The Bookpurnong Floodplain Trials were developed under the Murray Darling Basin Commission’s Living Murray Program to quantify and document the relationships between water manipulation, root zone salinity and vegetation health using established and new water manipulation techniques.
Bookpurnong is located between Berri and Loxton in the Riverland. This floodplain location was selected for the trial largely due to the disposal infrastructure that was available as part of the Bookpurnong Salt Interception Scheme (saline groundwater disposal associated with the trial could utilise this existing disposal infrastructure).
Whilst these trials are of benefit to the Bookpurnong floodplain, their primary aim is to inform the development of a floodplain management plan and associated activities for the Chowilla Floodplain.
In order to achieve this goal, four separate trials have been established on the Bookpurnong floodplain to test different groundwater manipulation experiments to determine which actions may be transferable to Chowilla.
Surface Watering Trial
This trial will involve pumping water onto a section of floodplain. This will occur at different intervals over several years, with the aim of maintaining water levels for approximately 3 months each time to try and replicate a “natural” flooding event.
This trial will evaluate the response of red gums to artificial flooding, and determine:
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How red gums respond to flooding
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The impact of flooding on soil salinity
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The ecological responses to flooding
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The impact flooding has on river salinity
Groundwater Inducement Trial
The groundwater inducement trial involves pumping of saline groundwater out of the aquifer and disposing it utilising the Salt Interception Scheme infrastructure. It is anticipated that this process will then create a natural gradient by which the aquifer will be replenished by freshwater from the River Murray, and create a freshwater lens on top of the remaining saline groundwater.
This trial will help evaluate:
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If bank storage of freshwater influences the health of near river vegetation
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How freshwater lenses develop and decay
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What determines the thickness or shape of the freshwater lens
Surface Water Flooding At Higher Elevations on the Floodplain
This trial will involve pumping water into a number of small creeks bordered by both red gum and black box communities. Although similar to the other surface watering trial, this one is located at a higher elevation on the floodplain, incorporating vegetation that is naturally flooded less frequently.
This trial will help determine:
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If flooding of high level vegetation will put freshwater into the banks of floodplain creeks
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If flooding will improve tree health
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How far away from the creek banks tree health improves
Freshwater Injection Trial
The aim of the freshwater injection trial is to pump freshwater into a shallow saline aquifer via an injection bore to create a freshwater lens within the vegetation root zone. This will then enable us to determine if this technique will deliver freshwater to stressed and dying red gum and black box trees which are unable to receive freshwater via flooding.
This trial will determine:
Progress
Results from 2005 to 2008, shows that vegetation condition has improved at all sites where the different forms of intervention have taken place, with the exception of the groundwater lowering site, where no positive vegetation response has yet been detected.
AWE (2005). Bookpurnong Floodplain Pilot Project. Report prepared for the DWLBC (2.1Mb)
Jolly, I., Holland, K. and McEwan, K. (2005). Work Plan for Centre for Natural Resources Project 16. Response of the River Murray floodplain to flooding and groundwater management. CSIRO: Water for a Healthy Country National Research Flagship Canberra (1.3Mb)
I.D. Jolly, K.L. Holland, K.L. McEwan, M. White,V. Berens and L. Mensforth (2006). The Bookpurnong Experiment: Will Groundwater management and flooding improve the health of the floodplain vegetation. CSIRO and DWLBC 307kb)
DWLBC (2008). The Bookpurnong Pilot Project (MDBC Project: I31); Living Murray Environmental Works and Measures Program Progress Report 2007/08. Report for DWLBC.