Summary Report
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SUMMARY REPORT RESULT OF THE MGB GEOHAZARD ASSESSMENT COVERING TWENTY FOUR (24) MUNICIPALITIES/CITIES IN THE PROVINCE OF BULACAN 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 of the municipality/cities in the province of Bulacan. 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 1 Low • Low to gently sloping • No presence of tension cracks 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 floodings and the corresponding recommendations particular to the barangay. 2 Table 1. Number of Assessed Municipalities/Cities//Barangays Municipality/City Total Barangays Number of Assessed Barangays 1. Angat 16 16 2. Balagtas 9 9 3. Baliuag 27 27 4. Bocaue 19 19 5. Bulacan 14 14 6. Bustos 14 14 7. Calumpit 29 29 8. Guiguinto 14 14 9. Hagonoy 26 26 10. City of Malolos 51 51 11. Marilao 16 16 12. City of Meycauayan 26 26 13. Norzagaray 13 13 14. Obando 11 11 15. Pandi 22 22 16. Paombong 14 14 17. Plaridel 19 19 18. Pulilan 19 19 19. San Ildefonso 36 36 20. San Jose del Monte 59 56 21. San Miguel 49 49 22. San Rafael 34 34 23. Sta. Maria 24 24 24. Doña Remedios 8 7 Trinidad TOTAL 569 565 SUMMARY OF THE ASSESSMENTS: 1. Municipality of Angat • In terms of landslide susceptibility, no barangays in Angat have the potential for landslide occurrence. • In terms of flood and flashflood susceptibility, ten (10) out of sixteen (16) barangays were found to be susceptible to flooding (Banaban, Baybay, 3 Binagbag, Donacion, Laog, San Roque (Pob.), Sta. Cruz (Pob.), Sta. Lucia, Sulucan and Taboc). 2. Municipality of Balagtas • The barangays in the municipality of Balagtas experienced three levels of susceptibility to flooding • There are six (6) barangays with low susceptibility to flooding in the municipality (Burol 1 st , Burol 2 nd , Panginay, Pulong Gubat, Santol and Wawa). The barangay centers and populated areas in the barangays has a low susceptibility to flooding; portions of the barangays usually inundated are the generally low lying areas and catchment areas of the barangays, adjacent to the agricultural areas, and near active creeks, rivers. Localized flooding is also common in these areas where insufficient/inadequate or clogged drainage are common due to improper garbage disposal • There are three (4) barangays with low susceptibility to flooding in the barangay centers but with some portions or puroks that have moderate to high susceptibility to flooding. Flood in these barangays easily subsides. Possible causes of flooding in the barangay are unusually heavy rains associated with typhoons; structures such as elevated roads or low-lying areas, overflow from silted rivers and creeks; back flooding when tributaries of the river are flooded, inadequate drainage and excessive surface run-off coming from higher elevation and areas adjacent to river and creek channels. • There are three (3) barangays with high susceptibility to flooding (Dalig, Longos and San Juan). Possible causes of flooding in the barangay are unusually heavy rains associated with typhoons; structures such as elevated roads and release of excess water in water dams, overflow from constricted and silted rivers/ creeks; Localized flooding also due to inadequate drainage. Excessive surface run-off from higher elevation. Rapid urbanization also contributes to the cause of flooding in these areas. • The agricultural areas/farm lots have a moderate to high susceptibility to flooding. • The municipality of Balagtas has a history of high level flooding especially along the Balagtas River. 3. Municipality of Baliuag • Most of the barangays in the municipality of Baliwag has a low susceptibility to flooding. Those with portion that has a moderate to high susceptibility to flooding are located along the Bustos-Baliwag River and near or adjacent to irrigation canals. 4 • There are ten (10) barangays with low susceptibility to flooding in the municipality (Tarcan, Makinabang, Concepcion, Sto. Cristo, Subic, Bagong Nayon, Tangos, Piel, Pinagbarilan, Pagala and Sto. Niño). The barangay centers and populated areas in the barangays has a low susceptibility to flooding; portions of the barangays usually inundated are the generally low lying areas and catchment areas of the barangays, adjacent to the agricultural areas, near active creeks, rivers and irrigation canals traversing the barangay. • There are six (6) barangays with low susceptibility to flooding in the baranagay centers but with purok that are located near the Bustos-Baliwag River with a moderate to high susceptibility to flooding (San Jose, Sta. Barbara, Tiaong, Sabang, Tibag and Poblacion). Flood in these barangays easily subsides. Possible causes of flooding in the barangay are unusually heavy rains associated with typhoons; structures such as elevated roads, irrigation canals, water impoundments and dams; overflow from constricted and silted rivers and creeks; back flooding when outlets and culverts were closed to control the release of water; and due to inadequate drainage. • There are seven (7) barangays with low susceptibility to flooding in most area but with purok and portion of the barangay that has a moderate to high susceptibility to flooding depending on the location (Virgen delas Flores, Concepcion, Matangtubig, Baranka, Hinukay, Catulinan, Tilapayong and Calantipay). Flooding is usually confined to the agricultural areas. Residential structures located near the creek are usually affected by the overflow from the creek and backflooding. • There are two (2) barangays with low to moderate susceptibility to flooding (San Roque and Suliban). Possible causes of flooding in the barangay are unusually heavy rains associated with typhoons; structures such as elevated roads, irrigation canals, water impoundments and dams; overflow from constricted and silted rivers and creeks; back flooding and due to inadequate drainage. • There is one (1) barangay with low, moderate to high susceptibility to flooding (Paitan). Flooding is usually topographic controlled; there are also portion of the barangay located near the creek and adjacent to the Candaba swamp. • The agricultural areas/farm lots have a moderate to high susceptibility to flooding. • The municipality of Baliwag has a history of high level flooding associated with the release of water from the Angat Dam in 1978. 4. Municipality of Bocaue • The barangays in the municipality of Bocaue have different levels of susceptibility to flooding • There are four (4) barangays with low susceptibility to flooding in the municipality (Turo, Batia, Bolacan and Bunducan). The barangay centers and populated 5 areas in the barangays has a low susceptibility to flooding; portions of the barangays usually inundated are the generally low lying areas and catchment areas of the barangays, adjacent to the agricultural areas, near active creeks, rivers and irrigation canals traversing the barangay. • There are four (4) barangays with low susceptibility to flooding in the barangay centers but with purok that have moderate to high susceptibility to flooding. Flood in these barangays easily subsides. Possible causes of flooding in the barangay are unusually heavy rains associated with typhoons; structures such as elevated roads, overflow from constricted and silted rivers and creeks; back flooding when tributaries of the river are flooded, inadequate drainage and excessive water associated from the release of floodwaters from the dams. • There are three (3) barangays with moderate to high susceptibility to flooding depending on the location (Bunlo, Igolot and Taal). Flooding is usually