Spatiotemporal Changes of Hazard Intensity-Adjusted Population Exposure to Multiple Hazards in Tibet During 1982–2015

Abstract The dynamic changes of population exposure to hazards in high-altitude areas are an important factor in the scientific evaluation of environmental risks. In this study, the hazards of hypoxia, earthquakes, and snowstorms in Tibet were respectively described by the percentage of oxygen at sea level, earthquake intensity, and mean annual maximum snow depth. The rates of population affected by hypoxia, earthquakes, and snowstorms were calculated by chronic mountain sickness and historical disaster data. Based on these, the study examined the change in population exposure to the three hazards and their combinations by hazard intensity level at the 1 km × 1 km grid scale in 1982–2015. The results show that population exposures to hypoxia, earthquakes, and snowstorms were about 745 thousand, 97 thousand, and 168 thousand in 2015, respectively, among a total population in Tibet of 3.24 million. These exposures were mainly concentrated in the 3400–5000 m above sea level zone. The population exposed to hypoxia and earthquakes showed a rising trend from 1982 to 2015, while the population exposed to snowstorms decreased after 2000 due to reduced snowstorm intensity. Hypoxia-earthquake and hypoxia-snowstorm are the main multiple hazard combinations that people in Tibet suffered from and their person·time exposures were estimated at around 842 thousand and 913 thousand in 2015, respectively, with an average annual increase of 1.7% and 1.3%. Hypoxia is the most important health risk in Tibet. The areas of high person·time exposure to multiple hazards of hypoxia-earthquake-snowstorm are the key areas for strengthening integrated risk governance