Spatiotemporal Changes of Lagged Compound Dry and Wet Spells in the Northwest North America Under Climate Change
Abstract
Recently, an upsurge in the occurrence of hydroclimatic extremes and their temporal swings is observed in several regions around the world. Such transitions to the contrasting extremes such as the drought to flood in California (2016 – 17) has raised concerns about the increasing variability and rapid transitions between hydrological extremes and their associated compounding economic and environmental impacts. The intensification of the global hydrological cycle associated with climate change can further alter the drivers of such extremes and their interactions. Therefore, it is important to understand the characteristics of consecutive flood and drought events, including their spatiotemporal frequency and intensity in a changing climate. In this study, wet-dry swings are investigated based on precipitation and streamflow data in the Northwest North America. To this end, wet and dry conditions, as drivers of hydrologic floods and droughts, are investigated using the Standardised Precipitation Index for multiple accumulation periods (1, 3, and 6-months), calculated based on the downscaled and statistically bias corrected simulations of six Global Climate Models from the 5th phase of the Coupled Model Intercomparison Project with two medium and high emission scenarios for 1.5°C-4 °C global warming levels. Further, we use the Variable Infiltration Capacity hydrologic model simulated streamflow to show the hydrological response of the study area to the lagged compound floods and droughts under global warming. We identify future hotspots for the lagged compound hydroclimatic events. Our findings assert the necessity of integrating mitigation measures targeting such events into Disaster Risk Reduction strategies at the identified hotspots.