Table of Contents - LLDA · 2019. 9. 27. · Mr. Neil V. Varcas, LLDA-PDMED . ... Pangil Sub-basin...
Transcript of Table of Contents - LLDA · 2019. 9. 27. · Mr. Neil V. Varcas, LLDA-PDMED . ... Pangil Sub-basin...
Table of Contents
Volume 11. Pangil Sub-basin .................................................................................................. 3
Geographic location ................................................................................................................ 3
Political and Administrative Boundary ..................................................................................... 4
Land Cover ............................................................................................................................. 5
Sub-basin Characterization and Properties............................................................................. 7
Drainage Network ............................................................................................................... 7
Sub-sub basin Properties .................................................................................................... 9
Water Quantity ......................................................................................................................10
Streamflow .........................................................................................................................10
Water Balance ...................................................................................................................11
LIST OF FIGURES Figure 11-1 Geographical Map ..................................................................................................................... 3 Figure 11-2 Political Map .............................................................................................................................. 5 Figure 11-3 Land Cover Map ........................................................................................................................ 6 Figure 11-4 Drainage Map ............................................................................................................................ 8 Figure 11-5 Sub-sub basin Map of Pangil Sub-basin ................................................................................... 9 Figure 11-6 Streamflow, 1990-2004 ........................................................................................................... 11 Figure 11-7 Water Balances based on model simulation, 1990-2004 ........................................................ 12
LIST OF TABLES Table 11-1 Geographic Extent ...................................................................................................................... 4 Table 11-2 Municipalities and Barangays Covered ...................................................................................... 4 Table 11-3 Population Distribution by Municipality, 2007 ............................................................................. 4 Table 11-4 Area Distribution of Land Cover .................................................................................................. 6 Table 11-5 Some Relief Features and Other Geo-Morphological Parameters ............................................. 7 Table 11-6 Pangil Sub-sub basin properties ............................................................................................... 10 Table 11-7 Streamflow Data, 1990-2004 .................................................................................................... 10 Table 11-8 Yearly Water Balances based on model simulation (mm) ........................................................ 11
Technical writer
For. Azyleah C. Abino, 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 11. Pangil Sub-basin
Geographic location The Pangil sub-basin is located at the eastern part of the Laguna de Bay basin. It is bounded by the Siniloan sub-basin on the north, east bay of the Laguna Lake in the west and to the southeast is the Caliraya sub-basin. Seven municipalities coming from two provinces are located within the sub-basin, namely Kalayaan, Lumban, Paete, Pakil, Pangil and Siniloan in the Province of Laguna and Real in Quezon Province. Figure 11-1 illustrates the geographic location and boundary of the Pangil sub-basin in the Laguna de Bay.
Source: LLDA GIS
Figure 11-1 Geographical Map
The whole sub-basin has a total area of 5,585.63 hectares, with a basin length of 14.73 kilometers (km) bounded with 52.98 km perimeter length having an average width of 5.71 km. The geographic extent of the sub-basin is presented in Table 11-1.
Table 11-1 Geographic Extent
CORNERS NORTHING (UTM) EASTING (UTM)
Upper Left 1582649.75000 344442.56250
Upper Right 1582649.75000 332602.43750
Lower Right 1596894.85196 332602.43750
Lower Left 1596894.85196 344442.56250 Source: LLDA GIS
Political and Administrative Boundary
The Pangil sub-basin covers 27 barangays located in seven (7) municipalities, six of which are situated in Laguna and one in Quezon Province (Figure 11-2). Pangil is the largest municipality accounting for almost 50% (2,674.62 hectares) of the total area of the sub-basin (Table 11-2). In view of barangays covered, Pakil has the most with seven (7) with an area of 816.41 hectares or 15.09% of the sub-basin, followed by Pangil with six (6).
Table 11-2 Municipalities and Barangays Covered
MUNICIPALITY NO. OF BARANGAYS AREA (ha) PERCENTAGE (%)
Kalayaan, Laguna 3 815.46 15.07
Lumban, Laguna 4 59.48 1.10
Paete, Laguna 2 782.13 14.45
Pakil, Laguna 7 816.41 15.09
Pangil, Laguna 6 2,674.62 49.42
Siniloan, Laguna 4 170.17 3.14
Real, Quezon 1 93.40 1.73
TOTAL 27 5,411.67 100.00 Source: LLDA GIS Based on the 2007 Census of Population by the National Statistics Office, the total population within the Pangil sub-basin is estimated at 63,563. Pangil, having the largest area percentage making up the sub-basin, also shared the highest number of inhabitants with 36% or 23,187. It is followed by Pakil with 32% or 20,040 residents. Pakil has the most number of barangays (7) within the sub-basin. On the other hand, Lumban is the least populated at 341 (1%) though there are the four (4) of its barangays located within the jurisdiction of the sub-basin. Table 11-3 shows the detailed population data of each municipalities as well as the annual growth rate.
Table 11-3 Population Distribution by Municipality, 2007
MUNICIPALITY POPULATION ANNUAL GROWTH RATE (%)
Kalayaan, Laguna 3,795 1.10
Lumban, Laguna 341 1.28
Paete, Laguna 13,583 0.98
Pakil, Laguna 20,040 1.62
Pangil, Laguna 23,187 1.72
Siniloan, Laguna 2,616 2.14
TOTAL 63,562 National Statistics Office, 2007 Census of Population
Source: LLDA GIS
Figure 11-2 Political Map
Land Cover Approximately 1,420.18 hectares or 25% of the Pangil sub-basin are covered with forests. However, the land validation activities as well as the analysis of the satellite image revealed that there are no more pristine or virgin forests in the sub-basin, only open forests exist. Other dominant land covers are brushland and plantations either by coconut or other agroforestry species. Brushland covers about 23% or 1,279.35 hectares while coconut/agroforestry plantation is estimated at 22% or 1,221.58 hectares. The built-up area composed of almost 15% or 831.66 hectares. Table 11-4 shows the land cover distribution in the sub-basin of Pangil while Figure 11-3 shows the land cover map.
Table 11-4 Area Distribution of Land Cover
LAND COVER AREA (ha) PERCENTAGE (%)
Urban 831.66 15%
Forest 1,420.18 25%
Arable 462.55 8%
Plantation 1,221.58 22%
Grassland 80.97 2%
Brushland 1,279.35 23%
Marsh 290.19 5%
TOTAL 5,586.48 100% Source: LLDA GIS
Source: LLDA GIS
Figure 11-3 Land Cover Map
Sub-basin Characterization and Properties Drainage Network The drainage map of the Pangil Sub-basin is shown in Figure 11-4 while the important watershed characteristics and geomorphological features are in Table 11-5.
Table 11-5 Some Relief Features and Other Geo-Morphological Parameters
Source: LLDA GIS
PARAMETERS VALUES
1. Area (ha) 5585.663
2. Perimeter (m) 52982.151
3. Total number of streams 29
4. Total length of streams (m) 50854.329
5. Stream Density (stream/ha) 0.00519
6. Drainage Density (m/ha) 9.1044
7. Constance of Channel Maintenance (ha/m) 0.1098
8. Length of Overland Flow (m) 4.5522
Source: LLDA GIS
Figure 11-4 Drainage Map
Sub-sub basin Properties
Source: LLDA GIS
Figure 11-5 Sub-sub basin Map of Pangil Sub-basin
Table 11-6 Pangil Sub-sub basin properties
SUB-SUB BASIN NAME AREA (Ha) PERIMETER (m)
SSB-11A 321.303 8164.845
SSB-11B 339.808 9429.827
SSB-11C 247.975 9555.525
SSB-11D 496.276 10072.559
SSB-11E 523.415 11588.588
SSB-11F 309.317 8435.548
SSB-11G 157.462 5973.008
SSB-11H 146.616 5581.476
SSB-11I 301.607 7765.399
SSB-11J 427.146 8719.570
SSB-11K 149.832 5460.211
SSB-11L 186.614 6953.386
SSB-11M 1978.602 34367.859 Source: LLDA GIS
Water Quantity
Streamflow The yearly average streamflow of the Pangil sub-basin from Year 1990 to Year 2004 is illustrated in Table 11-7 and Figure 11-6 wherein the highest peak flow can be observed in Years 1998 and 1999 with almost 10.61 m3/sec and 10.07 m3/sec, respectively. On the other hand, the lowest was recorded in Years 2001 (1.90 m3/sec) and 2003 (1.73 m3/sec). From 1991, the trend is increasing up to Year 1996; however declined on Year 1997 but peaks on the following year until Year 1999 and set the highest recorded data for the 15 year period. The Figures show, on the other hand, that the average streamflow again significantly decreased on the succeeding years.
Table 11-7 Streamflow Data, 1990-2004
YEAR STREAMFLOW
1990 5.831371
1991 4.484427
1992 5.162482
1993 6.574756
1994 5.718763
1995 8.595945
1996 7.345572
1997 4.13708
1998 10.61002
1999 10.07319
2000 2.857765
2001 1.904581
2002 2.178424
2003 1.731301
2004 4.735935 Source: LLDA PDMED
Source: LLDA PDMED
Figure 11-6 Streamflow, 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 Laguna de Bay. 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 Pangil River Basin, the long term water balances of the basin based on the hydrologic simulation is shown in the table below
. The 15-year average would show that 64.85% of the total rainfall becomes surface run-off, and about 20.98% of rainfall is lost as actual evapotranspiration. The base flow component of the total run-off is quite minimal, with only about 11.76% of rainfall, while the remaining 2.41% is stored as soil moisture and contributes to groundwater aquifer (Figure 11-7).
Table 11-8 Yearly Water Balances based on model simulation (mm)
YEAR RAINFALL ACTUAL EVAPO-TRANSPIRATION
DIRECT RUNOFF
BASEFLOW CHANGE IN STORAGE
1990 4,093 804 2,770 473 46
1991 3,445 858 2,065 409 113
1992 3,837 872 2,396 480 89
1993 4,703 858 3,202 474 170
1994 4,131 902 2,607 563 59
1995 5,878 835 4,297 537 209
1996 5,154 897 3,489 620 147
1997 3,270 944 1,733 530 62
1998 7,054 954 5,251 628 220
YEAR RAINFALL ACTUAL EVAPO-TRANSPIRATION
DIRECT RUNOFF
BASEFLOW CHANGE IN STORAGE
1999 6,574 807 4,883 714 169
2000 2,415 801 1,218 378 19
2001 1,877 804 782 299 (8)
2002 2,009 728 952 284 44
2003 1,713 739 709 274 (9)
2004 3,514 712 2,338 357 107
AVE RAGE 3,978 835 2,580 468 96
Source: LLDA PDMED
Source: LLDA PDMED
Figure 11-7 Water Balances based on model simulation, 1990-2004