San Juan Sub-Basin
Total Page:16
File Type:pdf, Size:1020Kb
Table of Contents Volume 19. San Juan Sub-basin ........................................................................................... 3 Geographic location ................................................................................................................ 3 Political and Administrative Boundary ..................................................................................... 4 Land Cover ............................................................................................................................. 6 Sub-basin Characterization and Properties............................................................................. 8 Drainage Network ............................................................................................................... 8 Sub-sub basin Properties ...................................................................................................10 Water Quantity ......................................................................................................................11 Streamflow .........................................................................................................................11 Water Balance ...................................................................................................................12 LIST OF FIGURES Figure 19-1 Geographical Map ..................................................................................................................... 3 Figure 19-2 Political Map .............................................................................................................................. 6 Figure 19-3 Land Cover Map ........................................................................................................................ 7 Figure 19-4 Drainage Map ............................................................................................................................ 9 Figure 19-5 Sub-sub basin Map of San Juan Sub-basin ............................................................................ 10 Figure 19-6 Streamflow, 1990-2004 ........................................................................................................... 12 Figure 19-7 Water Balances based on model simulation, 1990-2004 ........................................................ 13 LIST OF TABLES Table 19-1 Geographic extent ...................................................................................................................... 4 Table 19-2 Municipalities and Barangays Covered ...................................................................................... 4 Table 19-3 Population Distribution by Municipality, 2007 ............................................................................. 5 Table 19-4 Area Distribution of Land Cover .................................................................................................. 7 Table 19-5 Some Relief Features and Other Geo-Morphological Parameters ............................................. 8 Table 19-6 San Juan Sub-sub basin properties ......................................................................................... 11 Table 19-7 Streamflow Data, 1990-2004 .................................................................................................... 11 Table 19-8 Yearly Water Balances based on model simulation (units in mm) ........................................... 12 Technical writer Engr. Erwin Kim P. Mercado, 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 19. San Juan Sub-basin Geographic location The San Juan Sub-basin is located at the southwestern portion of the Laguna de Bay Basin. The sub-basin covers the barangays of two (2) municipalities and three (3) cities, namely: Municipality of Sto. Tomas, Municipality of Malvar, Calamba City, Tanauan City and Lipa City. It also covers small portions of the barangays which belong to Los Baños, Calauan, Bay, and Alaminos. However, these areas do not have significant impact on the San Juan Sub-basin, hence; these areas were not included in this report. Figure 19-1 illustrates the geographic location and boundary of the San Juan sub-basin in the Laguna de Bay. Source: LLDA GIS Figure 19-1 Geographical Map As to the coordinates of the five municipalities and cities within the San Juan Sub-basin, Calamba City is located at latitude 14°13' N, and longitude 121°10' E while Malvar’s geographical coordinates are 1403’ N and 12110’ E. Sto. Tomas on the other hand, is located at 1405 N, 12110’55”E. Tanauan City is located within 14°5’ N and 121°6’ E at the North- Eastern part of Batangas. As for Lipa City in Batangas, it is located in latitude 13o 57’ N and longitude 121o 10’ E. The geographic extent of the sub-basin is presented in Table 19-1. Its total land area is about 20,421.391 hectares. The City of Tanauan and Sto. Tomas have the largest land areas within the sub-basin while Malvar has the least. However, in terms of the number of barangays covered by the sub-basin, Sto. Tomas has the greatest proportion (100 percent), followed by Calamba City (90.74 percent), Tanauan City (58.33 percent), Malvar (40 percent) and Lipa City (4.17 percent). Table 19-1 Geographic extent CORNERS NORTHING (UTM) EASTING (UTM) Upper Left 1545663.50000 309923.09375 Upper Right 1545663.50000 288606.83957 Lower Right 1573821.50000 288606.83957 Lower Left 1573821.50000 309923.09375 Source: LLDA GIS Political and Administrative Boundary The San Juan sub-basin is one of the largest sub-basins within the Laguna de Bay region (Figure 19-2). It covers 123 barangays located in 10 municipalities and cities coming from the three provinces of Laguna, Batangas and Cavite. Four of which (Alaminos, Bay, Calamba and Los Baños) are situated in Laguna, other five (Tanauan, Lipa, Malvar, Sto. Tomas and Talisay) in Batangas while the remaining in the Province of Cavite (Tagaytay City). Table 19-2 shows the detailed figures on the jurisdiction of the sub-basin. Sto. Tomas is the largest municipality accounting for almost 44% (8,879.32 hectares) of the total area of the sub-basin. In view of barangays covered, Calamba City and Tanauan City have the most with 33 both, followed by Sto. Tomas with 30. Table 19-2 Municipalities and Barangays Covered MUNICIPALITY/CITY NUMBER OF BARANGAYS AREA (ha) PERCENTAGE (%) Calamba City 33 2795.588 13.68% Tanauan City 33 5232.298 25.61% Sto. Tomas 30 8879.320 43.45% Malvar 7 1438.652 7.04% Lipa City 8 1960.992 9.60% Los Baños 5 57.142 0.28% Bay 1 0.35 0.00% Alaminos 4 39.97 0.20% Tagaytay 1 15.807 0.08% Talisay 1 13.979 0.07% TOTAL 123 20,434.10 100% Source: LLDA GIS Based on the 2007 Census of Population by the National Statistics Office, the total population within the San Juan sub-basin is estimated at 376,555. Number of inhabitants residing in the barangays within the territories of Lipa City, Tagaytay City and Talisay, Batangas were not considered in the total number of population within the sub-basin since the same are not under the jurisdiction of LLDA Tanauan City, having the largest area percentage making up the sub-basin, also shared the highest number of inhabitants with 38% or 142,537. On the other hand, Los Baños contributes the least number of population at 1,479 (0.39%). Average growth rate was determined at 2.94%. Table 19-3 shows the detailed population data of each municipalities as well as the annual growth rate. Table 19-3 Population Distribution by Municipality, 2007 MUNICIPALITY POPULATION ANNUAL GROWTH RATE (%) Calamba City 65,931.42 3.48 Tanauan City 142,537 2.69 Sto. Tomas 113,105 4.82 Malvar 41,730 3.42 Los Baños 1,479.47 2.57 Bay 2,081.00 2.07 Alaminos 9,691.20 1.55 TOTAL 376,555 National Statistics Office, 2007 Census of Population Source: LLDA GIS Figure 19-2 Political Map Land Cover Based on the land cover validation undertaken by LLDA PDMED, grassland, brushland and plantation occupy vast areas of the sub-basin having 30%, 26% and 19% of the total area, respectively. Table 19-4 shows the land cover distribution in the sub-basin of San Juan while Figure 19-3 shows the land cover map. Table 19-4 Area Distribution of Land Cover LAND COVER AREA (ha) PERCENTAGE Urban 885.01 4.33% Forest 928.81 4.55% Arable 3341.08 16.36% Plantation 3827.55 18.74% Grassland 6049.20 29.62% Brushland 5351.24 26.20% Marsh 21.90 0.11% Unclassified 9.47 0.05% Cloud 8.95 0.04% TOTAL 20423.21 100.00% Source: LLDA GIS Source: LLDA GIS Figure 19-3 Land Cover Map Sub-basin Characterization and Properties Drainage Network The drainage map of the San Juan Sub-basin is shown in Figure 19-4 while the important watershed characteristics and geomorphological features are in Table 19-5. Table 19-5 Some Relief Features and Other Geo-Morphological Parameters PARAMETERS VALUES Area (ha) 20421.39 Perimeter (m) 96254.684 Total number of streams 31 Total length of streams (m) 196913.593 Stream Density (stream/ha) 0.0015 Drainage Density (m/ha) 9.6425 Constance of Channel Maintenance (ha/m) 0.1037 Length of Overland Flow (m) 4.8213 Source: LLDA GIS Source: LLDA GIS Figure 19-4 Drainage Map Sub-sub basin Properties Source: LLDA GIS Figure 19-5 Sub-sub basin Map of San Juan Sub-basin Table 19-6 San Juan Sub-sub basin properties SUB-SUB BASIN NAME AREA (Ha) PERIMETER (m) SSB-18A 7985.704 108295.963 SSB-18B 997.966 18844.909 SSB-18C 561.348 15217.305 SSB-18D 1321.432