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• If they are fixed at one or both ends, the modeller configures each owner’s ratio or percentage of the flow entering the wetland link from this end and this remains constant for the model run. At various times during the model run, some owners may not have sufficient water at the source node to sustain their fixed share of flow, while others will have a surplus. When this happens, owners with a deficit will borrow from those with a surplus. This borrow is accounted for, and may be paid back later (see Borrow and Payback - SRG for more information).
• If shares are defined to be proportional, each owner’s share is recalculated in each model time step. This calculation differs according to the type of node connected to the nominated end of the wetland link:

  • Hydraulic connector node: Each owner’s share is proportional to its current inflow from the upstream standard link:

    Equation 1	Image Added

    where:

Share_source(l, i) - Owner i’s share of outflow from the hydraulic connector along wetland link l
I_i - Owner ’s upstream inflow to the hydraulic connector over the current time step
I - Total upstream inflow to the hydraulic connector over the current time step

• • Storage node: Each owner’s share is proportional to its current storage volume:

    Equation 2	Image Added

    where:

Share_source(l, i) - Owner i’s share of outflow from the hydraulic connector along wetland link l
V_i - Owner i’’s storage volume.
V - Total volume in the storage.

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For a wetland link l, an owner i’s flow during the current time step (W_lⁱ) is:

Equation 3	Image Added

where:

Share_source(l, i) - Owner i’s share of outflow from the hydraulic connector along wetland link l

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An owner i’s total wetland flow volume entering/leaving a node over a time step (W_i) is the sum of its flow volume on all connected wetland links:

Equation 4	Image Added

where:

l - A wetland link connected to the wetland node

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An owner i’’s downstream outflow at a hydraulic connector (O_i) is their upstream inflow minus their wetland flow:

Equation 5	Image Added

where:

I_i - Owner i’s inflow at the hydraulic connector over the current time step

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An owner’s downstream outflow could be negative if they are assigned a fixed share of wetland outflow that exceeds their upstream inflow. Ownership rules dictate that every owner has non-negative outflow.  Hence, owners with a negative (deficit) downstream outflow volume must borrow from others with positive (surplus) flow. The surplus/deficit for each owner is their outflow volume:

Equation 6	Image Added

Equation 7	Image Added

The borrow method (described in Borrow and Payback - SRG) will return the amount an owner borrows (Borrowed_i) and lends (Lent_i). The owner’s outflow is then adjusted.

Equation 8	Image Added

As flow processing ensures that total downstream outflow is non-negative, this adjustment will ensure every owner has non-negative outflow.

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The storage ownership continuity equation described in Ownership in Storages - SRG is:

Equation 9	Image Added

where:

Vⁱ₂ - Owner ’s volume of water in the reservoir this time step.

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1. If this link has already been processed ((flow, (i, t) not null), exit here. (Ownership calculations only have to be done once on a wetland link).
2. Get the ‘source’ node that flow originates from this time step. Note that a positive flow value indicates that flow moves from Node1 to Node2. (Node1, Node2 are configured).
   • If flow(t) > 0, Source = Node1
   • Otherwise Source = Node2
3. Get the source node’s outflow share. Last time step’s values are used as ownership processing may not have been performed for the node as yet:
   • If the FlowSharing(Source) = 'Proportional'

     • If Source.Type = 'Storage'

       Equation 10	Image Added

     • Otherwise (hydarulic connector)

        

       Equation 11		Image Added

   • Otherwise (sharing is fixed)

     Equation 12	Image Added

4. For each owner: Apply the owner’s share to the total to determine their flow volume.

   Equation 13	Image Added

Wetland storage

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1. Determine total wetland flow per owner WetlandLoss(i) using the generic method for a wetland node (See Method Description section below).

2. Each owner’s share of downstream outflow is its inflow plus wetland loss/gain:

   Equation 14	Image Added

3. If any owner has a negative share of outflow, use the borrow method to bring its share to zero:

   1. Determine owner surpluses and deficits – this is simply their unmodified downstream outflow:

      Equation 15	Image Added

      Equation 16	Image Added

   2. If any owner deficit > 0, use the Borrow method described in Borrow and Payback - SRG.

   3. Update every owner’s outflows for volumes borrowed and lent:

      Equation 17	Image Added

Method Description

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1. Run the wetland link’s ownership processing – this determines WetlandLink.flow(i, t)
2. Add each owner’s share of the wetland link’s flow WetlandLink.flow(i, t) to their wetland flow total WetlandLoss(i). The default ‘upstream’ node on a wetland link is Node1, so if the current flow value is positive, flow is moving away from this node.
   • If (this Node = WetlandLink.Node1) the current node has been treated as ‘upstream’, so:
     For every owner ii 

      

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1. • Equation 18	Image Added

   • Otherwise: (the node is ‘downstream’ so the flow is a gain)
     For every owner i

      

     Equation 19	Image Added

Data

Input data

Details on data are provided in the Source User Guide.

Parameters or settings

Input parameters are summarised in Table 3.

Table 3. Wetland link: Ownership Parameters

*  Note: The initials o.s. refer to the current ownership system.

Output data

Recorded variables are listed in Table 4.

Table 4. Recorded variables: Wetland flow ownership