Hydrological Responses to Droughts Under Climate Change with an Integrated Physical Model in Mid-Atlantic Region

Drought risk under climate change depends not only on atmospheric forcing but also on how precipitation, snowpack, evapotranspiration, streamflow, soil moisture, and groundwater respond together. Using the severe 1960s drought as a baseline event, we examine hydrological responses to climate analogues of the 1960s drought in a regional hydrological domain of the northeastern United States. The integrated ParFlow-CLM model was driven at hourly, 1 km resolution with WRF pseudo-warming forcings for four scenarios: the historical 1960s drought (1961–1967) and future 2020s, 2040s, and 2090s scenarios. Model performance was evaluated against daily streamflow from 321 USGS gauges. Most gauges had correlation over 0.5 and absolute relative bias below 1, indicating that the model captured the main historical drought response. Under the pseudo-warming scenario applied here, future simulations showed higher precipitation and generally higher streamflow, but they also showed greater variability, with the 2090s producing the largest fluctuations. Warming sharply reduces spring snowpack, so that spring streamflow falls below the 1960s baseline despite wetter future conditions. Subsurface storage increases as precipitation and infiltration rise, contributing more baseflow to river. These results show the hydrological risk in these pseudo-warming analogues over the northeastern United States depends on the coupled response of snow, streamflow, and subsurface storage, rather than on precipitation alone, improving regional drought assessment and planning.