In response to the issues about flooding

IN RESPONSE TO THE ISSUES ABOUT FLOODING:

Before we explain the issue of flooding in the Salimbao Area, may we stress a few technical points that were the preliminary results of the ongoing master plan being prepared by the Woodfields Consultants. First: The River Hydrogeology – in the most simple terms so as it will be understood by everyone – the Rio Grande the Mindanao is the outlet of all the rivers in the Mindanao River Basin … water from the mountains in Bukidnon as well as the mountains of South Cotabato all flow into Ligawasan Marsh, and exits through the Rio Grande. Second: The siltation level of the river has risen so much that the current height of silt is the same as the height of the water level of the river 25 years ago. This means that the current water level of the Rio Grande is 1.5 meters higher than it was 25 years ago. Simply said, if you constructed your house level with the water 25 years ago, the current water level will flood your house by as deep as 100 inches.

The flooding in Salimbao Area is partly caused by the rise of the siltation. We are doing dredging operations, but this is not a long term solution, as we all know that the silt we dredge today will be replaced by new silt from the higher areas in less than a week. We need at least 20 dredgers working 24 hours daily, dredging from the mouth of the Ligawasan up to the mouth of the Rio Grande if we intend to bring the water level to where it was 25 years ago.

The construction of the Simuay Cut-Off channel was a stop-gap solution intended to divert 20% of the water flow of the Simuay-Ambal river. We have also initiated dredging in the mouth of the cut-off channel to enhance the effectiveness of the channel. However, there are technical issues that need to be resolved first. The Simuay-ambal river has an average width of 180 meters. The cut-off channel opening is about 60 meters that narrows to 30 meters in the middle and further narrows to 10 meters as it empties to the Illana Bay. This seemingly funnel type canal in itself needs to be revisited by DPWH and some changes to the design need to be undertaken so the channel will be able to attain maximum efficiency.

However it should be made clear that the cut-off channel was not designed to stop the flooding in the Salimbao area, but merely to minimize the flooding.  Even if the cut-off channel was completed as planned, the redirection of 20% of the water is not enough to stop the flooding.  It is in this context that the masterplan, in its preliminary reports, presented the need for permanent structures such as a Sabo Dam that will contain the silt generated by the confluence of the Simuay and Ambal River… A water impounding system that will hold the excess water and release it in a time-elapse manner, or the construction of a storm drainage that will absorb the excess water in the Salimbao area. This storm drain is similar to that of the storm drain in Los Angeles California.

As a whole, the flooding in the Salimbao area is merely the tip of the iceberg in the flooding issue. To fully resolve the issue, we need to understand the cause of the flooding and address it from the source, otherwise all other projects and programs that will be implemented without consideration of the source will eventually fall to naught. And, to understand, we need to look into the siltation that is on-going in the Ala River System in South Cotabato and the Upper Pulangi River System in Bukidnon. We have to understand the issues of our NCIP brothers in the mountains and the reason why slash and burn/kaingins still exist. We need to look into the condition of our aquifers in the 21 sub-basins of the Mindanao River Basin and we are happy to inform you that our Consultants are already in the final phase of the masterplan and in the next few months we shall be able to report, to you, with definitiveness the results of their study and from there we shall be able to recommend to the national  government to implement projects that will directly address the flooding issues.

Finally, the flooding issues have been existing for sometime even before the creation of the PTFMRBRD, it has been a long demanded clamor by many, this is to say that this issue is not localized in Salimbao… It exists in South Cotabato, North Cotabato, Davao City, Cebu City, Manila and the northern parts of the country. The long years of degradation of our rivers caused by either man or nature have risen to the point of concern that we hope the government would be able to address before it is too late.

NATHANIEL A. CAMPO

PTFMRBRD Deputy Executive Director

24may2011//11:02ayem