Georeferencing incidents from locality descriptions and its applications: A case study from Yosemite National Park Search and Rescue

Abstract

The Search and Rescue (SAR) of individuals who become lost, injured, or stranded in wilderness presents a unique and worthwhile spatiotemporal challenge to investigate. Once incidents are georeferenced they can be spatially queried and analyzed. However, one major challenge for evaluating SAR in a spatial context is the lack of explicitly spatial data (addresses or coordinates) for historic incidents; they must be georeferenced from textual descriptions. This study implemented two established approaches for georeferencing incidents, the 'Point-Radius' and 'Shape' methods. Incorporating uncertainty measurements into a spatial database allows for more appropriate analyses of spatial dependence and the spatial distribution of incidents. From 2005-2010, 1,271 of 1,356 Yosemite Search and Rescue YOSAR incidents (93.7%) could be georeferenced using the Point-Radius Method, with a mean uncertainty radius=560±51 m and mean uncertainty area of 3.60±0.840km2. However, when the Shape Method was applied to six case studies by considering the reference object shape, the uncertainty areas were reduced considerably (by up to 99.5% of the uncertain area generated by the Point-Radius Method). This is the first spatially-explicit study of SAR incidents and yields valuable insights into the role of georeferenced data in emergency preparedness. © 2011 Blackwell Publishing Ltd.