The Water Resources Institute has categorised India as being the 13th most water stressed country in the world. Agriculture is India’s largest consumer of fresh water, accounting for 80% of all fresh water resources. 
The State of Karnataka is one of the fastest growing economies in India and is heavily dependent on agriculture. Agriculture consumes an estimated 85% of the state’s available fresh water.
Increases in population growth, coupled with increasing water requirements across the agricultural, urban and industrial sectors have placed significant stress on the state’s river basins, resulting in a water supply-demand deficit. Due to these factors, an urgent need has been identified for coordinated action across Karnataka to better manage fresh water resources.
Solution details:
Karnataka’s Krishna Bhagya Jala Nigam Ltd. (KBJNL) is utilising Rubicon Water’s gravity-fed irrigation technology to modernise and rehabilitate their manually operated NLBC network to improve the efficiency, productivity and sustainability of the district’s water resources.  
In 2019, Rubicon Water won the tender to deliver innovative gravity-fed automation technology to improve the efficiency and productivity of the Narayanpur Left Bank Canal (NLBC) system in the Indian state of Karnataka.
The project scope includes the installation of more than 4,000 automated Rubicon control and regulating gates, along with sophisticated software and communications infrastructure that will precisely manage the delivery of water to farmers located along approximately 1,500km of canals. In addition, 60 microclimate weather stations and soil moisture probes will be strategically installed to assist farmers in making informed irrigation scheduling decisions. 
KBJNL operators have the ability to leverage the power of the solution’s irrigation management software to plan, manage and deliver water more efficiently while providing an equitable service to farmers, 24/7. 
The irrigation management software has the capability to precisely manage the demand of water within the system and coordinate the automated gates to adjust in real-time to precisely deliver the desired flow and volume to farmers located throughout the network.
To support the large project scope and align with the country’s ‘Made In India’ campaign, a purpose-built manufacturing facility was constructed in Hyderabad to produce the canal automation technology. The construction of the facility commenced in May 2019, with production of Rubicon’s precision PikoMeter flow measurement and control devices starting in 2020. To date, the facility has successfully manufactured more than 2,800 PikoMeters.
The original project completion was set for 2021. However, COVID-19 complications delayed the delivery of the project which is now scheduled for completion this year. 
The project is expected to improve water efficiency within the NLBC network by up to 20%, while delivering an equitable service to farmers and supplying water at consistent flow rates enabling farmers to increase their on-farm crop production and economic productivity. 
Automation of the NLBC system has already demonstrated benefits by improving tail end serviceability. For example, farmers located on the end of the network reported received water for the first time in decades. Farmers are praising the modernisation project, with one stating that “earlier [prior to modernisation], we never used to get [irrigation] water, but this year we got water.”
Farmers are also reporting significant improvements in crop yield in comparison to previous years. The table below highlights the yield improvements that farmers are already achieving from the early stages of modernisation. As automation throughout the network continues, it is expected that these yield improvements will continue to increase.
Upon completion, Rubicon’s canal automation technology will be servicing over 90% or 4.08 lakh hectares (408,000 hectares) of the NLBC command area.
Key Project Facts & Objectives:

• Largest automation project of its kind across the world
• Equitable service and on-farm efficiency improvements to support farmers in achieving higher yields and diversification into higher-value crops
• Modernisation is improving Seasonal Relative Water Deficit (RWD).
• Modernisation has the potential to significantly recover unserviced land and avoid over-watering of existing areas
• 80% of automated gates are built in India with the supply chain fully sourced from India
• In line with the National Water Missions goals, the modernisation project will improve water use efficiency by 20%, 

This innovation is software 'VARIwise' that combines sensing, modelling, optimisation and actuation to determine site-specific irrigation requirements to maximise yield and crop productivity for broad-acre crops. The innovation focuses on identifying irrigation timing and spatially variable depths across fields to best achieve maximum forecasted yield using models. This contrasts with existing commercial automated site-specific irrigation control strategies that are either time-based or are based on variability maps that may not necessarily relate to actual irrigation requirements. In addition, typical strategies developed in other research apply irrigation when the plant has reached a specific stress point if using canopy temperature sensors or soil-water deficit if using soil moisture sensors. These systems do not consider water availability and target seasonal performance objectives (e.g., maximise yield or water productivity). Therefore, they cannot adapt to different weather conditions or limited water situations. In particular, some crops (e.g., cotton) require stress in early growth stages to produce maximum yield, and simply managing irrigation according to soil moisture deficit does not target optimal yield.

VARIwise has been evaluated on cotton and dairy pasture crops to determine site-specific irrigation requirements with surface and centre pivot irrigation. The system developed involves a novel combination of the following components:

- Industry-standard crop biophysical models that are automatically parameterised from online and infield data sources of weather, soil properties, and irrigation management information

- Machine vision cameras to automatically detect growth rates from infield cameras and parameterise the crop biophysical model

- Optimisation algorithms that iteratively run the parameterised crop model to identify which irrigation day/volume will optimise yield and water productivity

VARIwise produces the best irrigation day in the next three days (if any) and the required irrigation depths. For centre pivot and lateral move irrigation machines with variable-rate irrigation capability, VARIwise automatically generates prescription maps in formats compatible with commercially available panels. The maps can then be approved by the grower, uploaded, and enabled.

Water Saving through the Innovation

This innovation improves water productivity by applying irrigation where it is needed, at the right time, specific to the crop's water requirements. For example, Water is saved by the model on cotton crops by recognising the impact of Water on potential yield at all growth stages. This has led to strategies that reduce irrigation depth and apply stress to the plant earlier in the season to encourage root development and flower production, and later in the season, full irrigation occurs to maximise yield. Implementation of this system has led to yield improvements of 4 to 11% and water savings of 12 to 22% for cotton. Water is saved by the model on dairy pasture when updated with the daily growth status from the machine vision system. For dairy pastures, infield cameras and machine vision algorithms have been developed to sense grazing status from pasture growth rates automatically. By updating the grazing status within the crop biophysical model, the resultant strategies reduce irrigation depths immediately after grazing and increase irrigation depth as pasture growth progresses. In contrast, grazing information is typically manually recorded and is not sensed as part of existing soil moisture or satellite monitoring systems. Trials on dairy pasture are currently being conducted to compare the performance of soil moisture sensor-based irrigation against optimisation strategies from VARIwise.

The performance of VARIwise irrigation strategies relies on the ability to predict yield accurately. Trials have been conducted to evaluate the yield prediction performance across 17 cotton sites with varying levels of fruit removal, hail damage, and heat stress. The overall yield prediction accuracies were: 81.2 to 89.8% at a date three months before the harvest; 91.1to 95.1% two months before the harvest; and 90.5 to 97.5% one month before harvest.

Implementation of the Innovation

VARIwise will be introduced to the industry through commercialisation opportunities with manufacturers of irrigation hardware or precision agriculture software. This will involve selecting commercial partners and sharing the intellectual property for implementation. Planning for commercialisation has commenced with the project's funders. An expression of interest process for commercial partners was released in 2020, and the applicant is currently providing support for commercialisation with the respondent. The software would initially be used for centre pivot and lateral move irrigation in the cotton and/or dairy industries. In the Australian cotton industry, there is 61,030 ha of land irrigated by centre pivot or lateral move irrigation machines, and around 287,2000 ha of land developed for surface irrigation, irrigated by about 1,000 irrigation systems that could each utilise one of these units. Australian cotton has an annual export value in New South Wales and Queensland of $1.3 billion and $670 million. These two industries will be targeted initially, as they have provided funding for this innovative development and field evaluation (Cotton Research and Development Corporation and Australian Government Department of Agriculture, Water and Environment as part of its Rural R&D for Profit program).

It is expected that the commercial partner would make the VARIwise system available as an add-on to existing variable-rate irrigation hardware. The integration of VARIwise prescription map development capability within the commercial partner existing systems may be phased, with implementation through the following steps: (a) generate VRI map compatible with commercial variable-rate irrigation systems; (b) supply data from on-site weather stations in a required format for VARIwise runs; (c) import variability maps from satellite, soil, or elevation maps; (d) read in data from cameras/grazing sensors; and, (€) purchase a commercial license for the crop biophysical model to link available data to the generation of prescription maps.

Scope for Further Expansion of the Innovation

There is potential for the VARIwise technology to be expanded across a range of crops and irrigation systems. The software could be transferred to any crop where the biophysical soil- plant-atmosphere relationships are available in a model that can be parameterised and can predict yield. Potential crops for technology transfer include vegetables and fruit, contributing $2.9 billion and $2.3 billion to the Australian economy, respectively. There is also potential for the control system to be implemented in the grains industry, particularly in the USA, where the irrigable area is 22 million ha. Over half of this area is irrigated with centre pivots and lateral moves that could each utilise one of these systems. In particular, the USA is the world's largest corn producer, with an annual irrigated crop value of $13 billion and irrigated corn area of ~5,500,000 ha.

The software could also be expanded to plan irrigation between multiple fields. For example, this would involve focussing available irrigation to fields with higher yield potential and then separately implementing optimisation within these fields. There is also potential for sub-components of this innovation to be adopted separately. This will enable phased adoption of irrigation automation technologies. These individual sub-components include the yield prediction software, the machine vision system to detect and record grazing events for pasture automatically, and the automated prescription map development process.

Trangie-Nevertire Co-operative Ltd (TNCL), a member-owned irrigation scheme, pumps water out of the Macquarie River in the central west of New South Wales-Australia (NSW) that had reached its use-by-date in the middle of the Millennium Drought. The combined impact of high conveyance losses, a series of low or zero water allocation years, the threat of losing water, and the possibility of government’s buying back the saved water from the members and ever-increasing costs, led to the general realization that it is high time to modernize the water use system.

To apply for the government funding, a strategic plan from a cooperative membership base, which quantified the issues, was developed for a modernization feasibility study, comprising of the following 5 major elements:

• Reducing the earthen channel system from 240 km to 138 km and retiring 17 members permanently from the irrigation scheme to improve sustainability.
• Rebuilding the remaining 138 km of channel system, lining 108 km with Firestone EPDM rubber membrane, and installing a complete Rubicon water gate system, all enclosed within electric animal exclusion fencing.
• Installing a 230 km pipeline from the river to all continuing and retiring farms to replace the previous reliance on the channel system.
• Modernizing the remaining members’ on-farm irrigation infrastructure, with 24 linear move or centre pivot irrigators installed, as well as upgraded field layouts, tailwater return systems, and storages.
• Decommissioning the irrigation infrastructure on retiring farms and reconfiguring them back to a dryland basis, including piped stock and domestic water reticulation.

The water savings in the modernization project came from 4 main areas:

• The lining of 138 km of the rebuilt main channel with EPDM rubber led to a massive reduction in seepage losses. The selection of Firestone Geo Gard EPDM for the channel liner was a major leap of faith as the product had never been used on such a large scale in irrigation channels worldwide. The inclusion of the automated Rubicon Total Channel Control system substantially increased the water delivery service level to the members, allowing on-time and accurate on-farm water supply and measurement.
• The combination of the technologies reduced the channel conveyance losses from a historical average of 25% (ranging between 20% to 50%) to 7%. A substantial volume of rainfall was captured and stored in the lined channel sections, often providing the initial pool fills before the pumping season. This led to the farming members having more water available at the farm gate as compared to the pre-project stage.
• The Stock and Domestic pipeline system exceeded all expectations, with over 90% water savings, and available clean pressurized river water around the year as compared to linked irrigation supplies. In years of low or no irrigation allocation, such deliveries were either unavailable or with very high wet-up losses, which meant thousands of ML needed to be pumped to deliver only a couple of hundred ML into open dams. This also resulted in a huge improvement in livestock health and human amenity, especially during droughts.
• The on-farm infrastructure up-gradation led to water savings and increased yield for summer and winter crops. Most of these projects were based on replacing traditional furrow surface irrigation with overhead sprinkler centre pivot and linear move irrigators. Water use on the predominant cotton crop with these machines reduced by around 1 ML/ha while crop yields rose by 0.45 ton/ha, leading to a 30% increase in water use efficiency. Rotational winter crops have also shown improvements, especially in chickpeas where surface flood irrigation would often damage the crop from phytophra root disease but the sprinkler irrigation allowed controlled application rates, prevented waterlogging, and enabled higher yields.

As a result of this project, channel conveyance losses have been reduced and on-farm productivity improved from greater water availability and promoted the installation of “state of the art” farm irrigation systems. Previous off-farm and on-farm irrigation losses are now being used for environmental benefit.

Given the system’s success, Narromine Irrigation Board of Management applied EPDM to a substantial length of their channel system using the TNCL developed laying system as part of their modernization plan. There is substantial scope for this channel lining system to be adopted across Australia and worldwide wherever seepage losses in open channels are a significant problem.

A proper irrigation scheduling method adjusted to the actual crop water requirements is crucial to use available water resources better. Following this approach, an app called IrriSAT was developed in Australia to manage daily crop water use based on weather data.

IrriSAT is weather-based irrigation management and benchmarking technology app that uses remote sensing to provide site-specific crop water management information across large spatial scales at acceptable resolution. It calculates crop coefficients (KC) from relationships with freely available satellite-derived Normalized Difference Vegetation Index (NDVI) data. Daily crop water use (ETc) is determined by multiplying KC and daily reference evapotranspiration (ETo) observations from nearby weather stations or nationally provided gridded ETo data.

IrriSAT is moving weather-based scheduling into the future. It automates satellite processing from both the Landsat NASA satellite platforms and the Sentinel ESA satellite platforms. Developed using the Google Earth Engine, it deliveries crop water use information to assist in irrigation scheduling and crop productivity benchmarking. It provides daily crop water use as well as a 7-day crop water use forecast. The app provides users with an estimate of crop water information that can be used for assisting with irrigation scheduling, ordering water, and also benchmarking the performance of crops within and between fields and regions. Daily, it shows historical and current crop water use for a selected field or region as well as cumulative crop water from the planting date.

Users can also enter applied irrigations, and the tool undertakes a water balance for the selected field or region, showing irrigation deficit information. IrriSAT also undertakes a 7-day crop water use forecast and provides an estimate of the following irrigation period based on the user-selected irrigation deficit.

IrriSAT was introduced to irrigators through a range of mediums, including direct meetings and presentations to irrigators and irrigation consultants at farmer field events throughout the Australian cotton and grain growing areas. The users reported water savings from using the tool in many ways, some of which are listed below:

• Modifying irrigation timing to better match crop water demands
• Better prediction  of extreme climate events (like high ET_C days) and modifying irrigation schedules/deficits to minimize impacts on crops
• Identifying poorer performing areas within irrigated crops and changing management, for instance using laser levelling
• Benchmarking performance of irrigated fields across farms and regions and using limited water resources on better performing fields

Currently, the app has full functionality across the entire Australian Continent and the USA. It allows users in these areas to get site-specific crop water use information historically. The app is useful across the globe to get seven-day crop water use forecasts. However, this scientific innovation needs the experience of irrigation scheduling and also access to and availability of gridded ET0 data.

In 2009, the Goulburn Broken Catchment Management Authority (GB CMA) and other Victorian and regional groups formed a consortium to develop the Farm Water Program (FWP). Developed under FWP, the water-saving calculator built on 20 years of agricultural data (Goulburn Murray Irrigation District (GMID), is an innovative way of determining water savings in real-time. 

The water-savings calculator was first used in 2010 to determine water-savings for the first few FWP projects. This followed further improvements and some work with FWP consortium partners to ensure that the calculations were correct and accepted. Several irrigators and irrigation specialists reviewed some examples of water-savings calculations and provided feedback on their accuracy and use.

Essentially the water-savings calculator gives an irrigator the confidence to adopt a new more water-efficient irrigation technology by estimating the expected annual water-savings if that irrigation technology were to be adopted on a predetermined area of land. It does this by taking into account both the existing and future irrigation methods, the soil type, and the crop type. Eligible irrigators work with FWP staff to develop a project using a previously prepared property farm plan which provides details of the proposed changes to the farm irrigation system. Using the whole farm plan, irrigators are then able to nominate all or parts of their property to be improved through an FWP project with a detailed change plan. The upgrades to the public delivery system included the renovation of sections of channels to minimise leakage and seepage with the use of clay or plastic lining together with the installation of remote-controlled, automated channel regulators and delivery gates to properties. Some sections of channels were replaced with pipelines while others were removed where no longer required. These changes resulted in a higher level of delivery service for irrigation farmers with more consistent and larger flows of water available which allowed for higher speed irrigations and improved water use efficiency. Irrigators were able to utilize the internet to plan and order the delivery of water onto their properties to suit their needs

FWP projects contain technologies and work for three types of irrigation systems:

Surface irrigation with activities including:

• Laser grading of irrigation bays to achieve a consistent grade down the bay to minimize waterlogging.
• Drainage reuse systems for collecting irrigation and rainfall-runoff and store it in a constructed sump and pump the water for irrigation.
• Improved gravity earthen channels and pumped pipe and riser systems that can accurately control the flow of water.

Micro and drip irrigation including:

• Installation and upgrades of pumps, piping, and sprays, and drippers.

Overhead sprinkler irrigation including:

Installation and upgrades of centre pivot, lateral move, and fixed sprinkler systems.

Water-savings Calculator: The water-savings calculator uses three crop types comprising

• Annual crops and pastures (ET_O = 3 ML/ha/year)
• Summer crops and horticulture (ET_O = 6 ML/ha/year)
• Perennial pastures, citrus, and almonds (ET_O = 8 ML/ha/year)

To calculate the amount of water saved, three groupings of soil types were used with the lightest textured soils, the sands, and sandy loams grouped as Light Soils, the loam soil types were grouped as Medium Soils and the clays grouped as Heavy Soils.

In a typical example with crops requiring 3 ML/ha/year, water-saving was as follows

• Improved surface irrigation adopting laser grading (14 ML/ha/year)
• Drainage reuse (16 ML/ha/year)
• Gravity earthen channel (36.5 ML/ha/year)
• Sprinkler upgrade, micro/ drip irrigation upgrade (no water-saving)

The water-savings calculator has now been used across 622 FWP projects, covering more than 37,000 ha with an expected 82,000 ML of the saved water. The improved irrigation systems provided irrigators with additional benefits of reduced labour requirement and ease of operating a more flexible irrigation system. Other irrigators have kept identical crops with the new upgraded system and experienced both a reduction in water use (ML/ha) and an increase in production (ton/ha and ton/ML).

The water-saving calculator was developed for a specific region using land use, crop type, irrigation activity in the form of drip or sprinkler, on-farm development and activity, improvement in the irrigation application tools, and so on. Thus, it is region-specific but can be developed for other regions as well. Besides GMID, the calculator has wider use in providing water use efficiency information for irrigators as they plan changes to their farm irrigation systems. It can be used as a decision support tool for irrigators to compare water use efficiency merits of technologies and practices they may consider adopting.

Northern Victoria Irrigation Renewal Project (NVIRP) delivered a large?scale irrigation modernization project in the Goulburn Murray Irrigation District (GMID), a region that is responsible for approximately 25% of the state’s agricultural production and contributes around AUD 1.45 billion per year in dairy and agricultural industries.

NVIRP provided an irrigation system that improved customer service levels, leveraged farm efficiencies, and increased productivity and profitability. Some of the features are presented below:

The 6,300 km irrigation channel network in operation for a century encountered inefficiencies due to record low rainfalls and long?term drought. NVIRP improvised the system to provide water at irrigator’s near?on?demand with higher and consistent flow rates facilitating increased opportunities and optimized water use efficiency and productivity. The project led to the installation of over 2,716 Rubicon gates and major control structures, as well as 117 km of channel lining with over 1,000 metered outlets decommissioned.

Full automation of the system reduced the carbon footprint of the scheme as the multiple daily manual adjustments of regulator gates and meters were no longer required. This significantly reduced the vehicle travel requirements too. Removing largely redundant assets reduced system water losses, increased operational efficiency, and reduced ongoing operations and maintenance costs – increasing the overall affordability of the scheme for current and future generations of irrigators.

Channels with high seepage and/or leakage rates were identified through a range of techniques such as soil maps, sandy soils, prior streams, aerial maps, leakage history (system operator), geophysics, field walks, and the operator’s knowledge. These were controlled with automated mechanisms.

Improved metering to customers allowed better water management and reduced losses occurring at customer outlets. Irrigation modernization project under the ten-year program reduced system water losses and generated savings which benefited both the environment and consumptive water users.

NVIRP works closely with partner agencies such as the Goulburn Broken Catchment Management Authority to support other water-savings projects such as on?farm efficiency programs which leverage off the benefits of a modernized distribution system. The lessons learned and implemented water-saving technology over the four years of the project were further used in catchment areas and irrigation regions throughout Australia and more broadly around the world. The Murray Darling Basin Authority has indicated that there is a need to improve the management practices. It is well established that infrastructural improvements targeted at savings will also enable new investments in agriculture and other industries across the basin.

Keywords: Irrigation mosaics; mosaics; irrigation impact; irrigation patches

Presented at: 63rd IEC Meeting 2012, Adelaide, Australia

Traditionally, the evaluation of surface irrigation water requirements for system improvement was based on data from a limited sample of furrows. Substantial spatial variability in soil infiltration characteristics and irrigation performance between furrows were completely ignored creating an erroneous evaluation of water requirements. Therefore, advanced simulation tools were developed for the evaluation and optimization of surface irrigation systems.

A model called SISCO solved the full hydrodynamic equation to simulate the hydraulics of multiple irrigation furrows and determined the optimum flow rate and time to give optimum performance for the whole field or a set of furrows. It had two components:

• IPARM - An inverse solution of the volume balance equation that allowed calculation of the time-dependent soil infiltration characteristic for a furrow or bay from measurements of the irrigation advance and runoff. The data obtained was used in an appropriate simulation model to simulate the irrigation and determine the best irrigation for the particular furrow or bay.
• IRRIPROB - A simulation tool to assist with managing furrow irrigation and the effect of soil spatial variability

An additional feature of this model was the graphical presentation of the interaction of the main performance measures and the user-specified objective function. SISCO, a new generation simulation model employed a solution of the full hydrodynamic equations. It was unique and unlike old simulation models, it could be applied to all surface irrigation methods, furrows, bays, level basins and drain back basins and performed the required calibration functions (inverse solution of the hydraulic resistance and infiltration parameters from the measured advance, recession, and runoff), simulation, and optimization in a single model. This calibration was also possible with limited data and accommodated user preferences in the selection of the optimum or preferred irrigation.

The model worked on an inverse solution from the measured irrigation and other data to give the infiltration and surface resistance parameters prevailing during the measured irrigation. It conducted ‘what if’ simulations to determine the preferred flow rate and irrigation time. It used a simulation of the measured irrigation as a means of calibrating and calculating the performance parameters for the measured irrigation. These improved evaluation tools can promote the uptake of the evaluation process among surface irrigators. The SISCO model could identify the surface resistance parameter as well as the infiltration characteristic and can use a wider range of measured data, for example, advance, recession, flow depths, and/or runoff. This improved the quality of the parameter estimates, the subsequent simulations, and hence the recommendations stemming from those simulations. It also allowed evaluations such as basin irrigation and irrigated bay pasture which were eliminated earlier. Even greater performance can be obtained if these systems can adapt to the different conditions prevailing at each irrigation.

Efficiency: With the new model, performance measurements across the main surface irrigated crops (cotton, grains, sugar, and pasture) showed application efficiencies ranging from 20 to 90% on average. Selection of more appropriate flow rates and irrigation times better suited to the specific soils achieved average efficiencies above 70%.

Expansion: Surface irrigation (furrow, bay, and basin) is a dominant irrigation method in Australia, used in 70% of the total area irrigated (1,000,000 ha and 4,000,000 ML). At the time, it was predicted that performance gains (water-savings) above 20% could easily be achieved in surface irrigation systems through the process of evaluation and practice change.

All around the world, including in Australia, communities are facing water-related issues such as reduced water availability, conflicting water uses, and water-related environmental problems. Water shortage and deteriorating water quality are contributing to a growing water crisis in many countries. Integrated water management in irrigated agricultural areas is the best strategy to optimize the use of available water resources in the face of reduced water availability, conflicting water uses, and other water-related environmental problems.

In the same light, a study was conducted on the Murrumbidgee River system to understand the viability of underground water banking as the new water storage and also a means of water-saving. This research investigated ‘water banking’ i.e., storing water in an aquifer (an underground layer of gravel or porous stone that yields water), by creating a 50 m or deeper underground water bank.

Water banking refers to delivering water earlier than it is used and storing it into groundwater so it is available to be pumped when required. In other words, redirecting surface water to subsurface water until it is utilized with zero evaporation losses. It is a unique water management technique with the ability to test and assess the impact of the allocation of limited water resources between agricultural production and the environment. Water banking is defined as the use, storage, and management of all surface and groundwater water resources available as one single resource (by using an aquifer as a storage system). Water banking can better manage biophysical demand, and enhance instream flows that are biologically and ecologically significant.

Benefits of Water bank included: i) adding flexibility in conjunctive water management, ii) enhancing in-stream flows that are biologically and ecologically significant, iii) reducing water use in over appropriate areas, iv) reducing the impact of water pumping on to stream, and v) facilitating the legal transfer and market exchange of various types of surfaces, groundwater and storage entitlements.

By combining system dynamics and multi-objective optimization with spatial and modeling data, an integrated hydrological-economic-environmental model was developed which helped land and water managers make decisions based on an evaluation of trade-offs between environmental, social, and economic factors. Farm, system, and catchment managers were able to collectively optimize water resource management and distribution at both the short-term tactical and long-term strategic levels.

This technique along with an aquifer downstream of Murrumbidgee resulted in reducing system losses estimated at 200 GL, ranging from 12 to 14% river loss and 12 to 20% channel loss in Coleambally and Murrumbidgee Irrigation areas. Deep groundwater pressures declined by 10 and 20 m over most of the area. With each year an improved scientific understanding of the hydrologic system was developed, however, the role and capabilities of the water bank leave scope for future research. Using the aquifer improved the efficiency of the water distribution system, as well as the natural seasonal flow of the river, by releasing water from the head dams during the winter or wet months and storing it for recovery during dry months, the high demand period (Figure 4.4). This in turn improved the health of the river by freeing more water to the environment and mimicking the river’s natural flow.

Water trading has been tested underwater banking to facilitate water movement between irrigation areas or water banks. Two artificial recharge methods were considered in this study with a changing crop mix option. The analysis indicated a clear trade-off between agricultural income and environmental performance to improve the seasonality of flows (Figure 4.5).

Water banking (storage and recovery water system underground scenario) by using infiltration and injection artificial recharge methods with changing crop mix improved agricultural income by 3 to 10% with potential water savings between 76 to 80 GL.

By using this technique, groundwater use could be reduced by 4 and 8%. The infiltration recharge method was more cost-effective than the injection where the river and aquifer system are connected. This integrated modeling framework is a useful policy and planning tool for catchment managers, water supply irrigation authorities, policy, decision-makers, and irrigators. It is a tool that has the potential to help stakeholders simulate and optimize the system, by evaluating and analyzing key decision variables. It can also provide a basis for examining the impact of physical changes to the system and for interactions with agricultural productivity, economics, and livelihoods to be predicted. For future expansion, the potential for artificial recharge sites using infiltration basins should be explored in detail to provide knowledge of evaporation-free, secure underground water dams. Additional economic water analysis needs to determine the water value under each use, such as environment, agriculture, and industry. Adding rainwater and water absorbed in soil moisture can add new dimensions to integrated catchment management with new degrees of freedom for water use to support both direct and indirect water needs. These could be facilitated by using a water banking approach to capture and manage different water resources with zero evaporation losses.