Web-based Near-real Time Flood EViDEns

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Background

The Web-based Near-real Time Flood Extent Visualization and Damage Estimations (Flood EViDEns) is an application developed by Phil-LiDAR 1.2.14 that utilizes LiDAR-derived elevation and information products as well as other elevation datasets, water level records by monitoring stations, and flood models to visualize in near-real time the current and possible future extent of flooding (and its associated damages to infrastructures) due to occurrence of a rainfall event. Presently, most of the LGUs rely on MGB flood hazard maps, and if available, the flood hazard maps available in Project NOAH. However, these hazard maps are static and only represent specific flooding scenarios.

With the availability of water level data recorded by monitoring stations, and in combination of various analytical and computing techniques, it is possible to generate the current extent of flooding in a certain water body (e.g., lakes, rivers). In the case of lakes, the extent of lake water inundation can be obtained just by knowing the elevation of the water surface (which is provided by water level monitoring stations) and utilizing this elevation information with a digital terrain model through GIS techniques. On the other hand, during actual rainfall events, the occurrence of flooding can be simulated/forecasted using flood models. Because of this possibility to forecast, it follows that the extent and depth of flooding can also be estimated by the synergistic utilization of the flood model results and the LIDAR DTMs to derived very detailed flood depth and inundation maps in near-real time. These near-real time maps are very important during actual flooding events 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.

To facilitate release and utilization of this near-real time flood-related information, the project built an automated system for flood model simulation, generation of near-real time flood depth and inundation extent maps and estimation of infrastructures at risk to the flooding event. This application is targeted to be utilized by the LGUs in the project areas to assist them in informed decision making in times of flood disasters.

Web-based Near-real Time Flood EViDEns for Lake Mainit

So far, we have developed a preliminary application for flood extent visualization/inundation monitoring for Lake Mainit. This initial app utilizes (at the moment) a 10-meter SAR DEM as source of topographic information. The concept behind the Lake Mainit Web-based Near-real Time Flood EViDEns is that lake water inundation extent can be generated by utilizing water surface elevation (WSE) data recorded by water level monitoring stations in combination with a DTM. Since the lake WSE is known, then we can find those areas within and in the vicinity of the lake whose elevations are equal to the lake WSE. These areas can be considered as inundated. Moreover, as lake WSE is constantly provided by monitoring stations, then it is possible to create and update in near-real time a map of lake water inundated areas.

The Google Map below reflects the initial output of the Lake Mainit Web-based Near-real Time Flood EViDEns. To know the date and time of inundation information, please click on the blue lines.

To know more about this app, please contact us.