Flood hazard exposure assessment of buildings through combined use of Lidar data and flood simulation models

By Meriam Makinano-Santillan, Jojene R. Santillan, Linbert C. Cutamora, Jesiree L. Serviano

ABSTRACT:

Determining the types and locations of buildings that are exposed to various flood hazards is important in flood disaster preparedness, risk assessment, and mitigation. In most cases, the availability of a 3D building database where each building is attributed in terms of name, type (e.g., residential, commercial, government, educational, etc.), and height (among many other attributes) makes the required analysis fast, efficient and informative. In this work, we conducted flood hazard exposure assessment of buildings in Cabadbaran River Basin, Mindanao, Philippines through combined use of LiDAR data and flood simulation models. First, we generated a 3D GIS database of buildings through analysis of various datasets that include 1-m resolution LiDAR Digital Surface Models (DSM) and Digital Terrain Model (DTM), high resolution images in Google Earth, and free online web maps such as Wikimapia. Building footprints were manually digitized from LiDAR DSMs and saved as GIS Shapefiles. The average of the base elevations and top elevations for each footprint were then extracted from the DTM and DSM, respectively, and used to compute for the building heights. Information on the name and type of the buildings was obtained by using Google Earth, Google Map, and Wikimapia as references. The generated 3D building database was used later on in the flood hazard exposure assessment through GIS overlay analysis. Prior to this assessment, we first developed a flood model of the river basin using a combination of HEC HMS hydrological model and HEC RAS hydraulic model. The flood model was used generate flood hazard maps that are representative of maximum flooding due to rainfall events of varying return periods (2-, 5-, 10-, 25-, 50-, and 100-year return periods). With these inputs (3D building database and flood hazard maps), we conducted overlay analysis to identify which buildings are exposed to various levels of flood hazards (e.g., low, medium, high). In addition to this, we also characterized the degree of flood exposure of buildings by comparing their heights with the simulated flood depths. The results of this study consist of a series of maps showing buildings exposed to various flood depth and hazard levels that can be utilized by Local Government Units in their flood disaster risk reduction and management strategies.

KEYWORDS: Flood hazard, exposure, buildings, assessment, LiDAR, flood simulation, Mindanao; Philippines


Publication Details/Metadata:

Paper Title: Flood Hazard Exposure Assessment of Buildings Through Combined Use of LiDAR Data and Flood Simulation Models

Authors: Meriam Makinano-Santillan, Jojene R. Santillan, Linbert C. Cutamora, Jesiree L. Serviano

Publication Date: 2015

Conference Name/Journal/Book Title: GeoSmart Asia 2015: Towards the Next Big Leap, September 29-October 1, Putra World Trade Center (PWTC), Kuala Lumpur, Malaysia

Publisher: Geospatial Media and Communications

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