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Debris-flow deposits in the New Bataan area. A= Boulder in ancient reverse-graded debris-flow deposit. Wellestablished trees indicate an age of some decades prior to the settlement of the town. B= Old debris-flow deposits underlying New Bataan – Andap highway. Boulders are separated from each other by a matrix of finer-grained sediment. For scale, the concrete is 15 centimeters thick. The coarse sediment atop the highway are new debris-flow deposits. C= Boulder-rich deposits of debris
Source publication
Category 5 Super Typhoon Bopha, the world's worst storm of 2012, formed abnormally close to the Equator, and its landfall on Mindanao set the record proximity to the Equator for its category. Its torrential rains generated an enormous debris flow in the Mayo River watershed that swept away much of Andap village in New Bataan municipality, burying a...
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With the unique rainfall patterns of typhoons, plum rains, and short-term heavy rainfalls, the frequent landslide and debris flow disasters have caused severe loss to people in Taiwan. In the studies of landslide susceptibility, the information of factors used for analysis was usually annual-based content, and it was assumed that the same elements...
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Category 5 Super Typhoon Bopha, the world's worst storm of 2012, formed
abnormally close to the Equator, and its landfall on Mindanao set the record
proximity to the Equator for its category. Its torrential rains generated an
enormous debris flow in the Mayo River watershed that swept away much of the
village Andap in the New Bataan municipality, b...
Ulleung-do is a volcanic island located 130 km east of the Gangwon-do province of South Korea. It is characterized by steep slopes covered with effusive rocks released from multiple volcanic activities. Having accumulated deep colluvium, Ulleung-do Island manifests a high vulnerability to landslides frequently caused by heavy rains or typhoons, deb...
Climate change has caused numerous disasters around the world. It has also influenced the climate of Taiwan, with urban areas exhibiting a temperature increase by 1 °C between 1998 and 2020. In this study, climate change and landslides in Taiwan were statistically analyzed. Cumulative annual precipitation in mountain watersheds in central Taiwan ex...
Citations
... Debris flows are fast-moving slurries of water and rock fragments, soil, and mud with the consistency of freshly mixed concrete (Rodolfo et al., 2016, Takahashi, 1981Hutter et al. 1994;Iverson 1997;Iverson et al., 1997)). Heavy rainfall that exceeds the critical threshold of intensity, duration and accumulation may dislodge soil, sediment and rock masses into landslides that may merge to form debris flow (Lagmay et al., 2007, Pierson andScott, 1985;Smith and Lowe, 1991). ...
... The municipality of New Bataan with 16 barangays was formally established by an act of Congress on 18 June 1948 in honor of Luz Banzon-Magsaysay, the widow of President Ramon Magsaysay who hailed from Bataan province in Luzon (Rodolfo et al. 2016). New Bataan is located in the province of Compostela Valley in the Davao region ( Figure 1). ...
... The valley was bounded by steeply sided slopes with deeply fractured rocks situated along the length of Mati Fault line. The location was not initially recognized as an alluvial fan (Rodolfo et al. 2016) where water drains. Its geological and geographical characteristics thus make the village susceptible to floods and landslides. ...
In December 2012, Brgy. Andap, New Bataan in Compostela Valley suffered catastrophic damages due to Typhoon Bopha. Participatory Rural Appraisal (PRA) activities were conducted in Brgy Andap six months after the calamity to elicit the community's local ecological knowledge on the land use and livelihood changes; their impacts on environmental degradation; causal factors of the 2012 flash flood and landslide; solutions for livelihood recovery; and recommendations to mitigate flashfloods and landslides The various PRA activities include timeline, community-based resource maps, causal mapping, and focus group discussion. New Bataan used to have lush primary forest, fertile soils and abundant minerals. For decades, the livelihood in the community was mainly agricultural planting vegetables, annual crops and perennial trees. Logging and mining activities since the 1950's resulted to deforestation. These decade-long activities have increased the area's vulnerability to natural disasters. Locals perceive logging and mining activities as the major causes of landslides and floods in the locality. Community recommendations to aid in the community's livelihood recovery include support for the restoration of farming activities in the form of subsidies for agricultural inputs, provision of trainings and seminars on modern agricultural practices and establishment of micro-credit financing institutions. To mitigate flashfloods and landslides, the community recommends logging ban and planting of trees in the denuded forests, moratorium on mining and introdution of livelihood opportunities. Protection of the environment will lead to sustainable livelihoods. Climate change adaptation and mitigation strategies as well as careful consideration of the local geological and geographical characteristics of the 62
... Each indicator is weighted (n − r i + 1) and then normalized by the sum of all weights (n − r j + 1). Therefore, the ranking method estimated weight should be considered as an approximation [60]. The results are given in Table 4. ...
... It has reached an average speed of 185 kph and gusts reaching 210 kph. Typhoon Pablo, as what Typhoon Bopha is called in the Philippines, was the most powerful storm to have hit the island of Mindanao, southern Philippines, in more than 100 years of recorded storms [60]. Its torrential rains generated massive debris flow in the Mayo River watershed in the Andap village in New Bataan municipality, causing some areas to be buried under a rubble as thick as 9 m and killing 566 people [60]. ...
... Typhoon Pablo, as what Typhoon Bopha is called in the Philippines, was the most powerful storm to have hit the island of Mindanao, southern Philippines, in more than 100 years of recorded storms [60]. Its torrential rains generated massive debris flow in the Mayo River watershed in the Andap village in New Bataan municipality, causing some areas to be buried under a rubble as thick as 9 m and killing 566 people [60]. Moreover, it was also revealed that a storm surge with a height of approximately 1 m has reached a distance of 500 m inland away from the coastline [12]. ...
Flooding is one of the major destructive natural disasters in Davao Oriental, Philippines, and results primarily from a high incidence of typhoons and heavy rainfalls. The main objective of this study was to identify flood-prone risk areas by mapping them based on the integration of multiple indicators, including rainfall, slope, elevation, drainage density, soil type, distance to the main channel and population density. For this purpose, a GIS-based flood risk spatial assessment was conducted by using analytic hierarchy process (AHP), weights by rank (WR) and ratio weighting (RW) frameworks to determine the relative importance of each indicator against another in the province of Davao Oriental. The resulting flood-prone areas by the three methods are validated by comparing with the estimated flood map based on ground truthing points from a field survey. The comparison results show that AHP is the most appropriate method among them to assess flood hazard. The result of the AHP flood risk map shows that 95.99% (5451.27 km2) of Davao Oriental is under low and moderate flood risk. The high and very high flood risk area covers approximately 3.39% (192.52 km2) of the province, primarily in the coastal areas. Thirty-one out of the one hundred eighty-three (31/183) barangays (towns) are at a high to very high risk of flooding at current climate, calling for the immediate attention of decision-makers to develop mitigation strategies for the future occurrence of flooding in Davao Oriental.
Purpose
Tropical storms Urduja and Vinta battered the Philippines in December 2017. Despite advances in disaster risk reduction efforts of the country, the twin December storms caused numerous deaths in the Visayas and Mindanao regions. Analysis of these events shows that alerts raised during the Pre-Disaster Risk Assessment (PDRA) for both storms were largely ineffective because they were too broad and general calling for forced evacuations in too many provinces. Repeated multiple and general warnings that usually do not end up in floods or landslides, desensitize people and result in the cry-wolf effect where communities do not respond with urgency when needed. It was unlike the previous execution of PDRA from 2014 to early 2017 by the National Disaster Risk Reduction and Management Council (NDRRMC), which averted mass loss of lives in many severely impacted areas because of hazard-specific, area-focused and time-bound warnings. PDRA must reinstate specific calls, where mayors of communities are informed by phone hours in advance of imminent danger to prompt and ensure immediate action. Mainstreaming Climate Change Adaptation and Disaster Risk Reduction information using probabilistic (multi-scenario) hazard maps is also necessary for an effective early warning system to elicit appropriate response from the community. The paper aims to discuss these issues.
Design/methodology/approach
Methods of early warning through the PDRA of the National Disaster Mitigation and Management Council (NDRRMC) of the Philippines during tropical storm Urduja and Typhoon Vinta were assessed in this study and compared to the previous PDRA system from 2014 to early 2017.
Findings
It was found out that the numerous casualties were due to inadequate warning issued during the approach of the tropical cyclones. During an impending hazard, warnings must be accurate, reliable, understandable and timely. Despite the availability of maps that identified safe zones for different communities, warnings raised during the PDRA for both tropical cyclones were deemed too general calling for evacuations of whole provinces. As such, not all communities were evacuated in a timely manner because of failure in the key elements of an effective early warning system.
Originality/value
To avoid future disasters from happening, it is recommended that the PDRA reinstate its hazards-specific, area-focused and time-bound warnings. Similarly, to increase the resilience of communities, more work on mainstreaming of Climate Change Adaptation and Disaster Risk and Vulnerability Reduction systems for communities must be done as well. Learning from the lessons of these previous disasters will enable communities, their leaders and every stakeholder, not to repeat the same mistakes in the future.
