PHIL-LIDAR 1.B.6. LiDAR Data Processing and Validation in Luzon: Bicol (Region V)

Duration: June 2014 – May 2017 (36 months)
Funding Agency: Department of Science and Technology – Grants-in-Aid
Monitoring Agency: Philippine Council for Industry, Energy, and Emerging Technology Research and Development (PCIEERD)
Program Lead Implementing Agency: UP Training Center for Applied Geodesy and Photogrammetry (UPTCAGP), University of the Philippines – Diliman

The study on the hydrologic model of identified watersheds within the Bicol Region as a means of predicting inundation was conducted by the Ateneo de Naga University PHIL-LIDAR 1. The university is one of the institutions commissioned by UP-DOST PHIL-LIDAR 1 to undertake a directed research of twenty four (24) watersheds in the Bicol Region in a period of three (3) years. The research task is divided into two working components; the Data Processing Component, and the Data Validation and Flood Modeling Component. The first group processed and edited LIDAR point cloud data using ARC-GIS, and generated the Digital Terrain Model (DTM) and Digital Surface Model (DSM) of each watershed. The second team modeled and simulated the hydrologic processes of watersheds by integrating real rainfall event and produced a rainfall-runoff model with calibrated parameters. Other inputs such as soil, and land use maps using remote sensing and GIS techniques in flood risk areas are considered in the hydrologic model. The hydrologic model underwent the process of calibration and optimization of the parameters used. The performance rating and efficiency of the hydrologic model was validated using statistical criteria; the Nash-Sutcliffe (E), Percent Bias (PBIAS), and Standard Deviation Ratio (RSR). A distinctive feature of the research is the use of Light Detection and Ranging (LIDAR) technology that generates precise spatial information about the shape and surface characteristics of the watershed, a significant data for reliable hydrologic and flood modeling.

The main objective of the study was to produce a rainfall-runoff model that can be used to forecast flood and create flood hazard maps at different return periods of rainfall intensity within the target river system. The model was created using the HEC-RAS software that is capable of performing one-dimensional steady flow and unsteady flow. A bathymetric survey was also conducted. The data were integrated in the DTM and was used in the river model. The generated flood hazard map was further validated through data gathering and survey of the history of actual flood level height and extent.