i am using SDR and Carbon Storage Model, but in my opinion the output values are too high.
For example:
1.The high value of avoided_erosion.tif is 48.85 and it has spatial resolution 25x25 m. So the high value is 48.85/0.0625ha/year, which sounds very high.
2. The high value of USLE.tif is 33.4 (25x25), so the high value is 33.4/0.0625ha/year. I can’t calibrate the results.
the high value of Carbon storage is 113.5 (500x500), so the high value is 113.5/25 ha.
Do you think the results are incorrect ?
Do you think it is better to represent the results with their value (which are high) or like high - low (without number) ?
Thank you in advance,
best regards,
Tsiatsiari Eva.
It’s hard for us to say whether those values are “correct”. For SDR, remember that it is a very simple model, so many real-world complexities are missing. With this, and really any model, we only recommend using the absolute values after you’ve calibrated the model against observed/real-world data. If the model is not calibrated, we feel much more confident in the relative patterns and values of high-low. Do these patterns make sense to you, based on your knowledge of the study area? One last thing is wondering which version of InVEST you’re using. The latest version (3.14) has an update to the LS factor that generally reduces the USLE and export values.
The Carbon model doesn’t really do any modeling at all. It simply adds up the carbon pool values that you provide, and converts them to a value per pixel. So the accuracy of the input values completely determines the accuracy of the output values. With the carbon model, I often represent the values as low to high, if I don’t feel very confident in the input data; and sometimes represent the absolute values, if I feel more confident in the carbon pool values I’ve provided.