I'm reviewing the erosion model described in "An advanced modelling tool for simulating complex river systems" from Trancoso et al. 2009 and I have a question about the erosion equation of the Drainage Network module (subroutine ComputeErosionFluxes):
Code: Select all
!kg m-2 s-1 = kg m-2 s-1 * m2
ErosionRate = Property%ErosionCoefficient &
* Property%BottomConc (NodeID) &
/ SedimentConc (NodeID) &
As far as I understand the code, the erosion rate is normalized by the ratio of the bottom concentration of the property divided by the "sediment concentration". My first question is: Why do we normalize since we already inputed an erosion coefficient? In my case, I want to erode particulate metals to which I give a Bottom Concentration many orders of magnitude lower than the "sediment concentration" and I know its erosion rate.
My second question: Isn't it dangerous to normalize all erosion rates by the TSS or Cohesive Sediment property? I mean that these two properties are independent and are not, for example, the sum of all particulate properties (or at least, I hope so!). This means that if, for example again, my cohesive sediment's bottom concentration is null (or very low) in a reach, the erosion rate will raise to unrealistic levels. Once again, in my case, I need at least two fractions of TSS (fine and coarse). If I define the Cohesive Sediment as the fine fraction, then I risk a division by zero in my model.
In my opinion, this normalization is tricky and might lead to misinterpretations. But before modifying my code, I would like your opinion.