Studies which have investigated the impacts of the transition from flood irrigation
to pressurised systems within the Murray-Darling Basin (Jackson et al. 2010, 2011)
have determined that whilst there was a reduction of between 10% and 66% in the
amount of water applied on farm, energy consumption increased by up to 163%. The
highest energy increases were seen in surface water systems, whereas energy
efficiencies could be achieved from groundwater application noting that ‘where
groundwater is used for irrigation, converting to pressurised micro-irrigation systems can decrease energy consumption if the conversion means that the operating
pressures and pumping volumes are reduced’ (Jackson et al. 2010). Energy savings
are possible when converting from gravity-fed systems to pressurised irrigation
methods in groundwater areas, as there is a reduction in the volume of water being
pumped (Jackson et al. 2010). However, Jackson et al. (2010) also note that excess
water applied from gravity-fed irrigation methods, which was not consumed by the
crop/plant and is subject to reuse and subject to geological conditions, will likely
drain to shallow aquifers or back to surface waters. The recharge effects of gravity
irrigation schemes are not taken into account, and there has not been any qualification of the consumed and nonconsumed fraction in the MDB.
Flood irrigation techniques are also an adopted strategy for managing groundwaters, particularly in areas of rising saline groundwaters. For example, in the late
1970s, QLD’s Burdekin region saw the finalisation of a surface water irrigation
channel scheme. With additional water supplies more readily available, the Lower
Burdekin saw a dramatic increase in surface water irrigation in the late 1980s which
led to increased groundwater recharge and rising groundwater tables with some parts
of the of the Lower Burdekin experiencing a rise in groundwater levels of up to 10 m
over the last 20 years. This has resulted in groundwater levels at less than 3 m below
the ground surface across approximately 15% of the irrigated area within the project
area. The situation is more acute in some areas where the groundwater table has been
measured at only 0.5 m below the surface (QLD Government 2017). High water
tables can result in water logging of the soil profile and can also mobilise salts from
the underlying bedrock which can increase salinity levels. These factors can reduce
the productivity of agricultural land and limit opportunities for future development.
High groundwater levels can also lead to higher rates of property and catchment
run-off flowing into downstream receiving environments.
7.9 Discussion
Whilst agricultural producers are intimately familiar with the interconnectedness
between energy, water and food production, policy and regulatory developments in
Australia continue to treat these three areas distinctly separate. This is highlighted by
the often deliberate separation of government departments and policy responsibilities. The lack of integration and coordination of water-energy-food policies paired
with the continuous restructuring of government departments and the frequent loss
of corporate knowledge (driven by regular election cycles) add further complexity to
7 Water Security: Challenges to the Irrigation Water-Energy Nexus in Australia
107
to pressurised systems within the Murray-Darling Basin (Jackson et al. 2010, 2011)
have determined that whilst there was a reduction of between 10% and 66% in the
amount of water applied on farm, energy consumption increased by up to 163%. The
highest energy increases were seen in surface water systems, whereas energy
efficiencies could be achieved from groundwater application noting that ‘where
groundwater is used for irrigation, converting to pressurised micro-irrigation systems can decrease energy consumption if the conversion means that the operating
pressures and pumping volumes are reduced’ (Jackson et al. 2010). Energy savings
are possible when converting from gravity-fed systems to pressurised irrigation
methods in groundwater areas, as there is a reduction in the volume of water being
pumped (Jackson et al. 2010). However, Jackson et al. (2010) also note that excess
water applied from gravity-fed irrigation methods, which was not consumed by the
crop/plant and is subject to reuse and subject to geological conditions, will likely
drain to shallow aquifers or back to surface waters. The recharge effects of gravity
irrigation schemes are not taken into account, and there has not been any qualification of the consumed and nonconsumed fraction in the MDB.
Flood irrigation techniques are also an adopted strategy for managing groundwaters, particularly in areas of rising saline groundwaters. For example, in the late
1970s, QLD’s Burdekin region saw the finalisation of a surface water irrigation
channel scheme. With additional water supplies more readily available, the Lower
Burdekin saw a dramatic increase in surface water irrigation in the late 1980s which
led to increased groundwater recharge and rising groundwater tables with some parts
of the of the Lower Burdekin experiencing a rise in groundwater levels of up to 10 m
over the last 20 years. This has resulted in groundwater levels at less than 3 m below
the ground surface across approximately 15% of the irrigated area within the project
area. The situation is more acute in some areas where the groundwater table has been
measured at only 0.5 m below the surface (QLD Government 2017). High water
tables can result in water logging of the soil profile and can also mobilise salts from
the underlying bedrock which can increase salinity levels. These factors can reduce
the productivity of agricultural land and limit opportunities for future development.
High groundwater levels can also lead to higher rates of property and catchment
run-off flowing into downstream receiving environments.
7.9 Discussion
Whilst agricultural producers are intimately familiar with the interconnectedness
between energy, water and food production, policy and regulatory developments in
Australia continue to treat these three areas distinctly separate. This is highlighted by
the often deliberate separation of government departments and policy responsibilities. The lack of integration and coordination of water-energy-food policies paired
with the continuous restructuring of government departments and the frequent loss
of corporate knowledge (driven by regular election cycles) add further complexity to
7 Water Security: Challenges to the Irrigation Water-Energy Nexus in Australia
107