LS factor in Sediment Retention Model
I'm using the Sediment Retention Model of InVEST 2 and I have a question about the LS factor in USLE equation: The user's guide describes two equations which are choosen according to Slope Threshold parameter. For slopes lower then the threshold, the 1st equation is used and for higher slopes, the second equation is used.
I've made a sensibility analysis with Slope Threshold = 0 and = 1000, so that InVEST would use only equation 1 and 2, respectively. But results are so different. With equation 1, LS is more than 15 times greater than LS calculated by equation 2 (see attached file).
So my question is, which equation is advisible to use? I believe mixing both equations would not be a good idea as that will be a a sharp fall in LS for slopes greater than Slope Threshold.