This forum is shutting down! Please post new discussions at

Negative AET output? SWY model

atutterowatutterow Member
edited March 2018 in Freshwater Models

I've run the Seasonal Water Yield model multiple times with varying alpha, beta, and gamma parameters, yet I am still getting extreme negative AET values (in the intermediate outputs). What could be the source of this?

To confirm, the Precip and ETO inputs are in total observed per month, correct? Not average per day over the month?

Thank you!
Post edited by atutterow on


  • PerrinePerrine Moderator, NatCap Staff

    Yes, Precip and ETo values are given in mm/month.

    The negative AET values may come from your parameter values for alpha, beta, gamma. In particular, can you check your alpha parameter (set to the default: 1/12)? 

  • Total mm/month, correct?

    And I have tried all of the parameters at the default and even tried shifting them around but still am getting negative values.
  • PerrinePerrine Moderator, NatCap Staff
    Ok, it may be easier to look at your data directly: would you mind sending me your input data at:

Sign In or Register to comment.