The Connections Project bases its channel modernisation solutions on a range of factors. Channel solutions are the actions we intend to take to upgrade, retain or decommission a channel
This page is also available as a fact sheet: Deciding on channel solutions
The GMW Connections Project prioritises channels for modernisation based on a range of factors, including:
When we talk about channel solutions, we are referring to the actions we intend to take to upgrade, retain or decommission a channel.
Solutions range from leaving a channel as is, to remediating channel with lining (clay or plastic) to replacing channel with GMW pipeline, to replacing channel with private infrastructure, such as a channel or pipeline.
Generally, decommissioning channels is the most complex and costly solution because we need to find alternative ways to connect landowners to their water supply in a different location. However, decommissioning is often the best way to achieve water savings for the project.
Solutions are explained in more detail below, from the most complex to the least.
The channel will be decommissioned and removed from the GMW system, and customers connected by privately-owned infrastructure (generally channel or pipeline). On-farm works will be carried out by the project to reconnect customers to the primary channel (previously referred to as the ‘backbone’).
Landowners with multiple meter outlets may choose to rationalise (remove) some outlets to reduce service fee costs.
This solution generally applies to channels where:
Example
Channel A has five connected landowners, each using a small amount of water in an average year. The channel is in poor condition and loses a lot of water to leakage.
Decommissioning the channel and reconnecting landowners to another nearby channel via private works may make sense in this case. The project saves water that would otherwise be lost, and the landowners benefit from a modernised connection.
At the same time, the landowners may have the option to reduce the number of meters they have to save money on service point fees.
The channel will be retained and upgraded to full automation (meter upgrades and regulators), and remodelled or remediated with plastic or clay lining. Some meters may not be upgraded if they have little to no historic use.
In some cases, channels may be replaced with a GMW-owned pipeline (where there are high water losses and low to medium flow rates).
Opportunities for landowners to reduce outlets are encouraged.
This solution generally applies to channels where:
Example:
Channel B has fifty connected landowners who are mostly large-scale, commercial irrigators.
A large section of the channel runs through lighter, sandy soils and it loses a lot of water to leakage and seepage in this area.
Due to the large number of landowners, the cost of decommissioning the channel would be very high. Instead, it makes sense to retain the channel and reduce water loss by plastic or clay lining.
If the entire length of the channel loses a lot of water and the flow rates are not too high, we may consider replacing the open channel with a GMW-owned pipeline.
At the same time, the landowners may have the option to reduce the number of meters they have to save money on service point fees.
The channel will be retained with part or full infrastructure modernisation (from meter upgrades only to regulators and meter upgrades). Some meters may not be upgraded if they have little to no historic use.
Opportunities for landowners to reduce outlets are encouraged.
This solution generally applies to channels:
Example:
Channel C has 20 connected landowners, many of who are dairy farmers using large amounts of water.
The channel is in a reasonable condition and only loses a small amount of water through leakage, seepage and evaporation. The largest water users are located at the end of the channel.
In this case, the best option may be to retain and fully automate the channel so that the large water users can benefit from the convenience of automation.
The channel will be retained with no infrastructure modernisation. Existing infrastructure, such as dethridge wheels, open outlets and stock and domestic connections will remain in place.
There may still be an opportunity for landowners to reduce outlets if the proposal meets value for money criteria.
This solution applies to channels where:
Example:
Channel D is about 450m in length in good clay with three connected customers using collectively less than 50ML/year.
In this example, the project team would need to assess whether the costs of modernisation (such as meter upgrades or installation of regulators) would provide enough water savings to justify those costs.
Factors influencing how we assess a channel
There are many ways that a channel can lose water, including seepage, leakage and outfalls.
Soil type and the condition of the channel may also influence water loss (for example, soils with a high proportion of clay tend to hold water better than sandy soils).
We calculate the channel loss rate as an average for the channel (generally between regulators).
We look at the average annual water use of all customers on the channel for the irrigation seasons 2011/2012 to 2013/2014. These seasons were 100% allocation years.
Soil type is a critical factor in assessing solutions for a channel. Heavy clay soils tend to retain water very well, with little leakage and seepage. In contrast, light, sandy soils allow water to seep through.
Other geographical factors, such as topography and vegetation, may also influence our assessment.
