Managing adverse water resource impacts from land use change

This action is to improve understanding about the impact of land use changes on water use and the capability to estimate and report on these interactions. New technologies (such as satellite imagery and remote-sensing) are improving our understanding of how changes in land use affect water resources, and the importance of this understanding is increasingly recognised. In 2011–12, the National Water Commission funded the (then) Department of Sustainability and Environment (DSE) to prepare the groundwork to regularly estimate and report on water use by land use.

This work included estimates of evapotranspiration, which is a key water use in vegetated landscapes. DSE contracted consultants to provide the tools and guidance to make evapotranspiration estimates, and they are now made annually using Victorian Land Use Information System land use data. However, water use estimates are only reported at a whole-of-basin scale, and they are not broken down by land use category or land use change.

While land use and vegetation cover will influence evapotranspiration, climatic conditions have a larger impact on changes in evapotranspiration.

Given this, the estimates of evapotranspiration in the Victorian Water Accounts will continue to use climatic information as the basis for annual reporting of evapotranspiration.

Since 2011, drivers for land use change across Victoria, particularly relating to the development of plantation forestry, have changed. Plantation areas across Victoria have been generally steady for the past decade.

Changes in land use will be tracked using available information, such as the 5-yearly State of the Forests report, which reports the area of plantation forest across the State.

Estimates of evapotranspiration will incorporate land use changes on a 10-yearly basis. This timing aligns with the commitment to review the net take from plantation forestry in Victoria’s WRPs under the Basin Plan. More frequent updates may be undertaken if significant land use changes are identified in the intervening period.

DEECA to estimate evapotranspiration in the Victorian Water Accounts based on annual climatic conditions. Land use changes will be incorporated periodically, to align with other reporting obligations, such as the 10-year review of the Basin Plan.

Action status (5-yearly assessment): Partly or not yet achieved

Delivery period: NA

This Action contributed to the methods for estimating whole-of-catchment water use through a review of the models for estimating evapotranspiration. New methods for estimating evapotranspiration were emerging around the time the WRSWS was developed. In 2012, the National Water Commission completed its Accounting for all significant water uses project.

The project compared and evaluated methods for estimating evapotranspiration.

Findings from the project were used as part of the framework for improving estimates of evapotranspiration (see comments for action 5.1).

Action status (5-yearly assessment): Achieved and completed

Delivery period: March 2012

This action focused on amending the Water Act 1989 to enable the Minister for Water to declare and manage an area according to the process explained in the WRSWS. To better manage the impact of land use change on water resources, the WRSWS proposed a process to declare intensive management areas, based on the intensity of water stress, the significance of water-dependent values and the potential for land use changes to affect these values. Intensive management areas would have specific rules and management actions to ensure the integrity of high-value water systems are maintained. Amendments to the Act to declare intensive management areas were proposed in the Water Bill 2014, but the Bill did not proceed through parliament.

Drivers for large-scale forestry have changed since 2011. In the 10 years prior to the development of the SWS, the area of commercial hardwood plantations in Victoria doubled. Since then, the Victorian ‘State of the forests’ 5 yearly report (2018) confirms that plantation areas have gradually decreased. No new plantation areas have been established since the 2012-13 financial year.

WfV recognises that large-scale changes in land use could affect water availability by intercepting water that would otherwise reach streams and aquifers. This can affect the water resource, entitlement holders and the environment. It changed the focus the SWS proposed and focused on better recording and reporting of emerging significant uses of water. For commercial plantation forestry, this reflected the reduced development compared to that expected when the Strategy was developed.

However, there is a recent interest in expanding plantation forestry for production purposes and for offsetting greenhouse gas emissions. The Victorian Government pledged $110 million in the 2017-18 budget to assist with plantation development in the Latrobe Valley, with the first areas to be planted in 2019. In 2018, the Australian Government announced funding of $20 million between 2018 and 2022, to underpin growth in Australia’s renewable timber and wood-fibre industry. South West Victoria was chosen as one of the four pilot Regional Forestry Hubs. The Commonwealth also offers financial support for a number of activities that seek to reduce greenhouse gas emissions through the Climate Solutions Fund. Some commercial plantations, revegetation and farm forestry activities may be eligible.

The Progress report highlighted the importance to have a process in place to manage adverse water resources impacts from land use change.

DELWP will revisit the state-wide approach to manage the impact of plantations on water availability, update the information and incorporate changes in circumstances since the Strategy was released, such as the shift in drivers influencing land use change, as well as other relevant plans and policies.

Action status (5-yearly assessment): Partially or not yet achieved

Delivery period: NA

Action linked to WfV 8.4 Better record and report on emerging significant uses of water. This action was to gain an improved understanding about the impact of land use changes on water quantity and quality, to make more informed decisions about water use.

The WRSWS recognised that land use changes from forestry and changing agricultural practices could make less water available and reduce water quality. Amendments to the Act to declare intensive management areas (explained above in action 5.3) did not occur, so this action has not progressed as planned.

Action 8.4 of WfV maintains the emphasis on considering land use impacts on water availability by better recording and reporting on significant uses of water in the Victorian Water Accounts.

Action status (5-yearly assessment): Being progressed through Water for Victoria or the Murray-Darling Basin Plan

Delivery period: NA

This ongoing action ensures alignment between the Victorian policy approach to managing the water impacts of land use changes and Murray-Darling Basin Plan requirements. As the comment on action 5.5 explains, the WRSWS requires the cumulative impacts of land use changes on water resources to be considered in water use decisions.

The basin plan also requires these impacts to be considered through the Basin Plan’s water resource plans, and they have been incorporated into the Wimmera-Mallee Water Resource Plan. Amendments to the Act to implement this WRSWS action were proposed in the Water Bill 2014, but the Bill did not proceed through parliament. Subsequently, the approach in the basin plan was incorporated into the Wimmera-Mallee Water Resource Plan through the Wimmera-Mallee risk assessment.

Action status (5-yearly assessment): Achieved and ongoing

Delivery period: Ongoing