Dams Under Pressure: 5 Biggest Constructed Dams to Monitor During Typhoon Season

Dams play a critical role in the Philippines, a country frequently impacted by typhoons, heavy rainfall, and flooding. These large structures help manage water resources for irrigation, electricity generation, flood control, and potable water supply. During typhoon season, dams serve as vital infrastructure for controlling water overflow and preventing catastrophic flooding downstream. However, large dams also pose risks when not properly managed. Sudden releases or overflows can cause flooding in nearby communities, leading to property damage, displacement, and loss of lives.

This article highlights the five largest dams in the Philippines, examining their capacity, benefits, and risks, especially during times of heavy rainfall and typhoons.

1. Angat Dam

• Location: Norzagaray, Bulacan (Region III – Central Luzon)
• Electricity Supply: Powers Metro Manila, providing 246 MW of electricity through its hydroelectric power plant.
• Overflow Impact: Nearby municipalities in Bulacan, such as Norzagaray and San Rafael, are vulnerable to flooding. If a severe overflow occurs, it could potentially affect portions of Metro Manila further downstream.
• Spilling Level: The dam’s spilling level is 212 meters above sea level.
• Capacity: Angat Dam has a total storage capacity of 850 million cubic meters, making it one of the largest sources of freshwater for Metro Manila.
• Purpose: In addition to hydropower, Angat also supports irrigation and provides drinking water to over 13 million people in Metro Manila.

2. San Roque Dam

• Location: San Manuel, Pangasinan (Region I – Ilocos Region)
• Electricity Supply: Provides up to 345 MW of electricity, benefiting regions in Luzon.
• Overflow Impact: Communities in Pangasinan, Benguet, and neighboring areas are at risk of flooding, especially in agricultural zones.
• Spilling Level: The spilling level is 280 meters above sea level.
• Capacity: San Roque Dam has a massive storage capacity of 835 million cubic meters, designed to aid in irrigation, flood control, and hydroelectric power generation.
• Purpose: San Roque is one of the largest multi-purpose dams in Southeast Asia, contributing to flood mitigation in the Agno River Basin and providing water for irrigation in Pangasinan.

3. Pantabangan Dam

• Location: Pantabangan, Nueva Ecija (Region III – Central Luzon)
• Electricity Supply: Supplies hydroelectric power to parts of Central Luzon, contributing 100 MW to the Luzon grid.
• Overflow Impact: Flood risks include communities along the Pampanga River, affecting towns in Nueva Ecija, Bulacan, and Pampanga.
• Spilling Level: Its maximum spilling level is 221 meters above sea level.
• Capacity: Pantabangan Dam boasts a total storage capacity of 3 billion cubic meters, making it one of the largest dams in the country.
• Purpose: Initially constructed for irrigation, Pantabangan Dam also generates hydropower and helps control flooding in the Pampanga River Basin.

4. Magat Dam

• Location: Ramon, Isabela (Region II – Cagayan Valley)
• Electricity Supply: Capable of producing 360 MW of electricity for northern Luzon.
• Overflow Impact: Flooding often affects communities in Isabela and nearby provinces such as Cagayan during intense rainfall.
• Spilling Level: The spilling level for Magat Dam is 194 meters above sea level.
• Capacity: With a total capacity of 1.08 billion cubic meters, Magat Dam supports irrigation and power generation for the region.
• Purpose: Built for both irrigation and power generation, Magat Dam irrigates more than 85,000 hectares of farmland, contributing significantly to the region’s agriculture sector.

5. Ipo Dam

• Location: Norzagaray, Bulacan (Region III – Central Luzon)
• Electricity Supply: Although it does not have a significant power generation capacity, it plays a crucial role in supplying water to Metro Manila.
• Overflow Impact: When water releases, communities near Norzagaray and downstream areas along the Angat River are vulnerable to flash floods.
• Spilling Level: The spilling level is approximately 101 meters above sea level.
• Capacity: Ipo Dam has a storage capacity of 7.5 million cubic meters. Although smaller compared to others, it is an integral part of the Angat-Ipo-La Mesa water system.
• Purpose: Its primary role is to supply raw water to Metro Manila for household use, complementing Angat Dam’s water storage capabilities.

The Philippines relies on its large dams for a variety of essential functions—ranging from power generation to flood control and irrigation. Dams like Angat, San Roque, Pantabangan, Magat, and Ipo not only provide energy and water but also offer protection against potential natural disasters such as floods. However, these structures face immense pressure, especially during the typhoon season, when heavy rains can push them to their limits.

To guarantee that these dams continue to fulfill their intended function while lowering the hazards to the surrounding populations, proper management and regular maintenance are essential. To avoid catastrophic overflow and protect people downstream, we must constantly improve early warning systems and efficient disaster preparedness programs. Although dams are important resources, their possible risks necessitate ongoing attention to detail and flexible management.

References:

Manila Water Company, Inc. (n.d.). Water and wastewater facilities. https://www.manilawater.com/corporate/services/water-and-wastewater-facilities#:~:text=The%20Angat%20Dam%20is%20a,about%20850%20million%20cubic%20meters.

Monitoring dams: Ipo dam, norzagaray – philippines – capetti Elettronica S.r.l. Capetti. (n.d.). https://www.capetti.it/en/case_studies/ipo-dam-norzagaray-philippines#:~:text=Ipo%20Dam%20is%20a%20gravity,of%207.5%20million%20cubic%20metres.

The Magat Reservoir, Philippines experience. International Society for Photogrammetry and Remote Sensing (ISPRS). (n.d.). https://www.isprs.org/proceedings/xxxviii/part7/a/pdf/227_xxxviii-part7a.pdf