Case study 3 - Monitoring linked to management - South West Groundwater Areas Allocation Plan

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Background and geographic area

The South West region of Western Australia contains large resources of fresh groundwater that are being tapped for domestic, irrigation, industrial and public water supply.

The regional towns of Busselton, Bunbury, Margaret River and Augusta are major towns in this region that depend on groundwater. The region is underlain by a very complex geological system and is experiencing a shift towards a drying climate.

Objective

To manage the water resource for current and future use while maintaining environmental, cultural and social values, the Department of Water has developed the South West Groundwater Areas Allocation Plan. Objectives in the plan specify the water resource condition and ecological values at key sites that must be maintained to achieve this balance. So that performance against objectives can be assessed over time, measurable performance indicators are set for these objectives and a monitoring program has been implemented.

Application of a risk–based approach to management

The key to the success of the South West region monitoring program was selecting the right measures to allow a streamlined approach, while still collecting sufficient information to trigger timely management.

The South West region environmental monitoring program comprises four components that cover different areas of groundwater management:

  • groundwater levels monitoring
  • groundwater quality monitoring
  • environmental water monitoring
  • connected systems investigations monitoring.

In the environmental water component, the focus is on the relationship between groundwater levels and vegetation condition. The size of the South West region meant that it was not practical to determine a site-specific ecological water requirement for every high-value ecosystem that is potentially groundwater dependent. Instead, representative sites have been selected from a range of ecosystem types and landforms. The premise is that by limiting drawdown and constraining impacts at these most sensitive sites, other groundwater dependent ecosystems within the vicinity should also be protected from drawdown impacts.

Although the groundwater dependent ecosystem information allows an understanding of what is happening at an individual site, the complexities of the underlying geology mean that often this cannot be used to understand what is happening to the overall aquifer or be used to identify changes on an annual basis.

To overcome the problems presented by the vast scale of the aquifer, another system has been developed, which is based on through-flow into and out of the water management units in the region. This model will be updated annually with the latest water use information. The results of this can be used to indicate whether the flow through the system is likely to be altered by the amount of water being abstracted.

Monitoring and reporting

The monitoring program needs to be clearly linked to objectives in the plan, comprehensive enough to detect changes in the resource or impacts on associated values, and where necessary, trigger management actions.

Each year the information gathered through the monitoring program will be collated into a web-based report on the performance of the water allocation plan and how it is tracking against plan objectives. A comprehensive statistical analysis of the measurement data will be undertaken every four years to allow the identification of new issues and to track the effects of climate variation.

More information

More infomation, please visit: National Water Initiative