Modelling the Murray-Darling Basin Southern Connected System

: The Southern Connected System (SCS) is located within the Murray–Darling Basin, Australia. It comprises the Snowy Mountains Hydro-electric Scheme, the Murrumbidgee river system, and the Murray– Darling Basin river system. These systems are described by four river system models: the Snowy Hydro Scheme, Upper Murrumbidgee, regulated Murrumbidgee and the Lower-Darling and Murray. However, more broadly many other upstream river system models contribute flow and allocation information. These include the NSW Barwon-Darling model, and Victoria Kiewa, Ovens, and Goulburn-Broken-Campaspe-Coliban-Loddon models. Noting that the Barwon-Darling model receives contributions from 10 upstream river system models, including contributions from 5 Queensland river system models (Figure 1). Previously the SCS models were largely run independently with inputs from upstream models as fixed inputs for a range of development scenarios. However, there are a range of feedbacks between these models that are sufficiently large enough that they need to be considered. The SCS modelling suite considers the connections and feedbacks via an iterative approach. This is the first time that these feedbacks have been considered. This paper describes the physical and management connections between the models that describe the SCS. It details the feedbacks between the models and how this was managed within the modelling framework. It provides insights into the relative importance of the different variables and the importance of considering these within the broader modelling process of downstream systems. The results demonstrate the significance of modelling feedbacks through iterations and the need to be considered in future modelling of the SCS.