River Gone Wild.

Lets take a pause for a moment and look at Fig I. The orange line beginning at Baguinsuso and ends at the Bacarra bridge is the shoreline of the river before 1995. Just below this line are areas of gray that were once rice fields, but has been washed away by the river. Most visible is the area just below the Vintar Dam and Baguinsuso, once the rice fields of Baldi, Daguii and Duguilla. Youll notice that this whole area is in direct line with the flow of the flood waters, as it breaks out from Visaya. The red line represents the ancient course of the river, the path of least resistence. Back to this in a moment. But first, why is the erosion happening now in recent years? And, why is it particulary damaging in this area? Without stating the obvious, like deforestation, changing weather pattern, and the like, the reason can be found in the course of the river.




FIG. I. Map of the Bislak River north of the Poblacion.

There are several characteristics that defines the Bislak river on its way to the China Sea. It has a tendency to fork into several branches, making it hard to tell which is the main fork. It forms islands between the forks and, it has a meandering course, virtually having a free reign over its course. A part of the river depicted at Fig I, shows these characteristics of the river. At the middle of the river is an island, we call kapanagan. Each side of the island are forks of the river that splits after it comes out from Visaya and joins again before it reaches the Bacarra bridge. At the south side of the island, close to town, the river meanders lazily, splitting apart , joins, then splits again.

During flood season, the whole basin, from Diaton to the Poblacion is covered with the river's turbulent waters. As it continues to flow towards the China Sea its path narrows down considerably at the Bacarra bridge. This becomes a bottleneck and water backs up (mapupok) all the way to the poblacion. When the volume increases, the only way out is to spill over the poblacion, hence we have a torrential flood.

The overhead picture of the river reveals another curious fact: the size of the island. It is now larger than the poblacion in length and width. The east end of the island has more considerable earth than before 1995. In fact, the area east of the red arrow that points to the island is a new addition. This tip of the island is strategically anchored at the mouth of the water breakout in Visaya, interrupting the southern flow of the river. The trajectory of the river as it shoots out from Visaya is towards the Dam. The Dam acts like a fortress and deflects the current at a northwest direction towards Diaton. It has been like that for years, hence the area southwest of the Dam has been spared from erosion.

Today, the topography has change considerably with the islands eastern tip growing bigger and closer to the Dam, therby closing the northern gap, leaving the southern side wide open for the flood water to reign free. As a result, the river follows the path of least resistance, and that is the eroded area of Baldi, Daguii and Duguilla. The red line is projecting the eventual course of the river as the island grows larger and its vegetation becomes thicker and entrenched deflecting back the river current flow towards the poblacion.

Flood waters always follow the path of least resistance  downhill. The poblacion is 83 ft above sea level. The kapanagan has an elevation of 90 ft and rising fast. Its new eastern tip is now 95 ft high. A river has only one rule: the path of least resistance always choose the way. The red line in FIG I is now becoming the path of least resistance.

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