These recent days heavy floodings have been reported in some parts of the Philippines–Northern Samar, the Agusan provinces (flooding due to the swelling of Agusan River), Cagayan de Oro (flooding due to the overflowing of Cagayan River of its banks), Iligan City and Linamon in Lanao del Norte, Capiz and Cagayan provinces.
The rains might have been frequent but not really that strong. And flood-prone areas like Metro Manila and Central Luzon were generally spared this time. But all know that during the habagat (southwest monsoons) those areas are almost always flooded when the heavy rains come.
If one will notice all of these now-flooded areas lie to the north of the island to where they belong. The floodings were due to the overflowing of the banks of their rivers which all flow northward.
Funny that the reporter in Lanao del Norte charged that “storm surge” was the cause of the flooding. What he meant was the rivers cannot empty to the sea (causing it to rise) because there’s a surge coming from the sea. A sea surge, yes, but not a “storm surge” because there’s no storm.
This sea surge fuelled by the amihan (northwest moonsoon) is capping the flow to the sea of these northward-flowing rivers. That’s why the river banks are being breached. And also why flooding occurs in the upper reaches of the rivers.
This is one relationship that people must understand. A strong amihan produce a southward-flowing sea surge capping the northward-flowing rivers thereby slowing their capacity to empty to sea and this in turn cause the river to overflow its banks. During habagat, the relationship is reversed. Southward-flowing rivers are bottled up by the sea surge going north.
If tropical cyclones or typhoons are not all bad so do this phenomenon. Storms and typhoons are the primary elements the sea and oceans have in order to cleanse themselves. Sea surges and storm surges have the capability to push back river flows. It is known that Manila Bay sea water even enters the Laguna de Bay through the Pasig River and these cleanses the lake. Flooding and the entry of sea water does the same for rivers.
But herein lies the classic confrontation between man and nature. In the olden days man will simply just give way to nature. But with ever-burgeoning population pressures and urbanization man now occupy nature’s former path.
And so disasters occur.
[Photo credit:Agence France-Presse]