Unusual heat affecting Baguio water supply

BAGUIO CITY—Residents of the summer capital have been experiencing a maximum average temperature of 26 to 27 degrees Celsius this month, but the city’s water supply manager said the high temperature continues a four-year pattern that has also disrupted the storing capacity of Baguio’s aquifers.

Long bouts of heat followed by intervals of rain have been preventing most of the city’s water sources from recharging fully, said Teresita de Guzman, Baguio Water District (BWD) manager.

“The difficulties we encounter with our water sources are not yet a cause for alarm because Baguio residents know how to conserve their water supply,” she said.

Recycling

Residents are used to recycling household water because BWD has rationed water since the 1990s to conserve its resources, De Guzman said.

Rationing helped address the problems posed by denuded watersheds and increased demand from a population of more than 300,000, which have been taxing Baguio’s water supply, she said.

But BWD has gradually reduced the rationing days for each section of the city in the past years, owing to observations that many of the 60 underground water sources have difficulty replenishing water even when rains are strong, De Guzman said on Thursday.

“Collectively, our aquifers have been recharging by as much as 60 percent according to a statistical model, although we have new underground sources that manage to recharge quickly after every rain,” she said.

The combined effects of the La Niña and El Niño weather patterns from 2008 to 2011 disrupted the rainy season upon which Baguio’s natural recharging cycle relies, De Guzman said.

El Niño is a weather anomaly that manifests as longer dry spells and reduced rainfall, while La Niña brings more rains.

Salvador Olinares, Baguio senior weather specialist, said the frequency of El Niño and La Niña in the past four years are manifestations of climate change and records show that Baguio’s warmest days sometimes took place when these conditions were present.

The city experienced its warmest day on March 15, 1988, when the mercury hit 30.4 degrees Celsius, he said.

“The record has not yet been breached. The second warmest day on record in Baguio was 29 degrees Celsius and this took place in 2008,” Olinares said.

The city’s warmest day this year was April 13 (28.2 degrees Celsius).

“Baguio still receives the highest rainfall amount [in the country]. But we don’t get the rains as often as we should,” De Guzman said.

The intense heat also affects ground moisture because high temperatures could trigger evaporation, but experts have yet to find a way to measure its impact in Baguio, she said.

The city’s only open water reservoir in Mt. Sto. Tomas had suffered from the heat and dry spell, De Guzman said. The last storms failed to fill up the Sto. Tomas rain basin, one of the oldest water storing facilities here, she said. The rain basin serves the southwestern section of the city, with a capacity to hold up to 500,000 cubic meters of water.

“But the levels barely reach 15 meters so the water supply that should last for six months is consumed in a month unless we compensate by pumping out more water for the areas normally served by the basin so we do not deplete its content,” De Guzman said.

Angat dam

In Bulacan, managers of Angat dam, the main facility supplying water to Metro Manila households and businesses, assured that there is enough water in the reservoir despite the absence of heavy rains.

Rodolfo German, general manager of Angat River Hydro Electric Power Plant, said its reservoir contains 201.31 meters above sea level (masl) of water.

While that level was below the normal 210 to 214 masl, Felicisima Mungcal, chief of the provincial disaster risk reduction and management council, said the dam could continue supplying Metro Manila with potable water and Bulacan and Pampanga farmers with irrigation water, even if the dry spell continues in May.  Vincent Cabreza, Inquirer Northern Luzon, with a report from Carmela Reyes-Estrope, Inquirer Central Luzon