NDR,the output retention rate

Why change the landuse input, the retention rate almost unchange? the retention rate=(load-export)/load

Hi @haowen, and welcome to the forum!

Here are a few things to consider that might help explain the results:

  • How exactly did your land use input change?
  • How different are the nutrient coefficients for the land covers that did change?
  • Do the output load and export raster values look reasonable based on the land use maps?

And a couple of additional questions that would help us provide advice:

  • What exactly is the difference in “retention rate”?
  • Are you calculating the retention rate per pixel or per watershed?

~ Stacie

1 Like

Thank you for your prompt reply! Inspired by your additional questions, I am trying to distinguish the difference between nutrients load and export. When coefficients “the eff_n” and “eff_p” for all land use cover are set to 0, the whole watershed still keep very low export, which means most loads left in basin, very few reaching the water finally, even without any retention infrastructure.
My goal is to discuss the wetland role in nutrients retention for agriculture watershed. Along with the huge decline of wetland area, the watershed export change little for per watershed. It seems the model is less sensitive to the detention practices.

Hi @haowen -

The results should definitely change if the eff_* parameters are changed - do you see any change at all?

If the export values are very small, think about the load_* parameters in the biophysical table - if they are small, then the results will be small. Also, what is the resolution of your results? The export values are given as kg/pixel, so if your pixel size is small, then the associated export values are more likely to be small.

If none of this explains the results adequately, you can send me your data and I’ll check it out.

~ Stacie