Braided Rivers Programme Update

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May, 2020

Lincoln Agritech Ltd was awarded ~$8m funding from the New Zealand Ministry of Business, Innovation and Employment (MBIE) for the Braided Rivers research programme. This research will provide the first accurate information about how much water is lost from braided rivers into groundwater.

Six months into the five-year programme, the team has reached several significant milestones. Taking advantage of the first summer, Lincoln Agritech and the programme collaborators have worked hard to get initial field work underway.

 

  

Left: Collaborator Aarhus University Engineer, Tor Eiskjær, undertakes a Towed Transient Electromagnetic (tTem) survey in the Selwyn River bed.
Right: Successful data collection from the Wairau River using Aarhaus University’s GCM unit.


Earlier this year, Tor Eiskjær, an engineer from Aarhus University (Denmark) flew to New Zealand to work with the Lincoln Agritech team and help set up the Aarhus University’s Ground Conductivity Meter (GCM) and Towed Transient Electromagnetic (tTem) ground-based geophysics rigs. These rigs were used to collect data from the Selwyn and Wairau River sites. To collect the data, the tTEM and GCM units were towed on a sled behind a quad bike. These ground-based methods were used to collect large amounts of electromagnetic soundings. The rigs collected subsurface resistivity values (depths of up to 60 m), which enabled researchers to map the geology of the landscape in 3D and the groundwater saturation.

While COVID-19 has disrupted initial research plans by preventing the arrival of international collaborators, Lincoln Agritech has managed to overcome most of the problems the lockdown has caused. Eddie Banks (Flinders University) was able to virtually assist on field work sites by video calling for the initial installation and equipment testing. Recent PhD graduate, Antoine Diciacca, from Belgium was similarly affected and was unable to fly to New Zealand to start his post-doctoral research position. Fortunately, Antoine has started work remotely and will be helping process the collected rivers data and initial model development while in Europe.

During level 3 lockdown, the Lincoln Agritech team installed heat-pulse fibre optic and Electrical Resistivity Tomography (ERT) cables under the Selwyn River to measure the water flux and saturation levels - a world first.  Installing two sets of 100 m cables - under a river - was a challenge and a high risk operation for the drilling team. It took a seven attempts to successfully install the cables. Now underway, the system will soon start collecting valuable data. During this time, a number of vertical peizometers were also installed in the Selwyn River to complement the horizontally placed sensors.

The National Institute of Water and Atmospheric Research (NIWA) assisted in establishing the accompanying flow monitoring site and completed a number of the gaugings and bed surveys at both the Selwyn and Wairau Rivers sites. Research teams from the University of Canterbury - staff and students - have been actively assisting in the field work activities.

Over the next few months, the programme researchers and collaborators will be kept busy collecting raw data from field sites, and modelling and interpreting the data.

 

  

Left: Lincoln Agritech Environmental Research Group Manager Blair Miller (left) and Programme Leader Scott Wilson (right) help install the heat-pulse fibre optic and Electrical Resistivity Tomography (ERT) cables under the Selwyn River.
Right: Lincoln Agritech staff member, Aaron Dutton, checks a meteorological station station at the Selwyn River.

Braided Rivers Programme Update