Multi-index drought characteristics in Songhua River basin, Northeast China

摘要

Due to global warming, Northeast China has been affected by droughts in recent decades, potentially leading to disastrous effects during the 21st century. Knowledge of drought characteristics, such as drought duration and severity, is very important to be able to mitigate natural hazards and manage water resources. Here, drought characteristics were assessed based on multiple meteorological drought indices (Standardized Precipitation Evapotranspiration Index, Supply Demand Drought Index, and Reconnaissance Drought Index) that are calculated using potential evapotranspiration (Thornthwaite equation) or reference evapotranspiration. Furthermore, a combination of general circulation models and drought indices was used to examine drought characteristics (duration, severity and intensity) and climate variables that possibly influence droughts for the periods 1961-2005 and 2006-2099. Different indices based on the Thornth-waite equation capture the same events but with varying magnitudes. Likewise, the reformulated drought indices based on reference evapotranspiration capture fewer drought years compared with temperature-based indices. In future projections of drought events, all indices show the highest drought occurrence under representative concentration pathway (RCP) 8.5 compared with other RCPs. The Harbin, Tonghe, Suihua, Jiamusi, and Mudanjiang stations experience a maximum of drought episodes in the late stage of the model calculations (2060-2099). Moreover, in the early and middle stages (2006-2030 and 2031-2060, respectively), the indices show fewer drought occurrences over the region compared with the late stage. The evaluation of potential contributors and climate-controlling factors suggests that temperature is a key climate factor that potentially contributes to drought behavior. Overall, the results imply that under future climate conditions, the risk of drought in Northeast China may increase at the end of the 21st century.