in Figure 3.4.17-1 to Figure 3.4.17-8.
- The water level of the 100-year probability scale is 14.3 m without the Parañaque Spillway (Present Condition), whereas it is 13.9 m with the Parañaque Spillway, and the water level lowering effect of 40 cm is confirmed. - The 3 to 5-year probability scale has 10 cm reduction, the 10 to 20-year probability scale is 20 cm reduction and the 30 to 50-year probability scale has 30 cm water level reduction effect. - As mentioned in 3.4.1(8), for the case with the Parañaque Spillway, since the preliminary discharge is started before a major flood events, there is a possibility that it may be lower than the predicted maximum water level calculated by the probability scale calculation.
Table 3.4.17 Outline of the Maximum Water Level of Laguna de Bay by Probability Scale (Operation Start Water Level: 12.0m)
Case-5 Case-6 Lake Water Level Probability Without PSW*1 With PSW*1 Decline ( m) 100 14.3 13.9 0.4 50 14.0 13.7 0.3 30 13.7 13.4 0.3 20 13.6 13.4 0.2 10 13.2 13.0 0.2 5 12.9 12.8 0.1 3 12.6 12.5 0.1 2 12.3 12.3 0.0 *1 PSW: Parañaque Spillway
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SML WL_without PSW SML WL_with PSW 2012 model WL_100y Operation level BMR(Marikina River Basin) BMR(Lake Surface) BMR(Lake Shore Area) 15.5 0
15.0
14.5
14.0
13.5
13.0
12.5 Lake Lake Level Surface (m) 12.0 BasinMean(mm) Rainfall
11.5
11.0
10.5 1 2 3 4 5 6 7 8 9 10 11 12 Month
2012 model WL_100y SML WL_without PSW SML WL_with PSW PWS_Discharge(m3/s)
15.0 350
14.0 300
13.0 250
12.0 200
11.0 150 Discharge (m3/s) Discharge
Lake Lake SurfaceLevel (m) 10.0 100
9.0 50
8.0 0 1 2 3 4 5 6 7 8 9 10 11 12 Month Figure 3.4.17-1 100-year Probability, Analysis Results of Water Level Fluctuation (1/8)
SML WL_without PSW SML WL_with PSW 2012 model WL_50y Operation level BMR(Marikina River Basin) BMR(Lake Surface) BMR(Lake Shore Area) 15.5 0
15.0
14.5
14.0
13.5
13.0
12.5 Lake Lake Level Surface (m) 12.0 Mean(mm) BasinRainfall
11.5
11.0
10.5 1 2 3 4 5 6 7 8 9 10 11 12 Month
2012 model WL_50y SML WL_without PSW SML WL_with PSW PWS_Discharge(m3/s)
15.0 350
14.0 300
13.0 250
12.0 200
11.0 150 Discharge (m3/s)Discharge
Lake Lake Level Surface (m) 10.0 100
9.0 50
8.0 0 1 2 3 4 5 6 7 8 9 10 11 12 Month Figure 3.4.17-2 50-year Probability, Analysis Results of Water Level Fluctuation (2/8)
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SML WL_without PSW SML WL_with PSW 2012 model WL_30y Operation level BMR(Marikina River Basin) BMR(Lake Surface) BMR(Lake Shore Area) 15.5 0
15.0
14.5
14.0
13.5
13.0
12.5 Lake Level Lake Surface (m) 12.0 Mean(mm) BasinRainfall
11.5
11.0
10.5 1 2 3 4 5 6 7 8 9 10 11 12 Month
2012 model WL_30y SML WL_without PSW SML WL_with PSW PWS_Discharge(m3/s)
15.0 350
14.0 300
13.0 250
12.0 200
11.0 150 Discharge (m3/s)Discharge
Lake Level Lake Surface (m) 10.0 100
9.0 50
8.0 0 1 2 3 4 5 6 7 8 9 10 11 12 Month Figure 3.4.17-3 30-year Probability, Analysis Results of Water Level Fluctuation (3/8)
SML WL_without PSW SML WL_with PSW 2012 model WL_20y Operation level BMR(Marikina River Basin) BMR(Lake Surface) BMR(Lake Shore Area) 15.5 0
15.0
14.5
14.0
13.5
13.0
12.5 Lake Level Lake Surface (m) 12.0 Mean(mm) BasinRainfall
11.5
11.0
10.5 1 2 3 4 5 6 7 8 9 10 11 12 Month
2012 model WL_20y SML WL_without PSW SML WL_with PSW PWS_Discharge(m3/s)
15.0 350
14.0 300
13.0 250
12.0 200
11.0 150 Discharge (m3/s)Discharge
Lake Level Lake Surface (m) 10.0 100
9.0 50
8.0 0 1 2 3 4 5 6 7 8 9 10 11 12 Month Figure 3.4.17-4 20-year Probability, Analysis Results of Water Level Fluctuation (4/8)
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SML WL_without PSW SML WL_with PSW 2012 model WL_10y Operation level BMR(Marikina River Basin) BMR(Lake Surface) BMR(Lake Shore Area) 15.5 0
15.0
14.5
14.0
13.5
13.0
12.5 Lake Level Lake Surface (m) 12.0 Mean(mm) BasinRainfall
11.5
11.0
10.5 1 2 3 4 5 6 7 8 9 10 11 12 Month
2012 model WL_10y SML WL_without PSW SML WL_with PSW PWS_Discharge(m3/s)
15.0 350
14.0 300
13.0 250
12.0 200
11.0 150 Discharge (m3/s)Discharge
Lake Level Lake Surface (m) 10.0 100
9.0 50
8.0 0 1 2 3 4 5 6 7 8 9 10 11 12 Month Figure 3.4.17-5 10-year Probability, Analysis Results of Water Level Fluctuation (5/8)
SML WL_without PSW SML WL_with PSW 2012 model WL_5y Operation level BMR(Marikina River Basin) BMR(Lake Surface) BMR(Lake Shore Area) 15.5 0
15.0
14.5
14.0
13.5
13.0
12.5 Lake Level Lake Surface (m) 12.0 (mm) MeanBasinRainfall
11.5
11.0
10.5 1 2 3 4 5 6 7 8 9 10 11 12 Month
2012 model WL_5y SML WL_without PSW SML WL_with PSW PWS_Discharge(m3/s)
15.0 350
14.0 300
13.0 250
12.0 200
11.0 150 Discharge (m3/s)Discharge
Lake Level Lake Surface (m) 10.0 100
9.0 50
8.0 0 1 2 3 4 5 6 7 8 9 10 11 12 Month Figure 3.4.17-6 5-year Probability, Analysis Results of Water Level Fluctuation (6/8)
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SML WL_without PSW SML WL_with PSW 2012 model WL_3y Operation level BMR(Marikina River Basin) BMR(Lake Surface) BMR(Lake Shore Area) 15.5 0
15.0
14.5
14.0
13.5
13.0
12.5 Lake Level Lake Surface (m) 12.0 BasinMean(mm) Rainfall
11.5
11.0
10.5 1 2 3 4 5 6 7 8 9 10 11 12 Month
2012 model WL_3y SML WL_without PSW SML WL_with PSW PWS_Discharge(m3/s)
15.0 350
14.0 300
13.0 250
12.0 200
11.0 150 Discharge (m3/s) Discharge
Lake Lake Level Surface (m) 10.0 100
9.0 50
8.0 0 1 2 3 4 5 6 7 8 9 10 11 12 Month Figure 3.4.17-7 3-year Probability, Analysis Results of Water Level Fluctuation (7/8)
SML WL_without PSW SML WL_with PSW 2012 model WL_2y Operation level BMR(Marikina River Basin) BMR(Lake Surface) BMR(Lake Shore Area) 15.5 0
15.0
14.5
14.0
13.5
13.0
12.5 Lake Level Lake Surface (m) 12.0 Mean(mm) BasinRainfall
11.5
11.0
10.5 1 2 3 4 5 6 7 8 9 10 11 12 Month
2012 model WL_2y SML WL_without PSW SML WL_with PSW PWS_Discharge(m3/s)
15.0 350
14.0 300
13.0 250
12.0 200
11.0 150 Discharge (m3/s)Discharge
Lake Level Lake Surface (m) 10.0 100
9.0 50
8.0 0 1 2 3 4 5 6 7 8 9 10 11 12 Month Figure 3.4.17-8 2-year Probability, Analysis Results of Water Level Fluctuation (8/8)
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3.4.2 Effects of climate change (1) Study Case
The change of occurrence probability of design rainfall was examined caused by climate change. The change of future rainfall in survey area was estimated based on the result of Regional Climate Model (RCM) by PAGASA. The outline of Climate Change Simulation is shown in below. Table 3.4.18 Outline of Climate Change Simulation Items Contents Climate Change Simulation Regional Climate Model（RCM） Organization PAGASA Target Region Cavite, Laguna, Quezon, Rizal, NCR Resolution of Grid 25km Scenario of Climate Change A1B Scenario Rainfall prediction year 1985（1971～2000）,2020（2006～2035）,2050（2036～2065） Source: JICA survey team
Based on the prediction results of the Regional Climate Model (RCM) above, the effect of two cases of rainfall change at Lake water level was investigated. Based on Regional Climate Model (RCM) 3- month rainfall prediction results, Table 3.4.20 shows organized by province included in this survey area and Table 3.4.21 shows the rate of change of 3-month rainfall calculated from area weighted average of the survey target area, based on the prediction result of the rain rate change by RCM. The rain rate change within the red frame in the table was used in the following two cases.
Table 3.4.19 Study Cases on the impact assessment of Laguna lake level due to climate change 3-month rain rate change used in this Period survey Case Contents (Month) Future Future (2006～2035) (2036～2065) 1 Regional Climate Model (RCM) with PAGASA 6~8 7.2% increase 15.1% increase consideration of 3-month rainfall change rate from June to August. 2 Regional Climate Model (RCM) with PAGASA 12~2 17.3% decrease 6.3% decrease implementation Considering the rain rate change for full 3~5 17.3% decrease 36.1% decrease year 6~8 7.2% increase 15.1% increase 9~11 1.3% increase 0.7% increase ⚫ Rainfall is expected to increase in the future, while December to May is a prediction that the rainfall will be lower than the present situation in June and November. ⚫ The average of rain rate change for fully year is predicted to decrease by 9.9% in the future from 2006 to 3025, and 6.7% in the future from 2036 to 2065. Although annual rainfall decreases than present, rainfall in June to November increases. Table 3.4.20 Predicted Result of 3-month rain change rate by RCM
Present Condition 1971-2000 Future 2006-2035 Future 2036-2065 Month Rainfall (mm) Rate of Rainfall change (%) Rainfall (mm) Rate of Rainfall change (%) Cavite Laguna Quezon Rizal NCR Cavite Laguna Quezon Rizal NCR Average Cavite Laguna Quezon Rizal NCR Cavite Laguna Quezon Rizal NCR Average 12~2 124.9 62.92 827.7 262.4 107.5 -26.1 -20.2 -6.5 -13.1 -12.8 -15.74 92.3 50.2 773.9 228.0 93.7 -19.1 0.1 6.6 -11.5 -17.3 -8.24 3~5 242.8 386.8 382.7 241.5 198.5 -28.2 -31.5 -18.6 -30.7 -33.3 -28.46 174.3 265.0 311.5 167.4 132.4 -30.5 -34.8 -20.6 -39.8 -38.5 -32.84 6~8 985.7 845 670 1001.3 1170.2 13.1 2.9 2.9 12.4 8.5 7.96 1,114.8 869.5 689.4 1,125.5 1,269.7 24.2 6.8 6.5 24.8 21.3 16.72 9~11 597 1065.5 1229.3 821.8 758.7 0.4 2.9 5.2 -0.9 0 1.52 599.4 1,096.4 1,293.2 814.4 758.7 5.9 0.4 0.9 -0.8 3.7 2.02 Source: JICA Survey Team compiled province regarding to this survey using PAGASA HP information （https://www1.pagasa.dost.gov.ph/index.php/93-cad1/472-climate-projections#climate-projections-for-provinces）
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Table 3.4.21 Area Weighted Average of Relevant Province
Future 2006-2035 Future 2036-2065 Month Rate of Rainfall change (%)_Weighted average Rate of Rainfall change (%)_Weighted average Cavite Laguna Quezon Rizal NCR Total Cavite Laguna Quezon Rizal NCR Total 12~2 -1.8 -10.0 -0.2 -4.3 -1.0 -17.3 -1.3 0.0 0.2 -3.8 -1.4 -6.3 3~5 -1.9 -15.6 -0.5 -10.2 -2.7 -30.8 -2.1 -17.2 -0.5 -13.2 -3.1 -36.1 6~8 0.9 1.4 0.1 4.1 0.7 7.2 1.6 3.4 0.2 8.2 1.7 15.1 9~11 0.0 1.4 0.1 -0.3 0.0 1.3 0.4 0.2 0.0 -0.3 0.3 0.7 Average -0.7 -5.7 -0.1 -2.7 -0.8 -9.9 -0.3 -3.4 -0.0 -2.3 -0.6 -6.7
(2) Water Level Fluctuation Analysis of Laguna de Bay Considering Climate Change
It calculated Basin Mean Rainfall (BMR) in the future Laguna lake basin using 3-month rainfall rate change in this surveyed area calculated in the previous section and examined influence on the Laguna lake level.
Regarding influence of lake water level, as a case where peak water level is high, the lake water level change was examined by probability scale of case 1, and for case 2 using rain rate change for fully year, Only the influence of lake water level in the 100-year probability scale was examined
As the rainfall in the dry season decreases, lake water level before flooding season is decreased.
When using the change rate for fully year (case-2), lake water level in dry season will be lower, so peak lake water level will be evaluated lower than Case 1 that only considers dry season.
Figure 3.4.18 Result of Lake Water Level Change in Case-1 and Case-2 (100-year)
(3) Impact of Climate Change on Laguna Lake Water level
Table 3.4.22 shows the change of lake water level by probability scale in Case 1 (rainy season: rain rate change rate considered only from June to August). ⚫ While the current 100-year return period level is 14.3 m, the predicted lake water level in the future (~ 2035) will be 14.6 m and a 30cm water level rise is assumed. ⚫ In addition, the predicted lake water level in the future from 2036 to 2065 will be 14.9 m, and a water level rise of 60 cm will be assumed
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Table 3.4.22 Changes of Lake Water Level Considering Climate Change (Case-1)
100
10 Return Period Return
Existing Condition Future -2035 Future 2050(2036-2065)
1 12.0 12.5 13.0 13.5 14.0 14.5 15.0 15.5 Laguna Lake Surface Level (m)
Figure 3.4.19 Change of Lake Water Level by Probability Scale
Table 3.4.23 Changes of Lake Water Level Considering Climate Change (Case-2) Return Existing Future~2035 Future 2050(2036-2065) Period Condition Water Level (m) Water Level (m) Difference (m) Water Level (m) Difference (m) 100 14.3 14.5 0.2 14.8 0.5
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3.4.3 Runoff/Inundation Analysis in the Laguna de Bay Basin (Short-term Analysis)
(1) Target Basin
In the Laguna de Bay Basin (SB-03～SB-23), the Kalayaan Pumped Storage Power Plant owned by CBK Power Company Limited is located in the Caliraya Basin (SB-12).
The Kalayaan Pumped Storage Plant was competed in 1982, and pumping of water I from the Caliraya Reservoir as the upper pond and Laguna de Bay as the lower pond. The Lumot Reservoir is located in the south side of the Kalayaan Reservoir, and these two reservoirs are connected by a tunnel of 6 m in diameter. The excess water of the Lumot Reservoir flows into the Caliraya Reservoir by the water level difference. The storage capacity of both reservoirs is 44,000,000 m3 where most of the rainfall flowing into the SB-12 Basin is stored. For this reason, a flood control measure is not necessary for the SB-12 Basin. Therefore, it is excluded from the study scope of the flood control measure.
Source：CBK brochure Figure 3.4.20 Outline of Kalayaan Pumped Storage Power Plant
The evaluation on countermeasures against floods in the Laguna de Bay Basin targets twenty (20) river basins (excluding the Caliraya Basin (SB-12)). The scope of the evaluation is shown in Figure 3.4.21.
Table 3.4.24 Target Basin of RRI Model Basin-ID Namge Area (km2) Basin-ID Namge Area (km2) SB-03 Angono 86.6 SB-14 Sta.Cruz 146.7 SB-04 Morong 95.9 SB-15 Pila 89.3 SB-05 Baras 21.7 SB-16 Calauan 154.5 SB-06 Tanay 52.2 SB-17 Los Baños 102.1 SB-07 Pililla 40.4 SB-18 San Juan 191.7 SB-08 Jala-jala 70.6 SB-19 San Cristobal 140.6 SB-09 Sta. Maria 202.2 SB-20 Sta.Rosa 119.8 SB-10 Siniloan 71.7 SB-21 Binan 84.8 SB-11 Pangil 50.1 SB-22 San Pedro 46.0 SB-13 Pagsanjan 301.2 SB-23 Muntinlupa 44.1
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：Watershed where RRI model was constructed
Source: JICA Survey Team created based on Google Earth Figure 3.4.21 Scope of Runoff/Inundation Analysis in the Laguna de Bay Basin
(2) Development of the Analysis Model
The runoff-inundation analysis is conducted to briefly review the type, scale and effect of the flood countermeasure plan in the Laguna de Bay Basin. In the runoff-inundation analysis, it is necessary to consider the following points:
- Since most of the Laguna de Bay Basin flows from the mountainous area to Laguna de Bay through
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the lowland area, it is necessary to properly express flood runoff from the mountainous rivers to the lowland area. - It is possible to analyze the flooding phenomenon during flood events even in rivers where no cross-section data is available and also when there is a lack of hydrological observation data (rainfall, water level and discharge) and topographical information.
By considering the above requirements, this study employed the Rainfall Runoff Inundation Model (RRI Model) developed and maintained by the International Centre for Water Hazard and Risk Management (ICHARM) of Japan.
The RRI Model is a distributed model that integrally analyzes river runoff to inundation rainfall by using rainfall as input. By analyzing the rainfall runoff and the inundation phenomenon on the same two-dimensional computation grid, it is possible to express the runoff inundation phenomenon in the lowland which is difficult to reproduce by a general distributed runoff model. For mountainous regions with valley plain, it is possible to analyze with high calculation accuracy by appropriately setting the calculation grid size.
However, due to the characteristics of the RRI Model that analyzes the cross-section shape of the river as rectangle, there are cases that the detailed water level in the river channel and the detailed necessary river cross section shape after the channel improvement may not be properly evaluated. In this study, the type and scale of the flood control measure plan for Laguna de Bay is generally investigated. Therefore, it is considered that there is no particular problem in the outline study.
Rainfall Ruoff Inundation Model：Outline of RRI Model
- The RRI model is the distributed runoff calculation model which is capable of river channel tracking calculation and the inundation analysis. At least it requires two information such as the DEM data (elevation) and the flow direction of river to express the basin, hence it is possible to develop the runoff inundation analysis model. - The RRI Model is a distributed model which integrally analyzes river runoff to inundation by using rainfall as an input data. By analyzing the rainfall runoff and the inundation phenomenon on the same two-dimensional computation grid, it is possible to express the runoff inundation phenomenon in the lowland that is difficult to reproduce by a general distributed runoff model. For the mountainous region with the valley plain, it is possible to analyze with high calculation accuracy by appropriately setting the calculation grid size. - Since hydrological observation data (water level, rainfall, discharge) and topographical information are insufficient in the Laguna de Bay Basin, the analytical model was developed by utilizing the global data (satellite elevation data and land cover data, etc.).
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Give rain to each grid and perform runoff analysis in units of grids. Surface runoff components are expressed as flooding. Section characteristics are given to the grid corresponding to river way, and river channel tracking calculation is performed.
It is possible to calculate inland flooding because give rain to each grid.
Laguna de Bay Figure 3.4.22 Conceptual Diagram of Runoff/Inundation Analysis Using RRI Model
The runoff-inundation analysis model is developed from the RRI Model. Various conditions for the runoff-inundation analysis is shown in the table below, and various setting conditions are shown in Table 3.4..
Table 3.4.25 Conditions of Runoff/Inundation Analysis Items Contents Runoff from river basin The basin average rainfall is estimated at each basin and given as the input data for the calculation. Water level at the downstream end of the Water Level of Laguna de Bay ＝ 14.0 m basin The calculation grid is set based on the basin area coverage. The calculation time becomes longer when the number of calculation mesh becomes large, so that the calculation grid size is set by Flood plain calculation confirming the computation time. The calculation grid size used in the study is as below. grid size SB-03～04, SB-08～23: 100m×100m SB-05～07: 25m×25m Flood plain elevation The flood plain elevation data is prepared by using ifSAR (5m elevation data). data Automatic estimation by RRI Model (estimated from the relational formula of catchment area, river River channel cross width and depth) is conducted. Then, the estimated value is adjusted based on the field survey section data results or aerial photographs. From the field survey results, the value is set within the range that can be confirmed. Land use data Land cover is prepared based on Landsat2017 Satellite data Land cover and Soil data MODIS data 2008: Utilizing the global land cover information of 500m pitch as of 2008 After checking the condition of river channel by using collected pictures, it is set by referring to River channel roughness Table 3.4.26 Protected inland With reference to the past literature (Technical Criteria for River Works: Practical Guide for Survey roughness (Draft)), the values are set by taking into consideration the land cover situation in the basin Permeability Coefficient Based on the past literature (Table 3.4.), utilizing the standard values of above-mentioned soil data.
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Relational Expression of Basin Area, River Width and River Depth
As shown in the Table above, the RRI model assumes the cross-section shape of river channel to be a rectangular and estimates based on the empirical formula as shown below. The relation between the runoff contribution catchment area A (km2), river width W (m), and depth D (m) of the target point is expressed by the following equations (1) and (2).
W = C ASW w ・・・（1）
SD D = CD A ・・・（2）
Here, CW, SW, CD, and SD are parameters which are defined according to the characteristics of the target river channel. In this study, based on the field survey results and aerial photos (such as Google Earth, etc.) that can be collected from the internet, these parameters are set by checking the river width of the target river basin. Table 3.4.26 Manning Roughness Coefficient Description Minimum Maximum 1. Some grass & weeds, little or no brush 0.028 0.033 2. Dense growth of weeds, flow depth greater weed height 0.033 0.030 3. Some weeds, light brush on banks 0.035 0.050 4. Some weeds, heavy brush on banks 0.050 0.070 5. Some weeds, dense trees 0.060 0.080 channel, with branches submerged at high flood increase all above values by 0.010 0.020 6. Winding, some pools & shoals, clean (1.) 0.035 0.045 7. Winding, some pools & shoals, clean, lower stages,more ineffective sections 0.045 0.055 8. Winding, some pools & shoals, clean, some weeds &stones (3.) 0.040 0.050 9. Winding, some pools & shoals, clean, lower stages,more ineffective sections, stony sections 0.050 0.060 10. Sluggish river reaches, rather weedy or with deep pools (4.) 0.060 0.080 11. Very weedy reaches (5.) 0.100 0.150 Source: DPWH Design Guideline, Criteria and Standards (DGCS) 2015 Table 3.4.27 Roughness Coefficient and Condition of River Basin Roughness Coefficient Condition of River basin （m-1/3 s） The hilly area where the housing land development was made in the stair shape 0.05 The hilly area includes the housing land in a part of the river basin (15%). 0.1 – 0.2 The stair-shaped field main river basin 0.2 – 0.4 The stair-shaped field main basin where the upstream mountains and the middle and lower basin which 0.3 – 0.5 include the city Mountain basin where the forest physiognomy is very good. 0.4 – 0.8 River basin where the upstream hilly area is 50%, the city in the middle basin is 20%, the downstream 0.6 – 1.1 low-lying area paddy is 30% The paddy field without drainage improvement was made 1 – 3 Source: Technical Criteria for River Works: Practical Guide for Survey, MLIT (Japan’s Ministry of Land, Infrastructure, Transport and Tourism) Table 3.4.28 Parameter for Different Soil Textures Reference Table: Green-Ampt Infiltration Parameters for Different Soil Textures Soil Texture Class Ksv (m/s) φ Sf (m) Sand 6.54 x 10-5 0.437 0.0495 Loamy Sand 1.66 x 10-5 0.437 0.0613 Sandy Loam 6.06 x 10-6 0.453 0.1101 Loam 3.67 x 10-6 0.463 0.0889 Silt Loam 1.89 x 10-6 0.501 0.1668 Sandy Clay Loam 8.33 x 10-7 0.398 0.2185 Clay Loam 5.56 x 10-7 0.464 0.2088 Silty Clay Loam 5.56 x 10-7 0.471 0.2730 Sandy Clay 3.33 x 10-7 0.430 0.2390 Silty Clay 2.78 x 10-7 0.479 0.2922 Clay 1.67 x 10-7 0.475 0.3163 Source: Handbook of Hydrology
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Source: JICA Survey Team created using ifSAR 5m Elevation data (NAMRIA) Figure 3.4.23 Topographic conditions in Laguna de Bay Basin
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Figure 3.4.24 River Stream Lines in RRI Modelling
(3) Rainfall Duration
The rainfall duration of the Laguna de Bay Basin is one day as shown in 3.1.1(4). Design Rainfall Duration
(4) Design Hyetograph
For the design hyetograph used in the runoff inundation analysis of the Laguna de Bay Basin, the hourly rainfall during Typhoon Ondoy in 2009 was observed at Science Garden Station in the Pasig-Marikina River Basin. In the Laguna de Bay Basin, the hourly rainfall data at the time of flood event was not measured. Therefore, the model hyetograph was prepared by extending or tightening suing the actual hourly hyetograph at the Science Garden so that it becomes daily rainfall by the probability scale.
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100 100 year 90 Science Garden observed Rainfall data 80
70
60
50
40 Rainfall (mm/h) Rainfall 30
20
10
0 8 9 1011121314151617181920212223 0 1 2 3 4 5 6 7 8 9 1011121314151617181920212223 0 1 2 3 4 5 6 7 8 2009/9/25 2009/9/26 2009/9/27 Time (hr)
Source: JICA Survey Team Figure 3.4.25 Design Hyetograph, Sample SB-03, 100-year Design Hyetograph
(5) Model Validation by Past Flood Events
Confirmation of the validity of the runoff-inundation model by RRI model is performed with the parameter setting based on the inundated area in Typhoon Ondoy 2009 and the calculated discharge in the past study (WB project), because there is no observation result of river water level and discharge in the Laguna de Bay Basin.
Source: Master Plan for Flood Management in Metro Manila and Surrounding Areas, World Bank,2013 Figure 3.4.26 Inundation Situation in Typhoon Ondoy in 2009 (Inundation area prepared based on the results of interview surveys)
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(6) Inundation Area by Probability Scale
The runoff and inundation analysis were conducted for the following cases. The inundation areas of probability scale are shown in Figure 3.4.27 to Figure 3.4.29.
Figure 3.4.27 50-year Probability Scale - Predicted Inundation Area
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Figure 3.4.28 25-year Probability Scale - Predicted Inundation Area
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Figure 3.4.29 15-year Probability Scale - Predicted Inundation Area
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(7) Specifications of Rivers in Laguna de Bay Basin
Several rivers exist in the Laguna Bay Basin. The specifications of each river (river length, catchment area, setting of design scale and design discharge) are gathered for the examination of flood control measures for the Laguna de Bay inflow rivers in this study.
In addition, the design discharge is set based on the results of the wall-stand calculation for convenience, because the RRI Model calculates the river discharge including inundation from the existing river channel.
In each river basin, since there are countless rivers and waterways with short length, the relatively large rivers are extracted in this study which may require flood control measures. The location of extracted rivers in each basin is shown below.
Figure 3.4.30 Location of Rivers in the Laguna de Bay Basin
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Table 3.4.29 Specifications of Rivers in Each Basin
3 Exsisting Condition Design Flood Probable River Discharge (m ) Proposed Proposed Basin Build-up specified by Sub-Basin Area Length Design Flood Desing Sub-Basin Name River ID River Name Area Area DPWH ID (km2) (km) Return Period Discharge (km2) (km2) Wide Depth Slope Standard 100-year 50-year 30-year 25-year 15-year 10-year 5-year 2-year (year) (m3/s) (m) (m) (1/I) Guideline
SB-03 Angono 86.6 - - - 86.6 - - - - - 1,795 1,506 1,311 1,246 1,074 945 741 483 - -
SB-03-1 Angono River 8.18 12.7 4.1 13.00 3.25 400 50 263 220 192 182 157 138 109 71 25 190
SB-03-2 SB-03-2 5.66 9.9 2.2 15.00 3.75 190 50 206 173 150 143 123 108 85 55 15 130
SB-03-3 SB-03-3 4.71 6.7 0.8 12.00 3.00 160 50 140 117 102 97 83 73 58 38 15 90
SB-03-4 SB-03-4 3.92 4.0 0.9 7.50 1.88 230 50 84 70 61 58 50 44 35 23 15 60
SB-03-5 SB-03-5 2.98 3.4 0.8 10.00 2.50 130 50 70 59 51 49 42 37 29 19 15 50
SB-04 Morong 95.9 - - - 95.9 - - - - - 1,610 1,439 1,313 1,267 1,137 1,034 849 572 - -
SB-04-1 Morong 29.16 67.0 9.3 35.00 8.75 2000 100 1,126 1,006 918 885 795 722 594 400 50 1,100
SB-04-2 8.15 22.5 2.0 10.00 2.50 5000 50 378 338 308 297 267 243 199 134 25 300
SB-05 Baras 21.7 - - - 21.7 - - - - - 509 442 395 379 333 298 239 157 - -
SB-05-1 Baras 13.01 17.6 0.6 14.00 3.50 360 50 412 358 320 307 270 241 194 127 25 310
SB-06 Tanay 52.2 - - - 52.2 - - - - - 1,041 894 791 756 662 590 471 310 - -
SB-06-1 Tanay 20.70 39.3 0.9 36.00 9.00 370 50 784 673 596 570 498 445 355 233 25 580
SB-07 Pililla 40.4 - - - 40.4 - - - - - 789 689 618 593 523 469 377 246 - -
SB-07-1 Pililla 16.06 32.8 1.6 24.00 6.00 710 50 642 561 502 482 425 382 306 200 25 490
SB-08 Jala-jala 70.6 - - - 70.6 - - - - - 1,483 1,247 1,093 1,039 901 798 631 419 - -
SB-08-1 Jala-jala 4.81 10.7 0.4 12.00 3.00 140 50 225 189 166 158 137 121 96 64 25 140
SB-09 Sta. Maria 202.2 - - - 202.2 - - - - - 2,390 2,134 1,946 1,876 1,685 1,534 1,268 876 - -
SB-09-1 Sta. Maria 31.91 167.0 6.2 40.00 10.00 830 100 1,974 1,762 1,607 1,549 1,391 1,267 1,047 723 50 1,800
SB-10 Siniloan 71.7 - - - 71.7 - - - - - 1,089 972 885 855 766 695 570 382 - -
SB-10-1 Romero 10.91 39.3 1.9 22.00 5.50 710 50 597 533 486 469 420 381 313 210 25 470
SB-11 Pangil 50.1 - - - 50.1 - - - - - 1,237 1,045 915 870 750 658 508 307 - -
SB-11-1 Pangil 13.72 21.2 0.3 20.00 5.00 480 50 524 443 387 369 318 279 215 130 25 370
SB-11-2 14.97 5.2 1.0 10.00 2.50 910 50 128 108 94 90 77 68 52 32 15 80
SB-11-3 2.41 2.2 0.6 12.00 3.00 310 50 55 47 41 39 34 29 23 14 15 40
SB-11-4 2.83 3.7 0.5 12.00 3.00 450 50 91 77 67 64 55 48 37 23 15 60
SB-11-5 2.68 2.2 0.2 7.00 1.75 180 50 54 46 40 38 33 29 22 13 15 40
SB-11-6 2.15 3.2 0.2 9.00 2.25 100 50 79 66 58 55 48 42 32 20 15 50
SB-12 Caliraya 128.8 - - - 128.8 - - - - - 2,244 1,941 1,727 1,652 1,446 1,286 1,013 633 - -
SB-12-1 Caliraya ------
SB-13 Pagsanjan 301.2 - - - 301.2 - - - - - 3,425 2,951 2,625 2,514 2,209 1,974 1,591 1,076 - -
SB-13-1 Pagsanjan 53.18 258.7 7.5 90.00 22.50 910 100 2,942 2,534 2,254 2,159 1,897 1,695 1,366 924 50 2,600
SB-14 Sta. Cruz 146.7 - - - 146.7 - - - - - 1,878 1,610 1,425 1,362 1,191 1,060 848 565 - -
SB-14-1 Sta. Cruz 33.12 116.6 4.2 60.00 15.00 1670 100 1,493 1,280 1,133 1,082 946 842 674 449 50 1,300
SB-15 Pila 89.3 - - - 89.3 - - - - - 1,532 1,285 1,118 1,061 912 799 620 388 - -
SB-15-1 Pila 12.43 31.2 1.0 14.00 3.50 450 50 535 449 391 371 319 279 216 135 25 380
SB-15-2 5.20 31.5 1.8 20.00 5.00 630 50 540 453 395 374 322 282 219 137 25 380
SB-16 Calauan 154.5 - - - 154.5 - - - - - 2,094 1,863 1,693 1,632 1,461 1,323 1,083 729 - -
SB-16-1 Calauan 31.25 64.7 2.0 23.00 5.75 500 100 877 780 709 683 612 554 454 305 50 800
SB-16-2 25.62 49.9 4.8 10.00 2.50 830 100 676 601 546 527 472 427 350 235 50 700
SB-17 Los Banos 102.1 - - - 102.1 - - - - - 2,184 1,933 1,748 1,684 1,499 1,351 1,094 714 - -
SB-17-1 Colo River 9.29 20.3 1.1 25.00 6.25 360 50 435 385 348 335 298 269 218 142 25 300
SB-17-2 Los Banos River 4.07 25.8 2.3 20.00 5.00 290 50 552 489 442 426 379 342 277 181 25 430
SB-17-3 6.38 2.8 0.2 10.00 2.50 80 50 60 53 48 46 41 37 30 20 15 50
SB-17-4 5.62 5.5 0.4 10.00 2.50 240 50 118 105 95 91 81 73 59 39 15 90
SB-17-5 6.28 12.5 1.8 20.00 5.00 170 50 267 236 214 206 183 165 134 87 25 210
SB-17-6 12.66 3.3 0.1 13.00 3.25 200 50 70 62 56 54 48 44 35 23 15 50
SB-17-7 6.00 7.6 1.0 15.00 3.75 110 50 163 145 131 126 112 101 82 53 15 130
SB-17-8 10.66 11.6 1.8 15.00 3.75 500 50 249 220 199 192 171 154 125 81 25 200
SB-18 San Juan 191.7 - - - 191.7 - - - - - 3,031 2,600 2,296 2,191 1,907 1,690 1,332 859 - -
SB-18-1 San Juan River 42.97 175.3 25.5 60.00 15.00 1110 100 2,772 2,377 2,100 2,004 1,744 1,546 1,218 785 50 2,400
SB-19 San Cristobal 140.6 - - - 140.6 - - - - - 2,000 1,716 1,519 1,451 1,268 1,127 896 587 - -
SB-19-1 San Cristobal River 36.22 123.7 24.3 50.00 12.50 670 100 1,759 1,509 1,336 1,276 1,115 991 789 516 50 1,600
SB-20 Sta. Rosa 119.8 - - - 119.8 - - - - - 1,570 1,387 1,255 1,205 1,071 963 772 491 - -
SB-20-1 Sta. Rosa River 30.18 44.1 10.8 18.00 4.50 770 100 578 511 462 444 394 355 284 181 50 520
SB-20-2 9.70 19.2 7.0 26.00 6.50 500 50 251 222 201 193 171 154 124 79 25 200
SB-20-3 9.05 16.0 3.3 30.00 7.50 630 50 210 186 168 161 143 129 103 66 25 170
SB-20-4 11.04 15.6 6.1 15.00 3.75 270 50 205 181 163 157 139 125 101 64 25 160
Remaining basin(targe to pump) - 24.8 ------
Remaining basin - 24.8 ------
SB-21 Binan 84.8 - - - 84.8 - - - - - 980 867 784 754 669 601 482 304 - -
SB-21-1 Binan River 36.00 67.7 16.8 30.00 7.50 300 100 783 693 626 602 535 480 385 243 50 700
SB-22 San Pedro 46.0 - - - 46.0 - - - - - 624 529 463 440 379 332 256 157 - -
SB-22-1 San Isidro River 36.77 29.3 7.6 16.00 4.00 320 50 398 338 295 281 242 212 163 100 25 290
SB-22-2 Tunasan River 9.58 6.1 1.7 10.00 2.50 480 50 82 70 61 58 50 44 34 21 15 60
SB-23 Muntinlupa 44.1 - - - 44.1 - - - - - 1,076 859 724 680 567 488 369 229 - -
SB-23-1 Alabang River 6.60 10.6 6.8 17.00 4.25 220 50 259 206 174 163 136 117 89 55 25 170
SB-23-2 Bayanan Creek 6.49 4.5 2.6 10.00 2.50 220 50 111 88 74 70 58 50 38 23 15 60
SB-23-3 Poblacion River 8.23 5.7 2.7 10.00 2.50 100 50 139 111 93 88 73 63 47 29 15 80
SB-23-4 Magdaong River 6.34 4.5 1.8 12.00 3.00 230 50 109 87 73 69 57 49 37 23 15 60
SB-23-5 3.73 3.4 2.6 20.00 5.00 120 50 82 65 55 52 43 37 28 17 15 50
SB-23-6 1.07 0.4 0.3 15.00 3.75 50 50 10 8 7 6 5 4 3 2 15 10 SB-23-7 1.52 1.8 1.4 10.00 2.50 70 50 44 35 30 28 23 20 15 9 15 30
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3.5 Runoff and Inundation Analysis of Parañaque and Las Piñas Areas
3.5.1 Present Status of Flood Damage in Las Pinas - Parañaque area
(1) Outline of Field Survey
Site visits were conducted to verify the present condition of channels and to identify the causes of inundation in Parañaque and Las Pinas areas. The current situation of flood damage in the Las Pinas- Parañaque area is organized as follows from field survey result.
- The cause of inundation along each channel is not inner water but river flooding. Recent inundations were two events; Typhoon Ondoy in 2009, and Habagat (monsoon) in 2012. In both inundations, depth was about 40 cm with some low-lying areas about 1 m, and duration was from a half to one day. - Dikes have been constructed along channels since 2012, and still in progress.
From the site inspection results, the causes of inundation in Parañaque and Las Piñas areas are noted as below:
- Inundation in Parañaque and Las Piñas areas is caused by river flooding. Upper area is flooded, then the flow goes toward the low-lying area in the lower reaches through roads and inland, causing inundation.
(2) Result of Field Survey
The results of field survey on representative 5 rivers (Parañaque, Dongalo, South Parañaque, San Dionisio and Las Pinas) are organized below.
No. River Figure and Table 1 Paranaque Figure 3.5.1,Table 3.5.1 2 San Dionisio Figure 3.5.2,Table 3.5.2 3 Las Pinas Figure 3.5.3,Table 3.5.3 4 South Paranaque Figure 3.5.4,Table 3.5.4 5 Dongalo Figure 3.5.5,Table 3.5.5
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Flood damage caused by Typhoon Ondoy Paranaque River
Figure 3.5.1 Location of Field Survey _Paranaque River Table 3.5.1 Result of Field Survey No Photo Result of hearing Excavated channel. Dike is installed on the right side downstream of the bridge (2013). No inundation occurred during Typhoon Site 01 Ondoy. (Paranaque R.)
Channel width is approximately 60 m. Dike of approximately 1.5 meters high is installed (2013). Site 02 No dike on the left side. A highway crosses (Paranaque R.) over the channel. Inundation depth during Typhoon Ondoy was 40 cm. Dike of approximately 50 cm-high is installed on the right side (2016) Site 03 Inundation depth during Typhoon Ondoy was (Paranaque R.) 40 cm. Another inundation of the same size occurred in 2012. Channel width is approximately 100 m. Sheet pile revetment is installed on both sides. Site 05 Dike is installed on the right side. (Paranaque R.) No inundation occurred during Typhoon Ondoy.
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Flood damage caused by Typhoon Ondoy San Dionisio R.
Las Pinas R.
Zapote R.
Figure 3.5.2 Location of Field Survey _San Dionisio River
Table 3.5.2 Result of Field Survey No Photo Result of hearing Excavated channel of approximately 10 m in width and 3 m in height. Revetment with stones is installed. Site 07 (San Dionisio R.) River flooding has not occurred. During Typhoon Ondoy, inundation occurred and continued for approximately one day.
Excavated channel of approximately 15 m in width. Revetment with stones is installed. River flooding has occurred only in the right Site 08 side, whose elevation is lower than the left (Las Pinas R.) side. Inundation occurred during Typhoon Ondoy and monsoon in 2012. The duration was approximately one day for both inundations. The channel width is approximately 20 meters. While dike is installed on the seaside, it is an excavated channel on the landside. Site09 (Las Pinas – Zapote Both river flooding and inner water inundation channel) have occurred. Inundation depth was approximately 40 cm for both Typhoon Ondoy and the monsoon in 2012. The channel width is approximately 20 meters. Dike is under construction. Site10 (Las Pinas R.)
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Flood damage caused by Typhoon Ondoy
Zapote R.
Las Pinas R.
Figure 3.5.3 Location of Field Survey _Las Pinas River
Table 3.5.3 Result of Field Survey No Photo Result of hearing The channel is approximately 30 meters in width and 6 meters in height. Dike is installed (2016). Site11 River flooding has occurred during Typhoon (Las Pinas.R) Ondoy and the monsoon in 2012. The duration was approximately one day in low lying area.
The channel width is approximately 10 meters. Dike of approximately 5 meters high is under construction. Site13 (Las Pinas.R) Only river flooding has occurred. The inundation depth during Typhoon Ondoy was 1 meter.
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South Paranaque R.
Baloc Creek.
Flood damage caused by Typhoon Ondoy
San Felipe R.
Figure 3.5.4 Location of Field Survey _South Paranaque、San Felipe
Table 3.5.4 Result of Field Survey No Photo Result of hearing The channel is approximately 20 meters in width and 5 meters in height. Dike is installed Site14 (2013). (San Felipe R.) Only river flooding has occurred. Inundation duration was approximately a half day.
The channel is approximately 10 meters in width and 6 meters in height. Site 16 Only river flooding has occurred. Inundation (San Felipe R.) depth during Typhoon Ondoy was 40 centimeters.
The channel is approximately 5 meters in width and 3 meters in height. Site 17 River flooding has occurred, in which the (右流入支川) inundation depth was 2 meters in low-lying area.
The channel is approximately 10 meters in width and 2 meters in height. Site 18 River flooding has occurred, in which the (San Felipe R.) inundation depth was 1 meter and the duration was approximately one day.
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Dongalo R. Flood damage caused by Typhoon Ondoy
Figure 3.5.5 Location of Field Survey _Dongalo River
Table 3.5.5 Result of Field Survey No Photo Result of hearing The channel is approximately 30 meters in width and 5 meters in height. Dike is installed (2014). Site 19 River flooding has occurred, in which the (Dongalo.R) inundation depth was 1.5 meters and the duration was approximately one day.
The channel is approximately 10 meters in width and 5 meters in height. Dike is installed (2016). Site 20 River flooding has occurred, in which the (Dongalo.R) inundation depth was 3 meters and the duration was one day at the maximum.
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3.5.2 Create Runoff and Inundation Analysis Model
(1) Outline of Las Pinas – Paranaque Area
River Network system in Las Pinas – Paranaque area is shown in Figure 3.5.6. South Paranaque river confluence to Dongalo river and confluence to Paranaque river then flow to Manila Bay. South Paranaque river, Las Pinas river and Zapote river
Las Pinas River is located southwest of South Parañaque River, and Zapote River is located southwest of South Parañaque River. South Parañaque, Las Pinas and Zapote rivers are connected by waterways near the mouth of the estuary, and river network is formed which unites Parañaque, South Parañaque, Las Pinas and Zapote river.
Paranaque River
Air Port
Dongalo River
South Paranaque River
San Dionisio River
Baloc Creek
San Felipe River
Zapote River Las Pinas River
Source: Created by JICA Study Team based on Open Street Map Figure 3.5.6 River Network System in Las Pinas – Paranaque Area
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(2) Segmentation of River Basin in Las Pinas – Paranaque Area
The river basin in Las Pinas – Paranaque area is shown in Figure 3.5.7. In this district, divided into five river basins (Paranaque, Dongalo, South Paranaque, Las Pinas and Zapote watershed) and set a sub-basin in each river basin.
Sub Area Basin Basin (km2) Paranaque PA-1 6.4 Sub Total 6.4 Dongalo DO-1 11.8 DO-2 3.7 Sub Total 15.5 South SP-1 11.7 Paranaque SP-2-1 6.1 SP-2-2 1.3 SP-3 2.4 SP-4 2.6 SP-5 1.8 SP-6 2.4 Sub Total 28.3 Las Pinas LA-1 8.2 LA-2 2.1 LA-3 1.9 LA-4 2.4 Sub Total 14.6 Zapote ZA-1-1 39.2 ZA-1-2 3.8 ZA-1-3 4.6 ZA-2 2.7 Sub Total 50.3 Total 115.1
Figure 3.5.7 River Basin Division Map in Las Pinas / Parañaque Area
(3) Outline of Analysis Model
The flooding analysis model in Parañaque, Las Pinasas district has constructed an analytical model that can appropriately represent the time scale such as time of flood concentrations and flow time.
For this analysis model, rainfall data is set as the external force condition, the discharge obtained from the rainfall runoff analysis is applied to the river channel, and the simulation is conducted by the combination of the one (1) dimensional unsteady flow model for modeling the river routing and the two (2) dimensional unsteady model for modelling the protected inland area. MIKE-FLOOD developed by DHI is applied.
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(4) Runoff Analysis Model
To calculate runoff from each river basin, The Soil Conservation Service (SCS) curve number method is employed. Runoff is determined primarily by amount of precipitation and by infiltration characteristics related to soil type, soil moisture antecedent rainfall, cover type, impervious surface and surface retention. In order to calculate surface runoff, United Department of Agriculture (USDA,1986) converted mass rainfall to mass runoff by using a runoff curve number (CN number) is applied. The equation of runoff volume is shown in below and model parameters for each basin is shown in Table 3.5.7. (푃 − 0.2푆)2 Q = 푃 + 0.8푆 Where; Q: the accumulated runoff depth or rainfall excess, P: the accumulated precipitation, P must exceed 0.2S, S: maximum soil water retention parameter given by 1000 S = ( − 10) × 25.4 (푚푚) 퐶푁 Where CN: curve number
푇퐿퐴퐺 = 0.6푇퐶
Where 푇퐿퐴퐺:Lag time, 푇퐶:time of concentration.
푇퐶 = 푇퐼푁 + 푇퐹
Where푇퐼푁:inlet time. 푇퐹:travel time of flood flow in a channel
For the calculation of inlet time (푇퐼푁) and travel time (푇퐹), iFSAR data was used to determine the upstream end of the river channel, and inlet time until the rainwater flowed into the river channel for the upstream area (inflow section) was set. The travel time was calculated from the relationship between the flow path length and flood propagation speed. The relationship between channel length and flood propagation speed is shown in Table 3.5.6. Table 3.5.6 Flood Propagation Speed Channel Slope >1/100 1/100～1/200 1/200> Propagation Speed 3.5 m/s 3.5 m/s 3.5 m/s Source: Technical Criteria for River Works: Practical Guide for Survey, MLIT,Japan Table 3.5.7 Target Basins and Model Parameters Highest Low Elevation Longest Time of Area Elevation Elevation difference Slope Velocity Lag Time River Sub-Basin CN flow path concentration in basin in basin DH km2 m m m m I m/s h h Paranaque PA-1 6.4 79 ------0.5 0.30 Dongalo DO-1 11.8 87 4,800 36.0 14.5 21.5 223 2.1 1.1 0.68 Dongalo DO-2 3.7 85 3,300 14.5 10.7 3.8 868 2.1 0.4 0.26 South Paranaque SP-1 11.7 87 7,960 48.9 16.1 32.8 243 2.1 1.6 0.93 South Paranaque SP-2-1 6.1 87 3,930 40.0 18.0 22.0 179 3.0 0.9 0.52 South Paranaque SP-2-2 1.3 87 2,260 18.0 12.3 5.7 396 2.1 0.3 0.18 South Paranaque SP-3 2.4 87 2,090 27.0 14.0 13.0 161 3.0 0.7 0.41 South Paranaque SP-4 2.6 86 2,700 30.0 12.7 17.3 156 3.0 0.8 0.45 South Paranaque SP-5 1.8 79 4,540 12.3 11.0 1.3 3492 2.1 0.6 0.36 San Dionisio SP-6 2.4 79 3,690 20.0 12.5 7.5 492 2.1 1.0 0.59 Las Pinas LA-1 8.2 87 6,850 48.5 16.5 32.0 214 2.1 1.4 0.85 Las Pinas LA-2 2.1 87 2,150 16.5 14.3 2.2 977 2.1 0.8 0.47 Las Pinas LA-3 1.9 87 2,010 23.3 11.6 11.7 172 3.0 0.7 0.41 Las Pinas LA-4 2.4 87 2,100 12.0 10.5 1.5 1400 2.1 0.3 0.17 Zapote ZA-1-1 39.2 83 16,607 147.0 18.0 129.0 129 3.0 2.0 1.22 Zapote ZA-1-2 3.8 83 540 18.0 12.0 6.0 90 3.5 0.0 0.02 Zapote ZA-1-3 4.6 83 6,000 35.0 12.0 23.0 261 2.1 1.3 0.77 Zapote ZA-2 2.7 82 4,860 14.0 12.5 1.5 3240 2.1 0.6 0.38
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(5) River Channel Model
The target rivers/channels are ten (10) rivers/channels in Figure 3.5.6 showing blue lines. The Conceptual diagram of analysis model is shown in Figure 3.5.8.The cross-section data is based on result of cross section survey which was provide by DPWH and ifSAR data (5m elevation data) was used to create cross section data for the river which no cross-section survey result. The section data of each river used in river channel model is summarized in Table 3.5.7.
Figure 3.5.8 Conceptual Diagram of Analysis Model
Table 3.5.8 Specification of Section Data Used in River Channel Model Range of River Section Survey Name of River Source / Provider Channel Model pitch Year Paranaque 0~3.0km 200m Metro Manila 2nd District Engineering Office (DEO) 2014 Dongalo 0~2.5km 100m Metro Manila 2nd District Engineering Office (DEO) 2014 South Paranaque 0~3.6km 100m Metro Manila 2nd District Engineering Office (DEO) 2014 San Felio 0~2.2km 200m IFSAR 2014 Baloc Creak 0~2.4km 200m IFSAR 2014 San Dionisio 0~0.6km 100m Metro Manila 2nd District Engineering Office (DEO) 2014 0.7~3.4km 100m IFSAR 2014 Las Pinas 0~5.0km 200m Las Pinas-Miuntinlupa District Engineering Office 2012 Zapote 0~5.4km 100~200m Cavite Sub District Engineering Office (DEO) 2017 Las Pinas- 0~0.5km 100m IFSAR 2014 Zapote Channel
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Scope of Modeling
Figure 3.5.9 Location of Cross Section
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(6) Floodplain Elevation (DEM)
The IFSAR data was collected for the entire Philippines in 2014. A portion covering the study area was obtained from NAMRIA and is utilized to develop the Digital Elevation Model (DEM) for the inundation analysis model. The arithmetic average value of the IFSAR data at every 5 m within 50-m grid is used to determine the elevation of every 50-m grid. Figure .5.3 shows the elevation distribution map which is generated on the created DEM.
Source: JICA Study Team created using IFSAR 5m elevation data (NAMRIA) Figure 3.5.10 Distribution Map of 50m Mesh Elevation
(7) Design Hyetograph
The observed hourly rainfall data at Science Garden in Pasig-Marikina river basin was used for design hyetograph for runoff and inundation analysis model in Las-Pinas – Paranaque area. There are no observed hourly rainfall data around Las Pinas – Paranaque area. therefore, observed hourly rainfall data of Science garden was used for model hyetograph and expanded or contracted to be equal to the probable daily rainfall in volume.
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Science Garden 100 90 80 70 60 50 40 30
Hourly Rainfall (mm) Rainfall Hourly 20 10 0 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 Port Area 2009/9/26 2009/9/27
NAIA
Figure 3.5.11 Observed Hourly Rainfall Data at Science Garden in Typhoon Ondoy
3.5.3 Validation of Analysis Model by Past Floods
Regarding the validity of the runoff and flood analysis model in the Las Pinas-Parañaque area, we targeted Typhoon Ondoy in 2009 which suffered great inundation damage. In addition, the river water level has been measured at Zapote river and the observed data was remaining during Typhoon Ondoy in 2009. The observed river water level data and result of field survey in this project and WB project was used for validation of analysis model.
Re-producing calculation result is shown in Figure 3.5.14. The basin mean rainfall for reproducing calculation was estimated based on daily rainfall data at Port Area using by correlation equation of basin mean rainfall and observed rainfall data at Port Area.
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400 Observed Daily Rainfall at Port Area and y = 0.5538x + 34.252 Estimation of Basin Mean Rainfall (BMR) 350 R² = 0.4242 Unit：mm/day Daily rainfall Basin Mean Date 300 at Port Area Rainfall 2009/9/23 53.4 64.1 250 2009/9/24 10.4 40.3 2009/9/25 66.7 71.5 200
BRM 2009/9/26 258.5 177.7 150
100 Basin Mean Rainfall (BMR) in Sep.26 2009 at Las
50 Pinas- Paranaque area is estimated 177.7mm/day. This BMR is equivalent to 8-year return period. 0 0 100 200 300 400 500 Port Area
Figure 3.5.12 Relationship Between Basin Mean Rainfall (BMR) and Daily Rainfall at Port Area
Ondoy 2009/9/26 Estimated Basin Mean Rainfall 100 90 Science Garden (Observed) 80 Estimated BMR_Ondoy 70 60 50 40
30 Rainfall (mm/hour) Rainfall 20 10 0 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 2009/9/26 2009/9/27
Figure 3.5.13 Hyetograph of Re-producing Calculation
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Figure 3.5.14 Result of Validation Analysis_ Maximum Flooding Depth (Sep.26 2009)
Table 3.5.9 Comparison Between Actual Depth atTyphoon Ondoy (depth of hearing) and Simulation Result Flooding Depth in Typhoon Ondoy Result of No. River （Result of hearing validation analysis Remarks
survey） 1 Paranaque R. 0.4 – 0.5m 0.5 m Survey result in this project 2 South Paranaque R. 0.5 m 0.6 m Survey result in WB*project 3 Dongalo R. 0.5 m 0.5 m Survey result in WB*project 4 Dongalo R. 1.5 m 1.8 m Survey result in WB*project 5 San Dionisio R. 0 m - Survey result in WB*project 6 San Dionisio R. Although the depth of 1.4 m Survey result in this project flooding is unknown, there is damage from overflowing floods 7 South Paranaque R. 1 m 1.3 m Survey result in this project 8 Right tributary 2 m 1.3 m Survey result in this project 9 San Felipe 0.5 m 0.5 m Survey result in WB*project 10 San Felipe R. 1 m 1.4 m Survey result in this project 11 Las Pinas R. 0 m - Survey result in WB*project 12 Las Pinas R. 1.0 m 1.1 m Survey result in this project 13 Las Pinas R. 0.8 m 0.9 m Survey result in WB*project 14 Zapote R. 2.0 m 1.6 m Survey result in WB*project ＊Result of hearing survey in Master Plan for Flood Management in Metro Manila and Surrounding Areas, World Bank,2013
The river water level is measuring by BRS (Bureau of Research and Standard) at Zapote river. Maximum monthly water level is shown in Figure 3.5.15 which was collected in this project. The observed station is located at ZA.2+000 and visual observation is conducted using by staff gauge.
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According observed data, maximum water level was 13.90m during Typhoon Ondoy. The bank elevation at observed station (ZA.2+000) was below 13.5m from cross section survey result and the bank elevation is lower than maximum water level (13.9m). According to observed water level data and cross section data, it is inferred that the damage was caused by overflowing floods from Zapote river during Typhoon Ondoy. The ground level inside this area is about 12.5 m, and it is considered that the depth of flooding is 1.4 m, which is the ground level minus the highest water level (13.9 m) at Typhoon Ondoy.
In the reproduction calculation result carried out in this project, the flood depth near water level observation point was calculated to be 1.6 m, and it was almost the same as the value assumed from the actual observation water level data assuming the flooding depth.
From the above, it can be judged that runoff and inundation analysis model constructed in this project is a model that can reproduce inundation / inundation situation of Las Pinas - Paranaque district at Typhoon Ondoy in 2009.
Figure 3.5.15 Observed Maximum Monthly Water Level at Zapote River
ZA 2+200 15.0 14.5 14.0 13.5 13.0 12.5 12.0 11.5 11.0 10.5 Elevation (m) Elevation 10.0 9.5 9.0 8.5 8.0 0 5 10 15 20 25 30 35 Distance (m)
Figure 3.5.16 Cross-Section at ZA.2+000
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3.5.4 Runoff and Inundation Analysis for Probable Rainfall
(1) Design Hyetograph
Observed hourly rainfall data of Science garden was used for model hyetograph and expanded or contracted to be equal to the probable daily rainfall in volume.
Model Hyetograph for 2-year return period Model Hyetograph for 5-year return period 100 100 90 Science Garden 90 Science Garden (Observed) (Observed) 80 2-year 80 5-year 70 70 60 60 50 50 40 40
30 30
Rainfall (mm/hour) Rainfall Rainfall (mm/hour) Rainfall 20 20 10 10 0 0 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 2009/9/26 2009/9/27 2009/9/26 2009/9/27
Model Hyetograph for 10-year return period Model Hyetograph for 15-year return period 100 100 90 Science Garden 90 Science Garden (Observed) (Observed) 80 10-year 80 15-year 70 70 60 60 50 50 40 40
30 30
Rainfall (mm/hour) Rainfall Rainfall (mm/hour) Rainfall 20 20 10 10 0 0 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 2009/9/26 2009/9/27 2009/9/26 2009/9/27
Model Hyetograph for 25-year return period Model Hyetograph for 50-year return period 100 100 90 Science Garden 90 Science Garden (Observed) (Observed) 80 25-year 80 50-year 70 70 60 60 50 50 40 40
30 30
Rainfall (mm/hour) Rainfall Rainfall (mm/hour) Rainfall 20 20 10 10 0 0 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 2009/9/26 2009/9/27 2009/9/26 2009/9/27
Model Hyetograph for 100-year return period 100 90 Science Garden (Observed) 80 100-year 70 60 50 40
30 Rainfall (mm/hour) Rainfall 20 10 0 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 2009/9/26 2009/9/27
Figure 3.5.17 Design Hyetograph
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(2) Result of Inundation Analysis
The result of inundation analysis is shown in Figure 3.5.18 to Figure 3.5.21, the inundation volume and area is shown inTable 3.5.10. Return Period 2-year
Return Period 5-year
Figure 3.5.18 Maximum Inundation Depth (2-year and 5-year)
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Return Period 10-year
Return Period 15-year
Figure 3.5.19 Maximum Inundation Depth (10-year and 15-year)
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Return Period 25-year
Return Period 50-year
Figure 3.5.20 Maximum Inundation Depth (25-year and 50-year)
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Return Period 100-year
Figure 3.5.21 Maximum Inundation Depth (100-year)
Table 3.5.10 Inundation Volume Unit:m3 Basin Sub Basin 1/2 1/5 1/10 1/15 1/25 1/50 1/100 PA-1 218,143.65 252,983.96 271,000.98 281,461.37 317,082.99 379,574.72 467,887.06 Paranaque Sub-Total 218,143.65 252,983.96 271,000.98 281,461.37 317,082.99 379,574.72 467,887.06 DO-1 - 15,488.76 18,932.80 25,075.37 35,092.45 44,380.42 64,162.59 Dongalo DO-2 236,582.83 301,820.73 369,642.86 420,485.92 479,092.75 585,866.19 717,338.02 Sub-Total 236,582.83 317,309.49 388,575.66 445,561.28 514,185.21 630,246.61 781,500.60 SP-1 - 97.32 1,724.38 4,732.46 7,130.96 10,095.65 13,373.29 SP-2-1 ------SP-2-2 105,753.74 144,212.07 168,244.14 182,510.41 204,202.00 231,351.26 258,650.76 SP-3 86,100.02 137,335.05 172,390.51 191,557.69 216,952.76 248,233.11 278,824.99 South Paranaque SP-4 19,062.87 41,210.93 83,801.25 131,424.81 171,044.67 214,405.67 253,042.29 SP-5 210,939.50 331,598.44 432,639.25 486,850.34 561,336.88 671,998.59 785,419.99 SP-6 55,149.40 200,609.95 336,407.15 420,038.01 554,187.31 748,621.96 938,811.35 Sub-Total 477,005.51 855,063.76 1,195,206.69 1,417,113.73 1,714,854.59 2,124,706.24 2,528,122.68 LA-1 ------LA-2 19,656.89 46,939.08 62,876.78 72,443.54 82,372.40 96,445.83 110,070.94 Las Pinas LA-3 42,131.14 84,201.84 111,992.98 127,785.12 149,096.17 176,992.33 212,957.97 LA-4 86,666.98 161,624.20 259,184.31 339,027.91 438,063.12 567,595.26 695,566.13 Sub-Total 148,455.01 292,765.12 434,054.07 539,256.57 669,531.69 841,033.42 1,018,595.04 ZA-1-1 ------ZA-1-2 19,341.92 54,245.80 73,925.76 84,713.45 103,996.16 175,503.76 268,623.86 Zapote ZA-1-3 45,601.47 179,141.13 258,566.60 300,985.46 351,984.12 421,403.14 500,018.63 ZA-2 507,818.22 802,119.54 992,772.92 1,099,158.56 1,226,159.91 1,396,653.86 1,593,101.07 Sub-Total 572,761.62 1,035,506.46 1,325,265.28 1,484,857.46 1,682,140.20 1,993,560.76 2,361,743.56 Total 1,652,949 2,753,629 3,614,103 4,168,250 4,897,795 5,969,122 7,157,849
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Table 3.5.11 Inundation Volume Unit:m3 Basin Sub Basin 1/2 1/5 1/10 1/15 1/25 1/50 1/100 PA-1 420,800.46 475,047.92 502,547.92 511,005.90 544,284.97 584,030.66 671,567.33 Paranaque Sub-Total 420,800.46 475,047.92 502,547.92 511,005.90 544,284.97 584,030.66 671,567.33 DO-1 - 19,069.26 19,069.26 36,569.26 49,069.26 51,222.94 80,228.93 Dongalo DO-2 292,217.13 403,147.87 488,147.87 547,396.09 591,126.55 717,895.53 873,567.35 Sub-Total 292,217.13 422,217.13 507,217.13 583,965.35 640,195.82 769,118.47 953,796.28 SP-1 - 619.89 5,619.89 14,192.47 16,692.47 19,192.47 24,192.47 SP-2-1 ------SP-2-2 107,898.42 130,758.28 149,849.64 164,849.64 190,040.55 208,087.58 223,065.29 SP-3 167,054.75 198,934.85 227,840.97 236,768.40 251,577.48 266,766.03 277,433.45 South Paranaque SP-4 47,337.63 54,733.48 153,380.89 236,709.67 292,576.26 316,117.47 353,362.47 SP-5 333,514.28 495,684.12 604,702.14 668,688.20 733,312.08 840,541.88 932,965.32 SP-6 97,019.89 341,564.19 542,472.09 676,059.91 868,007.24 1,035,518.45 1,161,007.75 Sub-Total 752,824.96 1,222,294.81 1,683,865.62 1,997,268.29 2,352,206.08 2,686,223.88 2,972,026.75 LA-1 ------LA-2 40,213.60 62,713.60 70,213.60 80,213.60 82,713.60 87,713.60 87,713.60 Las Pinas LA-3 57,309.88 108,192.48 141,241.07 148,544.74 168,561.36 188,561.37 233,556.06 LA-4 127,437.91 269,551.72 489,931.13 639,017.67 784,561.32 894,193.90 986,939.79 Sub-Total 224,961.40 440,457.81 701,385.80 867,776.02 1,035,836.28 1,170,468.86 1,308,209.45 ZA-1-1 ------ZA-1-2 33,238.48 72,156.70 87,070.49 94,569.30 120,776.58 245,719.38 338,266.57 Zapote ZA-1-3 100,005.02 264,889.85 325,926.14 353,427.34 381,774.86 435,060.02 488,054.45 ZA-2 823,820.94 1,183,231.90 1,309,457.34 1,364,965.96 1,423,524.42 1,539,536.09 1,656,356.92 Sub-Total 957,064.44 1,520,278.45 1,722,453.98 1,812,962.60 1,926,075.86 2,220,315.49 2,482,677.94 Total 2,647,868 4,080,296 5,117,470 5,772,978 6,498,599 7,430,157 8,388,278
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3.5.5 Investigation of Flood Countermeasures in Las Pinas – Paranaque Area
(1) Setting of Design Scale (Draft)
As flood damage in Las Pinas - Parañaque area is damaged by "overflow from river", as planned by design scale of 3.2, setting the design scale of river in the area set design scale for basin area coverage. Table 3.5.12 Design Scale Classification Area of River Basin Design Scale River A≧40km2 50 year 10km2≦A＜40km2 25 year A<10km2 15 year Drainage - 15 year
Table 3.5.13 Setting of Design Scale Area No. River Design Scale (km2) 1 Paranaque 41.3* 50 year 2 Dongalo 15.5 25 year 3 South Paranaque 28.3 25 year 4 Las Pinas 14.6 25 year 5 Zapote 50.3 50 year * The entire river basin area of Paranaque river basin is 41.3km2. However, target area is set only area where flow to Las Pinas – Paranaque area in this project.
Paranaque *
Dongalo
Las Pinas
South Paranaque
Zapote
Figure 3.5.22 Map of Each River Basin
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(2) Existing Flow Capacity
(a) Paranaque River Design Scale:50-year ⚫ From South Paranaque river junction to the point 1.8 km, flow capacity is high both on the right bank and on the left bank, and flow capacity is more than 50-year return period. ⚫ The flow capacity of upstream from 1.8km is remarkably small and this portion was inundated by Typhoon Ondoy regarding to field survey.
Paranaque River
Paranaque River Existing Flow Capacity 150 Flow Capacity_Left Flow Capacity_Right Estimated 50-year Flow Discharge Estimated 25-year Flow Discharge Estimated 15-year Flow Discharge 120
90
60 Flow CapacityFlow(m3/s)
30
0
0
200 600 800 400
1,400 2,000 2,600 1,000 1,200 1,600 1,800 2,200 2,400 2,800
Distance from Confluence with South Paranaque (m) Figure 3.5.23 (1) Existing Flow Capacity of Paranaque River
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(b) Dongalo River Design Scale:25-year ⚫ Flow capacity is low in downstream portion. In the section from 800 m to 900 m, flow capacity is insufficient on both the left and right banks, and flow capacity on the left bank side is insufficient in upstream section. ⚫ According field survey result, flooding damage has occurred due to flooding from a river at Typhoon Ondoy.
Dongalo River
Dongalo River Existing Flow Capacity 300 280 Flow Capasity_Left Flow Capasity_Right Estimated 50-year Flow Discharge Estimated 25-year Flow Discharge 260 Estimated 15-year Flow Discharge 240 220 200 180 160 140 120
Flow CapacityFlow(m3/s) 100 80 60 40 20
0
0
100
200
300
400
500
600
700
800
900
1,000
1,100
1,200
1,300
1,400 1,500
Distance from confluence of South Paranaque RIver (m) Figure 3.5.23 (2) Existing Flow Capacity of Dongalo River
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(c) South Paranaque River Design Scale:25-year ⚫ In the section upstream from 800 m, flow capacity is insufficient on both the left and right banks. in particular, flow capacity on the right bank side is low. ⚫ The existing flow capacity of Paranaque Spillway outlet site is about 100 m3/s.
South Paranaque River
South Paranaque River Existing Flow Capacity 800 Flow Capacity_Left Flow Capacity_Right Estimated 50-year Flow Discharge Estimated 25-year Flow Discharge 700 Estimated 15-year Flow Discharge
600
500
400
300 Flow CapacityFlow(m3/s)
200
100
0
0
200
400
600
800
1,000
1,200
1,400
1,600
1,800
2,000
2,200
2,400
2,600
2,800
3,000
3,200 3,400
Distance from Distance from confuluence point of Paranaque River (m)
Figure 3.5.23 (3) Existing Flow Capacity of South Paranaque River
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(d) Las Pinas River Design Scale:25-year ⚫ The right bank is below 25-year design discharge in almost all sections. This is thought to be due to the low moisture area being distributed from the downstream to the middle. ⚫ On the left bank, there are densely populated houses and there are sections where flow capacity is insufficient.
Las Pinas R.
Las Pinas River Existing Flow Capacity 260 Flow Capacity_Left Flow Capacity_Right 240 Estimated 50-year Flow Discharge Estimated 25-year Flow Discharge 220 Estimated 15-year Flow Discharge 200 180 160 140 120 100
Flow CapacityFlow(m3/s) 80 60 40 20
0
0
200
400
600
800
1,000
1,200
1,400
1,600
1,800
2,000
2,200
2,400
2,600
2,800
3,000
3,200
3,400
3,600
3,800
4,000
4,200
4,400
4,600
4,800 5,000
Distance from Manila Bay (m) Figure 3.5.23 (4) Existing Flow Capacity of Las Pinas River
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(e) Zapote River Design Scale:50-year ⚫ The flow capacity of Zapote river is also insufficient for almost 50-year design discharge. ⚫ On the downstream side of left bank side (up to 2.2 km from the downstream side), the current flow capacity is less than 100 m3/s, so there is a possibility that flooding damage may have occurred even with small rainfall. This is considered to be due to the densely populated illegal residents (ISFs) on the left bank side.
Existing Condition at 100m from river mouth Shot in February 2018
Zapote R.
Zapote River Existing Flow Capacity 800 Flow Capacity_Left Flow Capacity_Right Estimated 50-year Flow Discharge Estimated 25-year Flow Discharge 700 Estimated 15-year Flow Discharge
600
500
400
300 FlowCapacity (m3/s)
200
100
0
0
800 200 400 600
1,000 1,200 1,400 2,800 3,000 3,200 3,400 4,800 5,000 5,200 5,400 1,600 1,800 2,000 2,200 2,400 2,600 3,600 3,800 4,000 4,200 4,400 4,600
Distance from Manila Bay (m) Figure 3.5.23 (5) Existing Flow Capacity of Zapote River
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(3) Results of Examination for Flood Countermeasures by River Improvement
Due to the fact that houses are already densely populated in the Las Pinas- Paranaque district renovation by river channel widening is considered to be difficult, so this work is based on renovation with embankment as a basis. The required embankment height in each river was planned high water level + freeboard (= necessary embankment height).
(a) Paranaque River
The overall catchment area of Paranaque river basin is 41.3 km 2, the design scale is 50 years, and the height of embankment top elevation necessary for river restoration (in this work, only with renovation by embankment), the highest water level and flow rate per probability scale are summarized in the table below. The target area of Paranaque river is only area (6.4km2) where flow to Las Pinas – Paranaque area in this project.
Table 3.5.14 River Channel Specifications and Required Embankment Top Elevation Paranaque River
Existing River Profile Simulated Maximum Water Level (m) Simulated Maximum Discharge (m3/s) DHWL-GL* Required Acc.Dis Free Interval Right Bank No STA. No. tance River Left Right Left side Right board side Return Period Return Period Left side height Bed Bank Bank GL* side GL* (m) (m) (E.L.m) (E.L.m) (E.L.m) (E.L.m) (E.L.m) 100y 50-year 25-year 15-year 10-year 5-year 100y 50-year 25-year 15-year 10-year 5-year (m) (m) (m) (m) 1 PA_0+200 0 0 5.8 12.5 12.5 12.5 12.5 12.3 12.2 12.1 12.0 12.0 11.9 96.0 82.7 71.6 63.5 57.3 47.5 -0.3 -0.3 0.6 12.8 2 PA_0+400 200 200 7.8 12.5 12.5 12.5 12.5 12.3 12.2 12.1 12.0 12.0 11.9 95.6 83.6 72.2 64.0 57.7 47.7 -0.3 -0.3 0.6 12.8 3 PA_0+600 400 200 7.7 12.6 12.5 12.6 12.5 12.3 12.2 12.1 12.1 12.0 11.9 95.9 84.4 72.8 64.5 58.1 47.8 -0.4 -0.3 0.6 12.8 4 PA_0+800 600 200 8.4 14.0 12.5 14.0 12.5 12.4 12.2 12.1 12.1 12.0 11.9 97.0 85.2 73.3 64.9 58.4 47.9 -1.8 -0.3 0.6 12.8 5 PA_1+000 800 200 7.8 12.4 12.5 12.4 12.5 12.4 12.3 12.2 12.1 12.0 11.9 98.2 86.0 73.9 65.3 58.7 48.0 -0.1 -0.2 0.6 12.9 6 PA_1+200 1000 200 8.4 12.6 12.3 12.6 12.3 12.4 12.3 12.2 12.1 12.1 12.0 82.8 72.7 62.5 55.3 49.7 40.8 -0.3 -0.0 0.6 12.9 7 PA_1+400 1200 200 8.3 12.1 12.5 12.1 12.5 12.5 12.3 12.2 12.1 12.1 12.0 62.7 54.6 47.1 41.8 37.6 31.1 0.2 -0.2 0.6 12.9 8 PA_1+600 1400 200 8.4 12.5 12.5 12.5 12.5 12.5 12.3 12.2 12.1 12.1 12.0 44.5 38.3 32.6 28.5 25.5 21.4 -0.2 -0.2 0.6 12.9 9 PA_1+800 1600 200 8.4 12.5 12.5 12.5 12.5 12.5 12.3 12.2 12.1 12.1 12.0 26.3 22.7 19.3 16.9 15.1 11.9 -0.2 -0.2 0.6 12.9 10 PA_2+000 1800 200 8.3 12.7 12.3 12.8 12.3 12.5 12.3 12.2 12.1 12.1 12.0 9.5 7.8 6.3 5.3 4.7 3.7 -0.4 0.1 0.6 12.9 11 PA_2+200 2000 200 9.2 12.5 12.3 12.5 12.3 12.5 12.3 12.2 12.1 12.1 12.0 5.3 4.2 3.3 2.8 2.4 1.8 -0.1 0.0 0.6 12.9 12 PA_2+400 2200 200 9.8 12.7 12.6 12.7 12.6 12.5 12.3 12.2 12.1 12.1 12.0 4.4 3.6 2.9 2.4 2.1 1.6 -0.4 -0.2 0.6 12.9 13 PA_2+600 2400 200 10.0 12.6 12.4 12.6 12.5 12.5 12.3 12.2 12.1 12.1 12.0 3.6 2.9 2.4 2.1 1.8 1.5 -0.3 -0.1 0.6 12.9 14 PA_2+800 2600 200 9.2 12.6 12.3 12.6 12.3 12.5 12.3 12.2 12.1 12.1 12.0 2.6 2.2 1.9 1.7 1.5 1.3 -0.3 0.0 0.6 12.9 15 PA_3+000 2800 200 9.7 12.5 12.4 12.5 12.4 12.5 12.3 12.2 12.1 12.1 12.0 1.7 1.5 1.3 1.3 1.2 1.1 -0.2 -0.1 0.6 12.9
Paranaque River Longitudinal Profile River bed Left side Inland Elevation Right side Inland Elevation 50year_HWL 20 19 18 17 16 15 14 13 12 11
Elevation Elevation (E.L) 10 9 8 7 6
5
0
200
400
600
800
1,000
1,200
1,400
1,600
1,800
2,000
2,200
2,400
2,600 2,800 Distance from Infuluence point of South Paranaque River (m) Figure 3.5.24 Longitudinal Profile of Paranaque River (Return Period:50-year)
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(b) Dongalo River
The overall catchment area of Dongalo river basin is 15.5km 2, the design scale is 25 years, and the height of embankment top elevation necessary for river restoration (in this work, only with renovation by embankment), the highest water level and flow rate per probability scale are summarized in the table below. Table 3.5.15 River Channel Specifications and Required Embankment Top Elevation Dongalo River
Existing River Profile Simulated Maximum Water Level (m) Simulated Maximum Discharge (m3/s) DHWL-GL* Required Acc.Dis Free Interval Right Bank No STA. No. tance River Left Right Left side Right board side Return Period Return Period Left side height Bed Bank Bank GL* side GL* (m) (m) (E.L.m) (E.L.m) (E.L.m) (E.L.m) (E.L.m) 100y 50-year 25-year 15-year 10-year 5-year 100y 50-year 25-year 15-year 10-year 5-year (m) (m) (m) (m) 1 DO_0+010 10 10 8.4 12.0 13.5 12.0 15.4 13.0 12.8 12.6 12.5 12.4 12.0 242.9 210.4 179.4 158.0 141.8 25.6 0.6 -2.8 0.6 13.2 2 DO_0+050 50 40 8.8 12.0 13.5 12.0 14.6 13.1 12.8 12.6 12.5 12.4 12.0 243.1 210.6 179.5 158.1 141.9 25.6 0.6 -2.0 0.6 13.2 3 DO_0+090 90 40 8.9 12.0 13.5 12.0 16.3 13.1 12.8 12.6 12.5 12.4 12.0 243.4 210.9 179.8 158.3 142.1 25.6 0.6 -3.7 0.6 13.2 4 DO_0+130 130 40 9.0 12.0 13.4 12.0 13.5 13.1 12.8 12.6 12.5 12.4 12.0 243.8 211.2 180.1 158.6 142.3 25.7 0.6 -0.8 0.6 13.2 5 DO_0+170 170 40 8.8 11.8 13.5 11.8 13.5 13.1 12.9 12.6 12.5 12.4 12.1 244.1 211.5 180.3 158.8 142.5 25.8 0.9 -0.9 0.6 13.2 6 DO_0+210 210 40 9.0 12.0 13.5 12.0 13.5 13.1 12.9 12.6 12.5 12.4 12.1 244.5 211.8 180.6 159.0 142.7 25.9 0.6 -0.9 0.6 13.2 7 DO_0+250 250 40 9.1 12.0 13.5 12.8 13.5 13.1 12.9 12.7 12.5 12.4 12.1 243.9 211.3 180.2 158.6 142.3 25.5 -0.1 -0.8 0.6 13.3 8 DO_0+300 300 50 8.7 12.0 13.5 12.8 13.5 13.1 12.9 12.7 12.6 12.4 12.1 242.9 210.4 179.4 158.0 141.8 24.9 -0.1 -0.8 0.6 13.3 9 DO_0+340 340 40 9.1 13.9 13.5 13.9 13.5 13.1 12.9 12.7 12.6 12.4 12.1 241.8 209.5 178.7 157.3 141.1 24.4 -1.2 -0.8 0.6 13.3 10 DO_0+380 380 40 8.7 13.1 13.0 13.1 13.0 13.2 13.0 12.8 12.6 12.5 12.1 240.9 208.7 178.0 156.7 140.6 23.9 -0.3 -0.2 0.6 13.4 11 DO_0+420 420 40 8.8 13.6 13.5 13.6 13.5 13.2 13.0 12.8 12.6 12.5 12.1 240.0 207.9 177.3 156.1 140.1 23.4 -0.8 -0.7 0.6 13.4 12 DO_0+460 460 40 8.7 13.9 13.5 14.0 13.5 13.2 13.0 12.8 12.6 12.5 12.1 239.0 207.1 176.6 155.5 139.5 22.8 -1.2 -0.7 0.6 13.4 13 DO_0+500 500 40 8.7 12.0 12.0 12.0 12.0 13.3 13.0 12.8 12.7 12.5 12.1 238.1 206.3 175.9 154.9 139.0 22.3 0.8 0.8 0.6 13.4 14 DO_0+540 540 40 8.4 12.1 12.1 12.1 12.4 13.2 13.0 12.8 12.7 12.5 12.1 237.2 205.5 175.3 154.3 138.4 21.8 0.7 0.5 0.6 13.4 15 DO_0+580 580 40 9.0 12.2 12.0 12.2 12.0 13.3 13.1 12.8 12.7 12.6 12.1 236.2 204.7 174.5 153.6 137.9 21.3 0.6 0.8 0.6 13.4 16 DO_0+620 620 40 9.2 12.4 11.6 12.4 11.6 13.3 13.1 12.9 12.7 12.6 12.1 235.2 203.8 173.8 153.0 137.3 20.8 0.5 1.2 0.6 13.5 17 DO_0+660 660 40 9.3 13.5 12.0 13.5 12.5 13.4 13.1 12.9 12.7 12.6 12.1 234.2 203.0 173.1 152.4 136.8 20.3 -0.6 0.4 0.6 13.5 18 DO_0+700 700 40 8.6 12.4 11.9 12.4 11.9 13.3 13.1 12.9 12.7 12.6 12.1 233.3 202.2 172.4 151.8 136.2 19.8 0.5 1.0 0.6 13.5 19 DO_0+780 780 80 9.2 12.0 11.8 12.0 11.8 13.5 13.3 13.1 12.9 12.7 12.1 231.8 200.9 171.4 150.8 135.4 19.0 1.0 1.3 0.6 13.7 20 DO_0+820 820 40 9.1 11.7 11.7 11.7 11.7 13.5 13.3 13.1 12.9 12.8 12.1 230.4 199.7 170.4 150.0 134.6 18.2 1.3 1.3 0.6 13.7 21 DO_0+860 860 40 9.0 11.9 11.6 11.9 12.6 13.6 13.4 13.1 13.0 12.8 12.1 229.4 198.9 169.7 149.4 134.1 17.7 1.3 0.5 0.6 13.7 22 DO_0+900 900 40 9.1 11.8 11.7 11.8 12.3 13.6 13.4 13.1 13.0 12.8 12.1 228.5 198.1 169.0 148.8 133.5 17.2 1.3 0.9 0.6 13.7 23 DO_0+940 940 40 8.5 11.8 12.5 11.8 12.5 13.7 13.4 13.2 13.0 12.9 12.1 227.5 197.2 168.3 148.2 133.0 16.7 1.4 0.7 0.6 13.8 24 DO_0+980 980 40 9.9 11.7 12.8 11.7 12.8 13.7 13.4 13.2 13.0 12.9 12.1 226.5 196.4 167.6 147.6 132.5 16.2 1.5 0.4 0.6 13.8 25 DO_1+020 1020 40 9.8 11.7 12.9 11.7 12.9 13.7 13.5 13.2 13.1 12.9 12.1 225.6 195.6 166.9 147.0 131.9 15.7 1.5 0.3 0.6 13.8 26 DO_1+060 1060 40 9.6 12.0 12.9 12.0 12.9 13.8 13.5 13.3 13.1 13.0 12.1 224.6 194.7 166.2 146.4 131.3 15.2 1.3 0.4 0.6 13.9 27 DO_1+100 1100 40 9.6 10.6 12.8 11.6 12.8 13.7 13.4 13.2 13.1 12.9 12.1 223.6 193.9 165.5 145.7 130.8 14.7 1.6 0.4 0.6 13.8 28 DO_1+140 1140 40 9.1 12.1 13.4 13.3 13.4 13.8 13.6 13.4 13.2 13.1 12.1 222.5 193.0 164.7 145.1 130.2 14.1 0.0 -0.0 0.6 14.0 29 DO_1+180 1180 40 9.1 12.2 12.0 12.3 12.2 14.0 13.7 13.5 13.3 13.2 12.1 221.5 192.0 164.0 144.4 129.6 13.6 1.1 1.3 0.6 14.1 30 DO_1+220 1220 40 9.0 12.0 12.7 12.0 12.7 14.0 13.8 13.5 13.3 13.2 12.1 220.4 191.2 163.2 143.7 129.0 13.1 1.6 0.8 0.6 14.1 31 DO_1+260 1260 40 8.5 11.0 12.3 11.7 12.3 14.0 13.8 13.5 13.3 13.2 12.1 219.4 190.3 162.4 143.1 128.4 12.5 1.8 1.3 0.6 14.1 32 DO_1+300 1300 40 9.0 12.5 12.0 12.5 12.4 14.2 13.9 13.7 13.4 13.3 12.1 218.3 189.3 161.7 142.4 127.8 12.0 1.2 1.2 0.6 14.3 33 DO_1+340 1340 40 9.3 13.1 12.1 14.1 12.2 14.3 14.0 13.8 13.6 13.4 12.1 217.2 188.4 160.9 141.7 127.2 11.5 -0.3 1.6 0.6 14.4 34 DO_1+380 1380 40 9.6 13.1 14.1 13.1 14.1 14.5 14.2 13.9 13.7 13.5 12.1 216.1 187.4 160.1 141.0 126.6 10.9 0.9 -0.2 0.6 14.5 35 DO_1+420 1420 40 10.1 12.1 13.4 13.8 13.4 14.5 14.2 14.0 13.8 13.6 12.1 215.0 186.5 159.3 140.4 126.0 10.4 0.2 0.5 0.6 14.6 36 DO_1+460 1460 40 9.2 12.3 13.1 12.3 13.1 14.6 14.4 14.1 13.9 13.7 12.1 214.0 185.6 158.6 139.7 125.4 9.9 1.8 1.0 0.6 14.7 37 DO_1+500 1500 40 9.2 12.5 12.7 12.9 12.7 14.8 14.5 14.2 14.0 13.8 12.1 212.9 184.7 157.8 139.0 124.8 9.3 1.3 1.5 0.6 14.8 38 DO_1+540 1540 40 9.2 12.6 12.6 13.0 12.6 14.9 14.6 14.3 14.1 13.9 12.1 211.8 183.8 157.0 138.3 124.2 8.8 1.3 1.7 0.6 14.9 39 DO_1+580 1580 40 9.7 12.4 12.2 12.4 12.2 14.9 14.6 14.3 14.1 13.9 12.1 210.7 182.8 156.2 137.6 123.6 8.2 2.0 2.2 0.6 14.9 40 DO_1+620 1620 40 9.5 13.0 12.6 13.0 12.6 15.1 14.8 14.5 14.3 14.1 12.1 209.6 181.9 155.4 137.0 123.0 7.7 1.5 1.9 0.6 15.1 41 DO_1+660 1660 40 9.9 13.3 13.5 13.3 13.5 15.2 14.9 14.5 14.3 14.1 12.1 208.6 181.0 154.7 136.3 122.5 7.2 1.3 1.1 0.6 15.1 42 DO_1+700 1700 40 10.1 13.5 13.6 13.5 13.6 15.2 14.9 14.6 14.3 14.1 12.1 207.6 180.1 154.0 135.7 121.9 6.6 1.1 1.0 0.6 15.2 43 DO_1+740 1740 40 10.1 12.7 13.3 12.7 13.3 15.4 15.1 14.7 14.5 14.3 12.1 206.6 179.3 153.3 135.1 121.3 6.1 2.0 1.4 0.6 15.3 44 DO_2+000 2000 260 11.0 14.0 14.0 14.0 14.0 15.5 15.2 14.9 14.6 14.4 12.1 201.0 174.5 149.4 131.7 118.4 3.3 0.9 0.9 0.6 15.5 45 DO_2+100 2100 100 11.2 14.0 14.0 14.0 14.0 15.6 15.3 14.9 14.7 14.5 12.1 198.6 172.5 147.7 130.3 117.1 2.5 0.9 0.9 0.6 15.5 46 DO_2+200 2200 100 11.4 14.0 14.0 14.0 14.0 15.6 15.3 15.0 14.8 14.6 12.1 196.1 170.3 145.9 128.7 115.8 1.7 1.0 1.0 0.6 15.6 47 DO_2+300 2300 100 11.6 14.0 14.0 14.0 14.6 15.7 15.4 15.1 14.9 14.7 12.1 193.5 168.2 144.1 127.2 114.4 0.8 1.1 0.5 0.6 15.7 48 DO_2+400 2400 100 11.8 14.0 14.0 14.8 14.3 15.8 15.5 15.2 14.9 14.8 12.1 191.0 166.0 142.3 125.6 113.0 0.2 0.4 0.9 0.6 15.8 49 DO_2+500 2500 100 12.0 14.0 14.0 14.0 15.2 15.9 15.6 15.3 15.0 14.8 12.0 190.0 165.2 141.6 125.0 112.5 0.0 1.3 0.1 0.6 15.9
Dongalo River Longitudinal Profile River Bed Left side inland elevation Right Side Inland Elevation 25y_HWL Estimate Dike Elevation 18 17 16 15 14 13 12 11 Elevation Elevation (E.L) 10 9 8 7 6
5
0
100
200
300
400
500
600
700
800
900
1,000
1,100
1,200
1,300
1,400
1,500
1,600
1,700
1,800
1,900
2,000
2,100
2,200
2,300
2,400 2,500 Distance from influence point of South Paranaque River (m) Figure 3.5.25 Longitudinal Profile of Dongalo River (Return Period:25-year)
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(c) South Paranaque River
The overall catchment area of South Paranaque river basin is 28.3km 2, the design scale is 25 years, and the height of embankment top elevation necessary for river restoration (in this work, only with renovation by embankment), the highest water level and flow rate per probability scale are summarized in the table below. Table 3.5.16 River Channel Specifications and Required Embankment Top Elevation South Paranaque River
Existing River Profile Simulated Maximum Water Level (m) Simulated Maximum Discharge (m3/s) DHWL-GL* Required Acc.Dist Free Interval Bank No STA. No. ance Left side Right side Right board River Bed Left Bank Right Bank Return Period Return Period Left side height GL* GL* side
(m) (m) (E.L.m) (E.L.m) (E.L.m) (E.L.m) (E.L.m) 100 50 25 15 10 5 2 100 50 25 15 10 5 2 (m) (m) (m) (m) 1 SP_0+80 80 80 6.99 12.5 12.5 12.5 12.5 12.4 12.2 12.1 12.1 12.0 11.9 11.9 712.4 617.4 527.0 463.3 414.8 245.2 162.2 -0.4 -0.4 1.0 13.1 2 SP_0+100 100 20 7.03 12.5 12.5 12.5 12.5 12.4 12.3 12.2 12.1 12.1 11.9 11.9 712.4 617.4 527.0 463.3 414.8 245.2 162.3 -0.3 -0.3 1.0 13.2 3 SP_0+200 200 100 7.21 12.5 12.5 12.5 12.5 12.7 12.5 12.3 12.2 12.2 12.0 11.9 712.3 617.3 527.0 463.3 414.7 245.2 162.2 -0.2 -0.2 1.0 13.3 4 SP_0+300 300 100 7.39 12.5 12.5 12.5 12.5 12.9 12.7 12.5 12.4 12.3 12.0 11.9 712.1 617.2 526.9 463.2 414.7 245.2 162.2 0.0 0.0 1.0 13.5 5 SP_0+380 380 80 7.54 12.5 12.5 12.5 13.4 13.0 12.8 12.6 12.4 12.3 12.0 11.9 712.0 617.1 526.8 463.1 414.7 245.2 162.2 0.1 -0.8 1.0 13.6 6 SP_0+500 500 120 8.21 13.0 13.0 13.0 13.5 13.1 12.8 12.6 12.5 12.4 12.1 12.0 481.2 416.2 354.3 310.4 277.1 222.7 148.2 -0.4 -0.9 0.8 13.4 7 SP_0+600 600 100 8.37 13.0 13.0 13.0 13.0 13.2 12.9 12.7 12.5 12.4 12.1 12.0 481.1 416.1 354.2 310.4 277.1 222.7 148.2 -0.3 -0.3 0.8 13.5 8 SP_0+700 700 100 8.42 13.0 13.0 13.0 13.0 13.4 13.1 12.9 12.7 12.6 12.2 12.0 480.5 415.6 353.8 310.1 276.8 222.6 148.0 -0.1 -0.1 0.8 13.7 9 SP_0+800 800 100 9.06 13.0 13.0 13.0 13.0 13.5 13.3 13.0 12.8 12.6 12.3 12.1 479.7 415.0 353.3 309.6 276.4 222.3 147.8 0.0 0.0 0.8 13.8 10 SP_0+900 900 100 8.42 11.2 12.7 11.4 12.7 13.5 13.3 13.0 12.8 12.7 12.3 12.1 373.5 322.7 274.4 240.6 214.8 171.3 113.2 1.6 0.3 0.8 13.8 11 SP_1+0 1000 100 7.32 11.8 12.3 11.8 12.3 13.6 13.4 13.1 12.9 12.8 12.4 12.1 372.5 321.8 273.7 240.0 214.3 171.0 113.0 1.3 0.8 0.8 13.9 12 SP_1+100 1100 100 8.62 13.9 13.2 13.9 13.2 13.8 13.5 13.3 13.0 12.9 12.5 12.2 371.6 321.0 273.1 239.5 213.8 170.6 112.7 -0.6 0.1 0.8 14.1 13 SP_1+200 1200 100 9.52 13.4 12.3 13.5 12.3 13.9 13.6 13.3 13.1 12.9 12.6 12.2 370.6 320.2 272.4 238.9 213.4 170.3 112.5 -0.1 1.0 0.8 14.1 14 SP_1+300 1300 100 8.00 13.6 11.7 13.6 11.9 14.2 13.9 13.6 13.4 13.2 12.8 12.4 369.7 319.4 271.8 238.4 212.9 169.9 112.2 -0.0 1.7 0.8 14.4 15 SP_1+400 1400 100 9.51 13.9 12.3 13.9 12.3 14.3 14.0 13.7 13.4 13.2 12.9 12.4 368.7 318.6 271.1 237.8 212.4 169.6 111.9 -0.2 1.4 0.8 14.5 16 SP_1+500 1500 100 8.38 13.4 12.5 13.4 12.5 14.3 14.0 13.7 13.5 13.3 12.9 12.5 367.7 317.8 270.4 237.3 212.0 169.3 111.7 0.4 1.2 0.8 14.5 17 SP_1+600 1600 100 9.29 13.5 13.1 13.5 13.1 14.7 14.4 14.0 13.8 13.6 13.2 12.7 366.8 317.0 269.8 236.7 211.5 168.9 111.4 0.5 0.9 0.8 14.8 18 SP_1+700 1700 100 9.41 13.5 13.9 13.5 13.9 14.6 14.4 14.1 13.8 13.6 13.2 12.7 365.8 316.2 269.1 236.2 211.0 168.6 111.1 0.6 0.2 0.8 14.9 19 SP_1+800 1800 100 8.83 13.2 13.0 13.4 13.4 15.0 14.7 14.4 14.1 13.9 13.5 12.9 364.9 315.4 268.5 235.6 210.5 168.3 110.9 1.0 1.0 0.8 15.2 20 SP_1+900 1900 100 8.15 13.4 12.7 13.4 14.3 15.2 14.9 14.5 14.3 14.1 13.6 13.0 363.9 314.6 267.8 235.1 210.1 167.9 110.6 1.1 0.2 0.8 15.3 21 SP_2+0 2000 100 9.37 12.7 12.8 12.9 13.8 15.2 14.9 14.5 14.3 14.0 13.6 13.0 362.9 313.8 267.1 234.5 209.6 167.6 110.3 1.6 0.7 0.8 15.3 22 SP_2+100 2100 100 8.99 12.8 12.8 14.2 13.0 15.3 15.0 14.6 14.4 14.1 13.7 13.1 362.0 313.0 266.5 233.9 209.1 167.3 110.0 0.4 1.6 0.8 15.4 23 SP_2+200 2200 100 9.61 12.8 13.1 12.8 13.1 15.4 15.0 14.7 14.4 14.2 13.8 13.1 361.0 312.2 265.8 233.4 208.6 166.9 109.8 1.9 1.6 0.8 15.5 24 SP_2+300 2300 100 9.00 13.1 13.0 13.5 13.0 15.4 15.0 14.7 14.4 14.2 13.8 13.2 360.2 311.4 265.2 232.9 208.2 166.6 109.7 1.2 1.7 0.8 15.5 25 SP_2+400 2400 100 9.10 13.0 13.5 13.0 13.6 15.5 15.2 14.8 14.6 14.4 14.0 13.4 319.8 276.6 235.7 206.9 185.0 147.9 97.4 1.8 1.2 0.8 15.6 26 SP_2+500 2500 100 9.28 13.3 14.0 13.4 14.0 15.8 15.5 15.2 14.9 14.7 14.3 13.6 318.9 275.8 235.0 206.3 184.5 147.6 97.2 1.9 1.2 0.8 16.0 27 SP_2+600 2600 100 9.50 14.0 14.0 14.0 14.0 15.9 15.6 15.2 15.0 14.7 14.3 13.7 317.9 275.0 234.3 205.8 184.0 147.2 96.9 1.2 1.2 0.8 16.0 28 SP_2+700 2700 100 9.25 14.0 14.0 14.0 14.0 16.0 15.7 15.4 15.1 14.9 14.5 13.8 317.0 274.2 233.6 205.2 183.5 146.9 96.7 1.4 1.4 0.8 16.2 29 SP_2+800 2800 100 9.22 14.0 14.0 14.0 14.0 16.0 15.7 15.4 15.1 14.9 14.5 13.9 316.0 273.4 233.0 204.6 183.0 146.5 96.5 1.4 1.4 0.8 16.2 30 SP_2+900 2900 100 9.70 14.0 14.0 14.0 14.0 16.4 16.0 15.7 15.4 15.2 14.7 14.0 315.1 272.6 232.3 204.0 182.5 146.1 96.4 1.7 1.7 0.8 16.5 31 SP_3+0 3000 100 10.53 13.5 13.5 13.5 13.6 16.2 15.9 15.6 15.3 15.1 14.7 14.0 314.1 271.8 231.6 203.5 182.0 145.8 96.2 2.1 2.0 0.8 16.4 32 SP_3+100 3100 100 11.14 13.5 13.9 13.5 13.9 16.4 16.0 15.7 15.4 15.2 14.8 14.1 313.2 271.0 231.0 202.9 181.5 145.4 96.0 2.2 1.8 0.8 16.5 33 SP_3+200 3200 100 10.55 13.5 13.0 13.5 13.5 16.7 16.4 16.0 15.7 15.5 15.0 14.4 312.2 270.1 230.3 202.3 181.0 145.0 95.8 2.5 2.5 0.8 16.8 34 SP_3+300 3300 100 10.49 14.0 14.0 14.0 14.1 16.9 16.5 16.1 15.8 15.6 15.2 14.5 311.3 269.3 229.6 201.7 180.5 144.6 95.7 2.1 2.0 0.8 16.9 35 SP_3+400 3400 100 10.47 14.0 14.0 14.0 14.0 17.1 16.7 16.3 16.0 15.8 15.3 14.6 310.3 268.5 228.9 201.2 180.0 144.3 95.5 2.3 2.3 0.8 17.1 36 SP_3+500 3500 100 10.74 14.0 14.0 14.2 14.3 17.1 16.7 16.3 16.0 15.8 15.3 14.6 309.3 267.7 228.2 200.6 179.5 143.9 95.4 2.1 2.0 0.8 17.1 37 SP_3+600 3600 100 10.65 14.0 14.0 14.0 14.0 17.3 16.9 16.4 16.1 15.9 15.4 14.6 309.3 267.7 228.2 200.6 179.5 143.9 95.4 2.4 2.4 0.8 17.2
River Bed Left Side Inland Elevation South Paranaque River Longitudinal Profile Right Side Inland Elevation 25y_HWL Estimate Dike Elevation 20 19 Baloc Creek 18 17 San Dionisio 16 Dongalo.R 15 14 13 12 Elevation Elevation (E.L) 11 10 9 8 7 6
5
0
500
1,500 3,000 1,000 2,000 2,500 3,500 Distance from confuluence point of Paranaque River (m) Figure 3.5.26 Longitudinal Profile of South Paranaque River (Return Period:25-year)
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Table 3.5.17 River Channel Specifications and Required Embankment Top Elevation San Felipe River
Existing River Profile Simulated Maximum Water Level (m) Simulated Maximum Discharge (m3/s) DHWL-GL* Required Acc.Dis Free Interval Right Bank No STA. No. tance River Left Right Left side Right board side Return Period Return Period Left side height Bed Bank Bank GL* side GL* (m) (m) (E.L.m) (E.L.m) (E.L.m) (E.L.m) (E.L.m) 100 50 25 15 10 5 100 50 25 15 10 5 (m) (m) (m) (m) 1 SF_0+000 0 0 10.6 12.6 13.0 12.7 13.0 17.3 16.9 16.4 16.1 15.9 15.4 197.5 170.8 145.4 127.6 114.1 91.3 3.8 3.4 0.6 17.5 2 SF_0+400 400 400 10.6 13.6 13.1 14.2 14.2 17.3 16.9 16.4 16.1 15.9 15.4 192.0 166.0 141.4 124.2 111.2 89.1 2.3 2.3 0.6 17.5 3 SF_0+600 600 200 10.7 14.0 13.4 14.2 13.9 17.3 16.9 16.5 16.2 15.9 15.4 188.3 162.9 138.9 122.0 109.2 87.7 2.3 2.6 0.6 17.5 4 SF_0+800 800 200 11.1 14.7 14.0 14.7 14.0 17.3 16.9 16.5 16.2 15.9 15.4 184.7 159.8 136.3 119.8 107.3 86.2 1.8 2.5 0.6 17.5 5 SF_1+000 1000 200 12.2 15.8 13.8 15.9 14.4 17.2 16.9 16.5 16.2 16.0 15.6 181.1 156.8 133.7 117.6 105.3 84.7 0.6 2.1 0.6 17.5 6 SF_1+200 1200 200 11.9 15.9 16.0 15.9 16.0 17.6 17.2 16.8 16.6 16.4 16.0 177.6 153.8 131.2 115.4 103.4 83.2 0.9 0.8 0.6 17.8 7 SF_1+400 1400 200 11.8 15.5 15.3 15.5 15.3 17.7 17.4 17.0 16.7 16.5 16.2 174.2 150.8 128.7 113.2 101.5 81.7 1.5 1.7 0.6 18.0 8 SF_1+600 1600 200 12.3 16.0 16.0 16.0 16.8 17.8 17.4 17.0 16.8 16.6 16.3 170.7 147.8 126.2 111.0 99.5 80.2 1.1 0.3 0.6 18.0 9 SF_1+800 1800 200 12.8 15.4 15.7 15.4 15.7 17.9 17.6 17.3 17.0 16.8 16.5 167.3 144.9 123.7 108.8 97.6 78.6 1.9 1.5 0.6 18.2 10 SF_2+000 2000 200 13.9 15.4 16.8 15.4 16.8 18.1 17.8 17.4 17.2 17.0 16.6 164.9 142.5 121.3 106.6 95.6 77.1 2.0 0.6 0.6 18.4 11 SF_2+200 2200 200 13.6 17.3 17.2 17.3 17.2 18.4 18.0 17.6 17.4 17.2 16.9 1.3 1.3 1.3 1.2 1.2 1.2 0.4 0.5 0.6 18.6 River Bed Left Side Inland Elevation San Felipe River Longitudinal Profile Right Side Inland Elevation 25y_HWL Estimate Dike Elevation 22 21 20 19 18 17 16 15
14 Elevation Elevation (E.L) 13 12 11 10 9
8
0
200
400
600
800
1,000
1,200
1,400
1,600
1,800
2,000 2,200 Distance from Confluence poitn of South Paranaque River (m) Figure 3.5.27 Longitudinal Profile of San Felie River (Return Period:25-year)
Table 3.5.18 River Channel Specifications and Required Embankment Top Elevation Right Tributary
Existing River Profile Simulated Maximum Water Level (m) Simulated Maximum Discharge (m3/s) DHWL-GL* Required Acc.Dis Free Interval Right Bank No tance River Left Right Left side Right board side Return Period Return Period Left side height Bed Bank Bank GL* side GL* (m) (m) (E.L.m) (E.L.m) (E.L.m) (E.L.m) (E.L.m) 100 50 25 15 10 5 100 50 25 15 10 5 (m) (m) (m) (m) 1 0 0 10.5 14.0 14.0 14.0 14.0 17.3 16.9 16.4 16.1 15.9 15.4 109.7 95.1 81.4 71.7 64.3 51.9 2.4 2.4 0.6 17.0 2 200 200 11.1 14.1 13.6 14.1 13.6 17.3 16.9 16.4 16.1 15.9 15.4 108.6 94.2 80.6 71.1 63.8 51.5 2.3 2.8 0.6 17.0 3 400 200 11.2 13.8 12.6 13.8 13.8 17.3 16.9 16.5 16.1 15.9 15.4 106.9 92.4 79.1 69.8 62.7 50.7 2.7 2.6 0.6 17.1 4 600 200 11.4 14.2 13.9 14.2 13.9 17.3 16.9 16.5 16.1 15.9 15.4 106.5 92.2 78.3 68.7 61.5 49.9 2.3 2.6 0.6 17.1 5 800 200 12.5 14.9 14.7 14.9 14.9 17.3 16.9 16.5 16.2 15.9 15.4 106.3 92.1 78.4 69.1 61.9 49.7 1.6 1.5 0.6 17.1 6 1000 200 12.1 14.7 14.7 14.7 15.8 17.3 16.9 16.5 16.2 16.0 15.5 105.9 92.0 78.5 69.3 62.2 50.2 1.9 0.7 0.6 17.1 7 1200 200 12.2 17.1 14.0 17.1 14.0 17.3 16.9 16.5 16.2 16.0 15.6 105.3 91.6 78.2 69.2 62.2 50.1 -0.6 2.5 0.6 17.1 8 1400 200 12.8 15.1 16.0 16.7 16.4 17.4 17.0 16.7 16.4 16.2 15.8 104.2 90.7 77.5 68.5 61.6 49.6 0.0 0.3 0.6 17.3 9 1600 200 12.8 15.5 16.1 17.5 17.6 17.5 17.2 16.8 16.6 16.4 16.1 103.1 89.8 76.8 67.9 61.1 49.2 -0.6 -0.7 0.6 17.4 10 1800 200 13.4 16.3 16.3 16.6 16.6 17.7 17.3 17.0 16.8 16.6 16.3 102.0 88.8 76.0 67.2 60.4 48.7 0.4 0.4 0.6 17.6 11 2000 200 14.4 18.4 17.9 18.4 17.9 17.9 17.7 17.4 17.3 17.2 16.9 101.2 88.1 75.3 66.5 59.8 48.3 -0.9 -0.5 0.6 18.0 12 2200 200 14.7 17.0 17.9 18.2 18.5 18.4 18.1 17.9 17.7 17.6 17.3 2.1 1.8 1.7 1.6 1.6 1.5 -0.3 -0.6 0.6 18.5 River Bed Left Side Inland Elevation Longitudinal Profile Right Side Inland Elevation 25y_HWL Estimate Dike Elevation 20 19 18 17 16 15 14 13 Elevation Elevation (E.L) 12 11 10 9
8
0
200 400 600 800
1,000 1,200 1,400 1,600 1,800 2,000 2,200 Distance from Confluence poitn of South Paranaque River (m) Figure 3.5.28 Longitudinal Profile of Right Tributary (Return Period:25-year)
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(d) Las Pinas River
The overall catchment area of South Paranaque river basin is 14.6km 2, the design scale is 25 years, and the height of embankment top elevation necessary for river restoration (in this work, only with renovation by embankment), the highest water level and flow rate per probability scale are summarized in the table below.
Table 3.5.19 River Channel Specifications and Required Embankment Top Elevation Las Pinas River
Existing River Profile Simulated Maximum Water Level (m) Simulated Maximum Discharge (m3/s) DHWL-GL* Required Acc.Dis Free Interval Right Bank No STA. No. tance River Left Right Left side Right board side Return Period Return Period Left side height Bed Bank Bank GL* side GL* (m) (m) (E.L.m) (E.L.m) (E.L.m) (E.L.m) (E.L.m) 100 50 25 15 10 5 2 100 50 25 15 10 5 2 (m) (m) (m) (m) 1 LA_0+000 0 0 9.4 13.0 11.1 13.0 12.5 11.9 11.9 11.9 11.9 11.9 11.9 11.9 87.6 70.6 55.2 45.5 38.8 27.8 16.9 -1.2 -0.6 0.6 12.5 2 LA_0+200 200 200 9.5 12.9 11.8 12.9 11.8 12.0 12.0 11.9 11.9 11.9 11.9 11.9 87.6 70.6 55.2 45.5 38.8 27.8 16.9 -1.0 0.2 0.6 12.5 3 LA_0+400 400 200 9.5 13.8 11.8 14.2 12.7 12.2 12.1 12.0 12.0 11.9 11.9 11.9 87.6 70.6 55.2 45.5 38.8 27.8 16.9 -2.2 -0.7 0.6 12.6 4 LA_0+600 600 200 9.4 14.8 11.1 14.8 12.6 12.5 12.3 12.2 12.1 12.0 12.0 11.9 84.2 67.6 53.2 43.8 37.3 26.5 16.1 -2.6 -0.4 0.6 12.8 5 LA_0+800 800 200 9.6 12.9 12.3 12.9 12.4 12.8 12.6 12.4 12.3 12.2 12.1 11.9 80.5 65.0 51.0 41.9 35.6 25.0 15.1 -0.5 0.1 0.6 13.0 6 LA_1+000 1000 200 10.0 13.6 13.5 13.6 13.5 13.3 13.1 12.8 12.6 12.5 12.3 12.1 119.9 100.8 83.2 71.5 62.7 46.5 29.7 -0.8 -0.6 0.6 13.4 7 LA_1+200 1200 200 10.0 12.6 12.5 12.6 12.9 13.4 13.2 12.9 12.7 12.6 12.4 12.1 115.9 97.4 80.3 69.0 60.6 44.9 28.7 0.3 -0.0 0.6 13.5 8 LA_1+400 1400 200 9.5 13.3 12.7 13.7 12.7 13.6 13.3 13.1 12.9 12.7 12.5 12.2 111.9 94.0 77.5 66.6 58.5 43.2 27.8 -0.6 0.4 0.6 13.7 9 LA_1+600 1600 200 9.0 13.2 13.1 13.2 13.8 13.7 13.5 13.2 13.0 12.9 12.6 12.3 107.8 90.6 74.7 64.2 56.3 41.6 26.9 0.1 -0.5 0.6 13.8 10 LA_1+800 1800 200 9.6 11.9 12.3 12.6 13.2 14.0 13.7 13.4 13.2 13.0 12.7 12.3 173.5 149.5 126.7 110.7 98.6 78.3 51.0 0.8 0.3 0.6 14.0 11 LA_2+000 2000 200 8.9 14.3 12.8 14.3 12.8 14.2 14.0 13.7 13.5 13.3 13.0 12.5 169.7 146.2 123.9 108.3 96.5 76.7 50.0 -0.6 0.9 0.6 14.3 12 LA_2+200 2200 200 9.4 14.2 11.6 14.2 11.9 14.4 14.1 13.8 13.6 13.4 13.1 12.6 169.0 145.7 123.5 108.0 96.2 76.5 50.0 -0.4 1.9 0.6 14.4 13 LA_2+400 2400 200 9.6 14.2 12.7 14.2 13.5 14.6 14.3 14.0 13.7 13.5 13.2 12.7 168.9 145.6 123.5 108.0 96.3 76.6 50.0 -0.3 0.4 0.6 14.6 14 LA_2+600 2600 200 9.5 13.0 12.4 13.0 12.8 14.8 14.5 14.1 13.9 13.7 13.3 12.8 168.7 145.5 123.4 108.0 96.2 76.6 50.1 1.1 1.4 0.6 14.7 15 LA_2+800 2800 200 9.7 13.2 13.8 13.2 13.8 14.9 14.5 14.2 14.0 13.8 13.4 12.9 143.2 123.7 105.1 92.1 82.3 65.7 43.5 1.0 0.5 0.6 14.8 16 LA_3+000 3000 200 9.7 14.2 13.5 14.2 13.5 14.9 14.6 14.3 14.0 13.8 13.5 12.9 143.0 123.5 105.0 92.1 82.2 65.7 43.5 0.1 0.7 0.6 14.9 17 LA_3+200 3200 200 9.5 14.0 13.4 14.0 13.4 15.0 14.7 14.4 14.1 13.9 13.6 13.0 142.8 123.4 104.9 92.0 82.2 65.7 43.6 0.3 0.9 0.6 15.0 18 LA_3+400 3400 200 9.7 12.7 12.8 12.7 12.8 15.0 14.7 14.4 14.1 13.9 13.6 13.0 142.7 123.3 104.9 92.0 82.2 65.7 43.6 1.7 1.6 0.6 15.0 19 LA_3+600 3600 200 9.2 10.9 11.7 11.9 11.7 15.2 14.9 14.6 14.3 14.1 13.8 13.2 142.6 123.2 104.8 92.0 82.2 65.7 43.6 2.7 2.8 0.6 15.2 20 LA_3+800 3800 200 10.3 13.7 14.0 13.7 14.0 15.4 15.1 14.8 14.5 14.3 13.9 13.3 139.6 120.7 102.7 90.1 80.5 64.5 42.9 1.1 0.8 0.6 15.4 21 LA_4+000 4000 200 10.7 15.7 15.8 15.7 15.8 15.6 15.3 14.9 14.7 14.4 14.0 13.4 135.5 117.2 99.8 87.7 78.4 62.9 42.0 -0.8 -0.9 0.6 15.5 22 LA_4+200 4200 200 10.7 14.5 14.5 14.5 14.5 15.9 15.5 15.2 14.9 14.7 14.3 13.6 131.8 113.8 97.0 85.2 76.3 61.2 41.0 0.7 0.6 0.6 15.8 23 LA_4+400 4400 200 10.7 13.2 13.8 13.4 13.8 16.1 15.8 15.4 15.1 14.9 14.5 13.9 128.4 110.6 94.1 82.7 74.1 59.6 40.0 2.1 1.6 0.6 16.0 24 LA_4+600 4600 200 10.0 13.3 14.5 14.6 14.5 16.4 16.0 15.7 15.4 15.1 14.7 14.1 125.2 108.0 91.6 80.3 71.9 57.9 39.0 1.1 1.1 0.6 16.3 25 LA_4+800 4800 200 11.3 14.9 16.7 15.4 16.7 16.4 16.1 15.7 15.4 15.2 14.8 14.2 122.5 105.8 90.0 78.9 70.5 56.5 38.0 0.3 -1.0 0.6 16.3 26 LA_5+000 5000 200 11.5 15.9 15.2 16.0 16.0 16.7 16.3 16.0 15.7 15.5 15.0 14.4 119.4 103.3 88.0 77.3 69.2 55.6 37.3 -0.1 -0.1 0.6 16.6
River Bed Left Side Inland Elevation Las Pinas River Longitudinal Profile Right Side Inland Elevation 25y_HWL Estimate Dike Elevation 20 19 18 Laspinas-Zapote Channel 17 16 15 14 13 12
Elevation Elevation (E.L) 11 10 9 8 7 6
5
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500 5,000 Distance from River Mouth (m) Figure 3.5.29 Longitudinal Profile of Las Pinas River (Return Period:25-year)
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Data Collection Survey on Parañaque Spillway in Metro Manila in the Republic of the Philippines Final Report
(e) Zapote River
The overall catchment area of Zapote river basin is 50.3km 2, the design scale is 50 years, and the height of embankment top elevation necessary for river restoration (in this work, only with renovation by embankment), the highest water level and flow rate per probability scale are summarized in the table below.
Table 3.5.20 River Channel Specifications and Required Embankment Top Elevation Zapote River
Existing River Profile Simulated Maximum Water Level (m) Simulated Maximum Discharge (m3/s) DHWL-GL* Required Acc.Dis Free Interval Right Bank No STA. No. tance River Left Right Left side Right board side Return Period Return Period Left side height Bed Bank Bank GL* side GL* (m) (m) (E.L.m) (E.L.m) (E.L.m) (E.L.m) (E.L.m) 100 50 25 15 10 5 2 100 50 25 15 10 5 2 (m) (m) (m) (m) 1 ZA_0+000 0 0 6.9 13.5 13.0 13.5 13.1 11.9 11.9 11.9 11.9 11.9 11.9 11.9 692.1 598.8 513.1 453.3 406.9 319.1 216.1 -1.6 -1.2 1.0 12.9 2 ZA_0+100 100 100 7.0 13.7 13.0 13.7 13.0 12.2 12.1 12.0 12.0 12.0 11.9 11.9 692.1 598.8 513.1 453.3 406.9 319.1 216.1 -1.6 -0.9 1.0 13.1 3 ZA_0+200 200 100 6.4 13.0 13.1 13.0 16.2 12.5 12.4 12.2 12.1 12.1 12.0 11.9 692.1 598.8 513.1 453.3 406.9 319.1 216.1 -0.6 -3.8 1.0 13.4 4 ZA_0+300 300 100 7.1 12.5 12.7 12.5 13.5 12.8 12.5 12.3 12.2 12.1 12.0 11.9 692.1 598.9 513.1 453.3 406.9 319.0 216.1 0.0 -1.0 1.0 13.5 5 ZA_0+400 400 100 7.0 11.3 11.9 11.3 11.9 13.4 13.1 12.8 12.7 12.5 12.3 12.1 654.7 566.9 483.4 425.1 380.5 298.9 201.3 1.8 1.2 1.0 14.1 6 ZA_0+500 500 100 6.6 11.3 13.1 11.3 13.1 13.4 13.1 12.9 12.7 12.6 12.3 12.1 654.6 566.9 483.4 425.1 380.5 298.9 201.3 1.8 0.0 1.0 14.1 7 ZA_0+600 600 100 6.8 11.1 10.5 11.1 10.8 13.6 13.4 13.1 12.9 12.7 12.5 12.2 653.9 566.3 482.9 424.6 380.1 298.5 201.1 2.4 2.6 1.0 14.4 8 ZA_0+700 700 100 7.3 11.2 11.4 11.2 11.4 13.9 13.6 13.3 13.1 12.9 12.6 12.2 652.6 565.2 481.9 423.8 379.4 297.9 200.6 2.4 2.2 1.0 14.6 9 ZA_0+800 800 100 5.9 11.0 11.3 11.0 11.3 14.1 13.8 13.5 13.2 13.0 12.7 12.3 651.3 564.0 481.0 423.0 378.7 297.1 200.2 2.8 2.5 1.0 14.8 10 ZA_0+900 900 100 7.1 11.2 11.8 11.3 11.8 14.2 13.9 13.5 13.3 13.1 12.8 12.3 650.0 562.9 480.1 422.2 378.0 296.4 199.7 2.6 2.1 1.0 14.9 11 ZA_1+000 1000 100 7.6 11.2 12.8 11.2 12.8 14.2 13.9 13.6 13.3 13.1 12.8 12.4 648.7 561.8 479.1 421.4 377.3 295.7 199.3 2.7 1.1 1.0 14.9 12 ZA_1+200 1200 200 6.7 10.0 13.2 11.2 13.2 14.2 13.9 13.6 13.4 13.2 12.9 12.4 646.1 559.6 477.2 419.8 375.8 294.3 198.4 2.7 0.7 1.0 14.9 13 ZA_1+400 1400 200 7.4 11.4 11.8 11.4 11.8 14.9 14.5 14.2 13.9 13.7 13.2 12.6 643.5 557.3 475.4 418.2 374.4 292.9 197.5 3.1 2.7 1.0 15.5 14 ZA_1+600 1600 200 8.1 12.2 13.4 12.2 13.4 15.0 14.6 14.2 14.0 13.7 13.3 12.7 640.9 555.1 473.5 416.6 373.0 291.5 196.5 2.4 1.2 1.0 15.6 15 ZA_1+800 1800 200 7.3 12.4 12.9 12.5 12.9 15.3 14.9 14.5 14.3 14.0 13.5 12.9 638.3 552.9 471.7 415.0 371.6 290.1 195.6 2.5 2.0 1.0 15.9 16 ZA_2+000 2000 200 8.0 12.2 12.4 12.2 12.4 15.6 15.2 14.8 14.5 14.3 13.7 13.1 635.8 550.7 469.8 413.4 370.2 288.7 194.7 3.1 2.8 1.0 16.2 17 ZA_2+200 2200 200 8.9 14.4 13.3 14.4 13.3 15.9 15.5 15.1 14.7 14.5 13.9 13.2 633.2 548.6 468.0 411.8 368.8 287.7 193.8 1.1 2.2 1.0 16.5 18 ZA_2+400 2400 200 8.4 14.0 13.5 14.0 13.5 16.2 15.8 15.3 15.0 14.7 14.1 13.3 630.7 546.4 466.2 410.2 367.5 286.6 192.8 1.8 2.3 1.0 16.8 19 ZA_2+600 2600 200 8.6 14.0 14.0 14.0 14.0 16.3 15.9 15.4 15.1 14.8 14.2 13.4 628.2 544.3 464.4 408.7 366.1 285.6 191.9 1.9 1.9 1.0 16.9 20 ZA_2+800 2800 200 7.3 13.6 14.4 13.6 14.4 16.4 16.0 15.5 15.2 14.9 14.3 13.5 625.6 542.1 462.6 407.2 364.8 284.6 191.0 2.4 1.6 1.0 17.0 21 ZA_3+000 3000 200 8.3 13.5 14.0 13.5 14.0 16.6 16.2 15.7 15.3 15.1 14.5 13.6 625.1 541.6 462.3 406.9 364.6 284.5 190.7 2.7 2.2 1.0 17.2 22 ZA_3+200 3200 200 8.5 14.3 15.1 14.3 15.1 17.0 16.5 16.0 15.6 15.3 14.6 13.8 565.3 489.9 418.1 368.0 329.7 256.5 171.9 2.2 1.4 0.8 17.3 23 ZA_3+400 3400 200 8.4 13.1 14.1 13.1 15.1 16.9 16.5 16.0 15.6 15.3 14.7 13.8 562.2 487.2 415.8 366.1 328.0 255.2 170.7 3.4 1.4 0.8 17.3 24 ZA_3+600 3600 200 8.9 15.2 14.5 15.2 14.7 17.1 16.6 16.1 15.7 15.4 14.8 13.9 558.9 484.4 413.5 364.1 326.3 253.9 169.4 1.5 1.9 0.8 17.4 25 ZA_3+800 3800 200 8.2 13.8 14.4 13.8 14.4 17.2 16.7 16.2 15.9 15.6 14.9 14.0 555.8 481.7 411.3 362.1 324.6 252.6 168.1 2.9 2.3 0.8 17.5 26 ZA_4+000 4000 200 8.5 13.7 13.8 13.7 13.8 17.4 16.9 16.3 16.0 15.6 15.0 14.1 552.6 479.0 409.0 360.2 322.9 251.3 167.3 3.2 3.1 0.8 17.7 27 ZA_4+200 4200 200 8.9 14.6 14.5 14.6 14.5 17.3 16.8 16.3 15.9 15.6 15.0 14.1 549.4 476.3 406.8 358.2 321.2 250.1 166.6 2.3 2.3 0.8 17.6 28 ZA_4+400 4400 200 9.1 14.9 15.7 14.9 15.7 17.5 17.0 16.5 16.1 15.8 15.2 14.2 546.2 473.6 404.5 356.3 319.5 248.8 165.8 2.1 1.4 0.8 17.8 29 ZA_4+600 4600 200 8.3 16.0 16.1 16.0 16.1 17.7 17.2 16.7 16.3 16.0 15.3 14.3 543.1 470.9 402.2 354.3 317.8 247.5 165.1 1.2 1.1 0.8 18.0 30 ZA_4+800 4800 200 8.7 16.1 16.5 16.1 17.1 17.9 17.4 16.8 16.4 16.1 15.4 14.4 540.0 468.3 400.0 352.5 316.2 246.2 164.4 1.3 0.3 0.8 18.2 31 ZA_5+000 5000 200 8.5 16.7 17.2 16.7 17.2 17.9 17.4 16.9 16.6 16.2 15.6 14.5 536.9 465.7 397.9 350.7 314.6 245.1 163.7 0.7 0.3 0.8 18.2 32 ZA_5+200 5200 200 9.4 16.1 18.0 16.1 18.0 18.0 17.5 17.0 16.6 16.3 15.6 14.6 533.8 463.0 395.7 348.8 313.0 243.8 163.0 1.4 -0.5 0.8 18.3 33 ZA_5+400 5400 200 10.8 17.7 19.5 17.7 19.5 18.3 17.7 17.2 16.8 16.5 15.8 14.7 530.7 460.4 393.5 346.9 311.3 242.5 162.3 0.0 -1.8 0.8 18.5
River Bed Left Side Inland Elevation Zapote River Longitudinal Profile Right Side Inland Elevation 50y_HWL Estimate Dike Elevation 20 19 18 Laspinas-Zapote Channel 17 16 15 14 13 12
Elevation Elevation (E.L) 11 10 9 8 7 6
5
0
500
2,000 2,500 4,000 1,000 1,500 3,000 3,500 4,500 5,000 Distance from River Mouth (m) Figure 3.5.30 Longitudinal Profile of Zapote River (Return Period:50-year)
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