SDR : C and P for RKLS

[dhamma57]

Sir, I have 2 question for SDR ;

1. what are the C-factor and P-factor the model calculate total potential soil loss per pixel in the original land cover from the RKLS equation ?

2. I created difference scenarios in the same watershed, the result from each scenario running much be the [soil loss + avoided erosion] and [sediment exported + avoided export] much equal for each scenarios ?

Thanks

[swolny]

HI @dhamma57 -

The RKLS equation does not include the C and P factors. It represents the amount of erosion that could be produced, without taking into account vegetation or management practices. USLE is the total potential soil loss, which does take into account vegetation and management practices.

In general, different scenarios should produce different model results. Are you saying that you created scenarios, and there is no difference between their model results? What kind of scenarios are you using? What changes between them? How are you determining that there is no difference in results? Which model results are you comparing?

~ Stacie

[dhamma57]

thanks for the answer.
I try to figure out the value of the forest area for telling society how much currently forest cover is estimated to be worth and if these forest areas become agricultural areas How much value will be lost?
It refers to scenario 1: which is the forest area value for sediment capture by Comparing to no cover (bare soil), I use avoided erosion + avoided export from the attribute table.
Scenario 2: I created the scenario of the forest area to become an agricultural area. I use avoided erosion + avoided export from the attribute table from this running.

But the results of the soil loss + avoided erosion and sediment exported + avoided from each scenario running are not equal.

Thanks

[swolny]

As the User Guide describes, avoided export already includes avoided erosion, so it is not correct to add the two together, or that will double-count avoided erosion. If you’re valuing sediment retention for downstream uses (like drinking water), then use only avoided export.

If you’re changing the land cover, then the results will not be equal. The areas that changed will produce a different amount of erosion. And because of that change in erosion, both the areas that changed, as well as the areas downslope, will retain a different amount of erosion. So I would not expect the scenario results to be equal.

~ Stacie