Torrential rains in Central and Western Visayas on Oct. 4 and 5 caused by Typhoon Ramil displaced some 54,000 people from their homes, and killed several individuals.
The unusually-heavy rains resulted in floods and landslides in the provinces of Iloilo and Antique on the island of Panay, and in the provinces of Negros Oriental and Negros Occidental on the island of Negros. Several towns in these four provinces were flooded.
However, the city most affected was Bayawan in Negros Oriental, where a state of calamity has been declared.
To my recollection, Bayawan City never had a serious flooding occurrence in the past 70 years. Over the several years from the 1950s, the forests of Bayawan and environs were logged until no more commercial tree species could be found.
Now there are no more rainforests in the area of southern Negros except for the few scattered forest patches between Sipalay and Cauayan towns.
It has been estimated that only less than four percent of the total area of Negros Island (1.2 million hectares) remain forested with original rainforest, the only type of forest that has a tremendous capacity to absorb and retain rain water. (Forest ecologists claim that 30-40 percent of total land area should be covered by native forest species.)
Even southern Negros Oriental lacks an adequate forest cover. The forest at Lake Balinsasayao (8,000 hectares) is small, and could be one reason why rivers in Sibulan, San Jose, and Tanjay become flooded under heavy rainfall.
All other types of forests, including exotic forest species, have poor ability to accumulate moisture. So flooding easily occurs in times of continuous and heavy rainfall, and they also produce poisonous chemicals that kill native plant species.
I understand that on Oct. 4 and 5, there was high tide, which could have exacerbated the flooding; but the flooding was certainly caused to a certain extent by the inability of the rain water to percolate into the soil. The landslides must have been caused by the lack of root systems of large trees that hold the soil particles together.
Aside from endemic and native trees and other types of native vegetation, deforestation on Negros has wiped out some of our interesting and unique animal species that have co-evolved with the native plants.
Negros Island, like Panay Island, has suffered from poor original forest cover. The rate of deforestation of Negros was rather more rapid compared to that of Panay.
The people of Negros generally do not realize that the island is vulnerable to extreme weather events such as floods, landslides, high water temperatures, and strong wave action.
During the southwest monsoon season (habagat), the island (as well as Panay) is exposed to the southwest monsoon. The Sulu Sea is right at the islands’ western border, and storm surges could pose a risk to coastal residents.
Aside from extreme weather occurrences due to climate change, there is a Negros Trench in the Sulu Sea several kilometers from Sipalay City (which was also flooded this month).
This trench could act up, as it did some time ago, and add to the hazards posed by climate change and extreme weather conditions.
In the face of possible risks to life and limb as well as to the environment, the Negros local governments must come together to discuss, and to propose ways to mitigate the environmental risks that are bound to happen again.
Sometime ago, we were asked to discuss climate change. It is time to do it again, and to plan because destructive typhoons like Sendong, Pablo, and Ramil will surely visit us again at times unknown to us.
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