Flood and hazard maps produced using LIDAR

The Phil-LiDAR 1 Program, an expansion of the DREAM Program, aims to produce 3-D flood and hazard maps for the 2/3 of the Philippine river systems. Aside from addressing disaster risk reduction and climate change adaptation, the resource information to be generated from this project will also be useful in providing the information requirements of various sectors in the country.

In recent years, earth surface height data has become a vital component of many geospatial-planning strategies and is widely used by government agencies and the commercial sector for a variety of applications from flood risk modeling to urban development. The emergence of new spatial data acquisition systems such as Light Detection and Ranging (LiDAR) present complementary or even alternative solutions to the acquisition of spatial information unanswered by existing technologies such as aerial photography or satellite imagery. The coverage and accuracy of topographic data extracted by these systems, complemented by the features detected by an onboard digital aerial camera, provides rich information that would greatly benefit agencies using spatial data.

 Before such data could be utilized, the raw data collected from the LiDAR and SAR would need to undergo various processing steps to obtain information that are critical input to the calibration and validation of flood models for the Philippine river basins. The enormous amount of LiDAR data should be filtered using various types of filters to extract the Digital Terrain Model (DTM) from the Digital Surface Model (DSM). The DTM is the boundary surface between the solid ground and the air, which is also the surface of superficial water run-off. This is the surface needed to model the geometry of the watershed and the floodplain. The DSM will be used in presenting the impact of flooding to man-made and natural features on the floodplain. Features significant to flood modeling and flood impact assessment such as buildings, forest cover, road and river network will also be extracted.

The ongoing DOST-GIA Nationwide DREAM Program currently has covered only 1/3 of the total area of Philippine river systems, equivalent to 100,000 sq.km., or 18 major river basins. The Phil-LiDAR 1 program aims to cover the remaining 2/3 of river systems in the country by tapping state universities and colleges (SUCs) and private higher education institutions (HEIs) nationwide in the processing, validation, and modeling of the acquired LiDAR data.

Source: UP Dream Program