The response of streamflow to climate change over the conterminous U.S.: preliminary analyses using VEMAP Phase 2 model experiments

The Vegetation/Ecosystem Modeling and Analysis Project (VEMAP) Phase 2 model experiments investigate how alterations to future climate, as simulated through the end of the 21st century, are predicted to alter the biogeochemical cycles and the vegetation dynamics of the conterminous U.S. Changes in the dominance or distribution of various plant life forms are likely to affect the water balance of a region. Here we evaluate changes to the hydrologic cycle (e.g., changes in seasonality and interannual variability) under climate change by comparing predicted, future runoff to: 1) gauged runoff from the 20th century, and 2) simulated runoff from the 20th century. The changes are accounted for, in part, by changes in precipitation, but also by changes in vegetation and concomitant changes in evapotranspiration. We also present initial validation results comparing the hydrologic output of the models for the 20th century to U.S.G.S. streamflow records. These types of analyses are critical to enhancing our understanding of the interactions between changing land cover, hydrology, and climate, and will lead to better representation of these interactions in global climate models.