Ticket #1584 (new assessed)

Opened 6 years ago

flow scaling

Reported by: silviao Owned by: jeroens
Priority: normal Milestone: Ecopath 6: future version
Component: Flow diagram Version: 6.6 beta
Severity: tweak Keywords:


During this week I have spent quite a few hours exploring the flow diagram thoroughly and particularly how flows are being presented therein:

  1. The strength of a flow in the diagram to a prey corresponds to its proportion in the diet (consumption) of the predator.
  1. For each predator - though - another conversion factor for the transformation from consumption data into flow strength is apparently being applied. Therefore, flows to a prey item are not comparable between predators.
  1. Outgoing flows from a prey are still predator based, i.e. maintaining the flow strength to that respective prey in the consumption of the predator. The resulting assemblage of "out-flows" from a prey-box gives in my opinion a totally misleading impression of the outgoing flow of matter from a prey to its predators. This is also the reason why the outgoing flow from "herring" to "seals" in our model is much larger than the flow to the "pelagic fleet" although the pelagic fleet is extracting 200 times the amount that the seals are consuming (per m2 and year).

Summarizing, it is now clear to me that "the bug" in the flow strengths of the fishing fleets to their "prey" is not a bug but basically in line with the allover concept of the flow diagram routine except maybe for the fact that flows are even less in proportion with their real size when comparing them to other top predators such as harbour porpoises and seals in our WBS model.

I am not sure how time consuming it would be to modify the flow diagram routine and in what way it should be modified if at all (I am not the only user of course and the flow diagram in my understanding forms part of the core routine of EwE)

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