Authors: Mohammad Hadi Bazrkar*, North Dakota State University, Gregory Gust*, NOAA, NWS Grand Forks ND, Xuefeng Chu, North Dakota State University
Topics: Hazards and Vulnerability, Hazards, Risks, and Disasters, Water Resources and Hydrology
Keywords: Flash droughts, Cold climate regions, drought index, Frozen soil
Session Type: Virtual Paper
Start / End Time: 11:10 AM / 12:25 PM
Room: Virtual 17
Presentation File: No File Uploaded
The Northern Plains Region of North America is susceptible to significant spring snowmelt floods and/or periods of rapid-onset of flash droughts. For instance, the 2009 snowmelt flood was preceded by a flash drought, while the 2011 snowmelt flood was followed by a flash drought. However, existing drought indicators are unable to completely characterize such flash droughts due to their failure to consider wintertime frozen soils and/or snow-covered ground. The objectives of this research are to improve identification of flash droughts and investigate the primary causes of this specific type of drought in cold climate regions. The hydroclimatic aggregate drought index (HADI) and snow-based hydroclimatic aggregate drought index (SHADI) were developed and applied in the Red River of the North Basin (RRB), a typical cold climate basin in the Northern Plains. The impacts of temperature, precipitation, snowpack, snowmelt, surface runoff, and soil moisture on flash droughts were evaluated and the key factors were identified. Abnormally low temperature and snowpack throughout the cold season and abnormally high temperature and rapid snowmelt at the transition to the warm season were among the primary causes of flash droughts in the RRB. The twin HADI and SHADI showed some advantages over the existing drought indicators for identification of flash droughts since they better accounted for the dominant hydroclimatic processes common to cold climate regions. The twin indices provided early warnings of flash drought development and valuable drought mitigation information for the stakeholders in the RRB.