Don't rebuild communities in landslide-stricken areas

LOS BAÑOS, Laguna, Philippines — Don’t rebuild communities in areas where landslides had occurred.

This advice comes from Dr. Beatriz Cuevas-Jadina of the Visayas State University (VSU) in Baybay City, Leyte, who has been studying high-risk landslide areas in Leyte.

“No home settlements should be established within the four-kilometer runout distance of the unstable area,” she said.

Moreover, the mountainside should be planted to forest trees rather than cash crops such as coconut and agronomic or food crops, she added.

Jadina also called for continuous monitoring of rainfall by setting up additional rain gauge stations as part of an early warning system for the people in the landslide-stricken area.

The VSU scientist made these recommendations based on her study entitled “GIS-Aided Bio-physical Characterization and Assessment of a Landscape in Relation to Landslide Occurrences.” GIS stands for geographic information.

The Los Baños-based, Philippine government-hosted Southeast Asian Ministers of Education Organization-Regional Center for Graduate Study and Research in Agriculture (SEAMED SEARCA), through its Seed Fund for Research and Training, supported the study.

SEARCA, headed by director Gil Saguiguit Jr., is one of the 20 “centers of excellence” of SEAMEO, an inter-government treaty body founded in 1965 to foster cooperation among Southeast Asian nations in the fields of education, science and culture.

Jadina discussed recently the results of her study at SEARCA’s Agriculture and Development Seminar Series, a regular professional forum sponsored by the center every Tuesday afternoon.

Her research analyzed the causal and triggering factors contributing to the likelihood of a landslide.

She cited, as an example, the case of St. Bernard, Southern Leyte, where a landslide in 2006 killed more than a thousand people and destroyed homes and sources of livelihood.

“Before, and even on the day of the landslide, frequent earthquakes were recorded in the area where a major fault line is known to directly pass through,” Jadina said.

She said geologic formations, seismicity, steep slopes, vegetation and land cover, and soil properties are the causal factors of a landslide.

She also observed that before the 2006 landslide in St. Bernard, a large amount of rainfall was recorded in Southern Leyte, which most likely was one of the triggers of the incident.

Other triggering factors included changes in groundwater level, which was manifested by the presence of abundant springs emanating from the sides of “landslide cuts” in St. Bernard, Jadina added.

A few years after the disaster, people again established their houses near the landslide areas, and started setting up farms and other livelihood options.

Warning that “almost always, landslides will occur in areas where they happened before,” Jadina recommended the conduct of more comprehensive studies on the causes and effects of landslides.