SDR results, Calibration


I used the SDR model. In some subwatersheds, I succeed in calibrating the model. but, in other cases, i met two problems.

1- sed-exp and sed-ret values equal to 0

2- Very low value of sed-exp even if we increase the Kb factor

Could you please help to find an explanation

Thank you 


  • PerrinePerrine Moderator, NatCap Staff
    Hi Sana, 

    1. Are they equal to 0 or showing no data? If the latter, this could be a routing issue (please see some posts on the forum asking about pit filling and hydrologic routing) If they are equal to 0, I'd suggest the following for debugging: looking at each factor in the calculation of sed_export (i.e. erosivity, erodibility, LS , C, P, and the SDR factor), and see which one causes the product to be 0. Please consult the User's guide for a description of these variables.

    2. Similarly, the low values of sed_export could be due to low values of any of the above factors. Is it possible that there's a unit error in the erodibility or erosivity layers? (These are frequent). You could also try to change the IC_0 factor as both parameters, Kb and IC_0, are calibration factors.
    Finally, check the "observed data" to make sure that this is realistic (and remember that the InVEST model ignores some sediment sources such as landslides, bank erosion or gully erosion.


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