There are many ways by which the Mines and Geosciences Bureau (MGB) communicate information on geologic hazards to the public. One is through the dissemination of Landslide and Flood Advisories issued preceding a typhoon and/or severe weather event or at the onset of the rainy season. This is to warn the general public, through their Local Disaster Risk Reduction and Management Councils (LDRRMC), of the possible threat of landslides and floods in their areas. The advisories being issued are in the form of general advisories that include a list of barangays whose barangay centers have moderate to high and very high susceptibilities to landslides and those that have moderate to high and very high susceptibilities to floods. Issuance of advisories of this nature, started almost a decade ago. However, this type of advisory only answe rs the question “where will the landslide occur” and not “when will the landslide occur” or “will the rainfall be enough to initiate landslides?”
To enhance its warning system, the MGB Region V, through its Geosciences Division, developed an early warning for landslide using antecedent precipitation and forecast satellite rainfall. The maiden issue of the Landslide Bulletin was disseminated to the PDRRMCs and the RDRRMC-OCDV on 29 November 2019, in the advent of the Typhoon Tisoy. Initially, a singular rainfall threshold was used for the whole region. A 10-day antecedent precipitation using ground rainfall data was combined with forecast satellite rainfall to determine whether the accumulated rainfall is enough to trigger landslides. Since its maiden issue, several landslide bulletins have already been issued for a number of typhoons and sever weather events such as the December 2019 Typhoon Ursula, the May 2020 Typhoon Ambo, the June 2020 TD Butchoy, the October 2020 Typhoon Quinta, the November 2020 Super Typhoon Rolly, the November 2020 Typhoon Ulysses and most recently, the TECF at the close of calendar year 2020.
Although there many challenges in the development and operationalization of this landslide early warning system, particularly on the lack of operational ground rainfall stations necessary for data calibration and antecedent rainfall determination, the Geosciences Division of MGB Region V seeks to continually improve on its landslide early warning system. Presently, one of its geologists, is looking at determining the different rainfall thresholds for different landscapes in the region. Linkaging for a closer collaborative work with PAGASA is under process to gain real time access to its ground rainfall stations and local rainfall forecasts. A project proposal is also being prepared to augment the limited number ground rainfall stations that are strategically located in landslide prone terrains.