I’m curious about the relationship between “sed_export”, “sed_retent” and “sed_dep”. Am I to understand that the sum of “sed_export” and “sed_dep” is the sum of the amount of soil received by the basin from the upper basin?
Hi @littlepencil,
Sediment export is the amount of sediment from pixel i that reaches a stream (Eᵢ, equation 50 in the user’s guide). So, sed_export in the aggregate vector is the total amount of sediment going into the streams in that watershed.
Sediment deposition is the amount of sediment being deposited on pixel i (Rᵢ, equation 60). So, sed_dep in the aggregate vector is the total amount of sediment deposited on the watershed. This includes sediment movement within the watershed. It does not measure how much sediment is added to the watershed from outside it.
Sediment retention is calculated as: (RKLS - USLE) * SDR / SDRmax. I am not clear on how it should be interpreted.
I do not think it makes sense to add sed_export and sed_dep in the way you suggest. There is an intermediate output e_prime.tif (Eᵢ’, equation 52) that is the amount of sediment from pixel i that does not reach a stream. Thus, Eᵢ + Eᵢ’ = USLEᵢ, the total soil loss from pixel i (usle.tif).
I believe you could subtract usle.tif from sediment_deposition.tif pixelwise to get the net sediment change on each pixel, but I am not a hydrology expert. I hope that helps!
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