Document ID: chunk:federal_register_of_legislation:F2024C00760:reg:80:p2
Version: federal_register_of_legislation:F2024C00760
Segment Type: reg
Provision Reference: reg 80 (pt 2/9)
Character Range: 582000–585260

7.15.

        Part 1—Description

S6.01 Simplified outline
(1) This Schedule sets the default method by which the supply contribution is calculated for Chapter 7.
           Note: Section 7.15 sets out circumstances in which an alternative method may be used.
(2) The method is summarised as follows:
            (a) identify the hydrological model of the Basin that is to be used for the calculations (the benchmark model—this is the model that was used to arrive at the unadjusted SDL, with some modifications);
            (b) identify the indicator sites and regions that are to be used in applying the method (these will be chosen to be representative, while ensuring that areas of high ecological value are given due weight);
            (c) identify the flow regime characteristics that are to be used as a measure of environmental outcomes, and that are to be measured or assessed in relation to those indicator sites;
            (d) calculate the benchmark environmental outcomes;
            (e) identify the method of comparison between the benchmark environmental outcomes and another set of environmental outcomes—this will use a scoring method, including preference curves and weightings for environmental significance. A higher score will represent a preferable environmental outcome;
            (f) identify the limits of changes in score or outcome that ensure that supply contributions maintain environmental outcomes within identified limits;
            (g) calculate the supply contribution as follows:
                (i) choose a test supply contribution of an amount that is likely to be smaller than the actual supply contribution;
                (ii) calculate the environmental outcomes that result from applying the model under the assumptions of:
                   (A) the benchmark conditions of development with the addition of the relevant notified measures;
                   (B) a repeat of the historical climate conditions;
                   (C) consumptive use of water at the levels of the unadjusted SDL adjusted by the test supply contribution;
                (iii) compare the environmental outcomes against the benchmark environmental outcomes and assess whether the score is equivalent or higher;
                (iv) ensure that requirements of section 7.15 of the Basin Plan in relation to the supply contribution are satisfied;
                (v) repeat with successive test supply contributions until the largest contribution is found that still results in an equivalent or higher score;
                (vi) the supply contribution is equal to that test contribution.

        Part 2—Method

S6.02 Benchmark model
(1) The benchmark model run will comprise the MDBA model run 847, described in MDBA 2012a, with refinements to:
            (a) adjust the overall reduction from 2800 GL/year to 2750 GL/year;
            (b) incorporate appropriate rules for delivery of water from the Lower Lakes into the Coorong, including relating Lake level to release volumes;
            (c) incorporate Upper South East inflows as at 30 June 2009;
            (d) incorporate updated environmental watering event time‑series for without development and baseline model runs in the environmental event selection tool;