SIR Salt and Water Balance Project

Protecting Investment in

Modernised Irrigation

Salinity Risk Mitigation in the Shepparton Irrigation RegionTerry Hunter1; John Mansfield1; James Burkitt1; Carl

Walters2

SIR Salt and Water Balance Project

Partnership Acknowledgment

This project is funded as part of the Goulburn Broken Catchment Management Authority Regional Catchment Strategy in the Shepparton

Irrigation Region and is provided with support and funding from the Australian Government and Victorian Government. This project is

delivered primarily through partnerships between the Department of Environment and Primary Industries, Goulburn-Murray Water, the

Goulburn Broken Catchment Management Authority and other bodies.

SIR Salt and Water Balance Project

Where is the SIR?

You are

here

SIR Salt and Water Balance Project

Addressing Salinity Risk in the SIR– The Problem & Solutions in the Past– What’s Changed– New Understandings – Research– Implications for irrigation management and

what is being done to mitigate risk

SIR Salt and Water Balance Project

Late 20th Century

Wet Climate = Extreme & Inevitable Salinity Risk

SIR Salt and Water Balance Project

SIR Land & Water Salinity Management Plan - 1989

Significant investment in Salinity Mitigation. 30 Year Plan to Implement Works & Measures

•On Farm Planning•Surface Drainage•Public Managed Groundwater Pumps•Privately Operated Groundwater Pumps•Monitoring Programs•Community Involvement

SIR Salt and Water Balance Project

SIR Salinity HistorySIR Salinity HistoryEconomic Impacts by mid 1990’s

• 270,000 ha with watertables less than 2 m below NS

• 65,000 ha protected by groundwater pumps

• In current $ terms with no pumping

– Production losses due to salinisation estimated at ~$100 million/year

– Regional losses estimated at ~$400 million/year

SIR Salt and Water Balance Project

A Changed World1. Drought & Flood

SIR Salt and Water Balance Project

SIR Salt and Water Balance Project

SIR Salt and Water Balance Project

SIR Salt and Water Balance Project

SIR Salt and Water Balance Project

SIR Salt and Water Balance Project

SIR Salt and Water Balance Project

A Changed World1. Drought and Flood

2. Modernised Irrigation • Delivery System & On Farm

3. Drivers• Government emphasise on increased food and fibre production

4. Risk & Cost• Understanding

• Perceptions

SIR Salt and Water Balance Project

Understanding Future Salinity Risk

Salt & Water Balance Project (S&WBP)

• Understanding of water balance and salt mobilisation implications under variable climatic and water management regimes

• Development of adaptive management systems and “triggers” for salinity and shallow groundwater resource management

• Harmonisation of salinity management and shallow groundwater resource management

SIR Salt and Water Balance Project

• Hydrology

• Salinity

• Management Framework

Confirmation of ongoing risk of high watertables Recognition that the future risk will vary over time &

space – need adaptive management approach Rates of watertable rise & fall

Confirmation of understanding of salinisation risk Linkage between high watertables & salinisation Use of saline water needs to appropriately managed

Salinity risk management approach for privately pumped shallow groundwater

Salinity risk management system to manage shallow watertables & on-farm use of shallow groundwater within a variable climate

S&WBP Outputs

SIR Salt and Water Balance Project

Adaptive Management Approach

SIR Salt and Water Balance Project

S&WBP Conclusions:

• Winter/Spring rainfall on a wet catchment main driver for watertable response – irrigation wets the catchment

• High watertables (and an associated salinity threat) likely in all situations except severe drought

• Improved irrigation management will help but impact is minor compared with irrigation/rainfall interaction

• The Land & Water Management Plan is sound, however the hydrological loading is significantly more variable than originally envisaged

SIR Salt and Water Balance Project

Implications for Irrigation Management

• The groundwater from private pumps used for irrigation is generally between 500 and 4000 EC

• The use of the groundwater needs to be carefully managed by:

– Shandying (mixing with high quality water)

– Paddock rotation

– Matching irrigation to soil type

– Potentially remediating land (i.e Gypsum application)

• Transitioning from Regulatory Non regulatory approach with landholders managing their own risk

SIR Salt and Water Balance Project

Supporting Irrigators• Agency focus on developing digital delivery channels to

target irrigation landholders

• Targeted information on

– Managing brackish water

– Areas of salinity threat (e.g. risk maps)

– Groundwater level hydrographs

– Options for water table and salinity control

SIR Salt and Water Balance Project

Questions?