Geoff Podger

Drought and Climate Change in the Murray-Darling Basin: A Hydrological Perspective

The Murray-Darling Basin experiences frequent droughts and, at the time of this writing, parts of it are in the grip of the worst drought in the 110 years of comparatively high-quality records. In this chapter, we consider the term drought to be several years with less than median rainfall. The combined impacts of drought and over-allocation of water for irrigation use have led to severe stress on floodplains and wetlands. Climate change projections suggest that the Murray-Darling Basin will be on average drier in the future. The recent drought period has experienced lower autumn and winter rain and higher temperatures than past droughts, resulting in the lowest runoff totals on record in recent years. While these features may be associated with climate change, they may equally be a result of large, long-term climate variability. The recent drought and declining river health have exposed the inadequacy of current water management to cope with the variability of water availability in the Murray-Darling Basin. Future water management strategies should involve consideration of a range of scenarios, including those incorporating climate change.

Trajectory river modelling – a decision-support tool to help manage multiple risks associated with planning around variable water resources

The application of river-system models to inform water-resource planning and management is a growing global phenomenon. This requires models to be applied so that they are useful to water decision makers charged with setting targets that provide adequate water flows to sustain landholders and communities. This article examines why and how the innovative application of river-system models can facilitate interactions between water science and water management in Australia’s Murray–Darling Basin (the Basin). A trajectory river-modelling method was applied to run multiple short historical climate sequences through a river-system model to provide historical probabilities. These can allow better assessment of the risks and impacts associated with stream flow and water availability. This method allows known historical variability to be presented, and produces relevant results for a 10–15-year water-sharing plan lifetime. The benefits were demonstrated in the Basin’s Lachlan Catchment where modelled river-flow results demonstrated the increased variability between shorter 15-year sequences than for a single 114-year run. This approach highlighted the benefits of expressing modelling results as historical probabilities to inform short-term and strategic water-planning efforts.

An integrated modelling framework for building a daily river system model for the Murray–Darling Basin, Australia

ABSTRACT The Murray–Darling Basin (MDB) is home to two million people and accounts for about 60% of the water use in Australia. The MDB river system is a highly complex and mostly regulated system covering four states (Queensland, New South Wales, Victoria and South Australia) and one territory. Different jurisdictions used different models for water resources and planning. A number of difficulties were faced in combining those models (of different characteristics and spatio-temporal resolutions) for basin-wide water resources planning. In order to overcome those difficulties and enhance the consistency and transparency in modelling outcomes across multiple jurisdictions, this paper proposes a homogeneous agent-based integrated modelling framework. Each agent is used to represent a region in the MDB. Its behaviour is modelled by a newly built Source river model. The interactions between agents are modelled based on the hydrological connectivity in the real-world river systems. A three-level parallel computing mechanism is developed to significantly increase its efficiency and reduce computational time. Due to its homogeneousness, it largely reduces the system complexity and makes modelling results consistent, explainable and comparable. By nature, the agent-based system is flexible and portable. All these unique features of the platform suit the modelling needs of various states to federal government water resource management agencies.

Building Expertise in River Basin Modeling—Transfer of Knowledge from Australia to India

Abstract This chapter reports on a project that was established under the decade-long Memorandum of Understanding (MoU) on water resource management (2009–19) between the governments of India and Australia. This MoU supports the application of Australian water resources expertise to assist India in building capacity and managing water at a Basin scale. The project was largely technically based, focusing on the Brahmani-Baitarni River Basin located in the eastern part of India, and used Australian expertise in modeling developed largely in the Murray-Darling Basin. The project had two objectives. The first was building capacity in central and state government engineers in India to use river system models in a basin-planning context, and the second was using the modeling to deliver scenario options for management of water in the basin. This paper focuses on the former objective. The program of capacity-building activities was agreed upon at the outset of the project, which was aimed at three types of participants: trainers (those who could train others, with a focus on river modeling), users (those who could develop the skills to use the river models), and influencers (those who could understand the model outputs and use them in a policy sense). The capacity-building program was implemented over a 3-year period, with a mix of engagement activities. Basin planning forms a key component of Integrated Water Resource Management (IWRM). Both basin planning and IWRM are still emerging concepts, and there have been few applications in India. As with any program of work that is new and that has a substantial breadth, a number of challenges were experienced. These included limited availability of and access to data, advanced river system models requiring a depth of capacity and expertise for use, and a need to ensure that the policy drivers for basin planning in India from the various levels of government were represented within the project context. More broadly, the institutional arrangements for planning and managing in basin scale water resources in India are still evolving, and application and implementation of basin planning is still in its infancy. Nonetheless, the project has succeeded in building capacity in the use of river system models and in the development of river models that have the potential to support a basin-planning approach. The next challenge is to apply these skills within a basin-planning policy context.

A Method for comprehensively Assessing Economic Trade-Offs of New Irrigation Developments

To meet the anticipated increase in global demand for food and fibre products, large areas of land around the world are being cleared and infrastructure constructed to enable irrigation, referred to herein as ‘greenfield irrigation’. One of the challenges in assessing the profitability of a greenfield irrigation development is understanding the impact of variability in climate and water availability and the trade-offs with scheme size, cost and the sensitivity of crop yield to water stress. For example, is it more profitable to irrigate a small area of land most years or a large area once every few years? And, is it more profitable to partially or fully water the crop? This paper presents a new method for efficiently linking a river system model and an agricultural production model to explore the financial trade-offs of different management choices, thereby enabling the optimal scheme area and most appropriate level of farmer risk to be identified. The method is demonstrated for a hypothetical but plausible greenfield irrigation development based around a large dam in the Flinders catchment, northern Australia. It was found that a dam and irrigation development paid for and operated by the same entity is not, under the conditions examined in this analysis, economically sustainable. The method could also be used to explore the impact of different management strategies on the agricultural production and profitability of existing irrigation schemes within a whole of river system context.