Modelling river management

The river model, AWRA-R, is used to simulate some aspects of the management and regulation of the Namoi River, but this is undertaken differently to the Namoi and Peel Integrated Quantity-Quality Models (IQQM) (Simons et al., 1996), used by state agencies to set and assess river management rules, water sharing plans and allocations. This reflects the different purposes for which these models have been developed. The implementation of AWRA-R in the BA for the Namoi subregion is not specifically developed for river operations planning and management and, without further development, should not be used for this purpose.

Streamflow in the Namoi river basin is regulated by three major dams, Split Rock, Keepit and Chaffey dams (Figure 5). These dams supply water to downstream irrigation, industry and town water. Since reliable data on dam releases are not readily available, an irrigation module (which has as a constraint the regulated licensed irrigation volume) is used that is separate to the AWRA-R model to determine dam release values (Hughes et al., 2014). The data on water for domestic, industrial (e.g. mine) and other purposes (e.g. environmental release) are taken from the relevant agencies such as NSW Department of Primary Industries. Other variables required for AWRA-R are largely based on existing management rules.

A water resource assessment component (see companion submethodology M06 (as listed in Table 1) for surface water modelling (Viney, 2016) for a detailed description) was developed to estimate the allocation, which is the fraction of the licensed irrigation volume allowed to be extracted in the regulated section of the river system in a water year. This differs from the IQQM resource assessment, which includes all general security licences, whereas all irrigation licences are lumped in AWRA-R. This is a reasonable assumption since licences for irrigation comprise a large proportion of the general security licence volume. Within a year, allocations cannot go below the level estimated at the previous resource assessment.

Last updated:
6 December 2018
Thumbnail of the Namoi subregion

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