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Hydrological modelling using Source

Hydrological modelling plays an important role in water management. It helps inform policy and decision making for water resource sharing in the River Murray system.

In collaboration with our partners, we have supported the development of Source — Australia's national hydrological modelling platform, developed by eWater between 2005 and 2012.

With the long-term objective of replacing our current hydrological modelling platform (MSM-Bigmod), we're working on a project to integrate the use of Source into our hydrological modelling of the River Murray system.

Background

Under the Water Act 2007 (Cwth), we are required to build an integrated model of the Basin. In consultation with the states, we have achieved this by linking existing state models to the Integrated river system modelling framework.

The Basin Plan Implementation Agreement identifies the Source model as the standard for water resource plan accreditation. As a result, we're working together with the Basin states to replace their existing models with the Source platform.

Whilst Source is the preferred modelling platform it is recognised that not all existing state models will be converted to Source given the timelines for water resource plan accreditation.

The Integrated river system modelling framework will be progressively updated by replacing existing state models with Source models as they are completed.

Project objectives

The key project objectives are to build, calibrate and validate a daily time step model of the River Murray system in line with our river management responsibilities.

The unique interstate water sharing arrangements between New South Wales, Victoria and South Australia complicates implementing a hydrological model of the river system. This is further complicated by individual water sharing plans developed in each state to manage their share of the river system's water resources.

In addition, the model's functionality must meet accountability and audit requirements in managing salinity, environmental and river system health issues. It must also meet the individual and collective requirements of state and federal governments to be considered ‘fit for purpose'.

MDBA Project Plan and schedule for implementation of the Source model
MDBA Project Plan and schedule for implementation of the Source model

Project benefits

The key benefits of implementing the Source model include:

  • representing management and operational rules at a daily time step, including environmental flow processes
  • consideration of social and economic impacts of water trade and changes in water availability
  • better integration with Basin state models to enable more accurate modelling of interconnected systems, including water trade and delivery
  • greater transparency and efficiency, and better delivery and understanding by sharing a common modelling platform across the Basin
  • better model outcomes through a more visual and transparent modelling framework
  • application of contemporary software technology that meets current and future modelling needs and replaces existing legacy software.

What we have achieved

As at July 2015 we have built a Source model of the River Murray system using a daily timestamp. Configured for a baseline diversion limits scenario, the model runs for a 114 year period and represents the lowest limit for modelling the implementation of the Basin Plan.

This is a major achievement, given the inherent complex nature of the water sharing rules defined under the Murray–Darling Basin agreement and the delivery of water to the River Murray System.

We are currently refining the behavior of the model, with the aim of having it independently reviewed in 2016. The independent review process will inform the accreditation of the model, which needs to occur prior to its adoption for use in supporting water resource planning.

What we are working on now

We are focused on getting the Source model ready to support water resource planning for the River Murray system. The complexity of the baseline diversion limit model means a significant amount of analysis and testing must be carried out to ensure its performance is fit for purpose for the MDBA and our stakeholders.

We also plan to configure the model for another two scenarios:

  • without development — representation of the River Murray system without any regulation or extractive water consumption
  • current conditions — representation of the River Murray system with current policy and levels of development.

In 2015–16, we'll test and analyse the suitability of the model using project scenarios that represent key aspects of our modelling work, such as the Basin salinity management strategy scenarios used to maintain salinity registers. We'll continue working with our stakeholders to integrate the use of the Source model in their projects, and seek their review and feedback.

Collaborative development

In partnership with the Basin states and the CSIRO, we are developing a series of practice notes to detail the different methodologies and approaches to modelling water resources in the Basin.

The practice notes are expected to influence the building of Source models across the Basin, and highlight the different methods used between jurisdictions to build water resource models. Through this initiative, we're aiming to improve Basin-wide modelling practice as information and practices are shared.