Two different spatially-scaled, 2XCO2 climate change scenarios were used to simulate water yield for the Missouri River basin. The coarse resolution scenario was based on the Commonwealth Scientific and Industrial Research Organization Global Circulation Model (CSIRO GCM), while the high-resolution scenario was based on a nested regional model (National Center for Atmospheric Research Regional Climate Model, or NCAR RegCM). All water yield simulations were performed using the Soil and Water Assessment Tool (SWAT), a daily time step continuous simulation model.

Simulated water yields for the 25-year period increased using both resolutions of climate change scenarios. The RegCM simulation produced greater changes. Water yield differences for both resolutions were significantly different than that for the base case, and the RegCm yields were significantly higher than the GCM simulations.

The spatial resolution of climatic input is an important issue to address when simulating water yield and associated processes.