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An example set of Restriction Curves is shown in the following figure as implemented in Source. The stored water volume is expressed as a proportion of the stored volume at full supply level; when stored water volumes are declining and the proportion of full supply volume becomes equal to or less than 0.6, Restriction Level 0 changes to Restriction Level 1 (blue dotted line). Subsequently, when stored water volume rises to 0.7 or above the Restriction Level returns to 0 (solid red line). Hence, a "falling" Restriction Curve is used to indicate when the associated Restriction Level will be put in place if Restriction Level the day before was above the curve (i.e. it had a lower Level number and a less severe restriction). A "rising" Restriction Curve indicates when the associated Restriction Level will be put in place when Restriction Level on the preceding day was below the curve (higher Level number, more severe restriction). 'Rising' and 'falling' refer to the change in the stored water volume not the Restriction Level. The falling Restriction Curve for Restriction Level 0 is redundant and is not used (there is no less severe restriction than Level 0).
The figure above also shows that the critical values of stored water volume for changing Restriction Levels are allowed to change on a monthly basis. For example, lower levels in a water storage might be tolerated at the end of a dry season because of water use through this season – and an upcoming wet season is expected to provide inflows to the water storage and reduction in water demand.
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