ORCID Profile
0000-0002-4812-8180
Current Organisations
University of East Anglia
,
University of Exeter
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Publisher: Copernicus GmbH
Date: 19-05-2021
DOI: 10.5194/NHESS-21-1531-2021
Abstract: Abstract. In 2018 Typhoon Mangkhut (locally known as Typhoon Ompong) triggered thousands of landslides in the Itogon region of the Philippines. A landslide inventory of the affected region is compiled for the first time, comprising 1101 landslides over a 570 km2 area. The inventory is used to study the geomorphological characteristics and land cover more prone to landsliding as well as the hydrometeorological conditions that led to widespread failure. The results showed that landslides mostly occurred on grassland and wooded slopes of clay superficial geology, predominantly facing east-southeast. Rainfall (Integrated Multi-satellitE Retrievals for Global Precipitation Measurement, IMERG GPM) associated with Typhoon Mangkhut is compared with 33 high-intensity rainfall events that did not trigger regional landslide events in 2018. Results show that landslides occurred during high-intensity rainfall that coincided with the highest soil moisture values (estimated clays saturation point), according to Soil Moisture Active Passive level 4 (SMAP-L4) data. Our results demonstrate the potential of SMAP-L4 and GPM IMERG data for landslide hazard assessment and early warning where ground-based data are scarce. However, other rainfall events in the months leading up to Typhoon Mangkhut that had similar or higher rainfall intensities and also occurred when soils were saturated did not trigger widespread landsliding, highlighting the need for further research into the conditions that trigger landslides in typhoons.
Publisher: Copernicus GmbH
Date: 25-08-2020
Abstract: Abstract. In 2018, Typhoon Mangkhut (locally known as Typhoon Ompong) triggered thousands of landslides in the area of Itogon (Philippines). A landslide inventory of 1101 landslides over a 570 km2 area is used to study the geomorphological characteristics and land cover more prone to landsliding as well as the rainfall and soil moisture conditions that led to widespread failure. Landslides mostly occurred in slopes covered by wooded grassland in clayey materials, predominantly facing East–Southeast. The analysis of both satellite rainfall (GPM IMERG) and soil moisture (SMAP-L4) finds that, in addition to rainfall from the typhoon, soil water content plays an important role in the triggering mechanism. Rainfall associated with Typhoon Mangkhut is compared with 33 high intensity rainfall events that did not trigger regional landslide events in 2018 and with previously published rainfall thresholds. Results show that: (a) it was one of the most intense rainfall events in the year but not the highest, and (b) despite satellite data tending to underestimate intense rainfall, previous published regional and global thresholds are to be too low to discriminate between landslide triggering and non-triggering rainfall events. This work highlights the potential of satellite products for hazard assessment and early warning in areas of high landslide activity where ground-based data is scarce.
Publisher: Copernicus GmbH
Date: 28-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-7819
Abstract: & & The rain that falls weeks or months before the occurrence of landslides can play a major role in the failure process, therefore it is crucial to account for it in hazard assessments and warning systems. It is especially relevant in tropical areas, where the amount of water that falls during wet seasons can be very high. In the Philippines, rainfall and typhoon events trigger Multiple-Occurrence Regional Landslide Events (MORLEs, Crozier, 2005), which cause hundreds of fatalities and significant economic damage every year.& & & & Satellite-based rainfall measurements (IMERG GPM) associated with three typhoons that triggered MORLEs in the area of Itogon (Benguet, Philippines) and water infiltrated into the soil during the previous months are analysed. Data from the three typhoons are compared with 560 high intensity rainfall events (from period 2000-2020) that did not trigger regional landslide events. Results show that landslides occurred when typhoon rainfall exceeds 300 mm and the water infiltrated was higher than 1000 mm in the previous months. For one specific landslide-triggering typhoon event, satellite-based soil moisture data (1 m top soil layer) are analysed and compared to other non-landslide triggering rainfalls. Results do not show a clear correlation of critical rainfall and soil moisture values that triggered landslides.& & & & The findings of this work highlight that the antecedent rainfall, and in particular its infiltration below the top soil layer, plays a major role in the triggering process of landslides, especially in tropical regions.& & & & & em& & Crozier, M.J. Multiple-occurrence regional landslide events in New Zealand: Hazardmanagement issues. Landslides 2, 247& #8211 (2005). 0.1007/s10346-005-0019-7& /em& & &
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Georgina Bennett.