Hydrological modelling has long played an important role for informing and guiding Victorian water policy and water resource planning and management decision-making.

The Council of Australian Governments (COAG) has agreed  to the development of a National Hydrological Modelling Strategy to ensure future water planning and management across Australia is informed by best practice modelling.  eWAter SOURCE is the key deliverable of the strategy.

An integrated river basin water resources modelling platform known as SOURCE is being developed as part of this initiative. The platform is being developed and managed by eWater Limited, a joint government-owned, not-for-profit partnership, of which the State of Victoria is a company member.

Lake Eildon release is diverted for irrigation and environmental purposes and supplies around 60% of water used in the Goulburn-Murray Irrigation District. Photo sourced from G-MW webpage

Photo sourced from G-MW webpage

SOURCE is designed to simulate all aspects of water resource systems to support integrated planning, operations and governance from urban, catchment to river basin scales including human and ecological influences. Its purpose is to provide a common and consistent hydrological modelling platform initially across the Murray Darling Basin and Australia wide over long term.

DELWP is undertaking a project to implement SOURCE RIVERS in the development of a daily time-step hydrological model of the integrated Goulburn, Broken, Campaspe and Loddon (GBCL) water supply system (Victorian trial catchment). The project’s long-term objective is to progressively replace the current Victorian hydrological modelling platform, REALM (Resource Allocation Model). DELWP is closely working with eWater and other state agencies, including Victorian water corporations and the Murray-Darling Basin Authority (MDBA), to ensure that SOURCE RIVERS can be adequately applied across Victorian systems. Once the integrated GBCL SOURCE model is satisfactorily completed, DELWP will work towards migrating the remaining Victorian models to the SOURCE platform.

The key objectives of the project are to build, calibrate and validate a daily time-step model of the integrated GBCL water supply system using SOURCE RIVERS. This will be a complicated and challenging task given the complexity of multiple sources of supply under various operating and management rules, annual accounting resource assessments and carryover rules. The model needs to address complex environmental requirements, water use and salinity simulation in these valleys to ensure that SOURCE RIVERS meets all Victorian current and future water industry standards and needs. The adoption of the model will be subject to its 'fit for purpose' assessment.

The primary benefits expected from the SOURCE modelling platform are:

  • Opportunity to develop better hydrological models with more up-to-date data to represent management and operational rules at a daily time-step, including the environmental water delivery and flow processes;
  • Better visual and more transparent modelling framework based on modern and advanced software technology that will meet current and future modelling needs;
  • More consistent, transparent and defensible modelling framework as a result of enhancements to the SOURCE software;
  • Ability to better represent the Victorian water entitlement framework, including changes or creation of new entitlements, and the development and implementation of new policy;
  • The success of this project will be an opportunity to replace the existing Victorian REALM modelling platform with a  latest improved common modelling platform; and
  • Strengthen water resource modelling to better understand water availability, use and climate change.

Significant progress has been made on the project. These are:

  • Preliminary flow routing and loss parameter calibration including preliminary incorporation of operational and water management rules in individual valley models;
  • Development of daily inputs derivation methods and derivation of daily inputs for more than 120 years from 1891 to 2014, which is critical for transitioning from the existing monthly simulation time-step to daily time-step simulation;
  • DELWP has worked closely with the eWater SOURCE project team for 18 months to assist with the development of annual accounting and resource assessment functionality in SOURCE RIVERS, including in-house testing of the software. This will facilitate the implementation of the complex Victorian annual accounting resource assessment into the integrated GBCL model;
  • DELWP is also investigating irrigator, wetland, environmental demand, salinity  and ownership functionality in SOURCE RIVERS; and
  • Combined separate valley models into a single GBCL model and commenced the next phase of project with works on different aspects, namely flow and loss calibration, and water management  rules using the combined GBCL model.

The proposed timeline for implementation of SOURCE RIVERS in the integrated GBCL catchment consists of three stages:

  1. Building separate SOURCE models for each valley with preliminary flow and loss calibration along main river reaches and preliminary incorporation of operational and water management rules, and these have been completed;
  2. To combine all valley models into a single GBCL model with updated daily input data, refine the flow and loss calibration using the combined GBCL model and incorporate water management (operational, water accounting and water sharing) rules for each valley in the combined model. It is planned to get a version of the GBCL model with these features ready by June 2017; and
  3. The project will include calibration and validation of water management rules using the combined GBCL model. It is aimed to be completed by 2018. This stage will also include works on better representation of consumptive use such as development of irrigator demand models for Goulburn-Murray Irrigation District, improvement of environmental use representation such as exploring wetland and environmental demand functionality with case studies from the GBCL system and exploring salinity modelling capability in SOURCE.