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Critical review of Terrain Tile and Google Earth: Virtual image mapping methods for floodplain management

Richard Wise, MSCE, EIT, Andrew Darnell, MSCE, EIT, John Quaranta, PhD, PE


Inundation mapping is a major component of floodplain management, providing critical information as to the consequences of potential failures of flood control structures. Flood mitigation efforts rely on the creation of inundation maps to develop appropriate response measures for crisis situations, including dam failures. To develop inundation maps, a dam and river system is modeled with engineering computer programs, and a simulation of the dam failure is performed to generate data for the flood. This output data are input into other programs to develop inundation maps. Inundation maps have traditionally been produced in a paper format, but recent advances in computer modeling have provided the capability for virtual inundation maps. Virtual inundation maps offer new methods of presentation and analysis of flood impacts; thus, these mapping methods need to be investigated to determine the applications and relevance to floodplain management. The goal of this research is to advance the development and use of inundation maps by floodplain managers and emergency agencies. A simulation of a potential dam failure was performed using computer modeling for a candidate river system, and the inundation maps were created using two procedures: Terrain Tiles and Google Earth. An analysis of the strengths and weaknesses of each mapping procedure was conducted. The results indicated that the Terrain Tiles procedure has advantages in displaying critical information, such as arrival times and water depths. However, this mapping procedure is more labor intensive, and the online file sharing may not be accessible for all users. The strengths of the Google Earth procedure include two-dimensional and three-dimensional views for analysis, user-friendly file sharing, and the inclusion of built-in critical infrastructure and terrain data. Drawbacks of this procedure are that the inundation must still be generated in ArcGIS, the display of critical information is not as clear, and the online file sharing may pose security issues. Thus, the Terrain Tiles procedure should be used for the development of emergency response measures, and the Google Earth procedure should be used by emergency responders in the event of an actual emergency.


paper inundation mapping; virtual inundation mapping; floodplain management; HECRAS; hydrologic modeling; simulated dam failure; HEC-GeoRAS; Terrain Tiles; ArcGIS; Google Earth

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