WRR Publication

A new publication in the journal Water Resources Research (Ghimire et al., 2026) examined the roles of fall soil moisture and spring weather on modulating snow-streamflow dynamics in the Colorado River Basin using the Variable Infiltration Capacity model. These findings indicate that in the Upper Basin, soil moisture can help predict how much water will flow months in advance. Congratulations to the authors associated with the Center for Hydrologic Innovations!

• Abstract: The Colorado River Basin (CRB) has experienced a prolonged drought since 2000, with recent years showing a weakened relationship between snowpack conditions and streamflow. In this study, we examined the roles of fall soil moisture and spring weather on modulating snow-streamflow dynamics in the CRB and its sub-basins. To address this, we conducted numerical experiments using the Variable Infiltration Capacity (VIC) model that isolated the effects of 1 October soil moisture (SM) and April–May–June precipitation (P) and temperature (T), while maintaining average snowpack conditions of a representative water year. We also carried out a long-term VIC simulation (1984–2023) to extend the findings from the controlled experiments. Results indicate that fall SM accounts for 69%–77% of streamflow variability in the Upper Basin, while spring P has a dominant effect, ranging from 48% to 87% of streamflow variability, in the Lower Basin. For average snowpack years, multilinear regressions that predict streamflow changes based on fall soil moisture and spring weather had a high predictive power in the Upper Basin. As a result, seasonal streamflow predictions in the Upper Basin are enhanced with estimates of total column SM on 1 October. These findings highlight the effects of hydrologic memory embedded in the basin soil moisture storage and its impact on the conversion from snowmelt to streamflow, especially under the current drought. To help translate this effort, we provide guidance to water resources managers on how to use information on fall soil moisture and spring weather to improve water year streamflow predictions.