Comparison of ArcToolbox and Terrain Tiles processing procedures for inundation mapping in mountainous terrain

Abstract

Floodplain management consists of efforts to reduce flood damage to critical infrastructure and to protect the life and health of individuals from flooding. A major component of this effort is the monitoring of flood control structures such as dams because the potential failure of these structures may have catastrophic consequences. To prepare for these threats, engineers use inundation maps that illustrate the flood resulting from high river stages. To create the maps, the structure and river systems are modeled using engineering software programs, and hydrologic events are used to simulate the conditions leading to the failure of the structure. The output data are then exported to other software programs for the creation of inundation maps. Although the computer programs for this process have been established, the processing procedures vary and yield inconsistent results. Thus, these processing methods need to be examined to determine the functionality of each in floodplain management practices. The main goal of this article is to present the development of a more integrated, accurate, and precise graphical interface tool for interpretation by emergency managers and floodplain engineers. To accomplish this purpose, a potential dam failure was simulated and analyzed for a candidate river system using two processing methods: ArcToolbox and Terrain Tiles. The research involved performing a comparison of the outputs, which revealed that both procedures yielded similar inundations for single river reaches. However, the results indicated key differences when examining outputs for large river systems. On the basis of criteria involving the hydrologic accuracy and effects on infrastructure, the Terrain Tiles inundation surpassed the ArcToolbox inundation in terms of following topography and depicting flow rates and flood extents at confluences, bends, and tributary streams. Thus, the Terrain Tiles procedure is a more accurate representation of flood extents for use by floodplain engineers, hydrologists, geographers, and emergency managers.