Floodplain Modelling of Malaking-Ilog River in Southern Luzon, Philippines Using LiDAR Digital Elevation Model for the Design of Water-Related Structures

Abstract

Hydrologic and hydraulic model applications for floodplain analysis are very limited in the Philippines due to the insufficiency of topographic, river geometric and hydrologic data. However, with Light Detection and Ranging (LiDAR) technology, the country is able to overcome this problem resulting to much more accurate mapping and modeling possibilities. With the use of a modern hydrologic modelling software, rainfall runoff model based on LiDAR data was created for Malaking-Ilog River in Batangas-Quezon with precipitation input of five, ten, twenty-five, fifty and a hundred-year return period. In this study, the significance of the hydrologic model and the selection of return period in the design of various water related structures were discussed. Moreover, river analysis software was utilized in a case study for design of a dike. The communities which are politically grouped as "barangays" surrounding the river that are directly affected when the river overflows were identified. With the help of the hydrographs generated from the rainfall runoff model in this study, the design parameters of various water related structures are easily determined leading to a more efficient design process.