Tag Archives: GeoSmart Asia 2015

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

Link to Full Text: View/Download


Flood EViDEns: near-real time flood event visualization and damage estimations for geospatially-informed decision making in times of flooding

By Jojene R. Santillan, Meriam Makinano-Santillan, Edsel Matt Morales

ABSTRACT:

The Web-based Near-real Time Flood Event Visualization and Damage Estimations (Flood EViDEns) is an online geo-visualization application developed through the Phil-LiDAR 1 project of Caraga State University. The application is targeted to be utilized by the Local Government Units (LGUs) and communities in the Caraga Region, Mindanao, Philippines to assist them in geospatially informed decision making in times of flood disasters. The application is an amalgamation of web mapping technology, various geospatial datasets including LiDAR-derived elevation and information products, hydro-meteorological data, and flood simulation models to visualize in near-real time the current and possible future extent of flooding and its associated damages to infrastructures. The Flood EViDEns application facilitates the release and utilization of this near-real time flood-related information through a user-friendly front end interface consisting of web map, tables and charts. The application’s back-end consists of computers running flood simulation models and geospatial analysis to dynamically produce (in an automated manner) water level forecasts, current and future flood extents, and tabulated information on the structures affected by flooding including hazard types. These outputs are forwarded into a PostgreSQL/PostGIS spatial database where it is accessed by the front end interface for web visualization. The information provided by Flood EViDEns is very important especially to the LGUs and the community as it can increase awareness and responsiveness of the public to the impending flood disaster. Providing this kind of information during a heavy rainfall event is useful as it could assist in preparation for evacuation, in easily identifying areas that need immediate action, in identifying areas that should be avoided, and in estimating the severity of damage to people and infrastructure as flooding progresses.

KEYWORDS: Flood event, visualization, damage estimation, geospatially-informed decision making


Publication Details/Metadata:

Paper Title: Flood EViDEns: Near-real Time Flood Event Visualization and Damage Estimations for Geospatially-informed Decision Making in Times of Flooding

Authors: Jojene R. Santillan, Meriam Makinano-Santillan, Edsel Matt Morales

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

Link to Full Text: View/Download