Groundwater level around the Pike floodplain has been gradually increasing since the locks and weirs were installed, due to the combined effects of operating the river at a constant level with increased irrigation.
Elevated groundwater levels evaporate quickly, leaving behind salt, which does not evaporate. Without natural fluctuation in the river, the saline groundwater is not regularly drained into a lower river level and flushed out to sea. Instead, it is left to accumulate in the floodplains where the evaporation is the highest.
Trees of high ecological value such as River Red Gum, and native Black Box, have been impacted on the Pike floodplain over the last century due to the gradually increasing salinity present within the groundwater and root-zone soils.
Salinity Management Measures (SMM) is a groundwater management project designed to manage both in-stream salinity and floodplain ecological health through the extraction of highly saline groundwater.
Extracting groundwater in the optimum locations can have a two-fold benefit of reducing the build-up of salt in the groundwater, and also drawing freshwater from nearby surface water bodies through the banks of the creeks and rivers to help support high value vegetation.
Water Engineering Technologies installed approximately 26 automated submersible pumps into groundwater extraction bores, including all the mechanical and electrical control to operate the infrastructure, to intercept saline water as part of the Pike salt inception scheme.
Approximately two-thirds of the pump locations were chosen to create a barrier which will stop the regional saline groundwater from flowing down from the highland to the floodplain. Once the pressure from the highland groundwater diminished, the remaining third of the bores extend freshwater lenses on the floodplain in areas which are likely to support the long-term rejuvenation of native vegetation.
Groundwater extraction infrastructure has been previously installed in various locations along the River Murray, known as Salt interception scheme (SIS). The SMM project uses the same technology as the existing SIS, but focuses on the benefits to the ecology of the floodplain and river. At the completion of the project.