Mt. Pinatubo’s eruptions in 1991 are now being blamed for this because lahar flows have drastically altered Central Luzon’s geophysical layout, specifically the region’s waterways.
Retired Brig. Gen. Virgilio Florendo, executive chief of the provincial disaster coordinating council (PDCC), explained that because Tarlac is a landlocked province in the central plains of Luzon, it must have channels where excess floodwaters can spill out.
Floodwater streams along the Sacobia and Rio Chico rivers lead to Pampanga’s waterways, but because of the heavy deposits of lahar in Pampanga, there is now what is being called a "backflow" of currents.As a result, heavy deluge hit the two rivers’ adjacent villages during heavy downpours.
Meanwhile, the rise to critical levels of the Tarlac and Camiling rivers is mainly due to clogged waterways in Pangasinan, as they are linked to stream channels, which empty into the Lingayen Gulf and the South China Sea.
For the past several years, many parts of Pangasinan have also been suffering from perennial flooding during the rainy season mainly because of man-made colossal dams in the North. Florendo said this has practically made Tarlac into a "virtual catchbasin."
Gov. Jose Yap noted that any effort to solve the perennial floods in the province should be "complementary" with the efforts of Tarlac’s neighboring provinces, particularly Pampanga and Pangasinan, as well as Nueva Ecija.
According to him, as Tarlac continues with its desilting operations along lahar-covered river systems, it must be undertaken together with other projects Pampanga.As for Pangasinan, Yap said that waterways must be cleared in order to allow the free flow of excess waters from the Camiling and Tarlac rivers.