A major water crisis has emerged over the southwest U.S. since the early 2000s due to low precipitation totals and high temperatures resulting in what is often referred to as a “megadrought”. This ongoing drought has impacted the reliability of the Colorado River system to meet water allocation agreements and hydroelectric power generation targets. Future rising temperatures and shifting precipitation from snow to rain could make streamflow harder to predict and water resources less reliable. Any precipitation increases that might occur, are likely to be offset by the impacts of warming temperatures.

This presentation uses the DOE funded Integrated Multisector Multiscale Modeling/HyperFACETs Thermodynamic Global warming (TGW) simulations to study the potential impact of climate change on the intensity and spatial extent of drought over the southwest U.S. and the Colorado River Basin. Drought metrics including SPI, SPEI, PDSI, and soil moisture anomalies are explored in the study. The unique aspects of the TGW simulations over other pseudo global warming scenarios is that these runs allow for the exploration of uncertainty by including multiple time horizons (mid- and late-century) and multiple temperature and humidity change combinations. Results will examine the 2000-2019 drought period as well as two severe drought years, 2002 and 2018. The goal of this work is to eventually run these simulations through water resources models to understand the potential impact that warming could have on water resources in the west.