Tetra Tech’s Dr. Jonathan Butcher (lead author) and Saumya Sarkar collaborated with colleagues from the U.S. Environmental Protection Agency and U.S. Agency for International Development (USAID) to model the changes in plant use of atmospheric CO2, which can in turn have an important impact on the evapotranspiration component of the water balance. Their article, titled “Incorporating the effects of increased atmospheric CO2 in watershed model projections of climate change impacts,” was published sciencedirect.com and in the Journal of Hydrology, Volume 513, pages 322–334.

This work is based on simulations of watershed response to global change for five study areas that we performed as part of a larger modeling effort. Highlights from the article include:

  • Increased CO2 changes stomatal conductance, potentially reducing watershed transpiration
  • Reduced transpiration may help offset water balance impacts of increased future air temperature
  • Watershed models simulating this process predict higher total runoff than models that do not
  • New methods are developed to incorporate these effects in watershed models
  • Some existing models may over-estimate the effect of increased CO2 on the water balance

View the full article.

Jonathan Butcher,Thomas Johnson, Daniel Nover, Saumya Sarkar
May 26, 2014
Journal of Hydrology
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