TABLE OF CONTENTS

Volume 13. Sub-basin ...... 3 Geographic Location ...... 3 Political and Administrative Boundary ...... 4 Land Cover ...... 6 Watershed Characterization and Properties ...... 7 Drainage Network ...... 7 Sub-sub basin Properties ...... 9 Water Quantity ...... 10 Stream Flow ...... 10 Water Balance ...... 11

LIST OF FIGURES Figure 13-1 Geographical Map ...... 3 Figure 13-2 Political Jurisdiction Map ...... 5 Figure 13-3 Land Cover Map ...... 7 Figure 13-4 Drainage Map ...... 8 Figure 13-5 Sub-sub basin Map of Pagsanjan Sub-basin ...... 9 Figure 13-6 Stream Flow, 1990-2004 ...... 11 Figure 13-7 Water Balance Percentage, 1990-2004 ...... 12

LIST OF TABLES Table 13-1 Geographic extent ...... 4 Table 13-2 Municipalities and Barangays covered ...... 4 Table 13-3 Population Distribution by Municipality/City, 2007 ...... 5 Table 13-4 Land Cover ...... 6 Table 13-5 Some Relief Features and Other Geo-Morphological Parameters ...... 7 Table 13-6 Pagsanjan Sub-sub basin properties ...... 10 Table 13-7 Yearly Water Balances based on model simulation (mm)...... 11

Technical writer For. Alvin A. Faraon, LLDA-PDMED

Technical editors Ms. Adelina C. Santos-Borja Engr. Emiterio C. Hernandez Officer-In-Charge Officer- In Charge Resource Management and Development Officer Project Development Management and Evaluation Division

Map production Mr. Neil V. Varcas, LLDA-PDMED

Volume 13. Pagsanjan Sub-basin

Geographic Location The Pagsanjan Sub-basin is located in the Southern Tagalog Region, at the southeastern part of the de Bay basin. It is bounded by the // sub-basins in the east, Sta. Cruz sub-basin in the west, the east Bay of Laguna Lake to the north, and Mt. Banahaw to the south. Municipalities are located within the catchment, namely: , , , Magdalena, , and Pagsanjan in the Province of Laguna, and Municipality in Province (Figure 13-1).

The whole sub-basin has an aggregate area of 31,862.67 hectares (ha). The coordinates of the sub-basin is Table 13-1.

Source: LLDA GIS Figure 13-1 Geographical Map

Table 13-1 Geographic extent CORNERS NORTHING (UTM) EASTING (UTM) Upper Left 1555103.97468 352089.34375 Upper Right 1555103.97468 329364.40625 Lower Right 1586680.50000 329364.40625 Lower Left 1586680.50000 352089.34375 Source: LLDA GIS

Political and Administrative Boundary The Pagsanjan sub-basin covers 162 barangays located in ten (10) municipalities, eight of which are situated in Laguna and two in Quezon Province. Lucban to where headwater comes occupies the largest area accounting to 20.80% or 6628.09 hectares. In view of barangays covered, Majayjay has the most with forty (40) with an area of 6170.97 hectares or 19.37% of e sub-basin, followed by Lucban with thirty-one (31) (Figure 13-2).

The table below presents all municipalities within the Pagsanjan sub-basin and their corresponding land areas.

Table 13-2 Municipalities and Barangays covered Number of Barangays Municipality/City Area (ha) Percentage Covered Cavinti 19 4964.6644 15.5814 Lucban 31 6628.0975 20.8021 Luisiana 17 4042.6200 12.6876 Lumban 16 4001.9257 12.5599 Magdalena 18 1631.0418 5.1190 Majayjay 40 6170.9799 19.3674 Pagsanjan 16 3516.1494 11.0353 Kalayan 1 1.5322 0.0048 1 141.0847 0.4428 Sampaloc 3 764.5694 2.3996 Total 162 31862.6649 100.0000 Source: LLDA GIS

Per the 2007 census, the total population of the sub-basin is about 155,705. Among the ten municipalities, Lucban has the highest population of 40919 accounting for 26 percent of the total while Kalayaan has the lowest population of only 6 representing 0.004 percent of the total. As of 2007, the population density in the sub-basin is 4.88 persons per ha. In 2010, it is projected that there will be 3.35 persons/ha. A major proportion (74 percent) of the population is residing in the urban areas and the rest (26 percent) are in the rural areas. Average size of household in the watershed is five.

Table 13-3 Population Distribution by Municipality/City, 2007 Municipality/City Population Percentage Cavinti 16105 10.343 Lucban 40919 26.280 Luisiana 9288 5.965 Lumban 26228 16.845 Magdalena 11956 7.679 Majayjay 23027 14.789 Pagsanjan 27585 17.716 Sampaloc 110 0.071 Tayabas 481 0.309 Kalayaan 6 0.004 Total 155705 100.000 Source: National Statistics Office, 2007 Census of Population

Source: LLDA GIS Figure 13-2 Political Jurisdiction Map

Land Cover

Approximately 9614.93 ha or 3.47 percent are covered by coconut plantations. Other dominant land uses of the land are cropland mixed with coconut plantation and cultivated areas mixed with brushland/grassland. Arable land covers about 2117.59 ha or 6.71 percent or while brushland and grassland is 5841 ha or 18.50 percent. Forest covers only about 3292.39 ha or 10.43%. Other land uses include urban (6.91 percent or 2180.81 ha) and marshy areas and swamp at 2.12 percent or 668.46 ha. There is still 7665 ha falls within unclass category (Table 13-4). Land Cover map is presented in Figure 13-3.

Table 13-4 Land Cover Land Cover Area (ha) Percentage Urban 2180.808 6.91 Forest 3292.39 10.43 Arable 2117.592 6.71 Plantation 9614.934 30.47 Grassland 729.771 2.31 Brushland 5113.965 16.21 Marsh 668.464 2.12 Water 169.352 0.54 Unclass 7665.009 24.29 Total 31552.285 100 Source: LLDA GIS

Source: LLDA GIS Figure 13-3 Land Cover Map

Watershed Characterization and Properties

Drainage Network The drainage map of the Pagsanjan Sub-basin is shown in Figure 13-4 while the important watershed characteristics and geomorphological features are in Table 13-5.

Table 13-5 Some Relief Features and Other Geo-Morphological Parameters Parameters Values Area (ha) 31899.031 Perimeter (m) 129947.851 Total number of streams 101 Total length of streams (m) 297178.048 Stream Density (stream/ha) 0.00317 Drainage Density (m/ha) 9.3162 Constance of Channel Maintenance 0.1073 (ha/m) Length of Overland Flow (m) 4.658104 Source: LLDA GIS

Source: LLDA GIS Figure 13-4 Drainage Map

Sub-sub basin Properties

Source: LLDA GIS Figure 13-5 Sub-sub basin Map of Pagsanjan Sub-basin

Table 13-6 Pagsanjan Sub-sub basin properties Sub-sub basin Name Area (Ha) Perimeter (m)

SSB-13A 229.224 8249.607 SSB-13AA 492.748 13841.229 SSB-13B 855.522 14290.093 SSB-13C 672.619 17389.491 SSB-13D 238.314 15332.235 SSB-13E 250.796 9642.340 SSB-13F 663.687 17776.882 SSB-13G 331.358 11491.041 SSB-13H 290.704 10339.564 SSB-13I 674.848 14406.692 SSB-13J 237.392 14300.138 SSB-13K 525.894 15063.087 SSB-13L 913.036 18984.083 SSB-13M 495.931 13330.413 SSB-13N 565.220 17878.068 SSB-13O 361.501 8963.960 SSB-13P 2688.820 28909.773 SSB-13Q 2107.341 26830.869 SSB-13R 0.062 543.107 SSB-13R 2978.659 37621.597 SSB-13S 740.737 14835.337 SSB-13T 566.561 12134.778 SSB-13U 1990.480 25276.119 SSB-13V 805.602 21870.162 SSB-13W 882.594 12329.283 SSB-13X 10514.888 136860.383 SSB-13Y 476.209 15008.982 SSB-13Z 348.619 13555.238 Source: LLDA GIS

Water Quantity

Stream Flow

The yearly average stream flow of the Pagsanjan sub-basin from Year 1990 to Year 2004 is presented in Figure 13-6 wherein the lowest peak flow recorded is in Year 2000 with about 11.33 m3/sec while the highest was recorded in Years 1999 (28.26 m3/sec) and 2004 (27.98 m3/sec.).

Source: LLDA PDMED

Figure 13-6 Stream Flow, 1990-2004

Water Balance

The Sacramento Soil Moisture Accounting (SAC SMA) Hydrologic Model is used to simulate watershed rainfall-runoff relationship and to generate the long-term water balance of the 24 sub-basins of . The SAC SMA accounts for all water entering, stored in, and leaving a drainage basin. Though many parameters are used in this water balance accounting process, precipitation has the main impact on runoff.

For Pagsanjan River Basin, the long term water balances of the basin based on the hydrologic simulation is shown in the Table 13-7. The 15-year average would show that 55% of the total rainfall becomes surface run-off, and about 30% of rainfall is lost as actual evapotranspiration. The base flow component of the total run-off is quite minimal, with only about 14% of rainfall, while the remaining 11% is stored as soil moisture and contributes to groundwater aquifer (Figure 13-7).

Table 13-7 Yearly Water Balances based on model simulation (mm). YEAR Rainfall Actual Evapo- Direct Baseflow Change in transpiration Runoff Storage 1990 3,098 802 1,813 472 11 1991 2,572 881 1,272 403 15 1992 2,557 852 1,332 346 27 1993 2,770 698 1,596 349 128 1994 2,272 871 1,036 395 (30) 1995 3,212 757 1,934 408 114 1996 3,186 881 1,882 404 20 1997 1,900 866 738 331 (35) 1998 3,311 851 1,968 314 178 1999 3,562 795 2,202 510 54 2000 2,962 826 1,616 476 43 YEAR Rainfall Actual Evapo- Direct Baseflow Change in transpiration Runoff Storage 2001 2,364 856 1,060 435 14 2002 2,374 806 1,147 378 44 2003 2,146 826 959 364 (3) 2004 3,573 805 2,318 404 45 Average 2,791 825 1,525 399 42 Source: LLDA PDMED

Source: LLDA PDMED

Figure 13-7 Water Balance Percentage, 1990-2004