Botolan, Zambales — Zambales officials are on heightened alert as heavy rains triggered by the southwest monsoon (habagat) and recent typhoons continue to threaten communities situated along major river systems still laden with massive lahar deposits from the 1991 Mount Pinatubo eruption.
Governor Hermogenes Ebdane Jr. on Monday ordered the preemptive evacuation of residents in Barangay San Juan, Botolan, after inspecting a damaged section of the Bucao River dike that protects at least six low-lying villages from floodwaters and lahar flows.
“As of now, we are dropping armor rocks into the scoured portion and doing sandbagging to strengthen the dike foundation and prevent a total breach,” Ebdane said.
The governor said the provincial government is racing to reinforce the weakened structure to avoid a repeat of the devastating 2009 disaster, when the Bucao River earth dike collapsed and inundated several communities in Botolan.
“We’re doing all we can to prevent a dire situation like that in 2009 when the earth dike along Bucao gave way and caused a major disaster in Botolan. We don’t want that to happen again,” Ebdane said.
Provincial infrastructure development consultant Domingo Mariano warned that a failure of the Bucao River dike could inundate the barangays of San Juan, Paudpod, Carael, Bangan, Capayawan, and Batonlapoc, all of which lie directly along the river and were among the hardest-hit areas during the 2009 flooding.
Authorities are also closely monitoring the Sto. Tomas River, which traverses the towns of San Marcelino, San Felipe, and San Narciso, after strong currents washed away the Sta. Fe Bridge in Barangay Sta. Fe, San Marcelino, on Sunday, leaving the upland community isolated.
Mariano said at least 15 barangays in the three municipalities are situated along the Sto. Tomas River, which drains from the slopes of Mount Pinatubo and carries large volumes of lahar during prolonged rainfall.
Ebdane said lahar deposited by the 1991 eruption continues to pose a major hazard every rainy season as heavy downpours dislodge volcanic debris upstream and send it downstream through the province’s river systems.
According to the Mines and Geosciences Bureau-Central Luzon, an estimated 6.7 billion cubic meters of volcanic debris remain on the Zambales side of Mount Pinatubo. Of this volume, about 3 billion cubic meters are in the Bucao River basin, while another 1.6 billion cubic meters are in the Sto. Tomas River basin.
Mariano said the provincial government has been conducting dredging operations under the Zambales River Restoration Program since 2023.
However, only the river deltas have been cleared so far because of the enormous volume of lahar deposits, while recent heavy rains and typhoons have temporarily halted dredging activities.
Meanwhile, the Provincial Disaster Risk Reduction and Management Office (PDRRMO) reported that six infrastructure facilities sustained damage during the heavy monsoon rains enhanced by Typhoons Luis and Maymay.
Among those destroyed were the Sta. Fe Bridge in San Marcelino, which was swept away by strong river currents, and a P700,000 Small Water Impounding Project in Barangay Amungan, Iba.
The PDRRMO also reported partial damage to a multi-purpose hall in Barangay San Miguel, San Antonio; the Tanguay slope protection project in Sto. Niño, Cabangan; another slope protection structure in Bayto, Sta. Cruz; and the San Juan dike in Botolan.
PDRRMO chief Rolex Estella said that as of 5 p.m. Monday, a total of 7,044 individuals, or 2,441 families, had been displaced by flooding across the province.
Of the total evacuees, 4,706 individuals from 1,621 families were staying in evacuation centers, while 285 persons from 102 families sought temporary shelter with relatives, Estella added. (Malou Dungog)
