Characterizing the water extremes of the new century in the US South-west: a comprehensive assessment from state-of-the-art climate model projections

The impact of climate change scenarios in the hydrology of the Verde River basin (Arizona) is analyzed using an ensemble of downscaled climate model results, SPI analysis, and two hydrologic models of different complexity. To assess model uncertainty, 47 ensemble members combining simulations from 16 global climate models and 3 emission scenarios were used to provide an uncertainty envelope in the hydrologic variables. The analysis shows that simple lumped models and more complex distributed runoff models can yield similar results. Results show that under all scenarios, the distribution functions of hydrologic states will shift towards lower values and droughts will progressively become more frequent, longer and more intense.