Pantabangan Dam

Pantabangan Dam
Behind the dam's spillway
Location of Pantabangan Dam in Luzon Pantabangan Dam (Philippines)
Coordinates	15°48′52″N 121°06′29″E
Construction began	June 1971
Opening date	September 1974
Construction cost	$20.74 Million or 891.82 Million pesos (at current price)
Owner(s)	National Power Corporation National Irrigation Administration
Dam and spillways
Type of dam	Embankment, earth-fill
Impounds	Pampanga River
Height	107 m (351 ft)
Length	1,615 m (5,299 ft)
Elevation at crest	232 m (761 ft)
Width (crest)	12 m (39 ft)
Width (base)	535 m (1,755 ft)
Dam volume	12,000,000 cu yd (9,174,658 m3)
Spillways	3 x radial gates, 1 x overflow
Spillway capacity	4,200 m3/s (148,322 cu ft/s)
Reservoir
Creates	Pantabangan Lake
Total capacity	2,996,000,000 m3 (2,428,897 acre⋅ft)
Active capacity	2,083,000,000 m3 (1,688,716 acre⋅ft)
Catchment area	853 km2 (329 sq mi)
Surface area	69.62 km2 (27 sq mi) (max)
Normal elevation	230 m (755 ft) (max)
Commission date	1974
Turbines	2 x 60 MW Francis-type
Installed capacity	100 MW
Capacity factor	90%
Annual generation	232,000,000 kWh

Pantabangan Dam is an earth-fill embankment dam on the Pampanga River located in Pantabangan in Nueva Ecija province of the Philippines. The multi-purpose dam provides water for irrigation and hydroelectric power generation while its reservoir, Pantabangan Lake, affords flood control. The reservoir is considered one of the largest in Southeast Asia and also one of the cleanest in the Philippines. Construction on the dam began in 1971 and it was completed in 1974.

History

In May 1969, the Congress of the Philippines authorized the development of the Pampanga Basin with Republic Act No. 5499. In October of that year, detailed studies of the Pantabangan site were carried out and lasted two years. By June 11, 1971, Pantabangan was an old town of around 300 years old. President Ferdinand Marcos and many others arrived for a ground breaking ceremony in Palayupay, Pantabangan, Nueva Ecija, to signal the beginning of the construction of Pantabangan Dam. The dam went into operation in February 1977 and was completed later in May. Approximately 1,300 people were relocated from the dam's reservoir zone.

Design

The dam is a 107 m (351 ft) tall and 1,615 m (5,299 ft) long embankment-type with 12,000,000 cu yd (9,174,658 m³) of homogeneous earth-fill and an impervious core. The crest of the dam is 12 m (39 ft) wide while the widest part of its base is 535 m (1,755 ft). The dam's crest sits at an elevation of 232 m (761 ft) and is composed of three sections: the main dam, a saddle dam, and an auxiliary dam located with the spillway. The spillway is a chute-type controlled by three radial gates but equipped with an overflow section as well. The design discharge of the spillway is 4,200 m³/s (148,322 cu ft/s). The dam's reservoir has a gross capacity of 2,996,000,000 m³ (2,428,897 acre⋅ft) and 2,083,000,000 m³ (1,688,716 acre⋅ft) of that volume is active (or useful) for irrigation and power. The dam sits at the head of a 853 km² (329 sq mi) catchment area known as the Pantabangan–Carranglan Watershed Forest Reserve and its reservoir has a surface area of 69.62 km² (27 sq mi) and elevation of 230 m (755 ft) when at its maximum level. The reservoir's life is estimated at 107 years due to silt from denudation. The dam was designed to withstand an intensity 8 earthquake.

The power house is located at the base of the main dam and contains two 60 MW Francis turbine-generators for an installed capacity of 120 MW. Each turbine receives water via a 6 m (20 ft) diameter penstock. When the water is discharged, it is released into a 250 m (820 ft) long tailrace channel where it re-enters the river.