LAST Sunday was a blessed day for all of us in Baguio simply because the sun shone. Because before that, it rained continuously for eighteen days!
There was no typhoon --- just monsoon rains --- but the amount of rain was so tremendous that landslides were recorded on all roads leading to the city. Two people were killed when a landslide fell on their commuter van along Kennon Road just above the Lion’s Head. Other landslides in several areas in Baguio and Benguet also prompted officials to evacuate residents immediately.
Last Sunday, a shotcreted portion along Badiwan (Marcos Highway) finally gave way, causing visitors getting out of Baguio (it was a long weekend, after all) to be caught in a long jam that lasted for three hours.
There were longer periods of continuous rains in Baguio. Who can forget the ten days of the returning Typhoon Pepeng in 2009 which brought two meters of rains and killed hundreds of people, particularly in Little Kibungan?
Who can forget the forty days of rains in 1972 when typhoons hit Luzon from July to August, killing hundreds and inundating Central and Northern Luzon for months?
But the longest recorded continuous raining in the country was 47 days in Baguio in 1919 when it rained nonstop from July 17 to September 2.
Continuous rains are no longer new in Baguio, even in this era of climate change. But what makes it very different a century ago? There were much fewer people but much more trees 100 years ago.
We have replaced our vegetation with concrete and we now are under the administration which actually encourages cutting of trees after typhoons because they pose danger to people? Really now? Isn’t it the other way around? That the people pose danger to the trees? They don’t see that kind of logic because trees don’t vote.
But a bit of a lecture now. Runoff has been rapid in Baguio because of our high intensity rains (we are the 2nd rainiest city in the world). The Revised Universal Soil Loss Equation showed that the soil erosion (A) is equal to rainfall factor (R) times soil erodibility factor (K) times length of slope factor (L) times slope factor (S) times cropping system/ground cover factor (C) times management practices factor (P).
We cannot do anything with R, K, L and S but we were responsible for C and P. Even without man’s interference, soil erosion is already evident but C and P are the most crucial.
Vegetation has the so-called raindrop buffering effect, soil channeling effect and reservoir effect. Plants reduce the impact on the soil by intercepting the raindrops and absorb much of the energy. They channel the soil because of the root systems and the canopy which lead the rain to the stems. Ground covers are also portable reservoir, delaying its absorption to the ground.
But because we have greatly reduced C and P, what is 18 days of continuous rains now has the same effect as 40 days in the past. True enough; the same number of landslides in 1972 manifested itself in the recent 18 days of continuous rains.
What we have to do now is to decrease the C and P factors as soon as possible because climate change has already dealt us an unfortunate trump card that prayers for a strong card may no longer be enough.*