SUMMARY REPORT RESULTS OF THE MGB GEOHAZARD ASSESSMENT COVERING FOURTEEN (14) MUNICIPALITIES/CITY IN THE PROVINCE OF ZAMBALES In line with the recent Presidential Directive and NDCC resolutions following the February 17 Southern Leyte landslide incident, and the need to fast track the geohazard mapping program along the eastern seaboard of the Philippines, geologists from the Mines and Geosciences Bureau-Regional Office III (MGB-R3) conducted a geohazard assessment of the barangays in the municipalities/city of the province of Zambales. Each barangay was classified according to their susceptibility to landslide and/or flooding. For landslide susceptibility, the rating parameters are as follows: High • Presence of active and/ or recent landslides • Presence of numerous and large tension cracks along slope adjacent to the community and that would directly affect the community • Areas with drainages that are prone to landslides damming • Steep/Unstable slopes consisting of loose materials Moderate • Areas with indicative and/or old landslides • Presence of small tension cracks along slope and are located away from the community • Moderate slopes Low • Low to gently sloping • No presence of tension cracks 1 Each barangay was rated into low, moderate or high for flooding susceptibility with the rating parameters as follows: Low • 0 – 0.5 meter depth of floodwaters Moderate • 0.51 – 1 meter depth of floodwaters High • > 1 meter depth of floodwaters With regards to landslide susceptibility, the barangays assessed include areas that are located on and/or near slopes and riverbanks and have the potential for landslide occurrence. The rating of each barangay presented herein particularly refers to the barangay proper since majority of the population is located there. It should be noted, however, that the rating does not necessarily reflect those of the sitios. These barangays were presented with a Landslide Threat Advisory informing their susceptibility to landslides and the corresponding recommendations particular to the barangay. The flood susceptibility of the barangays in the municipalities/cities was also assessed. Barangays classified with moderate to high susceptibility to flooding are located in identified low portions of the barangay, in topographically low-lying areas and/or near a major river system. These barangays were presented with a Geohazard Threat Advisory informing their susceptibility to flooding and the corresponding recommendations particular to the barangay. 2 Table 1. Number of Assessed Barangays Munici pality/City Total Barangays Number of Assessed Barangays 1. Botolan 31 31 2. Cabangan 22 22 3. Candelaria 16 16 4. Castillejos 14 14 5. Iba 14 14 6. Masinloc 13 13 7. Olongapo City 17 17 8. Palauig 19 19 9. San Antonio 14 14 10. San Felipe 11 11 11. San Marcelino 18 18 12. San Narciso 17 17 13. Sta. Cruz 25 25 14. Subic 16 16 TOTAL 247 247 SUMMARY OF THE ASSESSMENT: 1. Municipality of Botolan • There are two (2) barangays with moderate landslide susceptibility (Nacolcol and Palis). • There are two (2) barangays with low to moderate landslide susceptibility (Moraza and Owaog-Nibloc). • There are seven (7) barangays with low landslide susceptibility (Belbel, Burgos, Cabatuan, Maguisguis, Malomboy, Poonbato and Villar). • There are seventeen (17) barangays with no landslide landslide susceptibility (Bancal, Bangan, Batonlapoc, Beneg, Capayawan, Carael, Danacbunga, Mambog, Paco, Parel, Paudpod, San Isidro, San Juan, San Miguel, Santiago, Tampo and Taugtog). • There are three (3) barangays (Porac, Binoclutan, Panan) with varying landslide susceptibility (i.e. none at the barangay proper but moderate to high at sitios and puroks). 3 • In terms of flood susceptibility, twenty (20) barangays experience varying degrees of flooding (Bancal, Bangan, Batonlapoc, Beneg, Binoclutan. Capayawan, Carael, Danacbunga, Mambog, Paco, Panan, Parel, Paudpud, Porac, San isidro, San Juan, san Miguel, Santiago, Tampo, Taugtog) 2. Municipality of Cabangan • There is one (1) barangay with low to moderate landslide susceptibility (New San Juan). • There are two (2) barangays with low landslide susceptibility (Cadmang-Reserva and Santa Rita). • There is one (1) barangay with no landslide susceptibility at the barangay proper, but with moderate landslide susceptibility in other portions (Sitio Kato). • There are two (2) barangays with no landslide susceptibility at the barangay proper but with low landslide susceptibility in other areas (Mabanglit and San Rafael). • There are sixteen (16) barangays with no landslide to low landslide susceptibility (Anonang, Apo-Apo, Arew, Banuambayo Camiling, Casaban, Del Carmen, Dolores, Felmida-Diaz, Laoag, Lomboy, Longos, San Antonio, San Isidro, Sto. Ni ño and Tondo ). • In terms of flood susceptibility, the twenty two (22) barangays experience varying degrees of flooding (Anonang, Apo-Apo, Arew, Banuambayo, Cadmang, Camiling, Casabaan, Del Carmen, Dolores, Fermida-Diaz, Laoag, Lomboy, Longos, Mabanglit, New San Juan, San Antonio, San Isidro, San Juan, San Rafael, Sta. Rita, Sto. Niño and Tondo). 3. Municipality of Candelaria • In terms of landslide susceptibility, there are four (4) barangays in Candelaria that have potential for landslide occurrence. Barangays Malabon, Pamibian and Pinagrealan have low to moderate susceptibility to landslides. Taposo has a moderate to high susceptibility to landslides. There are small scale mining activities in the area. • There are seven (7) barangays with low susceptibility to flooding (Catol, Babancal, Sinabacan, Poblacion, Libertador, Dampay and Yamot). • There are four (4) barangays with low to moderate susceptibility to flooding. Most of the residential area has low flooding susceptibility. Agricultural areas of the 4 barangay and those located near the river channel have moderate susceptibility (Malabon, Pamibian, Panayonan and Binabalian). • There are two (2) barangays with moderate to high susceptibility to flooding. The barangay has naturally low-lying areas; floodwater flows towards the low-lying areas of the barangay. Other factors include heavily silted and constricted natural creek/river channels (Taposo and Lauis). • There are three (3) barangays with low, moderate to high susceptibility to flooding. These barangays have portions adjacent to active creeks and river channel, and has naturally low-lying areas. Breaching of dikes protecting the riverbanks is also a factor of flooding in the barangays (Uacon, Malimanga and Pinagrealan). • Siltation and riverbank erosion along unprotected portions of the creek/river is evident along the active creek and river channels in Candelaria and nearby municipalities. The creeks/rivers that traverse the municipality and influence flooding include Taposo , Waloy , Malimanga , Gala-Gala creeks and Kitikit, Cabatuan and San Vicente Rivers. Overflow from Pamibian Lake also contributes to flooding. 4. Municipality of Castillejos • There is one (1) barangay with moderate to high landslide susceptibility (Balaybay). • There are thirteen (13) barangays with no landslide susceptibility (Buenavista, Del Pilar, Looc, Magsaysay, Nagbayan, Nagbunga, San Agustin, San Juan, San Nicolas, San Pablo, San Roque and Sta.Maria • In terms of flood susceptibility, twelve (12) barangays experience varying degrees of flooding. (Del Pilar, Looc, Magsaysay, Nagbayan, Nagbunga,San Agustin, San Jose, San Juan, San Nicolas, San Pablo, San Roque, Sta. Maria) 5. Municipality of Iba • There is one (1) barangay with low to moderate landslide susceptibility (Santa Barbara). • There are two (2) barangays with no landslide susceptibility at the barangay proper. Other portions of the barangay, however, have susceptibility to landslide (Brgy. Palanginan and San Agustin). 5 • There are eleven (11) barangays with no landslide susceptibility (Amungan, Bangantalinga, Dirita-Baloguen, Lipay-Dingin-Panibuatan, Santo Rosario, Zone 1 Poblacion (Libaba), Zone 2 Poblacion (Aypa), Zone 3 Poblacion (Botlay), Zone 4 Poblacion (Sagapan), Zone 5 Poblacion (Baño) and Zone 6 Poblacion (Baytan). • In terms of flood susceptibility, the fourteen (14) barangays experience varying degrees of flooding (Amungan, Bangantalinga, Dirita-Baloguen, Lipay-Dingin- Panibuatan, Palanginan, San agustin, Sta. Barbara, Sto. Rosario, Zone 1 Poblacion (Libaba), Zone 2 Poblacion (Aypa), Zone 3 Poblacion (Botlay), Zone 4 Poblacion (Sagapan), Zone 5 Poblacion (Baño), Zone 6 Poblacion (Batan). 6. Municipality of Masinloc • In terms of landslide susceptibility, the barangays in Masinloc have low susceptibility to landslide. • There are three (3) barangays with low susceptibility to flooding (Bamban, Baloganon and North Poblacion ). • There are three (3) barangays with low to moderate susceptibility to flooding. Flooding affects both the residential and agricultural areas of the barangay (Inhobol, Collat and Taltal). • South Poblacion, mostly affected by coastal flooding has moderate susceptibility. • There are two (2) barangays with moderate to high susceptibility to flooding. These barangays have portions adjacent to active creeks and river channel, and has naturally low-lying areas. Breaching of dikes protecting the riverbanks is also a factor to flooding in the barangays (Sta. Rita and Tapuac). • The creeks/rivers that traverse the municipality and influence flooding include Lauis and Masinloc rivers. 7. Municipality of Olongapo City • There are three (3) barangays with moderate to high landslide susceptibility (Barretto, Kalaklan and Gordon Heights). • There are two (2) barangays with moderate