Drought in the Twenty-First Century in a Water-Rich Region: Modeling Study of the Wabash River Watershed, USA

Abstract

Climate change is expected to alter drought regimes across North America throughout the twenty-first century, and, consequently, future drought risk may not resemble the past. To explore the implications of nonstationary drought risk, this study combined a calibrated, regional-scale hydrological model with statistically downscaled climate projections and standardized drought indices to identify intra-annual patterns in the response of meteorological, soil moisture, and hydrological drought to climate change. We focus on a historically water-rich, highly agricultural watershed in the US Midwest—the Wabash River Basin. The results show likely increases in the frequency of soil moisture and hydrological drought, despite minimal changes in the frequency of meteorological drought. We use multiple linear regression models to interpret these results in the context of climate warming and show that increasing temperatures amplify soil moisture and hydrological drought, with the same amount of precipitation yielding significantly lower soil moisture and significantly lower runoff in the future than in the past. The novel methodology presented in this study can be transferred to other regions and used to understand how the relationship between meteorological drought and soil moisture/hydrological drought will change under continued climate warming