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25/11/2019 12:25:25

Pic here

Hi All

I'm building a model of a reach of canal in Chesterfield for a water resources study for their restoration project - and finding the treatment of abstractions a bit confusing.

At each lock I've got two abstraction units:

  1. One representing the lock, connected to an upstream and a downstream node, with a positive value representing flow from the upper pound into the lower pound as boats use the lock.
  2. One representing infiltration and evaporation, with a negative value representing water lost in the upper pound.

Does this sound right? It all seems to make sense in terms of mass balance and how the model behaves, but I find it a bit odd that the second abstraction needs a negative value (ie I would have thought a positive abstraction = loss of water, rather than the other way round).

Anyone able to confirm?

TIA all




17/12/2019 15:17:42

Hi Matt,

Your thinking as  positive abstraction = loss of water is 'normal' but it is coded to accept negative values as abstraction. So when it is an abstraction, you need to specify it as negative values.



05/02/2020 11:44:03

Thanks Deepak - makes sense looking at the mass balance of the model

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