Hydrologic Modelling Practice Notes

River system models, developed by Basin states, MDBA and Snowy Hydro Limited, have been used to inform development and implementation of key water management policies across the Murray–Darling Basin for over 40 years. There are more than 20 of these models, developed using different methods and software. This makes it difficult to link the models for whole of Basin assessments and requires specific software and model expertise for each valley. To overcome these issues, MDBA and the States, together with CSIRO and many others in the Australian water sector, contributed to the development of a common hydrological modelling platform through the eWater CRC between 2005 and 2012. This platform, called Source, is identified in the Murray-Darling Basin Plan as the standard software to use for models underpinning water resource plans in the Basin.

More recently, MDBA, CSIRO and Basin states have worked together to develop a set of practice notes to facilitate the transparent, consistent, and efficient implementation of the Source modelling platform across the Murray-Darling Basin. The content for these practice notes comes from material provided by MDBA and jurisdictions and has been consolidated by MDBA and CSIRO, with the aid of a jurisdictional advisory group.

Some of the practice notes describe agreed modelling conventions, for example, general principles for naming nodes and links. Others describe recommended practices for methods, for example for flow routing and residual inflow estimation. Where practices differ and where the practice has an effect on model results (e.g. flow routing method), a practice based on scientific research is recommended.

The notes do not aim to be overly prescriptive. They aim to provide high-level principles for modellers to follow when undertaking a particular modelling task. It is anticipated that the practices will be adopted and adapted over time as the benefits of working together using the agreed conventions are realised. The development of the practice notes has provided a successful forum for jurisdictions to work with the MDBA to facilitate consistency and good practice in building models to support water resource planning.

While the notes address river system models developed using the eWater Source modelling platform, they are relevant and applicable to model development and application in other modelling environments.

List of Published Notes

The practice notes approved for publication can be found below, over time this list will be expanded as new notes are developed and agreed to. 

Gather, Clean Up and Storage of Input Data

• Selecting climate data - Recommendations for sourcing and quality assuring climate (rainfall and evaporation) data with examples of different sources and practices used by jurisdictions in the Murray-Darling Basin.
• Selecting flow data - General principles to be followed when assessing the availability and quality of observed flow data. It summaries flow data sources and the quality assurance checks that are used by different jurisdictions in the Murray-Darling Basin.
• Representing and Sourcing Demand Data - General principles and recommended practices for representing key demands in Source river system models; the sourcing, and quality assurance, of the data used to represent these key demands.
• Data Requirements for Modelling Reach Losses - General principles and recommended practices for sourcing of data to model known reach losses in Source river system models with examples of implementation.
• Infilling and Extension of Streamflow Data - General principles to be followed when infilling and extending streamflow data to cover the period of a model run in a Source river system model.

Setting Up and Building a Model

• Naming nodes and links - Recommended conventions for naming of nodes and links in river system models used in the Murray–Darling Basin
• Naming and storing functions and variables - Recommended conventions for naming and storing of functions and variables in river system models used in the Murray–Darling Basin.
• Naming and storing time-series data - Recommended conventions for naming and storing of functions and variables in river system models used in the Murray–Darling Basin
• Model Management - Recommended model management approach for the water resource management models being developed using eWater Source in the Murray Darling Basin
• Modelling Scenarios using Input Sets
• Using Recorder Sets

Model Calibration

• Storage Inflow Derivation - Describes the general principles that you should follow and a high-level method that you may choose to adopt when estimating storage inflows during model calibration.

Reach Flow Calibration

• Reach Conceptualisation - Identification of key fluxes - Describes the general principles that should be followed when conceptualising the reach water balance.
• Modelling a reach water balance - General principles and advice on what components of the water balance should be considered during reach calibration, how to derive acceptable values for modelled reach water balance components (e.g. residual inflows) and links to more detailed general principles and documentation currently used by the MDBA and State/territory jurisdictions
• Estimation and Assessment of Inflows - Describes the general principles and a high-level method that should be adopted when estimating and assessing the magnitude of inflows during the calibration of a reach water balance.
• Routing Calibration - Describes the general principles and a high-level method that should be adopted when undertaking the calibration of routing parameters during reach calibration.
• Estimation of Losses

Calibration of Diversions

Calibration of Irrigation Demands

• Estimation of Unmetered Irrigation Diversions (On- Farm Water Balance) - Describes the general principles and a suggested method for estimating the total unmetered irrigation diversions from floodwaters.
• Calibration of Crop Water Models - Describes the general principles and a high-level method that should be adopted when irrigation demands are to be estimated via crop water models that maintain a soil moisture account.

Calibration of Urban Demands

• Modelling Urban demand - General principles and practices for modelling of urban water demands in Source river system models.