Presentation on theme: "Partnership Acknowledgment"— Presentation transcript:
0 Protecting Investment in Modernised Irrigation Salinity Risk Mitigation in the Shepparton Irrigation RegionTerry Hunter1; John Mansfield1; James Burkitt1; Carl Walters2
1 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.
2 Where is the SIR? You are here Located in Central Northern Victoria Major towns – Echuca and Shepparton.Land area 500,000ha ,000ha irrigatedMajor industries Dairying, Horticulture- Agricultural production at the farm gate valued at $1.2 billion
3 Addressing Salinity Risk in the SIR The Problem & Solutions in the PastWhat’s ChangedNew Understandings – ResearchImplications for irrigation management and what is being done to mitigate riskQuestion you may be asking is how does this presentation fit into the theme of Irrigation Practice.In the SIR Catchment it has been determined that salinity mitigation is pivotal to sustainable irrigation.This presentation is focussed what needs to be done to provide assurance that salinity risk won’t limit irrigation or undermine the substantial investment in the region in irrigation infrastructure.Just a note that there are other presentations at this conference on other works currently been undertaken to facilitate this investmentI’ll touch onThe problem in the past and the original solutionsThe changed driversThe research we’ve undertakenThe finish with a summary of the implications for irrigation management and what is being done to mitigate risk
4 Wet Climate = Extreme & Inevitable Salinity Risk Late 20th CenturyDuring the late 1980’s when the Shepparton Irrigation Region Land & Water Salinity Management Plan was first developed, it was assumed that the wetter climate experienced over the second half of the 20th century in Northern Victoria would continue.Under that premise, the risk of salinity was extreme and inevitable.Wet Climate = Extreme & Inevitable Salinity Risk
5 SIR Land & Water Salinity Management Plan - 1989 Significant investment in Salinity Mitigation.30 Year Plan to Implement Works & MeasuresOn Farm PlanningSurface DrainagePublic Managed Groundwater PumpsPrivately Operated Groundwater PumpsMonitoring ProgramsCommunity InvolvementAs a result significant government investment was made in the form of WholeFarm Planning, surface drainage, groundwater pumping and communityengagement to protect the viability of the region.
6 Economic Impacts by mid 1990’s SIR Salinity HistoryEconomic Impacts by mid 1990’s270,000 ha with watertables less than 2 m below NS65,000 ha protected by groundwater pumpsIn current $ terms with no pumpingProduction losses due to salinisation estimated at ~$100 million/yearRegional losses estimated at ~$400 million/yearWater table less than 2m meant high salinity risks and waterlogging for horticultural cropsSignificant impacts and works.The SIRL&WSMP works & measures adopted (even though somewhatexpensive) were vale for money given the potential regional losses.Approx $400 Million/yr
7 A Changed World 1. Drought & Flood 12 years or so of drought reduced the threat from salinity .Realisation that the wet trend wasn’t going to continue in the same way it had in the past and was predicted.Also floods – which resulted in a significant rebound of the water tables.
8 X axis percentile of 414 monitoring bores exceeding waterlevel Y axis – water level as depth below natural surfaceInsert – is a water table contour map showing the spatial distribution of waterlevels across the region - in the “red” areas waterlevels are less than 1 m
12 2013 – Below average rainfall 43% increase in irrigation deliveries between 2012 and biut no change in watertable - Irrigation on its own doesn’t cause Wt’s to rise – needs rainfalFor 2014 – If have normal autumn spring conditions anticipate jump similarVery slow vertical drainage
13 The interaction between rainfall and waterlevel is demonstrated on this graph – The blue line is water levels in a sample bore from 1095 to 2013 (Depth below natural surfaceThe green line is residual rainfall curve showing the trend in rainfall(doesn’t start at zero as part of a larger dataset)
14 A Changed World 1. Drought and Flood 2. Modernised Irrigation Delivery System & On Farm3. DriversGovernment emphasise on increased food and fibre production4. Risk & CostUnderstandingPerceptions2. Modernised irrigationWater resources became priority – and saw large investment in modernisingirrigation infrastructure. & Water recoveryTwo Major programsa) Connection programInvesting more than $2 billion to develop a modernised water delivery networkFunded by the Victorian Government, Commonwealth Government and Melbourne Waterb) Farm water programFunding for on farm infractrure in exchange for water savings – in total $122 M to be invested for 35 GL of water transferred to the federal government3. DriversTalk to grow more with less water.4. Risk & CostThe perceived risk changed dramatically as many assumed salinity as a risk had gone and therefore no need to invest in any more. No longer funding to implement on ground works. – No Drains or groundwater Pumps.And as the previous graph showed, the return to wetter period saw a significant rebound of the water table and therefore salinity risk but perceptions of many still not chnaged.So – New world/information forces us to reassess to understand what the real risk is.
15 Understanding Future Salinity Risk Salt & Water Balance Project (S&WBP)Understanding of water balance and salt mobilisation implications under variable climatic and water management regimesDevelopment of adaptive management systems and “triggers” for salinity and shallow groundwater resource managementHarmonisation of salinity management and shallow groundwater resource managementProject began in 2009.Is collaborative research projectLed by GMWIn conjunction with GBCMA, DEPI, University of Melbourne and CSIROConducted to understand the drivers of groundwater behaviour. To date over $1.6 million dollars has been invested.Led to development of adaptative management systemIdentified need for harmonisationThere is 1000 privately owned groundwater pumps from which the pumped water is used for irrigation purposes.A number of these have been installed using government incentives to . provide salinity controlHarmonisation is about trying to ensure pumps will be operated when required for salinity management.Landholders may need to be encouraged to operate pumps when water tables are high and there is a high salinity threat as normally surface water is cheap and abundant.
16 S&WBP Outputs Hydrology Salinity Management Framework Confirmation of ongoing risk of high watertablesRecognition that the future risk will vary over time & space – need adaptive management approachRates of watertable rise & fallConfirmation of understanding of salinisation riskLinkage between high watertables & salinisationUse of saline water needs to appropriately managedSalinity risk management approach for privately pumped shallow groundwaterSalinity risk management system to manage shallow watertables & on-farm use of shallow groundwater within a variable climateHydrology - no detailed computer modelling, used the climate data – we’ve had the extremes and so can look at the existing data to understand how the catchment reacts to wetter & dryer periods.Both the Hydrology & Salinity components are complete – about to start on developing the Management Framework.
17 Adaptive Management Approach What we’ve come up with is an adaptive response where we understand the areas within the region where the highest risk remains based on past watertable levels, rate of change and the likely future irrigation footprint.The purple line is the management boundary where the salinity risk is deemed significant and requires a higher level of monitoring. Out side the boundary is lower level of monitoring.The green area is where productive irrigation is occurring and is at the highest risk, so that is where we will prioritise works
18 S&WBP Conclusions:Winter/Spring rainfall on a wet catchment main driver for watertable response – irrigation wets the catchmentHigh watertables (and an associated salinity threat) likely in all situations except severe droughtImproved irrigation management will help but impact is minor compared with irrigation/rainfall interactionThe Land & Water Management Plan is sound, however the hydrological loading is significantly more variable than originally envisaged
19 Implications for Irrigation Management The groundwater from private pumps used for irrigation is generally between 500 and 4000 ECThe use of the groundwater needs to be carefully managed by:Shandying (mixing with high quality water)Paddock rotationMatching irrigation to soil typePotentially remediating land (i.e Gypsum application)Transitioning from Regulatory Non regulatory approach with landholders managing their own riskGroundwater can be up to EC but is not used for irrigation but can be pumped and discharged to drains, channels and evaporation basins.
20 Supporting Irrigators Agency focus on developing digital delivery channels to target irrigation landholdersTargeted information onManaging brackish waterAreas of salinity threat (e.g. risk maps)Groundwater level hydrographsOptions for water table and salinity control