Dehydration Rate and a Novel Model to Aid Search and Relief for Undocumented Border Crossers in the Sonoran Desert

There has been a proliferation of geographic literature exploring the fatal effects of immigration policy since the early 2000s. Studies have used geographic information systems (GIS) and predictive modeling to explore potential relationships between border protection infrastructure, environment, and migrant death. Although some studies have used GIS to determine the probable effects of heat stress, none have included the potential perspiration as a limiting factor to pedestrian travel in an arid environment during daylight hours. Heat exposure is the leading cause of mortality for migrants in the desert regions of the U.S.-Mexico border, and humans rely on water to regulate temperature. For a more systematic methodology and higher precision, we calculated the maximum distances a person could walk in Arizona's Sonoran Desert accounting for sweat rate. The locations of recovered human remains (RHR) correlate with water usage and increased difficulty of pedestrian travel. Further, our results showed at higher precision a significant correlation of mortality and spatial rates of dehydration and demonstrate that sweat rate is a better predictor of RHR location than heat or slope alone and will be more informative for search and relief operations in the region.