Using the Hazus-MH flood model to evaluate community relocation as a flood mitigation response to terminal lake flooding: The case of Minnewaukan, North Dakota, USA

Devils Lake, a terminal lake in eastern North Dakota, has risen nearly 9.0 m since 1993, resulting in over $1 Billion in direct federal payments for disaster mitigation. More than 500 homes and 700 total structures have either been relocated or destroyed by the rising lake. The City of Minnewaukan, once nearly 13.0 km from the lake shoreline, is now facing the possibility of partial or complete relocation. We use the Hazus-MH MR4 Flood Model to examine potential flood damages in Minnewaukan associated with potential future lake levels ranging from 442.57 to 445.01 m at fixed water surface elevation (WSE) increments. We use three data sets to conduct a level 2 analysis in which user-supplied data allows for a site-specific analysis of flood damages. These include: 1) structure elevation surveyed by the U.S. Army Corps of Engineers, b) the 2010 Real Property Assessment Book for the City of Minnewaukan, and c) more than 200 individual property cards. Flood depth grids were provided by the Federal Emergency Management Agency in the form of bare-earth digital elevation models derived from LiDAR point clouds. Results include a series of graduated circle flood maps showing the location and assessed value of inundated buildings, and flood damage profiles showing the cumulative number of buildings inundated and their assessed value over a range of WSE increments. We show that the functionality of Hazus-MH can be extended to examine lakeshore flood hazards, and that it provides an important geovisualization tool in evaluating relocation as a flood mitigation alternative. (C) 2011 Elsevier Ltd. All rights reserved.