The Mines and Geosciences Bureau Region IV CALABARZON, as part of its mandate, is currently administering a study titled, “In-Depth Study on Audit of Sediment Source, Load and Transport Within the Sub-River Basins of Marikina River in Rizal Province to Determine the Factors that Caused the August 11, 2018 Flooding of Adjacent Areas Within Marikina River Basin.” The said study, being conducted by Permata Resources, Inc., is a response to the concerns raised that the quarry operations might have caused the said flooding in Rizal Province.
The study aims to delineate the influence of the existing land uses within the Marikina River Basin on the said flooding. In line with this, the research objectives and methodology are:
- To determine the inundated areas and identify the depth of the flood caused by the storm on the August 11, 2018 using data gathered from field interviews and sediment analysis simulation
- To identify and plot the existing land uses of any kind within the Marikina River Basin using the digital elevation model (DEM). Auxiliary data were mapped using the Geographic Information System (GIS). The possible effects of these land uses were to be correlated to the sedimentation and flooding.
- To perform watershed modelling through the Hydrologic Engineering Center – Hydrologic Modelling System (HEC-HMS) followed by the estimation of the average basin rainfall, rainfall-runoff conversion and hydrologic frequency analysis. This is to estimate the peak discharge and the flood level at each identified sub-basin for every given return period.
- To estimate the sedimentation rate of each identified sub-basin.
- To approximate the change in riverbed elevation at the identified sub-basin channel points.
- To estimate the change in the flood levels in the same points.
At present, a desk review of the available data and findings based on the rapid and initial survey by Permata Resources, Inc. was already carried out on February 16-17, 2019. The study is scheduled to last for one hundred twenty (120) days (four months), commencing from the date of the receipt of Notice to Proceed.
by: Engr. Patrizia S. Benedicto | 22 April 2019