Water planning science & monitoring

Risk assessment

A risk assessment is a key step in the development of a water resource plan for each valley and groundwater source in the Murray-Darling Basin. The Basin Plan requires that a water resource plan must be prepared having regard to current or future risks to the condition and continued availability of water resources of a water resource plan area. This risk assessment will form Schedule D of the water resource plan.

The risk assessment framework adopts a cause/threat/impact model that describes the risk pathway of impacts to a receptor. The risk level of an impact is a function of the likelihood of a cause and threat occurring, and the consequence of the impact on the receptor. The risk level is assessed with the current strategies and rules in place, as provided for under the NSW Water Management Act 2000 and the relevant water sharing plan/s. The relevant water management actions and mechanisms in place to address particular risks are listed in each chapter.

The risk level of an impact is a function of the likelihood of a cause and threat occurring, and the consequence of the impact on the receptor. For risk assessments completed in the Murray Darling Basin, the following definitions have been adopted:

  • Likelihood: the probability that a cause will result in a threat. It is not an indication of the size of the threat, but rather conveys the probability that the threat will be significant.
  • Consequence: the loss of value for an impacted receptor.

An example of how the cause/threat/impact model and likelihood/consequence standard have been combined is illustrated below, for risks arising from river regulation and surface water extraction.

Cause, threat and impact model

For many aspects of the risk assessments completed for the Murray Darling Basin, the Likelihood is based on alteration to flow. An outline of the modelling used in the Basin ((PDF 3.2 MB)) is now available. The consequence is based on the value of ecological assets and ecosystem functions. The approach to mapping ecological assets can be found at Applying the HEVAE Framework for Riverine Ecosystems ((PDF 2.5 MB)).

Medium and high risk results that are identified in risk assessments are reviewed to determine whether they are adequately addressed by existing strategies, or whether modifications or new strategies may be required.

Risk-based management assists water managers to prioritise and plan and direct resources to monitor, mitigate or respond to the factors that pose the highest overall risks. It ensures that strategies (both existing and proposed) are targeted at the appropriate part of the water system. In the context of the NSW risk assessment process, a medium or high risk does not automatically imply that existing water sharing plan rules are inadequate or require change, or that new strategies are required. Rather, the risk assessment can be considered a ‘red flag’ process to provide guidance for where more detailed investigation may be required during the life of the Plan.

Across the NSW Murray-Darling Basin there will be 8 surface water risk assessments and 12 groundwater risk assessments prepared.

Monitoring, evaluation and reporting

The NSW Government is committed to the sustainable management of our rivers and groundwater systems through water sharing plans, which define the rules for sharing water between the environment and all other water users. Water sharing plans stipulate how water is shared to meet the needs of water dependent ecosystems, and water users including town and rural water, industry and irrigation.

Water sharing plans contain a set of broad and targeted environmental, economic, social, cultural and Aboriginal cultural objectives. These objectives have been developed according to the Guidelines for setting and evaluating plan objectives for water management ((PDF 904.1 KB)). These Guidelines describe how to ensure that targeted objectives are specific enough so that their achievement can be accurately measured, assessed and attributed to the strategies within the Plan. If an objective has not been met during the term of a Plan, then the Guidelines approach makes it easier to understand why not and if possible, modify the water sharing plan so that it is more effective in the future.

Accurate monitoring is essential to determine how well a water sharing plan is meeting its objectives. Environmental monitoring assesses how water dependent ecosystems are responding to water resource management practices, but also investigates how different patterns of water flow affect the way rivers function. The scope of environmental monitoring includes the river's physical form, its fringing vegetation and of the organisms (e.g. frogs, fish and insects) that live in our rivers. All this information is then used to gauge the health of rivers and floodplain systems, so that we can then assess the effectiveness of management strategies.

Monitoring, evaluation and reporting (MER) Plans are currently being prepared for each valley in NSW, in collaboration with the NSW Office of Environment and Heritage and DPI Fisheries. These plans link directly to the environmental objectives in each water sharing plan and drive the focus for monitoring activities.

As our scientific understanding increases, we will be able to more effectively allocate water to the environment and other water users, better evaluate the performance of water sharing plans, and contribute to evaluating the Basin Plan. Scientific feedback makes efficient sharing of water possible.

Satellite assessments of irrigated areas – Murray Darling Basin

In order to increase transparency in water management under the 2018 NSW Government Water Reform Action Plan, this project provides public access to a series of high quality Landsat image mosaics covering the Murray-Darling Basin during the peak summer irrigation seasons. Landsat mosaics are used by the Department of Industry Water Division to assess change over time in the extent of irrigated areas across regulated, groundwater and unregulated river water sources. This tool enables water stakeholders to 'zoom-in' to any part of the Murray-Darling Basin and compare spatial patterns in irrigated areas with information on volumes of water being used across the Murray-Darling Basin that are available in the NSW Water Accounting reports.

Access the project

Landsat mosaic infrared map