Heidari, Hadi, authorArabi, Mazdak, advisorWarziniack, Travis, committee memberBrown, Thomas C., committee memberBailey, Ryan, committee memberGoemans, Christopher G., committee member2021-06-072022-06-022021https://hdl.handle.net/10217/232577Future changes in climate and population across the United States may cause a decrease in freshwater availability and an increase in water demand. These trends may lead to more frequent water shortage conditions when water demand exceeds water supply. The enhanced characterizations of changes in both long‐term anomalies such as aridity and evaporative indices and short-term anomalies such as multi-year and interannual water shortage events in a changing environment are requisite to the appropriate management and planning of future water resources, and improved implementation of regional adaptation and mitigation strategies. The main goal of this dissertation is thus to assess shifts in hydroclimatic conditions and water shortage (IDF) relationships across the conterminous United States (CONUS) over the 21st century. To achieve this goal, first, the effects of climate change on the regional hydroclimatology of U.S. river basins were assessed over the 21st Century to determine regions with prolonged dry or wetting periods. This analysis shows that U.S. river basins within the CONUS can be clustered into seven groups with unique hydroclimatic behaviors in response to climate change that are highly associated with regional landform, climate, and ecosystems of river basins. The South United States is more likely to experience warmer and drier conditions meaning higher chances of aridification. Second, the impact of climate change on hydroclimatic conditions of U.S. national forests (NFs) and national grasslands (NGs) was investigated. The results of this study indicate that NFs and NGs are more likely to experience larger changes in hydroclimatic variables compared to the average of the United States. The findings help environmental scientists and forest managers to mitigate the negative consequences of climate change on forest and grassland resources. Third, shifts in hydroclimatology of U.S. megaregions in response to climate change were investigated. This analysis reveals that Houston may experience more arid climatic conditions with higher evaporative loss of freshwater resources in the future. These steps provide an improved understanding of the effects of climate change on the regional aridification or desertification across the CONUS. To accomplish the goal of the study, fourth, a probabilistic approach was developed to improve the characterization of both within-year and over-year socioeconomic droughts in a changing environment. The proposed approach provides a procedure to update sub-annual socioeconomic drought IDF relationships while taking into account changes in water supply and demand. Fifth, the developed probabilistic approach was applied to examine the effects of urban development patterns, i.e., sprawl versus high-density development, on the socioeconomic drought characteristics. The results of this study highlight that urban regions under the sprawl development pattern are likely to experience more frequent socioeconomic drought events with higher intensity and longer duration compared to the high-density development pattern. Finally, the developed approach was implemented across the CONUS to characterize vulnerability of U.S. river basins to water shortage from 1986-2015 to 2070-2099 periods. The results show that prolonged water shortage conditions in drier basins and interannual water shortage events in wetter basins are likely to be the main concerns in the future and should gain more attention in future water resource planning and management.born digitaldoctoral dissertationsengCopyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright.Text