Table of Contents

Volume 7. Pililla Sub-basin ........................................................................................... 3

Geographic Location .................................................................................................... 3

Political Boundary ........................................................................................................ 4

Landcover .................................................................................................................... 5

Watershed Characterization......................................................................................... 7

Drainage Network .................................................................................................... 7

Sub-sub basin Properties ......................................................................................... 9

Water Quantity ........................................................................................................... 10

Stream Flow ........................................................................................................... 10

Water Balance ....................................................................................................... 10

LIST OF FIGURES

Figure 7-1 Geographical Map .................................................................................................. 3 Figure 7-2 Political Boundary ................................................................................................... 5 Figure 7-3 Land Cover Map ..................................................................................................... 6 Figure 7-4 Drainage Map ......................................................................................................... 8 Figure 7-5 Pililla Sub-sub basin Map ....................................................................................... 9 Figure 7-6 Annual Stream flow, 1990 - 2004 ......................................................................... 10 Figure 7-7 Water Balance Percentage, 1990 - 2004 ............................................................. 11

LIST OF TABLES

Table 7-1 Geographic extent ................................................................................................... 4 Table 7-2 Municipalities and Barangays covered .................................................................... 4 Table 7-3 Population, NSO 2007 ............................................................................................. 4 Table 7-4 Land cover and Area ............................................................................................... 6 Table 7-5 Some Relief Features and Other Geo-Morphological Parameters ......................... 7 Table 7-6 Pililla Sub-sub basin properties ............................................................................. 10 Table 7-7 Water Balances based on model simulation, 1990-2004 ...................................... 11

Technical writer

Engr. Rochelle Ivy M. Reyes, LLDA-PDMED

Technical editors Ms. Adelina C. Santos-Borja Officer-In-Charge Resource Management and Development Officer

Engr. Emiterio C. Hernandez Officer- In Charge Project Development Management and Evaluation Division

Map production

Mr. Neil V. Varcas, LLDA-PDMED

Volume 7. Pililla Sub-basin

Geographic Location The Pililla watershed is composed of the municipality of Pililla, around 53.88% (21,528,218.52 square meters) of the watershed, and the rest is from Tanay municipality and the Laguna de Bay. Table 7-1 presents the total area and the percentage of the municipality in the watershed.

Source: LLDA GIS

Figure 7-1 Geographical Map

Table 7-1 Geographic extent

CORNERS NORTHING (UTM) EASTING (UTM)

Upper Left 1599658.87500 324077.46875

Upper Right 1599658.87500 316329.43750

Lower Right 1609476.75000 316329.43750

Lower Left 1609476.75000 324077.46875

Political Boundary The Pililla watershed is located in the municipality of Tanay and Pililla. The north side is bounded by Tanay, Rizal, to the northeast by Sta. Maria, Laguna, to the west by Mabitac, Laguna, southeast by Pakil, Laguna, south by Jala-Jala, Rizal, and to the west is the Laguna Lake. The watershed covers 7 barangays, namely; Bagumbayan, Hulo, Imatong Takungan and Wawa in Pililla, Sampaloc and Plaza Aldea in Tanay Table 7-2.

Table 7-2 Municipalities and Barangays covered

Municipality Barangay Area (sq.m.) Percentage

Pililla Halayhayin 5,903,686.94 14.78%

Takungan (Pob.) 779,486.53 1.95%

Imatong (Pob.) 1,096,329.89 2.74%

Wawa (Pob.) 1,908,516.37 4.78%

Bagumbayan (Pob.) 5,478,021.00 13.71%

Hulo (Pob.) 6,362,177.78 15.92%

Subtotal 6 21,528,218.52 53.88%

Tanay Pinagkamaligan (Pob.) 621,947.63 1.56%

Wawa (Pob.) 15,589.71 0.04%

Plaza Aldea (Pob.) 14,376,026.28 35.98%

San Andres 221,288.00 0.55%

Tandang Kutyo (Pob.) 3,191,861.35 7.99%

Subtotal 5 18,426,712.96 46.12%

Total 39,954,931.47 100.00%

The total population of Pililla as of May 2000 was 45,275, with 9,001 households. Average household size is 5.45. (MPDO, 2007) Table 7-3 Population, NSO 2007

Barangay Total

Population %Share

Number of Household

Average Hh Size

Bagumbayan 6,620 14.63 1,301 5.58

Halayhayin 5,985 13.22 1,142 5.52

Hulo 6,927 15.29 1,381 5.58

Imatong 879 1.94 171 5.71

Malaya 6,379 14.09 1,271 5.24

Niogan 3,425 7.57 669 5.22

Quisao 9,416 20.79 1,993 5.04

Takungan 1,611 3.56 303 6.09

Wawa 4,033 8.91 770 5.10

Population density in Pililla is 550.92 individuals per square kilometer. Annual growth rate is 3.05% (1,380/year). (MPDO, 2007)

Figure 7-2 Political Boundary

Landcover The Pililla watershed has seven land cover namely: urban, forest, arable, plantation, grass, brush and marsh. Majority of the landcover in the watershed is brush with an area of 17,722,421.472 square meters, grassland and plantation follows with area of 9,226,143.163 square meters and 6,451,681.712 square meters, respectively. It should be noted that only 69,900.00 square meters are forested land, there should be a move to improve the forest management in the watershed Table 7-4.

Table 7-4 Land cover and Area

Land cover Area (sq.m.) Percentage

urban 3,546,602.21 8.61%

forest 69,900.00 0.17%

arable 3,794,590.84 9.21%

plantation 6,451,681.71 15.66%

grass 9,226,143.16 22.40%

brush 17,722,421.47 43.03%

marsh 379,412.59 0.92%

Total 41,190,751.99 100.00%

Figure 7-3 Land Cover Map

Watershed Characterization Drainage Network The sub-basin was delineated based on the topography and river network. The topographic map (scale: 1:10,000) was used to delineate the divide. In addition, all rivers and their tributaries were identified and used as the basis for the delineation. Below are some of the characteristics of the watershed. The drainage map of the Pililla Sub-basin is shown in Figure 7-4 while the important watershed characteristics and geomorphological features are in Table 7-5.

Table 7-5 Some Relief Features and Other Geo-Morphological Parameters Source: LLDA GIS

Parameters Values

Area (ha) 4118.745

Perimeter (m) 33657.294

Total number of streams 19

Total length of streams (m) 34356.336

Stream Density (stream/ha) 0.00461

Drainage Density (m/ha) 8.3415

Constance of Channel Maintenance (ha/m) 0.1199

Length of Overland Flow (m) 4.170728

Figure 7-4 Drainage Map

Sub-sub basin Properties

Figure 7-5 Pililla Sub-sub basin Map

Table 7-6 Pililla Sub-sub basin properties

Sub-sub basin Name Area (Ha) Perimeter (m)

SSB-7A 2409.269 44306.187

SSB-7B 168.144 6363.742

SSB-7C 594.458 15328.621

SSB-7D 238.680 8039.178

SSB-7E 130.070 5844.392

SSB-7F 215.091 6734.042

SSB-7G 363.034 8678.182

Water Quantity Stream Flow The annual Stream flow from 1990 to 2004 in Pililla watershed is shown in Figure 7-6. Maximum stream flow of 3.454254 m3 per second was experienced in the year 2000 while minimum flow is in the year 1997 with 0.782703 m3 per second.

1990

1992

1994

1996

1998

2000

2002

2004

Pilillia

0

0.5

1

1.5

2

2.5

3

3.5

Year

Stream Flow

(m3/sec)

Pilillia

Figure 7-6 Annual Stream flow, 1990 - 2004

Water Balance The long term water balance of the Pililla watershed was based on the Sacramento Soil Moisture Accounting (SAC SMA) Hydrologic Model. The 1990 – 2004 data was used and shows that most of the total rainfall is transformed into direct runoff with 52.40 % of rainfall and the actual evapotranspiration is 33.44%, while the base flow and change in storage of the total rainfall is about 13.39% and 0.78%, respectively.

Table 7-7 Water Balances based on model simulation, 1990-2004

YEAR Rainfall Actual Evapo-transpiration

Direct Runoff

Baseflow Change in

Storage

1990 2,170 709 1,201 392 (132)

1991 1,763 666 835 232 30

1992 1,873 750 879 229 15

1993 1,815 653 776 251 135

1994 2,005 812 953 308 (68)

1995 1,928 642 985 229 73

1996 1,819 766 831 248 (26)

1997 1,186 742 393 179 (129)

1998 2,468 648 1,414 165 242

1999 2,668 767 1,438 450 14

2000 3,526 802 2,202 427 95

2001 2,723 831 1,520 414 (41)

2002 2,745 773 1,640 311 20

2003 2,166 721 1,185 286 (25)

2004 1,979 703 945 274 58

Average 2,189 732 1,147 293 17

Water Balance of Pililla Watershed

33.44%

52.38%

13.38% 0.79%

Actual Evapo-transpiration Direct Runoff Baseflow Change in Storage

Figure 7-7 Water Balance Percentage, 1990 - 2004