Each development of a Bradfield Scheme is different from others, and others are different from each other. Each one has been approached with different goals in mind, the plans are different, and so also they cannot be criticized as too expensive, impractical, etc. without being clear about what plan is being referred to.

For instance, my plan is to define a staged development with a revenue center at each one. In that way, the scheme would be financed in stages, and the cost of each stage for aqueducts etc would only be local, from the low point of the previous scheme to the high point of the next. Each scheme would cost of the order of $1B dollars, far less than alternative estimates.

The blue line on the image shows five schemes connected by the gravitational flow of water, originating in the Upper Burdekin region, and defined as far as Blackall, but harvesting water and storing it at locations on the way. The half-open channel design allows both temporary storage and harvesting of flood flows with little disruption of natural flows of rivers and environmental harm while providing water for irrigation and mining purposes.

The scheme can be seen as a newly-created inland river that harvests flood flows from the upper catchments of rivers and creeks in transit, potentially terminating in the Murray-Darling Basin near St George. It accepts intermittent flows and provides reliable flood-proofing of a vast inland area.

So-far I have identified 5 potential revenue schemes fed by a single gravitational aqueduct with adjacent storages:

1. Upper Burdekin Irrigation Area
2. Galilee Basin mining pipeline
3. Muttaburra/Aramac Irrigation Area
4. Barcaldine/Longreach Irrigation Area
5. Blackall Irrigation Area

Beyond that, the route shown in yellow has not yet been defined, but it is clear that a pumped section would be needed to get from Blackall to above Tambo for a downhill run to Charleville to St George.

In addition to the agricultural and industrial benefits of large water diversion projects, there are many environmental benefits that could help to popularise these large water diversions by contributing to renewable energy, CO2 sequestering, countering land degradation, and enhancing habitat.

Sequestration of CO2 by vegetation if a feature of the great green wall in Africa, China’s reforestation projects, Israel, and Australia’s approach to meeting Kyoto Protocol commitments. A source of revenue for a Bradfield Scheme could be companies looking for carbon credits under “Removal Units” (RMUs) issued by the Kyoto Protocol country on the basis of land use, land use change and forestry activities under Article 3.3 or Article 3.4 of the Kyoto Protocol.

The Australian Kyoto target involves limiting emissions to 5 percent below 2000 levels by 2020, emissions of 524 million tonnes in 2020. It adopts a methodology where it calculates the cumulative level of emissions over eight years needed to hit the target.

Under the articles, forest management, cropland management, grazing land management, and re-vegetation, could help Australia meet its commitment to continue to reduce emissions. Under Kyoto Protocol rules, a tradable allowance called an assigned amount unit is issued for every tonne of emissions from Forest conversion in the 1990 base year. This treatment of Forest Conversion emissions is exactly the same as the treatment of emissions from sources in the industrial sectors.

Growing forestry in the flood flow section of the half-open channel would be similar to the Great Green Wall – an African-led movement to grow an 8,000km forest across the entire width of Africa that is already bringing life back to Africa’s degraded landscapes at an unprecedented scale, providing food security, jobs and a reason to stay for the millions who live along its path.

Flood irrigation is possible for deep watering of trees for example, in “flood basins”. For intermittent storages on average 100km long and 1 km wide, this would provide a flood irrigated area of 1000ha per unit or 10,000ha over the extent of the project. Forest trees can be completely inundated for short periods without damage, and control of the periods of inundation ensures that the vegetation is watered but not killed. While the forest absorbs water increasing the losses, it may be that these losses help to maintain the optimal operating conditions of the system. We will have established an Australian Green Wall.

The South–North Water Transfer Project, a multi-decade infrastructure mega-project in the People’s Republic of China, ultimately aims to channel 44,800 GL of fresh water annually from the Yangtze River in southern China to the more arid and industrialized north. Of the three channels, the Central Channel is gravitationally driven and similar in size and scope to the proposed Bradfield Scheme from North Queensland to the Murray-Darling Basin at St George.

The Central Route conveys 13,000 GL/year approximately 1,264 km from the Danjiangkou Reservoir on the Han river (a tributary of Yangtze River) at 170 m above the sea level to Beijing and Tianjin at around 50m (1:10,000 gradient). The canal route required the building of two tunnels under the Yellow River, to carry the canal’s flow. 

The Eastern Route follows the course of the Grand Canal, is 1,152 km long, and equipped with 23 pumping stations conveying 14,800 GL/year. The Western Route is planned to connect three tributaries of Yangtze River with huge dams and long tunnels under Tibetan Plateau and Western Yunnan Plateaus. This route is 500km long and designed for 3,800 GL/year.

Mao Zedong discussed the idea for a mass engineering project as an answer to China’s water problems as early as 1952. He reportedly said, “there’s plenty of water in the south, not much water in the north. If at all possible; borrowing some water would be good.” By 2014, more than $79 billion had been spent, making it one of the most expensive engineering projects in history.

Let’s examine the statistical characteristics of a long open half-channel, considering the property of an intelligent system – i.e. responding appropriately to intermittent disturbances to maintain a constant or homeostatic environment.

We have all experienced the intermittency of rainfall, lasting a day or so, and subsequent flooding. We also are familiar with the pleasant and even flow of rivers even though there might be occasional rainfall upstream.

In a long open half-channel we have the capacity to adjust the flow according to the intermittent inputs along its length, and through the storages and controlled outflows, achieve a constant and regulated outflow along its length (see upper image).

Thus, the reliability of water is ensured through intelligent responses to
the variability of the environment and this reliability increases with length of the aqueduct (see lower image).

An irrigation system drawn from a low storage flow, such as a river, increases the variability of the system. That is, when the weather is dry, farmers withdraw more water for thirsty crops thus decreasing the flow even more. When the weather is rainy, little water is withdrawn for crops are they also receive water from the rain, and so the flow is enhanced. In this way, the natural variability of flow in the stream is exaggerated.

It is the enhancement of variability of flows that is responsibile for the environmental deterioration of our rivers and streams in the Murray-Darling Basin and elsewhere. That is, it is an example of systems being pushed beyond their natural variability, reaching breaking points from which they cannot recover easily. Sustainability, on the other hand, requires maintaining the system within its natural bounds.

The presence of a storage dam or weir increases the availability of water during the dry season, but it does not address the central problem of exaggeration of rainfall variability. Consequently, during a dry spell, the water levels in a local dam fall rapidly as demand increases. During a wet spell when water is not tapped for irrigation, the dam over-tops and the excess spills over the floodway. Thus variation is exaggerated. This is an inefficient usage of water resources.

Thus it seems that a fully established open half-channel aqueduct has the capacity to provide reliable water supplies along its length. Due to the capturing of inflows along its length, it can provide a similar average flow at the end as at the beginning (see image), e.g. 2000GL pa in and 2000GL pa out. By contrast due to losses, the volume of flows diminishes with length. By contrast with a pipeline, a gravitationally driven flow requires no energy for pumping, and delivers water long distances cheaply, reliability and intelligently.

The breakthrough system developed by Leon Ashby for capturing and transferring flood flows in a Bradfield Scheme has a number of advantages over pipelines. The slide above is taken from Leon’s presentation and lists 3 benefits over a pipeline system.

The profile of the system can be described as an ‘open half-channel’ profile. Whereas a typical profile of a river has a single low flow channel and a high flow channel defined by banks at a distance from both sides of the low flow channel. The aqueduct is half of the natural profile as the constructed levee bounds the conveyed water on the downhill side. Up-slope there is a low flow channel and flood flow space as shown in the inserted image.

The system is also more correctly described as a series of connected storages, contained by a levee bank following a contour for more than 100km, before being connected to the next with a short 10m section containing a hydropower unit, and traversing road or rail infrastructure (see insert).

The three advantages of this system over a pipeline for conveying water are:

1. Due to friction, pipelines permit water to be gravitationally transferred in a fall of only 1m per 1-1.5km or 1:150. The open aqueduct described may convey water up to 100km per 10m fall, or 1:10,000. This allows the open-channel to transfer water over very long distances.
2. The open-channel collects water along its length, greatly increasing the catchment area over a closed pipeline. Collecting intermittent falls along the length of the levee bank thus increases the mean volume of flow and decreases the flow variability over the length of the channel.
3. The aqueduct sited along a contour serves a dual purpose as a reservoir, storing up to 1000GL per 100km of water depending on topography and levee height. Pipes inserted through the base of the levee enables the gravitation irrigation of a series of small irrigation schemes down-slope of the levee.

The images shows the increase in catchment area due to the use of an open half-channel between the Burdekin River and Lake Buchanan (red circle) and another potential route for an open half-channel between the Walsh River and Hughenden (purple).

We see that the open half-channel aqueduct can be likened to an artificial river, constructed to divert water across the slope in the desired direction, instead of taking the natural direct downhill path. A lossless artificial river will have the flow characteristics of a natural river, increasing in flow volume and decreasing in flow variability from start to end.

However, the flow would be efficaciously extracted at points along the length so that the mean and variability of flow remains within the optimal operating conditions of the open half-channel design.

The groundwater at Rome was notoriously unpalatable, and water from the Tiber was unsafe to drink. Aqua Appia, Rome’s first aqueduct (312 BC) was commissioned by the censor Appius Claudius Caecus as a publicly funded major project.

By the late 3rd century AD, Roman aqueducts supplied Rome with water by a combined conduit length of 800 kilometres, of which only 47 km were carried above ground level by the familiar masonry supports. They supplied around 1 million cubic metres (ie 10,000 GigaLitres) a day; enough to supply a modern city of population of 10 million. The longest was the Constantinople (Turkey) around 500 km. Gradients for Roman Aqueduct were 1:4800 and typically around a metre wide and deep with a flow rate estimated to be about 35,000 m3 /day (or 350GL/day) depending on the season .

With the fall of the Roman Empire, some aqueducts were deliberately cut by enemies but many more fell into disuse through lack of organized maintenance. Their failure had an impact on the population of cities; Rome declined from its high of over 1 million people in the Imperial era to as low as 30,000 in the medieval era. 

The New Bradfield Scheme is very similar length, capacity and function to the Roman aqueducts being totally gravity fed. With an estimated fall of 1:5000, 100m from Hell’s Gate over a distance of 500 km to the Lakes Buchanan and Galilee Storages, a wider, lined channel could easily provide the 20,000GL per annum. Harvesting the flow from streams along would be possible, or desirable helping to reduce flooding lower in the catchments and leading to potentially greater harvest rates. Spillways would dump the excess if the water level got too high.

As Sir Humphrey Appleby said about public projects (‘Yes, Minister’): “Anything is possible for government, so long as it isn’t the first time.” The Roman Empire has done a similar-sized gravity-fed aqueduct system 2000 years ago.