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Not long after Typhoon Ondoy inundated the metropolis with flood waters, Typhoon Pepeng reversed course to hover around Western Luzon and drop more than 600mm of rain in the area. This time, it was the Cordillera region and Pangasinan that were under distress. More than 40 landslides occurred in the Cordilleras triggered by the massive rain which resulted in as many as 250 deaths. Local groups attributed the area’s increased vulnerability to landslides to the long-term large-scale mining activities especially in Itogon and Mankayan in Benguet province. We remember the Colalo landslide that happened in 1999 in Mankayan which AGHAM visited with the Cordillera People’s Alliance (CPA) and environmental groups. And only three months ago, geologists from AGHAM and the Center for Environmental Concerns conducted an inspection of land subsidence in the same area.
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PESANTE NEWS
October 16, 2009
Dams, flooding and power
Thursday, 15 October 2009 00:00
By Giovanni Tapang, Ph.D.
MAnila, Philippines ---Not long after Typhoon Ondoy inundated the metropolis with flood waters, Typhoon Pepeng reversed course to hover around Western Luzon and drop more than 600mm of rain in the area. This time, it was the Cordillera region and Pangasinan that were under distress.
More than 40 landslides occurred in the Cordilleras triggered by the massive rain which resulted in as many as 250 deaths. Local groups attributed the area’s increased vulnerability to landslides to the long-term large-scale mining activities especially in Itogon and Mankayan in Benguet province. We remember the Colalo landslide that happened in 1999 in Mankayan which AGHAM visited with the Cordillera People’s Alliance (CPA) and environmental groups. And only three months ago, geologists from AGHAM and the Center for Environmental Concerns conducted an inspection of land subsidence in the same area.
Typhoon Pepeng’s rains also brought floodwaters cascading downstrem. As early as 1998, the Kalikasan People’s Network for the Environment, CPA and BAYAN Central Luzon campaigned against the construction of the San Roque Multipurpose Dam in Pangasinan.
We raised the issue to the Ramos and the Arroyo governments and even to the Japanese funders of the project, the Japan Bank for International Cooperation.
The reasons were many. It was a .2-billion project that was given government guarantee. It is also part of the infamous (and now embedded) Power Purchase Agreements (PPA) that bloats up your electricity bill. Issues regarding accelerated siltation due to the mining activities upriver as well as its problem as a flood control program were also raised.
The San Roque dam is the third large dam along the Agno River in the Cordillera Region. The Agno River traverses the areas where the Ibalois and the Kan-kanaey indigenous peoples reside making it a very important part of their life and culture.
Upstream is the Ambuklao dam built in the 1950s and the Binga dam is next built in the 1960s. Both dams are now heavily silted due to the rapid erosion and mining activities in the area.
The SRMP and the Disaster in 2009
In 1998 the construction on the San Roque dam started despite the vigorous opposition not only of the people from the Cordillera but also those from the low lying areas of Pangasinan and Central Luzon.
Impoundment of water in the reservoir started in August 2002 and the dam became operational in May 2003. It stands 220 meters from the ground and traverses 1.13 km along its length. It can hold up to 850 million cubic meters and covers over 12.8 square kilometers in area.
Today, the dam is operated by the San Roque Power Corp. (SRPC) and it is responsible for the operations and maintenance of the power-facility. The SRPC is owned by the Marubeni Corp. (75 percent) and Kansai Electric Power Co. Ltd. (25 percent). It is a stock corporation incorporated in the Philippines.
It is a hydroelectric dam designed to produce 345 megawatts of power. Water must be kept high within the dam to be released to turn the turbines to generate electricity. This is the bone of contention right now. During the period when Pepeng reversed its direction, there were news reports quoting dam officials speaking of their reluctance to release water because they wanted to keep it for electricity.
We noticed that between October 4 and 5, the data from the Pagasa flood monitoring website showed that the water in the dam reached the spilling level of 280 meters. Surprisingly, a day after (October 5), the spilling level was shifted higher to 288 m even if there was no massive release of water yet from the dam. This adjustment of the spill level has not been explained yet by the SRPC, Napocor officials and the Pagasa.
The adjusted spilling level at 288 m would justify the late release of water from the dam since it was only on October 8 that the water level broke this adjusted line. However, before the adjustment, it was at 280 meters that the San Roque dam would already release water. With water levels rising to more than 9 meters above 280 meters, the dam would have to release water as fast as it could. Water levels also came dangerously close to the height of the dam itself which is at 290 meters.
Why did they have to wait for 288 meters during Pepeng? They could have released water slowly during October 4 when they saw the water levels rising above the then-280-meter mark.
The San Roque Multipurpose Dam failed in its flood management function. The opposing interest of power generation and flood management makes the situation dangerous since a power corporation will prioritize its own interests rather than those of the low-lying communities below.
The two flooding disasters we went through is a result of a failure of our disaster response systems compounded by long standing environmental problems and gross mismanagement at all levels.
Dr. Tapang is the chairperson of AGHAM.
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Original: Dams, flooding and power