Chapter 5 Water Level Fluctuation in Laguna Lake During Flood in Pasig-Marikina River

Chapter 5 Water Level Fluctuation in Laguna Lake During Flood in Pasig-Marikina River

The Republic of the Philippines Data Collection Survey on Flood Management in Metro Manila CHAPTER 5 WATER LEVEL FLUCTUATION IN LAGUNA LAKE DURING FLOOD IN PASIG-MARIKINA RIVER In order to examine the water level fluctuation of Laguna Lake, and validity of the flood management measures, related data is collected and analyzed such as flow regime of the water fluctuation data of Laguna Lake and both Manggahan Floodway and Napindan Channel during the floods, and the water level fluctuation analysis model of Laguna Lake is built based on the water level fluctuation characteristic of Laguna Lake as follows. 5.1 Characteristics of Water Level Fluctuation of Laguna Lake 5.1.1 Available Data The available data regarding water level of Laguna Lake, rainfall in the basin, inflow discharge to Laguna Lake and flow regimes of Manggahan Floodway and Napindan Channel during floods (occurrence of reverse flow to/from Laguna Lake) are summarized in Table 5.1, Table 5.2, Figure 5.1 and Figure 5.2. Table5.1 Availability of Hourly Rainfall and Water Level Data (EFCOS) 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 Science Garden × × × × × × × × × ○ ○ ○ ○ ○ ○ ○ △ × × Napindan × × × × × × × × × ○ ○ ○ ○ ○ △ × × × × Mt.Campana × × × × × × × × × ○ ○ ○ ○ ○ △ × × × × Aries × × × × × × × × × ○ ○ ○ ○ ○ ○ ○ ○ ○ △ Nangka × × × × × × × × × ○ ○ ○ ○ ○ ○ △ △ ○ △ Rainfall BosoBoso ○ ○ ○ ○ ○ △ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ △ ○ △ Mt.Oro ○ ○ ○ ○ ○ △ ○ ○ ○ ○ ○ ○ ○ ○ △ ○ △ ○ △ Sulipan × × × × × × × × × × × × × × × × × × × Ipo dam × × × × × × × × × × × × × × × × × × × San Rafael × × × × × × × × × × × × × × × × × × × Rosario JS ○ ○ ○ ○ ○ △ ○ ○ ○ ○ ○ ○ ○ ○ △ △ ○ ○ △ Rosario LS ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ △ ○ × × × × × Napindan JS ○ ○ ○ ○ ○ ○ △ ○ ○ ○ ○ ○ ○ ○ × × △ × × Napindan LS ○ ○ △ △ ○ ○ ○ ○ ○ ○ ○ ○ △ ○ × × × × × Nangka × × × × × × × × ○ ○ ○ ○ ○ ○ ○ △ △ ○ △ Waterlev San Juan × × × × × × × × ○ ○ ○ ○ ○ ○ ○ △ △ ○ △ el Montalban ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ △ △ ○ ○ △ Sto.Nino ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ △ △ ○ △ Pandacan ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ △ △ ○ ○ △ Fort Santiago ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ △ △ △ ○ △ Angono △ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ △ △ ○ ○ △ Missing Data percentage : ≧90% ⇒× Missing Data percentage : ≧10% <90% ⇒△ Missing Data percentage : <10% ⇒○ Table 5.2 Availability of Daily Rainfall Data (PAGASA) 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 Pakil ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ NAS ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ SanPedro × × × × × × × × × × × × × NPP × × × × × × × × × × × × × PasigElem ○ ○ ○ ○ ○ ○ ○ ○ ○ × × ○ ○ Tipas × × × × × × × × × × × × × StaMaria ○ ○ ○ ○ ○ ○ ○ ○ × × × ○ ○ StaCruz ○ ○ ○ ○ ○ ○ ○ ○ △ △ ○ ○ ○ Missing Data percentage : ≧90% ⇒× Missing Data percentage : ≧10% <90% ⇒△ Missing Data percentage : <10% ⇒○ Final Report 5-1 The Republic of the Philippines Data Collection Survey on Flood Management in Metro Manila Figure 5.1 Locations of Rainfall Gauging Stations Figure 5.2 Locations of Water Level Gauging Stations Final Report 5-2 The Republic of the Philippines Data Collection Survey on Flood Management in Metro Manila 5.1.2 Monthly Fluctuation of Water Level Secular change of monthly variation of water level at Anogono Station from 1994 to 2012 is summarized as follows. Water level of Laguna Lake becomes the lowest in the end of dry season in April or May and becomes the highest in late rainy season in September to January. (Refer to Figure 5.3) The average annual lowest and highest water levels are EL. 10.8m and EL. 12.4m, respectively. The average annual lowest water level is almost same as the mean sea level (MSL) of Manila Bay. It means that sea water intrusion to Laguna Lake occurs when high tide in the end of dry season. Monthly average waterlevel at Angono, Lake Laguna 1994 1995 14.00 1996 1997 13.50 1998 1999 2000 13.00 2001 2002 2003 12.50 2004 2005 12.00 2006 2007 2008 11.50 AngonoWaterLevel (EL.m) 2009 2010 2011 11.00 2012 10.50 10.00 Jul Jan Jun Oct Apr Sep Feb Dec Aug Nov Mar May year next Janin Figure 5.3 Monthly Variation of Water Level in Laguna Lake 5.1.3 Water Level Fluctuation during Floods In order to identify flow regime of Manggahan Floodway and Napindan Channel during floods, difference of water levels of Rosario JS Station for Manggahan Floodway and Napindan JS Station for Napindan Channel against Angono Station are calculated. The hourly fluctuations are shown in Figure 5.4 and 5.5 and the fluctuations of daily mean water level is shown in Figure 5.6 and 5.7. It is noted that the positive number of difference means that water level of Angono is higher. Hourly hydrograph in 2004 in which two floods were occurred by the tropical cyclone Wennie in August and the typhoon Yoyong in December is analyzed. During flooding stage, water level of Rosario JS is more sensitive and always higher than Laguna Lake. It is expected that natural discharge to Laguna Lake through Manggahan Floodway always occurs during floods. On the other hand, clear correlation cannot be found between the water levels of Napindan JS and Laguna Lake. It is judged that natural diversion from Pasig River to Laguna Lake through Napindan Channel does not always occur. Using daily mean water level, this tendency is more emphasized. Since the hourly water level data of Typhoon Ondoy and Typhoon Pepeng are not available, calculation results using 2009 data is not utilized. Final Report 5-3 Figure 5.5Comparison ofHourly Hydrograph Between Napindan JS andAngono (2004) Water Level (m) Water Level (m) 10 11 12 13 14 15 16 17 18 19 20 10 11 12 13 14 15 16 17 18 19 20 0101 01:00 0101 01:00 0106 01:00 0106 01:00 0111 01:00 0111 01:00 0116 01:00 (W- Rosario JS) - (W-Angono) +Q:Flow to Laguna AngonoW- RosarioW- LS RosarioW- JS W- Napindan JS Napindan W- 0116 01:00 Laguna to +Q:Flow Angono) (W- - JS) Napindan (W- Angono W- LS Napindan W- 0121 01:00 0121 01:00 0126 01:00 0126 01:00 0131 01:00 0131 01:00 Figure 5.4Hourly Hydrograph ofRosario JSandAngono (2004) 0205 01:00 0205 01:00 0210 01:00 0210 01:00 0215 01:00 zero is Chang WL 0215 01:00 0220 01:00 WL Change is zero zero is Change WL 0220 01:00 0225 01:00 0225 01:00 0301 01:00 0301 01:00 Change WL 0306 01:00 0306 01:00 0311 01:00 Hourly Hydrograph of Rosario JS and Angono Angono 2004) and (Year: of HourlyJS Rosario Hydrograph 0311 01:00 0316 01:00 WL Changes Changes WL HourlyHydrograph of Napindanand Angono (Year: 2004) 0316 01:00 0321 01:00 0321 01:00 0326 01:00 0326 01:00 0331 01:00 0331 01:00 0405 01:00 0405 01:00 0410 01:00 0410 01:00 0415 01:00 0415 01:00 0420 01:00 0420 01:00 0425 01:00 0425 01:00 0430 01:00 0430 01:00 0505 01:00 0505 01:00 0510 01:00 0510 01:00 0515 01:00 0515 01:00 Data Collection Survey on Flood Management in Metro Manila 0520 01:00 0520 01:00 0525 01:00 0525 01:00 0530 01:00 0530 01:00 0604 01:00 0604 01:00 0609 01:00 0609 01:00 0614 01:00 0614 01:00 0619 01:00 0619 01:00 5-4 0624 01:00 0624 01:00 0629 01:00 0629 01:00 0704 01:00 0704 01:00 0709 01:00 0709 01:00 0714 01:00 0714 01:00 0719 01:00 0719 01:00 0724 01:00 0724 01:00 0729 01:00 0729 01:00 0803 01:00 0803 01:00 0808 01:00 0808 01:00 0813 01:00 0813 01:00 0818 01:00 0818 01:00 0823 01:00 0823 01:00 0828 01:00 0828 01:00 0902 01:00 0902 01:00 0907 01:00 0907 01:00 0912 01:00 0912 01:00 0917 01:00 0917 01:00 0922 01:00 0927 01:00 0922 01:00 The Republic of the Philippines 1002 01:00 0927 01:00 1007 01:00 1002 01:00 1012 01:00 1007 01:00 1017 01:00 1012 01:00 1022 01:00 1017 01:00 1027 01:00 1022 01:00 1101 01:00 1027 01:00 1106 01:00 1101 01:00 1111 01:00 1106 01:00 1116 01:00 1111 01:00 1121 01:00 1116 01:00 1126 01:00 1121 01:00 1201 01:00 1126 01:00 1206 01:00 1201 01:00 1211 01:00 1206 01:00 1216 01:00 1211 01:00 Final Report 1221 01:00 1216 01:00 1226 01:00 1221 01:00 1231 01:00 1226 01:00 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 1231 01:00 Water Depth(m) [Plus value means 'Flow to Laguna'] -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 Water Depth(m) [Plus value means 'Flow to Laguna'] Figure 5.7Comparison ofDaily MeanHydrograph Between Napindan JSandAngono (2004) Figure 5.6Comparison ofDaily MeanHydrograph between Rosario JSandAngono (2004) Water Level (m) Water Level (m) 10.00 11.00 12.00 13.00 14.00 15.00 16.00 17.00 18.00 19.00 20.00 10.00 11.00 12.00 13.00 14.00 15.00 16.00 17.00 18.00 19.00 20.00 01/01 01/01 01/05 01/05 01/09 01/09 01/13 01/13 01/17 01/17 01/21 01/21 01/25 01/25 01/29 01/29 02/02 02/02 WL Change WL WL Change WL 02/06 02/06 02/10 (W-Napindan JS)-(W- Angono) +H:Flow to Laguna W- Angono W- NapindanLS W- NapindanJS 02/10 02/14 02/14 (W-Rosario JS)-(W- Angono) +H:Flowto Laguna W- Angono W- Rosario LS W- Rosario JS 02/18 02/18 02/22 02/22 02/26 02/26 03/01 03/01 03/05 03/05 03/09 is Change WL 03/09 is Change WL 03/13 03/13 03/17 03/17 03/21 03/21 03/25 zero 03/25 zero 03/29 03/29 04/02 04/02 04/06 04/06 Daily Hydrograph of Napindan JS and Angono (Year: 2004) (Year: Angono and JS of Napindan Hydrograph Daily 04/10 04/10 2004) (Year: Angono and JS of Rosario Hydrograph Daily 04/14 04/14 04/18 04/18 04/22 04/22 04/26 04/26 04/30 04/30 05/04 05/04 05/08 05/08 05/12 05/12 05/16 05/16 Data Collection Survey on Flood Management in Metro Manila 05/20 05/20 05/24 05/24 05/28 05/28 06/01 06/01 06/05 06/05 06/09 06/09 06/13 06/13 06/17 06/17 06/21 06/21 5-5 06/25 06/25 06/29 06/29 07/03 07/03 07/07 07/07 07/11 07/11 07/15 07/15 07/19 07/19 07/23 07/23 07/27 07/27 07/31 07/31 08/04 08/04 08/08 08/08 08/12 08/12 08/16 08/16 08/20 08/20 08/24 08/24 08/28 08/28 09/01 09/01 09/05 09/05 09/09 09/09 09/13 09/13 09/17 09/17 09/21 09/21 The Republic of the Philippines 09/25 09/25 09/29 09/29 10/03 10/03 10/07 10/07

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