BY NELJOY N. GALIGAO
ILOILO City – The National Irrigation Administration (NIA) has assured Ilonggos that the Jalaur High Dam can withstand major structural and seismic risks, citing a safety factor three times higher than standard requirements, multiple geological validations and real-time monitoring systems as it answered calls for greater scrutiny of the mega dam.
It rejected comparisons between a Jalaur dam worst-case scenario and the recent catastrophic flooding in Nepal raised by local environmental watchdog Jalaur River for the People Movement (JRPM).
The Nepal disaster resulted from a glacial lake outburst flood, a phenomenon involving glaciers that could not occur in tropical Iloilo, said NIA Region 6 spokesperson Steve Cordero.
The 109-meter-high dam in Calinog, Iloilo – a component of the Jalaur River Multipurpose Project Stage II (JRMP II) – was subjected to extensive hydrological, geological and engineering studies before and during construction, with seismic risks specifically incorporated into its design, Cordero stressed.
NIA is the government implementing agency of JRMP II.
“An active fault line in the area was thoroughly factored into our design parameters,” Cordero said.
NIA consultants designed the project with a factor of safety of three, he revealed.
“This means our considerations for managing risks — including water volume pressure, seismic movements, and river dynamics — are three times higher than standard requirements to ensure structural stability,” Cordero said.
Following the flooding in Nepal, JRPM called for an independent risk assessment of the Jalaur mega dam and pressed for a public disclosure of emergency procedures, geological and structural monitoring results, and downstream inundation maps amid concerns over potential cascading hazards.
Cordero said NIA’s safety assurances on the JRMP II are based on scientific studies and planning involving numerous experts.
“Safe. We have conducted meticulous planning. Our project did not happen overnight; there are a series of studies with a lot of experts involved to make sure that all risks and hazards are managed or mitigated sa implementation and operation sang dam,” he said.
The project was meticulously researched and strategically planned based on comprehensive hydrological studies of the Jalaur River in Calinog, covering flow behavior, water quality, and environmental dynamics, Cordero insisted.
THREE LEVELS OF CHECKS
According to Cordero, geological and geo-hazard assessments were undertaken at different stages of the project.
“The dam underwent meticulous engineering, geological, geo-hazard assessment or EGA which is a requirement before we were issued an Environmental Compliance Certificate. Plus may ara pa gid kita gin ubra nga geological hazard modelling nga gin tun-an nila ang pag-ilig sang tubig sa suba,” he said.
NIA said the design-stage evaluation was conducted by the Korea Rural Community Corporation Joint Venture with Faman and partner firms.
Geological conditions were revalidated during construction by main contractor Daewoo Engineering & Construction Co., Ltd., also from Korea, while the Export-Import Bank of Korea commissioned Arup, a Singapore-based international engineering consultancy, for another confirmatory geological investigation. The Export-Import Bank of Korea funded JRMP II through a loan taken by the Philippine government.
“By completing all these steps, we have guaranteed that the structure stands on a solid foundation,” Cordero said.
NIA said the dam itself is anchored directly onto solid rock strata instead of loose sediment to enhance structural stability during seismic events.
NO SUDDEN GATE RELEASES
Cordero also sought to allay fears of sudden downstream flooding, saying the Jalaur High Dam uses an ungated spillway that allows excess water to flow naturally once it reaches the spillway level instead of depending on manually operated gates.
“If the water reaches cascading levels, it flows naturally through the spillway without needing human intervention,” Cordero said.
This natural flow design avoids potential flash floods caused by sudden gate releases, he explained.
The dam also has a foundation gallery equipped with instruments that monitor structural and foundation movements in real time, Cordero added.
“The dam has advanced monitoring instrumentation housed within its foundation gallery to track structural and foundation movements in real time. Any unusual shift immediately alerts the Project Management Office (PMO) with the precise location for swift intervention,” Cordero further revealed.
NIA also has an Emergency Action Plan covering rising water levels and seismic events.
“Should water levels rise or seismic activity occur, we conduct thorough inspections of the dam site and immediately inform the public through our official Facebook page and social media channels,” Cordero said.
WATERSHED SAFEGUARDS
Safety measures also extend beyond the dam structure to the surrounding watershed, he pointed out.
In partnership with the Department of Environment and Natural Resources (DENR), the agency said a watershed management plan includes reforestation to maintain forest cover and reduce soil erosion as well as alternative livelihood programs aimed at discouraging slash-and-burn farming among upstream communities.
“In partnership with the DENR, a watershed management plan is underway to ensure reforestation and prevent soil erosion. To address slash-and-burn farming (kaingin) among upstream communities, socioeconomic and cultural programs are being introduced to provide sustainable alternative livelihoods,” Cordero said.
NIA’s emergency action measures include public updates on water levels, weather forecasting and post-earthquake assessments through its official social media platforms.
Cordero invited critics, civil society organizations and indigenous communities to engage directly with the project management office.
“We sincerely appreciate the concerns of our friends, but our assurances are based on scientific data, rigorous studies, and international expert consensus,” he said.
“Our Project Management Office remains open to their concerns. We encourage them to accept our invitation for a meaningful dialogue so we can work together as we complete this vital project for our farmers,” Cordero stressed.
JRMP II is currently 84 percent complete. The project is intended to expand irrigation for Iloilo farmers, provide bulk water and contribute hydroelectric power./PN
