Overview
Description and rationale
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Using the borrow method described in Borrow and Payback - SRG Bi for each owner can be calculated. Any owner that had to borrow will have Vi2 = 0.
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Equation (6) returns a value of zero for owners that had to borrow water. It is only necessary to calculate the repayment for owners with a positive surplus that have previously borrowed from other owners (Surplusi > 0, |BPSystem.NetBorrow(i, OtherOwner)| > 0 ). Borrow and Payback - SRG describes distribution systems and priority levels.
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Accumulate amount the owner owes other owners at the priority level:
Equation 7 - If the owner has borrowed from any other at the priority level ( (CanPayback(pl, i) > 0):
Calculate the ratio to limit the owner’s payback to their current ability to repay:
Equation 8 - For every other owner OtherOwner that shares with owner i at the priority level:
Calculate the payback to the other owner using the ratio above
Equation 9 Update the borrow record for the payback to the other owner
Equation 10 Equation 11 Adjust current time step borrow totals for the payback:
Equation 12 Equation 13 Update the surplus remaining to be shared at the next priority level down:
Equation 14
Forfeiture of credit
If a reservoir is a payback storage, a check is made to ensure that no owner’s credit owing to them exceeds their capacity to store it. If any owner has more water owed to them than they have remaining airspace, the excess is forfeited back to the debtors in order of priority. This methodology is similar to that used for calculating payback, but in this case the forfeits run in the opposite direction to the repayments.
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